sha3.h: doxygen fixes, improve documentation, shrink list of algorithms in header block

1 files changed, 566 insertions, 161 deletions

diff --git a/sha3.h b/sha3.h
index ed59bed..6dc7546 100644
--- a/sha3.h
+++ b/sha3.h
@@ -1,4 +1,5 @@
 /**
+ * @file sha3.h
  * sha3
  * https://pablotron.org/sha3
  *
@@ -7,24 +8,13 @@
  *
  * C11 implementations of the following SHA-3 algorithms:
  *
- * - SHA3-224
- * - SHA3-256
- * - SHA3-384
- * - SHA3-512
- * - HMAC-SHA3-224
- * - HMAC-SHA3-256
- * - HMAC-SHA3-384
- * - HMAC-SHA3-512
- * - SHAKE128 and SHAKE128-XOF
- * - SHAKE256 and SHAKE256-XOF
- * - cSHAKE128 and cSHAKE128-XOF
- * - cSHAKE256 and cSHAKE256-XOF
- * - KMAC128 and KMAC128-XOF
- * - KMAC256 and KMAC256-XOF
- * - TupleHash128 and TupleHash128-XOF
- * - TupleHash256 and TupleHash256-XOF
- * - ParallelHash128 and ParallelHash128-XOF
- * - ParallelHash256 and ParallelHash256-XOF
+ * - SHA3-224, SHA3-256, SHA3-384, and SHA3-512
+ * - HMAC-SHA3-224, HMAC-SHA3-256, HMAC-SHA3-384, and HMAC-SHA3-512
+ * - SHAKE128, SHAKE128-XOF, SHAKE256, and SHAKE256-XOF
+ * - cSHAKE128, cSHAKE128-XOF, cSHAKE256, and cSHAKE256-XOF
+ * - KMAC128, KMAC128-XOF, KMAC256, and KMAC256-XOF
+ * - TupleHash128, TupleHash128-XOF, TupleHash256, and TupleHash256-XOF
+ * - ParallelHash128, ParallelHash128-XOF, ParallelHash256, and ParallelHash256-XOF
  * - TurboSHAKE128 and TurboSHAKE256
  * - KangarooTwelve
  */
@@ -39,27 +29,64 @@ extern "C" {
 #include <stddef.h> // size_t
 #include <stdint.h> // uint8_t, uint64_t
 
-// Internal SHA-3 state.
+/**
+ * @defgroup sha3 SHA-3
+ *
+ * @brief [Cryptographic hash functions][hash] with fixed-length output,
+ * as defined in section 6.1 of [FIPS 202][].
+ *
+ * [FIPS 202]: https://csrc.nist.gov/pubs/fips/202/final
+ *   "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions"
+ * [hash]: https://en.wikipedia.org/wiki/Cryptographic_hash_function
+ *   "Cryptographic hash function"
+ */
+
+/**
+ * @defgroup shake SHAKE
+ *
+ * @brief [eXtendable Output Functions (XOF)][xof] with both
+ * fixed-length and arbitrary length output, as defined in section 6.2
+ * of [FIPS 202][].
+ *
+ * [FIPS 202]: https://csrc.nist.gov/pubs/fips/202/final
+ *   "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions"
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ */
+
+/**
+ * @brief Internal SHA-3 state (all members are private).
+ * @ingroup sha3
+ */
 typedef union {
-  uint8_t u8[200];
-  uint64_t u64[25];
+  uint8_t u8[200]; /**< 8-bit unsigned integers. */
+  uint64_t u64[25]; /**< 64-bit unsigned integers. */
 } sha3_state_t;
 
-// Iterative SHA-3 context (all members are private).
+/**
+ * @brief Iterative SHA-3 context (all members are private).
+ * @ingroup sha3
+ */
 typedef struct {
-  size_t num_bytes; // number of bytes absorbed
-  sha3_state_t a; // internal state
-  _Bool finalized; // mode (absorbing or finalized)
+  size_t num_bytes; /**< number of bytes absorbed */
+  sha3_state_t a; /**< internal state */
+  _Bool finalized; /**< mode (absorbing or finalized) */
 } sha3_t;
 
-// Iterative XOF context (all members are private).
+/**
+ * @brief Iterative XOF context (all members are private).
+ * @ingroup shake
+ */
 typedef struct {
-  size_t num_bytes; // number of bytes absorbed
-  sha3_state_t a; // internal state
-  _Bool squeezing; // mode (absorbing or squeezing)
+  size_t num_bytes; /**< number of bytes absorbed */
+  sha3_state_t a; /**< internal state */
+  _Bool squeezing; /**< mode (absorbing or squeezing) */
 } sha3_xof_t;
 
-/**
+/*!
+ * @brief Calculate SHA3-224 hash of input data.
+ * @ingroup sha3
+ *
  * Hash `len` bytes of input data from source buffer `src` with SHA3-224
  * (FIPS 202, section 6.1), then write 28 bytes of output to destination
  * buffer `dst`.
@@ -71,18 +98,22 @@ typedef struct {
 void sha3_224(const uint8_t *src, size_t len, uint8_t dst[static 28]);
 
 /**
- * Initialize SHA3-224 hash context.
+ * @brief Initialize SHA3-224 hash context.
+ * @ingroup sha3
  *
  * @param[out] hash SHA3-224 hash context.
  */
 void sha3_224_init(sha3_t *hash);
 
 /**
+ * @brief Initialize SHA3-224 hash context.
+ * @ingroup sha3
+ *
  * Absorb `len` bytes of input data from source buffer `src` into
  * SHA3-224 hash context `hash`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] hash SHA3-224 hash context.
+ * @param[in,out] hash SHA3-224 hash context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -91,15 +122,19 @@ void sha3_224_init(sha3_t *hash);
 _Bool sha3_224_absorb(sha3_t *hash, const uint8_t *src, const size_t len);
 
 /**
- * Finalize SHA3-224 hash context and write 28 bytes of output to
+ * @brief Finalize SHA3-224 hash context and write 28 bytes of output to
  * destination buffer `dst`.
+ * @ingroup sha3
  *
- * @param[in/out] hash SHA3-224 hash context.
+ * @param[in,out] hash SHA3-224 hash context.
  * @param[out] dst Destination buffer.  Must be at least 28 bytes in length.
  */
 void sha3_224_final(sha3_t *hash, uint8_t dst[28]);
 
 /**
+ * @brief Calculate SHA3-256 hash of input data.
+ * @ingroup sha3
+ *
  * Hash `len` bytes of input data from source buffer `src` with SHA3-256
  * (FIPS 202, section 6.1), then write 32 bytes of output to destination
  * buffer `dst`.
@@ -111,18 +146,22 @@ void sha3_224_final(sha3_t *hash, uint8_t dst[28]);
 void sha3_256(const uint8_t *src, size_t len, uint8_t dst[static 32]);
 
 /**
- * Initialize SHA3-256 hash context.
+ * @brief Initialize SHA3-256 hash context.
+ * @ingroup sha3
  *
  * @param[out] hash SHA3-256 hash context.
  */
 void sha3_256_init(sha3_t *hash);
 
 /**
+ * @brief Absorb input data into SHA3-256 hash context.
+ * @ingroup sha3
+ *
  * Absorb `len` bytes of input data from source buffer `src` into
  * SHA3-256 hash context `hash`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] hash SHA3-256 hash context.
+ * @param[in,out] hash SHA3-256 hash context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -131,15 +170,19 @@ void sha3_256_init(sha3_t *hash);
 _Bool sha3_256_absorb(sha3_t *hash, const uint8_t *src, const size_t len);
 
 /**
- * Finalize SHA3-256 hash context and write 32 bytes of output to
+ * @brief Finalize SHA3-256 hash context and write 32 bytes of output to
  * destination buffer `dst`.
+ * @ingroup sha3
  *
- * @param[in/out] hash SHA3-256 hash context.
+ * @param[in,out] hash SHA3-256 hash context.
  * @param[out] dst Destination buffer.  Must be at least 32 bytes in length.
  */
 void sha3_256_final(sha3_t *hash, uint8_t dst[32]);
 
 /**
+ * @brief Calculate SHA3-384 hash of input data.
+ * @ingroup sha3
+ *
  * Hash `len` bytes of input data from source buffer `src` with SHA3-384
  * (FIPS 202, section 6.1), then write 48 bytes of output to destination
  * buffer `dst`.
@@ -151,18 +194,22 @@ void sha3_256_final(sha3_t *hash, uint8_t dst[32]);
 void sha3_384(const uint8_t *src, size_t len, uint8_t dst[static 48]);
 
 /**
- * Initialize SHA3-384 hash context.
+ * @brief Initialize SHA3-384 hash context.
+ * @ingroup sha3
  *
  * @param[out] hash SHA3-384 hash context.
  */
 void sha3_384_init(sha3_t *hash);
 
 /**
+ * @brief Absorb input data into SHA3-384 hash context.
+ * @ingroup sha3
+ *
  * Absorb `len` bytes of input data from source buffer `src` into
  * SHA3-384 hash context `hash`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] hash SHA3-384 hash context.
+ * @param[in,out] hash SHA3-384 hash context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -171,15 +218,19 @@ void sha3_384_init(sha3_t *hash);
 _Bool sha3_384_absorb(sha3_t *hash, const uint8_t *src, const size_t len);
 
 /**
- * Finalize SHA3-384 hash context and write 48 bytes of output to
+ * @brief Finalize SHA3-384 hash context and write 48 bytes of output to
  * destination buffer `dst`.
+ * @ingroup sha3
  *
- * @param[in/out] hash SHA3-384 hash context.
+ * @param[in,out] hash SHA3-384 hash context.
  * @param[out] dst Destination buffer.  Must be at least 48 bytes in length.
  */
 void sha3_384_final(sha3_t *hash, uint8_t dst[48]);
 
 /**
+ * @brief Calculate SHA3-512 hash of input data.
+ * @ingroup sha3
+ *
  * Hash `len` bytes of input data from source buffer `src` with SHA3-512
  * (FIPS 202, section 6.1), then write 64 bytes of output to destination
  * buffer `dst`.
@@ -191,18 +242,22 @@ void sha3_384_final(sha3_t *hash, uint8_t dst[48]);
 void sha3_512(const uint8_t *src, size_t len, uint8_t dst[static 64]);
 
 /**
- * Initialize SHA3-512 hash context.
+ * @brief Initialize SHA3-512 hash context.
+ * @ingroup sha3
  *
  * @param[out] hash SHA3-512 hash context.
  */
 void sha3_512_init(sha3_t *hash);
 
 /**
+ * @brief Absorb input data into SHA3-512 hash context.
+ * @ingroup sha3
+ *
  * Absorb `len` bytes of input data from source buffer `src` into
  * SHA3-512 hash context `hash`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] hash SHA3-512 hash context.
+ * @param[in,out] hash SHA3-512 hash context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -211,15 +266,38 @@ void sha3_512_init(sha3_t *hash);
 _Bool sha3_512_absorb(sha3_t *hash, const uint8_t *src, const size_t len);
 
 /**
- * Finalize SHA3-512 hash context and write 64 bytes of output to
+ * @brief Finalize SHA3-512 hash context and write 64 bytes of output to
  * destination buffer `dst`.
+ * @ingroup sha3
  *
- * @param[in/out] hash SHA3-512 hash context.
+ * @param[in,out] hash SHA3-512 hash context.
  * @param[out] dst Destination buffer.  Must be at least 64 bytes in length.
  */
 void sha3_512_final(sha3_t *hash, uint8_t dst[64]);
 
 /**
+ * @defgroup hmac HMAC
+ *
+ * @brief [HMAC][hmac] instantiated with [SHA-3][] hash functions, as
+ * specified in section 7 of [FIPS 202][], [RFC 2104][], and
+ * [FIPS 198-1][].
+ *
+ * [FIPS 202]: https://csrc.nist.gov/pubs/fips/202/final
+ *   "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions"
+ * [SHA-3]: https://en.wikipedia.org/wiki/SHA-3
+ *   "Secure Hash Algorithm 3"
+ * [hmac]: https://en.wikipedia.org/wiki/HMAC
+ *   "Keyed Hash Message Authentication Code (HMAC)"
+ * [rfc 2104]: https://datatracker.ietf.org/doc/html/rfc2104
+ *   "RFC 2104: HMAC: Keyed-Hashing for Message Authentication"
+ * [FIPS 198-1]: https://csrc.nist.gov/pubs/fips/198-1/final
+ *   "The Keyed-Hash Message Authentication Code (HMAC)"
+ */
+
+/**
+ * @brief Calculat HMAC-SHA3-224 of given key and data.
+ * @ingroup hmac
+ *
  * Calculate HMAC-SHA3-224 (FIPS 202, Section 7) of key in buffer `k` of
  * length `k_len` and input message in buffer `m` of length `m_len`
  * bytes and write 28 bytes of output to destination buffer `dst`.
@@ -233,6 +311,9 @@ void sha3_512_final(sha3_t *hash, uint8_t dst[64]);
 void hmac_sha3_224(const uint8_t *k, const size_t k_len, const uint8_t *m, const size_t m_len, uint8_t dst[28]);
 
 /**
+ * @brief Calculate HMAC-SHA3-256 given key and data.
+ * @ingroup hmac
+ *
  * Calculate HMAC-SHA3-256 (FIPS 202, Section 7) of key in buffer `k` of
  * length `k_len` and input message in buffer `m` of length `m_len`
  * bytes and write 32 bytes of output to destination buffer `dst`.
@@ -246,6 +327,9 @@ void hmac_sha3_224(const uint8_t *k, const size_t k_len, const uint8_t *m, const
 void hmac_sha3_256(const uint8_t *k, const size_t k_len, const uint8_t *m, const size_t m_len, uint8_t dst[32]);
 
 /**
+ * Calculate HMAC-SHA3-384 of given key and data.
+ * @ingroup hmac
+ *
  * Calculate HMAC-SHA3-384 (FIPS 202, Section 7) of key in buffer `k` of
  * length `k_len` and input message in buffer `m` of length `m_len`
  * bytes and write 48 bytes of output to destination buffer `dst`.
@@ -259,6 +343,9 @@ void hmac_sha3_256(const uint8_t *k, const size_t k_len, const uint8_t *m, const
 void hmac_sha3_384(const uint8_t *k, const size_t k_len, const uint8_t *m, const size_t m_len, uint8_t dst[48]);
 
 /**
+ * @brief Calculate HMAC-SHA3-512 of given key and data.
+ * @ingroup hmac
+ *
  * Calculate HMAC-SHA3-512 (FIPS 202, Section 7) of key in buffer `k` of
  * length `k_len` and input message in buffer `m` of length `m_len`
  * bytes and write 64 bytes of output to destination buffer `dst`.
@@ -271,14 +358,19 @@ void hmac_sha3_384(const uint8_t *k, const size_t k_len, const uint8_t *m, const
  */
 void hmac_sha3_512(const uint8_t *k, const size_t k_len, const uint8_t *m, const size_t m_len, uint8_t dst[64]);
 
-// HMAC-SHA3 (Hash-based Message Authentication Code) context.
+/**
+ * @brief HMAC-SHA3 (Hash-based Message Authentication Code) context.
+ * @ingroup hmac
+ */
 typedef struct {
-  sha3_t inner, outer;
-  _Bool finalized;
+  sha3_t inner, /**< Inner hash context (private) */
+         outer; /**< Outer hash context (private) */
+  _Bool finalized; /**< Is this context finalized (private) */
 } hmac_sha3_t;
 
 /**
- * Initialize HMAC-SHA3-224 (FIPS 202, Section 7) context.
+ * @brief Initialize HMAC-SHA3-224 (FIPS 202, Section 7) context.
+ * @ingroup hmac
  *
  * @param[out] hmac HMAC-SHA3-224 context.
  * @param[in] k Key.
@@ -287,11 +379,14 @@ typedef struct {
 void hmac_sha3_224_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len);
 
 /**
+ * @brief Absorb data into HMAC-SHA3-224 context.
+ * @ingroup hmac
+ *
  * Absorb input data in `src` of length `len` bytes into HMAC-SHA3-224
  * context `hmac`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] hmac HMAC-SHA3-224 context.
+ * @param[in,out] hmac HMAC-SHA3-224 context.
  * @param[in] src Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -300,16 +395,18 @@ void hmac_sha3_224_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len)
 _Bool hmac_sha3_224_absorb(hmac_sha3_t *hmac, const uint8_t *src, const size_t len);
 
 /**
- * Finalize HMAC-SHA3-224 hash context and write 28 bytes of output to
- * destination buffer `dst`.
+ * @brief Finalize HMAC-SHA3-224 hash context and write 28 bytes of
+ * output to destination buffer `dst`.
+ * @ingroup hmac
  *
- * @param[in/out] hmac HMAC-SHA3-224 hash context.
+ * @param[in,out] hmac HMAC-SHA3-224 hash context.
  * @param[out] dst Destination buffer.  Must be at least 28 bytes in length.
  */
 void hmac_sha3_224_final(hmac_sha3_t *hmac, uint8_t dst[28]);
 
 /**
- * Initialize HMAC-SHA3-256 (FIPS 202, Section 7) context.
+ * @brief Initialize HMAC-SHA3-256 (FIPS 202, Section 7) context.
+ * @ingroup hmac
  *
  * @param[out] hmac HMAC-SHA3-256 context.
  * @param[in] k Key.
@@ -318,11 +415,14 @@ void hmac_sha3_224_final(hmac_sha3_t *hmac, uint8_t dst[28]);
 void hmac_sha3_256_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len);
 
 /**
+ * @brief Absorb data into HMAC-SHA3-256 context.
+ * @ingroup hmac
+ *
  * Absorb input data in `src` of length `len` bytes into HMAC-SHA3-256
  * context `hmac`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] hmac HMAC-SHA3-256 context.
+ * @param[in,out] hmac HMAC-SHA3-256 context.
  * @param[in] src Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -331,16 +431,18 @@ void hmac_sha3_256_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len)
 _Bool hmac_sha3_256_absorb(hmac_sha3_t *hmac, const uint8_t *src, const size_t len);
 
 /**
- * Finalize HMAC-SHA3-256 hash context and write 32 bytes of output to
- * destination buffer `dst`.
+ * @brief Finalize HMAC-SHA3-256 hash context and write 32 bytes of
+ * output to destination buffer `dst`.
+ * @ingroup hmac
  *
- * @param[in/out] hmac HMAC-SHA3-256 hash context.
+ * @param[in,out] hmac HMAC-SHA3-256 hash context.
  * @param[out] dst Destination buffer.  Must be at least 32 bytes in length.
  */
 void hmac_sha3_256_final(hmac_sha3_t *hmac, uint8_t dst[32]);
 
 /**
- * Initialize HMAC-SHA3-384 (FIPS 202, Section 7) context.
+ * @brief Initialize HMAC-SHA3-384 (FIPS 202, Section 7) context.
+ * @ingroup hmac
  *
  * @param[out] hmac HMAC-SHA3-384 context.
  * @param[in] k Key.
@@ -349,11 +451,14 @@ void hmac_sha3_256_final(hmac_sha3_t *hmac, uint8_t dst[32]);
 void hmac_sha3_384_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len);
 
 /**
+ * @brief Absorb data into HMAC-SHA3-384 context.
+ * @ingroup hmac
+ *
  * Absorb input data in `src` of length `len` bytes into HMAC-SHA3-384
  * context `hmac`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] hmac HMAC-SHA3-384 context.
+ * @param[in,out] hmac HMAC-SHA3-384 context.
  * @param[in] src Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -362,16 +467,18 @@ void hmac_sha3_384_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len)
 _Bool hmac_sha3_384_absorb(hmac_sha3_t *hmac, const uint8_t *src, const size_t len);
 
 /**
- * Finalize HMAC-SHA3-384 hash context and write 48 bytes of output to
- * destination buffer `dst`.
+ * @brief Finalize HMAC-SHA3-384 hash context and write 48 bytes of
+ * output to destination buffer `dst`.
+ * @ingroup hmac
  *
- * @param[in/out] hmac HMAC-SHA3-384 hash context.
+ * @param[in,out] hmac HMAC-SHA3-384 hash context.
  * @param[out] dst Destination buffer.  Must be at least 48 bytes in length.
  */
 void hmac_sha3_384_final(hmac_sha3_t *hmac, uint8_t dst[48]);
 
 /**
- * Initialize HMAC-SHA3-512 (FIPS 202, Section 7) context.
+ * @brief Initialize HMAC-SHA3-512 (FIPS 202, Section 7) context.
+ * @ingroup hmac
  *
  * @param[out] hmac HMAC-SHA3-512 context.
  * @param[in] k Key.
@@ -380,11 +487,14 @@ void hmac_sha3_384_final(hmac_sha3_t *hmac, uint8_t dst[48]);
 void hmac_sha3_512_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len);
 
 /**
+ * @brief Absorb data into HMAC-SHA3-512 context.
+ * @ingroup hmac
+ *
  * Absorb input data in `src` of length `len` bytes into HMAC-SHA3-512
  * context `hmac`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] hmac HMAC-SHA3-512 context.
+ * @param[in,out] hmac HMAC-SHA3-512 context.
  * @param[in] src Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -393,15 +503,33 @@ void hmac_sha3_512_init(hmac_sha3_t *hmac, const uint8_t *k, const size_t k_len)
 _Bool hmac_sha3_512_absorb(hmac_sha3_t *hmac, const uint8_t *src, const size_t len);
 
 /**
- * Finalize HMAC-SHA3-512 hash context and write 64 bytes of output to
- * destination buffer `dst`.
+ * @brief Finalize HMAC-SHA3-512 hash context and write 64 bytes of
+ * output to destination buffer `dst`.
+ * @ingroup hmac
  *
- * @param[in/out] hmac HMAC-SHA3-512 hash context.
+ * @param[in,out] hmac HMAC-SHA3-512 hash context.
  * @param[out] dst Destination buffer.  Must be at least 64 bytes in length.
  */
 void hmac_sha3_512_final(hmac_sha3_t *hmac, uint8_t dst[64]);
 
 /**
+ * @defgroup shake SHAKE
+ *
+ * @brief [SHA-3][] [XOFs][xof] with both fixed-length output and
+ * arbitrary-length output, as defined in section 6.2 of [FIPS 202][].
+ *
+ * [FIPS 202]: https://csrc.nist.gov/pubs/fips/202/final
+ *   "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions"
+ * [SHA-3]: https://en.wikipedia.org/wiki/SHA-3
+ *   "Secure Hash Algorithm 3"
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ */
+
+/**
+ * @brief Hash data with SHAKE128.
+ * @ingroup shake
+ *
  * Hash input message in buffer `m` of length `m_len` bytes with
  * SHAKE128 (FIPS 202, section 6.2) and write 16 bytes of output to
  * destination buffer `dst`.
@@ -413,6 +541,9 @@ void hmac_sha3_512_final(hmac_sha3_t *hmac, uint8_t dst[64]);
 void shake128(const uint8_t *m, size_t m_len, uint8_t dst[static 16]);
 
 /**
+ * @brief Hash data with SHAKE256.
+ * @ingroup shake
+ *
  * Hash input message in buffer `m` of length `m_len` bytes with
  * SHAKE256 (FIPS 202, section 6.2) and write the result to output
  * buffer `dst`.
@@ -424,18 +555,22 @@ void shake128(const uint8_t *m, size_t m_len, uint8_t dst[static 16]);
 void shake256(const uint8_t *m, size_t m_len, uint8_t dst[static 32]);
 
 /**
- * Initialize SHAKE128 extendable-output function (XOF) context.
+ * @brief Initialize SHAKE128 extendable-output function (XOF) context.
+ * @ingroup shake
  *
  * @param[out] xof SHAKE128 XOF context.
  */
 void shake128_xof_init(sha3_xof_t * const xof);
 
 /**
+ * @brief Absorb data into SHAKE128 XOF context.
+ * @ingroup shake
+ *
  * Absorb input data in `m` of length `len` bytes into SHAKE128 XOF
  * context `xof`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] xof SHAKE128 XOF context.
+ * @param[in,out] xof SHAKE128 XOF context.
  * @param[in] m Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -444,17 +579,23 @@ void shake128_xof_init(sha3_xof_t * const xof);
 _Bool shake128_xof_absorb(sha3_xof_t *xof, const uint8_t *m, const size_t len);
 
 /**
+ * @brief Squeeze bytes from SHAKE128 XOF context.
+ * @ingroup shake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * SHAKE128 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
  *
- * @param[in/out] xof SHAKE128 XOF context.
+ * @param[in,out] xof SHAKE128 XOF context.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void shake128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into SHAKE128 XOF, then squeeze bytes out.
+ * @ingroup shake
+ *
  * Absorb data in buffer `src` of length `src_len` bytes into SHAKE128
  * XOF context, then squeeze `dst_len` bytes of output into destination
  * buffer `dst`.
@@ -462,23 +603,27 @@ void shake128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t dst_len);
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void shake128_xof_once(const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
- * Initialize SHAKE256 extendable-output function (XOF) context.
+ * @brief Initialize SHAKE256 extendable-output function (XOF) context.
+ * @ingroup shake
  *
  * @param[out] xof SHAKE256 XOF context.
  */
 void shake256_xof_init(sha3_xof_t *xof);
 
 /**
+ * @brief Absorb data into SHAKE256 XOF context.
+ * @ingroup shake
+ *
  * Absorb input data in `m` of length `len` bytes into SHAKE256 XOF
  * context `xof`.  Can be called iteratively to absorb input data in
  * chunks.
  *
- * @param[in/out] xof SHAKE256 XOF context.
+ * @param[in,out] xof SHAKE256 XOF context.
  * @param[in] m Input data.
  * @param[in] len Input data length, in bytes.
  *
@@ -487,17 +632,23 @@ void shake256_xof_init(sha3_xof_t *xof);
 _Bool shake256_xof_absorb(sha3_xof_t *xof, const uint8_t *m, const size_t len);
 
 /**
+ * @brief Squeeze bytes from SHAKE256 XOF context.
+ * @ingroup shake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * SHAKE256 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
  *
- * @param[in/out] xof SHAKE256 XOF context.
+ * @param[in,out] xof SHAKE256 XOF context.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void shake256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into SHAKE256 XOF, then squeeze bytes out.
+ * @ingroup shake
+ *
  * Absorb data in buffer `src` of length `src_len` bytes into SHAKE256
  * XOF context, then squeeze `dst_len` bytes of output into destination
  * buffer `dst`.
@@ -505,19 +656,37 @@ void shake256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t dst_len);
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void shake256_xof_once(const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
-// cSHAKE parameters.
+/**
+ * @defgroup cshake cSHAKE
+ *
+ * @brief Fixed-length and [XOF][] variants of the customizable-SHAKE
+ * primitive, as defined in section 3 of [SP 800-185][800-185].
+ *
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ * [800-185]: https://csrc.nist.gov/pubs/sp/800/185/final
+ *   "SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash, and ParallelHash"
+ */
+
+/**
+ * @brief cSHAKE parameters.
+ * @ingroup cshake
+ */
 typedef struct {
-  const uint8_t *name; // NIST function name
-  const size_t name_len; // length of NIST function name, in bytes
-  const uint8_t *custom; // customization string
-  const size_t custom_len; // length of customization string, in bytes
+  const uint8_t *name; /**< NIST function name */
+  const size_t name_len; /**< NIST function name length, in bytes */
+  const uint8_t *custom; /**< Customization string */
+  const size_t custom_len; /**< Customization string length, in bytes */
 } cshake_params_t;
 
 /**
+ * @brief Initialize cSHAKE128, absorb data, then squeeze bytes out.
+ * @ingroup cshake
+ *
  * Initialize internal cSHAKE128 (customizable SHAKE128, as defined in
  * section 3 of NIST SP 800-185) context with customization parameters
  * `params`, absorb data in buffer `src` of length `src_len` bytes into
@@ -532,11 +701,14 @@ typedef struct {
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void cshake128(const cshake_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize cSHAKE256, absorb data, then squeeze bytes out.
+ * @ingroup cshake
+ *
  * Initialize internal cSHAKE256 (customizable SHAKE256, as defined in
  * section 3 of NIST SP 800-185) context with customization parameters
  * `params`, absorb data in buffer `src` of length `src_len` bytes into
@@ -551,11 +723,14 @@ void cshake128(const cshake_params_t params, const uint8_t *src, const size_t sr
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void cshake256(const cshake_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize cSHAKE128 XOF context.
+ * @ingroup cshake
+ *
  * Initialize cSHAKE128 (customizable SHAKE128, as defined in section 3 of
  * NIST SP 800-185) XOF context with customization parameters `params`.
  *
@@ -569,6 +744,9 @@ void cshake256(const cshake_params_t params, const uint8_t *src, const size_t sr
 void cshake128_xof_init(sha3_xof_t *xof, const cshake_params_t params);
 
 /**
+ * @brief Absorb data into cSHAKE128 XOF context.
+ * @ingroup cshake
+ *
  * Absorb data in buffer `src` of length `len` bytes into cSHAKE128 XOF
  * context `xof`.  Can be called iteratively to absorb input data in
  * chunks.
@@ -577,8 +755,8 @@ void cshake128_xof_init(sha3_xof_t *xof, const cshake_params_t params);
  * functions (XOF) defined in NIST SP 800-185 and should generally not
  * be used directly.
  *
- * @param[in/out] xof cSHAKE128 context.
- * @param[in] msg Source buffer.
+ * @param[in,out] xof cSHAKE128 context.
+ * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
  * @return True if data was absorbed, and false otherwise (e.g., if context has already been squeezed).
@@ -586,6 +764,9 @@ void cshake128_xof_init(sha3_xof_t *xof, const cshake_params_t params);
 _Bool cshake128_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from cSHAKE128 XOF context.
+ * @ingroup cshake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * cSHAKE128 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -594,13 +775,16 @@ _Bool cshake128_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len
  * functions (XOF) defined in NIST SP 800-185 and should generally not
  * be used directly.
  *
- * @param[in/out] xof cSHAKE128 context.
+ * @param[in,out] xof cSHAKE128 context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void cshake128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Initialize cSHAKE256 XOF context.
+ * @ingroup cshake
+ *
  * Initialize cSHAKE256 (customizable SHAKE256, as defined in section 3 of
  * NIST SP 800-185) XOF context with customization parameters `params`.
  *
@@ -608,12 +792,17 @@ void cshake128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
  * functions (XOF) defined in NIST SP 800-185 and should generally not
  * be used directly.
  *
+ * @ingroup cshake
+ *
  * @param[out] xof cSHAKE256 context.
  * @param[in] params cSHAKE256 customization parameters.
  */
 void cshake256_xof_init(sha3_xof_t *xof, const cshake_params_t params);
 
 /**
+ * @brief Absorb data into cSHAKE256 XOF context.
+ * @ingroup cshake
+ *
  * Absorb data in buffer `src` of length `len` bytes into cSHAKE256 XOF
  * context `xof`.  Can be called iteratively to absorb input data in
  * chunks.
@@ -622,8 +811,8 @@ void cshake256_xof_init(sha3_xof_t *xof, const cshake_params_t params);
  * functions (XOF) defined in NIST SP 800-185 and should generally not
  * be used directly.
  *
- * @param[in/out] xof cSHAKE256 context.
- * @param[in] msg Source buffer.
+ * @param[in,out] xof cSHAKE256 context.
+ * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
  * @return True if data was absorbed, and false otherwise (e.g., if context has already been squeezed).
@@ -631,6 +820,9 @@ void cshake256_xof_init(sha3_xof_t *xof, const cshake_params_t params);
 _Bool cshake256_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from cSHAKE256 XOF context.
+ * @ingroup cshake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * cSHAKE256 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -639,21 +831,39 @@ _Bool cshake256_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len
  * functions (XOF) defined in NIST SP 800-185 and should generally not
  * be used directly.
  *
- * @param[in/out] xof cSHAKE256 context.
+ * @param[in,out] xof cSHAKE256 context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void cshake256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
-// KMAC configuration parameters (key and customization string).
+/**
+ * @defgroup kmac KMAC
+
+ * @brief Keccak [Message Authentication Code (MAC)][mac], as defined in
+ * section 4 of [SP 800-185][800-185].
+ *
+ * [800-185]: https://csrc.nist.gov/pubs/sp/800/185/final
+ *   "SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash, and ParallelHash"
+ * [mac]: https://en.wikipedia.org/wiki/Message_authentication_code
+ *   "Message authentication code"
+ */
+
+/**
+ * @brief KMAC configuration parameters (key and customization string).
+ * @ingroup kmac
+ */
 typedef struct {
-  const uint8_t *key; // key string
-  const size_t key_len; // length of key string, in bytes
-  const uint8_t *custom; // customization string
-  const size_t custom_len; // length of customization string, in bytes
+  const uint8_t *key; /**< Key string. */
+  const size_t key_len; /**< Key string length, in bytes. */
+  const uint8_t *custom; /**< Customization string. */
+  const size_t custom_len; /**< Customization string length, in bytes. */
 } kmac_params_t;
 
 /**
+ * @brief Absorb data into KMAC128, then squeeze bytes out.
+ * @ingroup kmac
+ *
  * Initialize internal KMAC128 (Keccak Message Authentication Code, as
  * defined in section 4 of NIST SP 800-185) context with configuration
  * parameters `params`, absorb data in buffer `src` of length `src_len`
@@ -664,11 +874,14 @@ typedef struct {
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
-void kmac128(const kmac_params_t params, const uint8_t *msg, const size_t msg_len, uint8_t *dst, const size_t dst_len);
+void kmac128(const kmac_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into KMAC256, then squeeze bytes out.
+ * @ingroup kmac
+ *
  * Initialize internal KMAC256 (Keccak Message Authentication Code, as
  * defined in section 4 of NIST SP 800-185) XOF context with
  * configuration parameters `params`, absorb data in buffer `src` of
@@ -679,11 +892,14 @@ void kmac128(const kmac_params_t params, const uint8_t *msg, const size_t msg_le
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
-void kmac256(const kmac_params_t params, const uint8_t *msg, const size_t msg_len, uint8_t *dst, const size_t dst_len);
+void kmac256(const kmac_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize KMAC128 XOF context.
+ * @ingroup kmac
+ *
  * Initialize KMAC128 XOF (Keccak Message Authentication Code eXtendable
  * Output Function, as defined in section 4.3.1 of NIST SP 800-185)
  * context with configuration parameters `params`.
@@ -699,10 +915,13 @@ void kmac256(const kmac_params_t params, const uint8_t *msg, const size_t msg_le
 void kmac128_xof_init(sha3_xof_t *xof, const kmac_params_t params);
 
 /**
+ * @brief Absorb data into KMAC128 XOF context.
+ * @ingroup kmac
+ *
  * Absorb data in buffer `src` of length `len` bytes into KMAC128 XOF
  * context.  Can be called iteratively to absorb input data in chunks.
  *
- * @param[in/out] xof KMAC128 XOF context.
+ * @param[in,out] xof KMAC128 XOF context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -711,6 +930,9 @@ void kmac128_xof_init(sha3_xof_t *xof, const kmac_params_t params);
 _Bool kmac128_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze data from KMAC128 XOF context.
+ * @ingroup kmac
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * KMAC128 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -720,13 +942,16 @@ _Bool kmac128_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len);
  * KMAC128 XOF does not.  See section 4.3.1 of NIST SP 800-185 for
  * details.
  *
- * @param[in/out] xof KMAC128 XOF context.
+ * @param[in,out] xof KMAC128 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void kmac128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb data into KMAC128 XOF context, then squeeze bytes out.
+ * @ingroup kmac
+ *
  * Initialize internal KMAC128 XOF (Keccak Message Authentication Code
  * eXtendable Output Function, as defined in section 4 of NIST SP
  * 800-185) context with configuration parameters `params`, absorb data
@@ -742,11 +967,14 @@ void kmac128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void kmac128_xof_once(const kmac_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize KMAC256 XOF context.
+ * @ingroup kmac
+ *
  * Initialize KMAC256 XOF (Keccak Message Authentication Code eXtendable
  * Output Function, as defined in section 4.3.1 of NIST SP 800-185)
  * context with configuration parameters `params`.
@@ -762,18 +990,24 @@ void kmac128_xof_once(const kmac_params_t params, const uint8_t *src, const size
 void kmac256_xof_init(sha3_xof_t *xof, const kmac_params_t params);
 
 /**
+ * @brief Absorb data into KMAC256 XOF context.
+ * @ingroup kmac
+ *
  * Absorb data in buffer `src` of length `len` bytes into KMAC256 XOF
  * context.  Can be called iteratively to absorb input data in chunks.
  *
- * @param[in/out] xof KMAC256 XOF context.
+ * @param[in,out] xof KMAC256 XOF context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
  * @return True if data was absorbed, and false otherwise (e.g., if context has already been squeezed).
  */
-_Bool kmac256_xof_absorb(sha3_xof_t *xof, const uint8_t *msg, const size_t len);
+_Bool kmac256_xof_absorb(sha3_xof_t *xof, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze data from KMAC256 XOF context.
+ * @ingroup kmac
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * KMAC256 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -783,13 +1017,18 @@ _Bool kmac256_xof_absorb(sha3_xof_t *xof, const uint8_t *msg, const size_t len);
  * KMAC256 XOF does not.  See section 4.3.1 of NIST SP 800-185 for
  * details.
  *
- * @param[in/out] xof KMAC256 XOF context.
+ * @ingroup kmac
+ *
+ * @param[in,out] xof KMAC256 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void kmac256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb data into KMAC256 XOF context, then squeeze bytes out.
+ * @ingroup kmac
+ *
  * Initialize internal KMAC256 XOF (Keccak Message Authentication Code
  * eXtendable Output Function, as defined in section 4 of NIST SP
  * 800-185) context with configuration parameters `params`, absorb data
@@ -805,51 +1044,78 @@ void kmac256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void kmac256_xof_once(const kmac_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
-// TupleHash tuple element.
+/**
+ * @defgroup tuplehash TupleHash
+ * @brief Misuse-resistant cryptographic hash function and [XOF][] for
+ * hashing a [tuple][] of byte strings, as defined in section 5 of [SP
+ * 800-185][800-185].
+ *
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ * [800-185]: https://csrc.nist.gov/pubs/sp/800/185/final
+ *   "SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash, and ParallelHash"
+ * [tuple]: https://en.wikipedia.org/wiki/Tuple
+ *   "Ordered list of elements."
+ */
+
+/**
+ * @brief TupleHash tuple element.
+ * @ingroup tuplehash
+ */
 typedef struct {
-  const uint8_t *ptr; // pointer to byte string
-  size_t len; // byte string length, in bytes.
+  const uint8_t *ptr; /**< Pointer to byte string. */
+  size_t len; /**< Byte string length, in bytes. */
 } tuplehash_str_t;
 
-// TupleHash configuration parameters.
+/**
+ * @brief TupleHash configuration parameters.
+ * @ingroup tuplehash
+ */
 typedef struct {
-  const tuplehash_str_t *strs; // strings
-  const size_t num_strs; // number of strings
-  const uint8_t *custom; // customization string
-  const size_t custom_len; // length of customization string, in bytes
+  const tuplehash_str_t *strs; /**< Pointer to tuple elements. */
+  const size_t num_strs; /**< Number of elements. */
+  const uint8_t *custom; /**< Customization string. */
+  const size_t custom_len; /**< Customization string length, in bytes. */
 } tuplehash_params_t;
 
 /**
+ * @brief Absorb data into TupleHash128, then squeeze bytes out.
+ * @ingroup tuplehash
+ *
  * Initialize internal TupleHash128 (NIST SP 800-185, section 5) context
  * with configuration parameters `params`, then squeeze `dst_len` bytes
  * of output from internal context into destination buffer `dst`.
  *
  * @param[in] params TupleHash128 configuration parameters.
- * @param[in] src Source buffer.
- * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void tuplehash128(const tuplehash_params_t params, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into TupleHash256, then squeeze bytes out.
+ * @ingroup tuplehash
+ *
  * Initialize internal TupleHash256 (NIST SP 800-185, section 5) context
  * with configuration parameters `params`, then squeeze `dst_len` bytes
  * of output from internal context into destination buffer `dst`.
  *
+ * @ingroup tuplehash
+ *
  * @param[in] params TupleHash256 configuration parameters.
- * @param[in] src Source buffer.
- * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void tuplehash256(const tuplehash_params_t params, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize a TupleHash128 XOF context.
+ * @ingroup tuplehash
+ *
  * Initialize TupleHash128 XOF (TupleHash eXtendable Output Function, as
  * defined in section 5.3.1 of NIST SP 800-185) context with
  * configuration parameters `params`.
@@ -865,6 +1131,9 @@ void tuplehash256(const tuplehash_params_t params, uint8_t *dst, const size_t ds
 void tuplehash128_xof_init(sha3_xof_t *xof, const tuplehash_params_t params);
 
 /**
+ * @brief Squeeze data from TupleHash128 XOF context.
+ * @ingroup tuplehash
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * TupleHash128 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -874,13 +1143,16 @@ void tuplehash128_xof_init(sha3_xof_t *xof, const tuplehash_params_t params);
  * input while TupleHash128 XOF does not.  See section 5.3.1 of NIST SP
  * 800-185 for details.
  *
- * @param[in/out] xof TupleHash128 XOF context.
+ * @param[in,out] xof TupleHash128 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void tuplehash128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb data into TupleHash128 XOF, then squeeze bytes out.
+ * @ingroup tuplehash
+ *
  * Initialize internal TupleHash128 XOF (TupleHash eXtendable Output
  * Function, as defined in section 5 of NIST SP 800-185) context with
  * configuration parameters `params`, then squeeze `dst_len` bytes of
@@ -893,11 +1165,14 @@ void tuplehash128_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
  *
  * @param[in] params TupleHash128 configuration parameters.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void tuplehash128_xof_once(const tuplehash_params_t params, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize a TupleHash256 XOF context.
+ * @ingroup tuplehash
+ *
  * Initialize TupleHash256 XOF (TupleHash eXtendable Output Function, as
  * defined in section 5.3.1 of NIST SP 800-185) context with
  * configuration parameters `params`.
@@ -913,6 +1188,9 @@ void tuplehash128_xof_once(const tuplehash_params_t params, uint8_t *dst, const
 void tuplehash256_xof_init(sha3_xof_t *xof, const tuplehash_params_t params);
 
 /**
+ * @brief Squeeze bytes from a TupleHash256 XOF context.
+ * @ingroup tuplehash
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * TupleHash256 XOF context `xof`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -922,13 +1200,16 @@ void tuplehash256_xof_init(sha3_xof_t *xof, const tuplehash_params_t params);
  * input while TupleHash256 XOF does not.  See section 5.3.1 of NIST SP
  * 800-185 for details.
  *
- * @param[in/out] xof TupleHash256 XOF context.
+ * @param[in,out] xof TupleHash256 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void tuplehash256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb data into TupleHash256 XOF, then squeeze bytes out.
+ * @ingroup tuplehash
+ *
  * Initialize internal TupleHash256 XOF (TupleHash eXtendable Output
  * Function, as defined in section 5 of NIST SP 800-185) context with
  * configuration parameters `params`, then squeeze `dst_len` bytes of
@@ -945,24 +1226,44 @@ void tuplehash256_xof_squeeze(sha3_xof_t *xof, uint8_t *dst, const size_t len);
  */
 void tuplehash256_xof_once(const tuplehash_params_t params, uint8_t *dst, const size_t len);
 
-// ParallelHash configuration parameters.
+/**
+ * @defgroup parallelhash ParallelHash
+ * @brief Hash function and [XOF][], as defined in section 6 of [SP
+ * 800-185][800-185].
+ *
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ * [800-185]: https://csrc.nist.gov/pubs/sp/800/185/final
+ *   "SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash, and ParallelHash"
+ */
+
+/**
+ * @brief ParallelHash configuration parameters.
+ * @ingroup parallelhash
+ */
 typedef struct {
-  const size_t block_len; // block size, in bytes
-  const uint8_t *custom; // customization string
-  const size_t custom_len; // length of customization string, in bytes
+  const size_t block_len; /**< Block size, in bytes. */
+  const uint8_t *custom; /**< Customization string. */
+  const size_t custom_len; /**< Customization string length, in bytes. */
 } parallelhash_params_t;
 
-// ParallelHash context.
+/**
+ * @brief ParallelHash context (all members are private).
+ * @ingroup parallelhash
+ */
 typedef struct {
-  sha3_xof_t root_xof, // root xof
-             curr_xof; // xof for current block (note: shake128, not cshake128)
-  size_t ofs, // offset in current block, in bytes
-         block_len, // block size, in bytes
-         num_blocks; // total number of blocks
-  _Bool squeezing; // current state
+  sha3_xof_t root_xof, /**< root xof */
+             curr_xof; /**< current block xof (note: shake128, not cshake128) */
+  size_t ofs, /**< offset in current block, in bytes */
+         block_len, /**< block size, in bytes */
+         num_blocks; /**< total number of blocks */
+  _Bool squeezing; /**< current state */
 } parallelhash_t;
 
 /**
+ * @brief Absorb data into ParallelHash128, then squeeze bytes out.
+ * @ingroup parallelhash
+ *
  * Initialize internal ParallelHash128 (NIST SP 800-185, section 6)
  * context with configuration parameters `params`, then squeeze
  * `dst_len` bytes of output from internal context into destination
@@ -976,11 +1277,14 @@ typedef struct {
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void parallelhash128(const parallelhash_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into ParallelHash256, then squeeze bytes out.
+ * @ingroup parallelhash
+ *
  * Initialize internal ParallelHash256 (NIST SP 800-185, section 6)
  * context with configuration parameters `params`, then squeeze
  * `dst_len` bytes of output from internal context into destination
@@ -989,15 +1293,20 @@ void parallelhash128(const parallelhash_params_t params, const uint8_t *src, con
  * Note: This implementation of ParallelHash256 is sequential, not
  * parallel.
  *
+ * @ingroup parallelhash
+ *
  * @param[in] params ParallelHash256 configuration parameters.
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void parallelhash256(const parallelhash_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize a ParallelHash128 XOF context.
+ * @ingroup parallelhash
+ *
  * Initialize ParallelHash128 XOF (ParallelHash eXtendable Output
  * Function, as defined in section 6.3.1 of NIST SP 800-185) context
  * with configuration parameters `params`.
@@ -1013,9 +1322,12 @@ void parallelhash256(const parallelhash_params_t params, const uint8_t *src, con
  * @param[out] xof ParallelHash128 XOF context.
  * @param[in] params ParallelHash configuration parameters.
  */
-void parallelhash128_xof_init(parallelhash_t *hash, const parallelhash_params_t params);
+void parallelhash128_xof_init(parallelhash_t *xof, const parallelhash_params_t params);
 
 /**
+ * @brief Absorb data into a ParallelHash128 XOF context.
+ * @ingroup parallelhash
+ *
  * Absorb data in buffer `src` of length `len` bytes into
  * ParallelHash128 XOF context.  Can be called iteratively to absorb
  * input data in chunks.
@@ -1023,13 +1335,16 @@ void parallelhash128_xof_init(parallelhash_t *hash, const parallelhash_params_t
  * Note: This implementation of ParallelHash128 is sequential, not
  * parallel.
  *
- * @param[in/out] hash ParallelHash128 XOF context.
+ * @param[in,out] hash ParallelHash128 XOF context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  */
 void parallelhash128_xof_absorb(parallelhash_t *hash, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from a ParallelHash128 XOF context.
+ * @ingroup parallelhash
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * ParallelHash128 XOF context `xof`.  Can be called iteratively to
  * squeeze output data in chunks.
@@ -1042,13 +1357,16 @@ void parallelhash128_xof_absorb(parallelhash_t *hash, const uint8_t *src, const
  * Note: This implementation of ParallelHash128 is sequential, not
  * parallel.
  *
- * @param[in/out] xof ParallelHash128 XOF context.
+ * @param[in,out] xof ParallelHash128 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
-void parallelhash128_xof_squeeze(parallelhash_t *hash, uint8_t *dst, const size_t len);
+void parallelhash128_xof_squeeze(parallelhash_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb bytes into ParallelHash128 XOF, then squeeze bytes out.
+ * @ingroup parallelhash
+ *
  * Initialize internal ParallelHash128 XOF (ParallelHash eXtendable
  * Output Function, as defined in section 6.3.1 of NIST SP 800-185)
  * context with configuration parameters `params`, absorb data in buffer
@@ -1072,6 +1390,9 @@ void parallelhash128_xof_squeeze(parallelhash_t *hash, uint8_t *dst, const size_
 void parallelhash128_xof_once(const parallelhash_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize a ParallelHash256 XOF context.
+ * @ingroup parallelhash
+ *
  * Initialize ParallelHash256 XOF (ParallelHash eXtendable Output
  * Function, as defined in section 6.3.1 of NIST SP 800-185) context
  * with configuration parameters `params`.
@@ -1087,9 +1408,12 @@ void parallelhash128_xof_once(const parallelhash_params_t params, const uint8_t
  * @param[out] xof ParallelHash256 XOF context.
  * @param[in] params ParallelHash configuration parameters.
  */
-void parallelhash256_xof_init(parallelhash_t *hash, const parallelhash_params_t params);
+void parallelhash256_xof_init(parallelhash_t *xof, const parallelhash_params_t params);
 
 /**
+ * @brief Absorb data into a ParallelHash256 XOF context.
+ * @ingroup parallelhash
+ *
  * Absorb data in buffer `src` of length `len` bytes into
  * ParallelHash256 XOF context.  Can be called iteratively to absorb
  * input data in chunks.
@@ -1097,13 +1421,16 @@ void parallelhash256_xof_init(parallelhash_t *hash, const parallelhash_params_t
  * Note: This implementation of ParallelHash256 is sequential, not
  * parallel.
  *
- * @param[in/out] hash ParallelHash256 XOF context.
+ * @param[in,out] hash ParallelHash256 XOF context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  */
 void parallelhash256_xof_absorb(parallelhash_t *hash, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from a ParallelHash256 XOF context.
+ * @ingroup parallelhash
+ *
  * Squeeze `len` bytes of output into destination buffer `dst` from
  * ParallelHash256 XOF context `xof`.  Can be called iteratively to
  * squeeze output data in chunks.
@@ -1116,13 +1443,16 @@ void parallelhash256_xof_absorb(parallelhash_t *hash, const uint8_t *src, const
  * Note: This implementation of ParallelHash256 is sequential, not
  * parallel.
  *
- * @param[in/out] xof ParallelHash256 XOF context.
+ * @param[in,out] xof ParallelHash256 XOF context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
-void parallelhash256_xof_squeeze(parallelhash_t *hash, uint8_t *dst, const size_t len);
+void parallelhash256_xof_squeeze(parallelhash_t *xof, uint8_t *dst, const size_t len);
 
 /**
+ * @brief Absorb bytes into ParallelHash256 XOF, then squeeze bytes out.
+ * @ingroup parallelhash
+ *
  * Initialize internal ParallelHash256 XOF (ParallelHash eXtendable
  * Output Function, as defined in section 6.3.1 of NIST SP 800-185)
  * context with configuration parameters `params`, absorb `src_len`
@@ -1146,6 +1476,20 @@ void parallelhash256_xof_squeeze(parallelhash_t *hash, uint8_t *dst, const size_
 void parallelhash256_xof_once(const parallelhash_params_t params, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @defgroup turboshake TurboSHAKE
+ * @brief Faster, reduced-round [XOFs][xof], as defined in the [draft
+ * KangarooTwelve and TurboSHAKE specification][turboshake-ietf].
+ *
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ * [turboshake-ietf]: https://www.ietf.org/archive/id/draft-irtf-cfrg-kangarootwelve-10.html
+ *   "KangarooTwelve and TurboSHAKE"
+ */
+
+/**
+ * @brief Absorb bytes into TurboSHAKE128, then squeeze bytes out.
+ * @ingroup turboshake
+ *
  * Initialize internal TurboSHAKE128 context, absorb `src_len` bytes of
  * input from source buffer `src`, then squeeze `dst_len` bytes of
  * output into destination buffer `dst`.
@@ -1158,6 +1502,9 @@ void parallelhash256_xof_once(const parallelhash_params_t params, const uint8_t
 void turboshake128(const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb bytes into TurboSHAKE128 with custom padding byte, then squeeze bytes out.
+ * @ingroup turboshake
+ *
  * Initialize internal TurboSHAKE128 context with custom padding byte
  * `pad`, absorb `src_len` bytes of input from source buffer `src`, then
  * squeeze `dst_len` bytes of output into destination buffer `dst`.
@@ -1165,6 +1512,8 @@ void turboshake128(const uint8_t *src, const size_t src_len, uint8_t *dst, const
  * Note: The padding byte value must be in the range [0x01, 0x7F] and
  * can be used for domain separation.
  *
+ * @ingroup turboshake
+ *
  * @param[in] pad Padding byte.
  * @param[in] src Source buffer.
  * @param[in] src_len Source buffer length, in bytes.
@@ -1174,6 +1523,9 @@ void turboshake128(const uint8_t *src, const size_t src_len, uint8_t *dst, const
 void turboshake128_custom(const uint8_t pad, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb bytes into TurboSHAKE256, then squeeze bytes out.
+ * @ingroup turboshake
+ *
  * Initialize internal TurboSHAKE256 context, absorb `src_len` bytes of
  * input from source buffer `src`, then squeeze `dst_len` bytes of
  * output into destination buffer `dst`.
@@ -1186,6 +1538,9 @@ void turboshake128_custom(const uint8_t pad, const uint8_t *src, const size_t sr
 void turboshake256(const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb bytes into TurboSHAKE256 with custom padding byte, then squeeze bytes out.
+ * @ingroup turboshake
+ *
  * Initialize internal TurboSHAKE256 context with custom padding byte
  * `pad`, absorb `src_len` bytes of input from source buffer `src`, then
  * squeeze `dst_len` bytes of output into destination buffer `dst`.
@@ -1201,20 +1556,27 @@ void turboshake256(const uint8_t *src, const size_t src_len, uint8_t *dst, const
  */
 void turboshake256_custom(const uint8_t pad, const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
-// TurboShake XOF context.
+/**
+ * @brief TurboShake XOF context.
+ * @ingroup turboshake
+ */
 typedef struct {
-  sha3_xof_t xof;
-  uint8_t pad;
+  sha3_xof_t xof; /**< XOF context (private) */
+  uint8_t pad; /**< Padding byte (private) */
 } turboshake_t;
 
 /**
- * Initialize TurboSHAKE128 context.
+ * @brief Initialize TurboSHAKE128 context.
+ * @ingroup turboshake
  *
  * @param[out] ts TurboSHAKE128 context.
  */
 void turboshake128_init(turboshake_t *ts);
 
 /**
+ * @brief Initialize TurboSHAKE128 context with custom padding byte.
+ * @ingroup turboshake
+ *
  * Initialize TurboSHAKE128 context with custom padding byte.  The
  * custom padding byte can be used as a domain separator and must be in
  * the range [0x01, 0x7f].
@@ -1227,11 +1589,14 @@ void turboshake128_init(turboshake_t *ts);
 _Bool turboshake128_init_custom(turboshake_t *ts, const uint8_t pad);
 
 /**
+ * @brief Absorb data into TurboSHAKE128 context.
+ * @ingroup turboshake
+ *
  * Absorb `src_len` bytes of input from source buffer `src` into
  * TurboSHAKE128 context `ts`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] ts TurboSHAKE128 context.
+ * @param[in,out] ts TurboSHAKE128 context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -1240,24 +1605,31 @@ _Bool turboshake128_init_custom(turboshake_t *ts, const uint8_t pad);
 _Bool turboshake128_absorb(turboshake_t *ts, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from TurboSHAKE128 context.
+ * @ingroup turboshake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * TurboSHAKE128 context `ts`.  Can be called iteratively to squeeze
  * output data in chunks.
  *
- * @param[in/out] ts TurboSHAKE128 context.
+ * @param[in,out] ts TurboSHAKE128 context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void turboshake128_squeeze(turboshake_t *ts, uint8_t *dst, const size_t len);
 
 /**
- * Initialize TurboSHAKE256 context.
+ * @brief Initialize TurboSHAKE256 context.
+ * @ingroup turboshake
  *
  * @param[out] ts TurboSHAKE256 context.
  */
 void turboshake256_init(turboshake_t *ts);
 
 /**
+ * @brief Initialize TurboSHAKE256 context with custom padding byte.
+ * @ingroup turboshake
+ *
  * Initialize TurboSHAKE256 context with custom padding byte.  The
  * custom padding byte can be used as a domain separator and must be in
  * the range [0x01, 0x7f].
@@ -1270,11 +1642,14 @@ void turboshake256_init(turboshake_t *ts);
 _Bool turboshake256_init_custom(turboshake_t *ts, const uint8_t pad);
 
 /**
+ * @brief Absorb data into TurboSHAKE256 context.
+ * @ingroup turboshake
+ *
  * Absorb `src_len` bytes of input from source buffer `src` into
  * TurboSHAKE256 context `ts`.  Can be called iteratively to absorb
  * input data in chunks.
  *
- * @param[in/out] ts TurboSHAKE256 context.
+ * @param[in,out] ts TurboSHAKE256 context.
  * @param[in] src Source buffer.
  * @param[in] len Source buffer length, in bytes.
  *
@@ -1283,22 +1658,43 @@ _Bool turboshake256_init_custom(turboshake_t *ts, const uint8_t pad);
 _Bool turboshake256_absorb(turboshake_t *ts, const uint8_t *src, const size_t len);
 
 /**
+ * @brief Squeeze bytes from TurboSHAKE256 context.
+ * @ingroup turboshake
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
- * TurboSHAKE128 context `ts`.  Can be called iteratively to squeeze
+ * TurboSHAKE256 context `ts`.  Can be called iteratively to squeeze
  * output data in chunks.
  *
- * @param[in/out] ts TurboSHAKE128 context.
+ * @param[in,out] ts TurboSHAKE256 context.
  * @param[out] dst Destination buffer.
  * @param[in] len Destination buffer length, in bytes.
  */
 void turboshake256_squeeze(turboshake_t *ts, uint8_t *dst, const size_t len);
 
-// KangarooTwelve context
+/**
+ * @defgroup k12 KangarooTwelve
+ * @brief Faster, reduced-round [XOF][] with a customzation string, as
+ * defined in the [draft KangarooTwelve and TurboSHAKE
+ * specification][turboshake-ietf].
+ *
+ * [xof]: https://en.wikipedia.org/wiki/Extendable-output_function
+ *   "Extendable-Output Function (XOF)"
+ * [turboshake-ietf]: https://www.ietf.org/archive/id/draft-irtf-cfrg-kangarootwelve-10.html
+ *   "KangarooTwelve and TurboSHAKE"
+ */
+
+/**
+ * @brief KangarooTwelve context.
+ * @ingroup k12
+ */
 typedef struct {
-  turboshake_t ts;
+  turboshake_t ts; /**< Internal turboshake context (private) */
 } k12_t;
 
-/**
+/**!
+ * @brief Absorb data into KangarooTwelve, then squeeze bytes out.
+ * @ingroup k12
+ *
  * Initialize internal KangarooTwelve context, absorb `src_len` bytes of
  * input from source buffer `src`, then squeeze `dst_len` bytes of
  * output into destination buffer `dst`.
@@ -1311,6 +1707,9 @@ typedef struct {
 void k12_once(const uint8_t *src, const size_t src_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Absorb data into KangarooTwelve with customization string, then squeeze bytes out.
+ * @ingroup k12
+ *
  * Initialize internal KangarooTwelve context with custom string
  * `custom` of length `custom_len`, absorb `src_len` bytes of input from
  * source buffer `src`, then squeeze `dst_len` bytes of output into
@@ -1326,6 +1725,9 @@ void k12_once(const uint8_t *src, const size_t src_len, uint8_t *dst, const size
 void k12_custom_once(const uint8_t *src, const size_t src_len, const uint8_t *custom, const size_t custom_len, uint8_t *dst, const size_t dst_len);
 
 /**
+ * @brief Initialize KangarooTwelve context.
+ * @ingroup k12
+ *
  * Initialize KangarooTwelve context with message `src` of length
  * `src_len` bytes and custom string `custom` of length `custom_len`
  * bytes.
@@ -1342,6 +1744,9 @@ void k12_custom_once(const uint8_t *src, const size_t src_len, const uint8_t *cu
 void k12_init(k12_t *k12, const uint8_t *src, const size_t src_len, const uint8_t *custom, const size_t custom_len);
 
 /**
+ * @brief Squeeze bytes from KangarooTwelve context.
+ * @ingroup k12
+ *
  * Squeeze `dst_len` bytes of output into destination buffer `dst` from
  * KangarooTwelve context `k12`.  Can be called iteratively to squeeze
  * output data in chunks.
@@ -1349,9 +1754,9 @@ void k12_init(k12_t *k12, const uint8_t *src, const size_t src_len, const uint8_
  * Note: This implementation of KangarooTwelve is sequential, not
  * parallel.
  *
- * @param[in/out] k12 KangarooTwelve context.
+ * @param[in,out] k12 KangarooTwelve context.
  * @param[out] dst Destination buffer.
- * @param[in] len Destination buffer length, in bytes.
+ * @param[in] dst_len Destination buffer length, in bytes.
  */
 void k12_squeeze(k12_t *k12, uint8_t *dst, const size_t dst_len);