diff options
| -rw-r--r-- | main.c | 100 |
1 files changed, 57 insertions, 43 deletions
@@ -4,7 +4,15 @@ #include <string.h> #include "sha3.h" -static void run_shake128_xof(const uint8_t *msg, const size_t msg_len, const size_t out_len) { +// print hex-encoded buffer to stdout. +static void print_hex(const uint8_t * const buf, const size_t len) { + for (size_t i = 0; i < len; i++) { + printf("%02x", buf[i]); + } +} + +// shake128-xof handler +static void do_shake128_xof(const uint8_t *msg, const size_t msg_len, const size_t out_len) { // init xof sha3_xof_t xof; shake128_xof_init(&xof); @@ -15,22 +23,19 @@ static void run_shake128_xof(const uint8_t *msg, const size_t msg_len, const siz exit(-1); } - // squeeze uint8_t buf[64]; for (size_t i = 0; i < out_len; i += sizeof(buf)) { + // squeeze and print const size_t len = (out_len - i < sizeof(buf)) ? out_len - i : sizeof(buf); shake128_xof_squeeze(&xof, buf, len); - - // print result - for (size_t j = 0; j < len; j++) { - printf("%02x", buf[j]); - } + print_hex(buf, len); } fputs("\n", stdout); } -static void run_shake256_xof(const uint8_t * const msg, const size_t msg_len, const size_t out_len) { +// shake256-xof handler +static void do_shake256_xof(const uint8_t * const msg, const size_t msg_len, const size_t out_len) { // init xof sha3_xof_t xof; shake256_xof_init(&xof); @@ -41,22 +46,18 @@ static void run_shake256_xof(const uint8_t * const msg, const size_t msg_len, co exit(-1); } - // squeeze uint8_t buf[64]; for (size_t i = 0; i < out_len; i += sizeof(buf)) { + // squeeze and print const size_t len = (out_len - i < sizeof(buf)) ? out_len - i : sizeof(buf); shake256_xof_squeeze(&xof, buf, len); - - // print result - for (size_t j = 0; j < len; j++) { - printf("%02x", buf[j]); - } + print_hex(buf, len); } fputs("\n", stdout); } -// available functions +// available hash functions static const struct { const char *name; const size_t size; @@ -88,14 +89,31 @@ static const struct { .hash_func = shake256, }, { .name = "shake128-xof", - .size = 16, - .xof_func = run_shake128_xof, + .size = 16, // default size + .xof_func = do_shake128_xof, }, { .name = "shake256-xof", - .size = 32, - .xof_func = run_shake256_xof, + .size = 32, // default size + .xof_func = do_shake256_xof, }}; +// number of hash functions +#define NUM_FNS (sizeof(fns) / sizeof(fns[0])) + +// get hash function offset in fns. returns NUM_FNS if the function is +// unknown. +static size_t get_fn_ofs(const char * const name) { + for (size_t i = 0; i < NUM_FNS; i++) { + if (!strncmp(name, fns[i].name, strlen(fns[i].name) + 1)) { + return i; + } + } + + // not found + return NUM_FNS; +} + +// usage format string #define USAGE "Usage: %s <algo> <data> [xof-size]\n" \ "\n" \ "Algorithms:\n" \ @@ -113,40 +131,36 @@ static const struct { " dd2781f4c51bccdbe23e4d398b8a82261f585c278dbb4b84989fea70e76723a9\n" int main(int argc, char *argv[]) { + // check command-line arguments if (argc < 3) { const char *app = (argc > 0) ? argv[0] : "sha3"; fprintf(stderr, USAGE, app, app); return -1; } + // get message and message length const uint8_t * const msg = (uint8_t*) argv[2]; const size_t len = strlen(argv[2]); - for (size_t i = 0; i < sizeof(fns)/sizeof(fns[0]); i++) { - if (strncmp(argv[1], fns[i].name, strlen(fns[i].name) + 1)) { - continue; - } - - if (fns[i].xof_func) { - // get output size - const size_t out_size = (argc == 4) ? (size_t) atoi(argv[3]) : fns[i].size; - fns[i].xof_func(msg, len, out_size); - } else { - // hash into buf - uint8_t buf[64]; - fns[i].hash_func(msg, len, buf); - - // print result - for (size_t j = 0; j < fns[i].size; j++) { - printf("%02x", buf[j]); - } - fputs("\n", stdout); - } + // get function offset + const size_t ofs = get_fn_ofs(argv[1]); + if (ofs == NUM_FNS) { + fprintf(stderr, "Unknown algorithm: %s\n", argv[1]); + return -1; + } - // exit with success - return 0; + if (fns[ofs].xof_func) { + // get output size from argument, or use default output size + const size_t out_size = (argc == 4) ? (size_t) atoi(argv[3]) : fns[ofs].size; + fns[ofs].xof_func(msg, len, out_size); + } else { + // hash into buffer, print buffer, print newline + uint8_t buf[64]; + fns[ofs].hash_func(msg, len, buf); + print_hex(buf, fns[ofs].size); + fputs("\n", stdout); } - fprintf(stderr, "Unknown algorithm: %s\n", argv[1]); - return -1; + // exit with success + return 0; } |