diff options
| -rw-r--r-- | sha3.c | 135 |
1 files changed, 135 insertions, 0 deletions
@@ -408,6 +408,70 @@ static inline size_t left_encode(uint8_t buf[static 9], const uint64_t n) { } } +// NIST SP 800-105 utility function. +static inline size_t right_encode(uint8_t buf[static 9], const uint64_t n) { + if (n > 0x00ffffffffffffffULL) { + buf[0] = (n >> 56) & 0xff; + buf[1] = (n >> 40) & 0xff; + buf[2] = (n >> 32) & 0xff; + buf[3] = (n >> 24) & 0xff; + buf[4] = (n >> 16) & 0xff; + buf[5] = (n >> 8) & 0xff; + buf[6] = n & 0xff; + buf[7] = 8; + return 9; + } else if (n > 0x0000ffffffffffffULL) { + buf[0] = (n >> 56) & 0xff; + buf[1] = (n >> 40) & 0xff; + buf[2] = (n >> 32) & 0xff; + buf[3] = (n >> 24) & 0xff; + buf[4] = (n >> 16) & 0xff; + buf[5] = (n >> 8) & 0xff; + buf[6] = n & 0xff; + buf[7] = 7; + return 8; + } else if (n > 0x000000ffffffffffULL) { + buf[0] = (n >> 40) & 0xff; + buf[1] = (n >> 32) & 0xff; + buf[2] = (n >> 24) & 0xff; + buf[3] = (n >> 16) & 0xff; + buf[4] = (n >> 8) & 0xff; + buf[5] = n & 0xff; + buf[6] = 6; + return 7; + } else if (n > 0x00000000ffffffffULL) { + buf[0] = (n >> 32) & 0xff; + buf[1] = (n >> 24) & 0xff; + buf[2] = (n >> 16) & 0xff; + buf[3] = (n >> 8) & 0xff; + buf[4] = n & 0xff; + buf[5] = 5; + return 6; + } else if (n > 0x0000000000ffffffULL) { + buf[0] = (n >> 24) & 0xff; + buf[1] = (n >> 16) & 0xff; + buf[2] = (n >> 8) & 0xff; + buf[3] = n & 0xff; + buf[4] = 4; + return 5; + } else if (n > 0x000000000000ffffULL) { + buf[0] = (n >> 16) & 0xff; + buf[1] = (n >> 8) & 0xff; + buf[2] = n & 0xff; + buf[3] = 3; + return 4; + } else if (n > 0x00000000000000ffULL) { + buf[0] = (n >> 8) & 0xff; + buf[1] = n & 0xff; + buf[2] = 2; + return 3; + } else { + buf[0] = n & 0xff; + buf[1] = 1; + return 2; + } +} + // Write prefix for encode_string() to the given buffer. Accepts the // length of the string, in bytes. // @@ -2028,6 +2092,76 @@ static void test_left_encode(void) { } } +static void test_right_encode(void) { + static const struct { + const char *name; + uint64_t val; + uint8_t exp[9]; + size_t exp_len; + } tests[] = {{ + .name = "zero", + .val = 0, + .exp = { 0x00, 0x01 }, + .exp_len = 2, + }, { + .name = "120", + .val = 120, + .exp = { 0x78, 0x01 }, + .exp_len = 2, + }, { + .name = "256", + .val = 256, + .exp = { 0x01, 0x00, 0x02 }, + .exp_len = 3, + }, { + .name = "65535", + .val = 65535, + .exp = { 0xff, 0xff, 0x02 }, + .exp_len = 3, + }, { + .name = "65536", + .val = 65536, + .exp = { 0x01, 0x00, 0x00, 0x03 }, + .exp_len = 4, + }, { + .name = "0xff00ff", + .val = 0xff00ff, + .exp = { 0xff, 0x00, 0xff, 0x03 }, + .exp_len = 4, + }, { + .name = "0x01000000", + .val = 0x01000000, + .exp = { 0x01, 0x00, 0x00, 0x00, 0x04 }, + .exp_len = 5, + }, { + .name = "0xffffffff", + .val = 0xffffffff, + .exp = { 0xff, 0xff, 0xff, 0xff, 0x04 }, + .exp_len = 5, + }, { + .name = "0x0100000000", + .val = 0x0100000000, + .exp = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x05 }, + .exp_len = 6, + }}; + + for (size_t i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) { + uint8_t got[9]; + const size_t got_len = right_encode(got, tests[i].val); + + // check length and data + if (got_len != tests[i].exp_len) { + fprintf(stderr, "test_right_encode(\"%s\") length check failed: got %zu, exp %zu:\n", tests[i].name, got_len, tests[i].exp_len); + } else if (memcmp(got, tests[i].exp, got_len)) { + fprintf(stderr, "test_right_encode(\"%s\") failed, got:\n", tests[i].name); + dump_hex(stderr, got, got_len); + + fprintf(stderr, "exp:\n"); + dump_hex(stderr, tests[i].exp, got_len); + } + } +} + static void test_encode_string_prefix(void) { static const struct { const char *name; @@ -2315,6 +2449,7 @@ int main(void) { test_shake256_xof(); test_shake256_xof_once(); test_left_encode(); + test_right_encode(); test_encode_string_prefix(); test_bytepad_prefix(); test_cshake128(); |