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Diffstat (limited to '')
| -rw-r--r-- | sha256.c | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/sha256.c b/sha256.c new file mode 100644 index 0000000..fe7eca6 --- /dev/null +++ b/sha256.c @@ -0,0 +1,274 @@ +/* sha256 implementation, taken (with minor modification) from sha256crypt.c, + which states: + Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>. + Neglegible modifications by Bernhard R. Link, also in the public domain. +*/ + +#include <config.h> + +#include <limits.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/param.h> +#include <sys/types.h> + +#include "sha256.h" + +#ifndef WORDS_BIGENDIAN +# define SWAP(n) \ + (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24)) +#else +# define SWAP(n) (n) +#endif + + +/* This array contains the bytes used to pad the buffer to the next + 64-byte boundary. (FIPS 180-2:5.1.1) */ +static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ }; + + +/* Constants for SHA256 from FIPS 180-2:4.2.2. */ +static const uint32_t K[64] = + { + 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, + 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, + 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, + 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, + 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, + 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, + 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, + 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, + 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, + 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, + 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, + 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, + 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, + 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, + 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, + 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 + }; + + +/* Process LEN bytes of BUFFER, accumulating context into CTX. + It is assumed that LEN % 64 == 0. */ +static void +sha256_process_block (const void *buffer, size_t len, struct SHA256_Context *ctx) +{ + const uint32_t *words = buffer; + size_t nwords = len / sizeof (uint32_t); + uint32_t a = ctx->H[0]; + uint32_t b = ctx->H[1]; + uint32_t c = ctx->H[2]; + uint32_t d = ctx->H[3]; + uint32_t e = ctx->H[4]; + uint32_t f = ctx->H[5]; + uint32_t g = ctx->H[6]; + uint32_t h = ctx->H[7]; + + /* First increment the byte count. FIPS 180-2 specifies the possible + length of the file up to 2^64 bits. Here we only compute the + number of bytes. */ + ctx->total += len; + + /* Process all bytes in the buffer with 64 bytes in each round of + the loop. */ + while (nwords > 0) + { + uint32_t W[64]; + uint32_t a_save = a; + uint32_t b_save = b; + uint32_t c_save = c; + uint32_t d_save = d; + uint32_t e_save = e; + uint32_t f_save = f; + uint32_t g_save = g; + uint32_t h_save = h; + + /* Operators defined in FIPS 180-2:4.1.2. */ +#define Ch(x, y, z) ((x & y) ^ (~x & z)) +#define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z)) +#define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22)) +#define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25)) +#define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3)) +#define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10)) + + /* It is unfortunate that C does not provide an operator for + cyclic rotation. Hope the C compiler is smart enough. */ +#define CYCLIC(w, s) ((w >> s) | (w << (32 - s))) + + /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */ + for (unsigned int t = 0; t < 16; ++t) + { + W[t] = SWAP (*words); + ++words; + } + for (unsigned int t = 16; t < 64; ++t) + W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16]; + + /* The actual computation according to FIPS 180-2:6.2.2 step 3. */ + for (unsigned int t = 0; t < 64; ++t) + { + uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t]; + uint32_t T2 = S0 (a) + Maj (a, b, c); + h = g; + g = f; + f = e; + e = d + T1; + d = c; + c = b; + b = a; + a = T1 + T2; + } + + /* Add the starting values of the context according to FIPS 180-2:6.2.2 + step 4. */ + a += a_save; + b += b_save; + c += c_save; + d += d_save; + e += e_save; + f += f_save; + g += g_save; + h += h_save; + + /* Prepare for the next round. */ + nwords -= 16; + } + + /* Put checksum in context given as argument. */ + ctx->H[0] = a; + ctx->H[1] = b; + ctx->H[2] = c; + ctx->H[3] = d; + ctx->H[4] = e; + ctx->H[5] = f; + ctx->H[6] = g; + ctx->H[7] = h; +} + + +/* Initialize structure containing state of computation. + (FIPS 180-2:5.3.2) */ +void +SHA256Init(struct SHA256_Context *ctx) +{ + ctx->H[0] = 0x6a09e667; + ctx->H[1] = 0xbb67ae85; + ctx->H[2] = 0x3c6ef372; + ctx->H[3] = 0xa54ff53a; + ctx->H[4] = 0x510e527f; + ctx->H[5] = 0x9b05688c; + ctx->H[6] = 0x1f83d9ab; + ctx->H[7] = 0x5be0cd19; + + ctx->total = 0; + ctx->buflen = 0; +} + + +/* Process the remaining bytes in the internal buffer and the usual + prolog according to the standard and write the result to digest. + */ +void +SHA256Final(struct SHA256_Context *ctx, uint8_t *digest) +{ + /* Take yet unprocessed bytes into account. */ + uint32_t bytes = ctx->buflen; + uint32_t bitslow, bitshigh; + size_t pad; + int i; + + /* Now count remaining bytes. */ + ctx->total += bytes; + + pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes; + memcpy (&ctx->buffer[bytes], fillbuf, pad); + + /* Put the 64-bit file length in *bits* at the end of the buffer. */ + bitslow = ctx->total << 3; + bitshigh = ctx->total >> 29; + bitslow = SWAP(bitslow); + memcpy(ctx->buffer + bytes + pad + 4, &bitslow, 4); + bitshigh = SWAP(bitshigh); + memcpy(ctx->buffer + bytes + pad, &bitshigh, 4); + + /* Process last bytes. */ + sha256_process_block (ctx->buffer, bytes + pad + 8, ctx); + + for (i = 0; i < SHA256_DIGEST_SIZE; i++) { + digest[i] = (uint8_t) + ((ctx->H[i>>2] >> ((3-(i & 3)) * 8) ) & 255); + } +} + + +void +SHA256Update(struct SHA256_Context *ctx, const uint8_t *buffer, size_t len) +{ + /* When we already have some bits in our internal buffer concatenate + both inputs first. */ + if (ctx->buflen != 0) + { + size_t left_over = ctx->buflen; + size_t add = 128 - left_over > len ? len : 128 - left_over; + + memcpy (&ctx->buffer[left_over], buffer, add); + ctx->buflen += add; + + if (ctx->buflen > 64) + { + sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx); + + ctx->buflen &= 63; + /* The regions in the following copy operation cannot overlap. */ + memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63], + ctx->buflen); + } + + buffer = buffer + add; + len -= add; + } + + /* Process available complete blocks. */ + if (len >= 64) + { +/* To check alignment gcc has an appropriate operator. Other + compilers don't. */ +#if __GNUC__ >= 2 +# define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0) +#else +# define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0) +#endif + if (UNALIGNED_P (buffer)) + while (len > 64) + { + sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx); + buffer = buffer + 64; + len -= 64; + } + else + { + sha256_process_block (buffer, len & ~63, ctx); + buffer = buffer + (len & ~63); + len &= 63; + } + } + + /* Move remaining bytes into internal buffer. */ + if (len > 0) + { + size_t left_over = ctx->buflen; + + memcpy (&ctx->buffer[left_over], buffer, len); + left_over += len; + if (left_over >= 64) + { + sha256_process_block (ctx->buffer, 64, ctx); + left_over -= 64; + memcpy (ctx->buffer, &ctx->buffer[64], left_over); + } + ctx->buflen = left_over; + } +} |