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Diffstat (limited to 'sha256-helpers.h')
| -rw-r--r-- | sha256-helpers.h | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/sha256-helpers.h b/sha256-helpers.h new file mode 100644 index 0000000..9d17729 --- /dev/null +++ b/sha256-helpers.h @@ -0,0 +1,466 @@ +/*- + * Copyright 2009 Colin Percival, 2011 ArtForz + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * This file was originally written by Colin Percival as part of the Tarsnap + * online backup system. + */ + +#ifndef __SHA256_HELPERS_H__ +#define __SHA256_HELPERS_H__ + +#include <stdlib.h> +#include <stdint.h> +#include <string.h> + +static inline uint32_t +be32dec(const void *pp) +{ + const uint8_t *p = (uint8_t const *)pp; + + return ((uint32_t)(p[3]) + ((uint32_t)(p[2]) << 8) + + ((uint32_t)(p[1]) << 16) + ((uint32_t)(p[0]) << 24)); +} + +static inline void +be32enc(void *pp, uint32_t x) +{ + uint8_t * p = (uint8_t *)pp; + + p[3] = x & 0xff; + p[2] = (x >> 8) & 0xff; + p[1] = (x >> 16) & 0xff; + p[0] = (x >> 24) & 0xff; +} + +static inline uint32_t +le32dec(const void *pp) +{ + const uint8_t *p = (uint8_t const *)pp; + + return ((uint32_t)(p[0]) + ((uint32_t)(p[1]) << 8) + + ((uint32_t)(p[2]) << 16) + ((uint32_t)(p[3]) << 24)); +} + +static inline void +le32enc(void *pp, uint32_t x) +{ + uint8_t * p = (uint8_t *)pp; + + p[0] = x & 0xff; + p[1] = (x >> 8) & 0xff; + p[2] = (x >> 16) & 0xff; + p[3] = (x >> 24) & 0xff; +} + + +typedef struct SHA256Context { + uint32_t state[8]; + uint32_t count[2]; + unsigned char buf[64]; +} SHA256_CTX; + +typedef struct HMAC_SHA256Context { + SHA256_CTX ictx; + SHA256_CTX octx; +} HMAC_SHA256_CTX; + +/* + * Encode a length len/4 vector of (uint32_t) into a length len vector of + * (unsigned char) in big-endian form. Assumes len is a multiple of 4. + */ +static void +be32enc_vect(unsigned char *dst, const uint32_t *src, size_t len) +{ + size_t i; + + for (i = 0; i < len / 4; i++) + be32enc(dst + i * 4, src[i]); +} + +/* + * Decode a big-endian length len vector of (unsigned char) into a length + * len/4 vector of (uint32_t). Assumes len is a multiple of 4. + */ +static void +be32dec_vect(uint32_t *dst, const unsigned char *src, size_t len) +{ + size_t i; + + for (i = 0; i < len / 4; i++) + dst[i] = be32dec(src + i * 4); +} + +/* Elementary functions used by SHA256 */ +#define Ch(x, y, z) ((x & (y ^ z)) ^ z) +#define Maj(x, y, z) ((x & (y | z)) | (y & z)) +#define SHR(x, n) (x >> n) +#define ROTR(x, n) ((x >> n) | (x << (32 - n))) +#define S0(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22)) +#define S1(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25)) +#define s0(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3)) +#define s1(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10)) + +/* SHA256 round function */ +#define RND(a, b, c, d, e, f, g, h, k) \ + t0 = h + S1(e) + Ch(e, f, g) + k; \ + t1 = S0(a) + Maj(a, b, c); \ + d += t0; \ + h = t0 + t1; + +/* Adjusted round function for rotating state */ +#define RNDr(S, W, i, k) \ + RND(S[(64 - i) % 8], S[(65 - i) % 8], \ + S[(66 - i) % 8], S[(67 - i) % 8], \ + S[(68 - i) % 8], S[(69 - i) % 8], \ + S[(70 - i) % 8], S[(71 - i) % 8], \ + W[i] + k) + +/* + * SHA256 block compression function. The 256-bit state is transformed via + * the 512-bit input block to produce a new state. + */ +static void +SHA256_Transform(uint32_t * state, const unsigned char block[64]) +{ + uint32_t W[64]; + uint32_t S[8]; + uint32_t t0, t1; + int i; + + /* 1. Prepare message schedule W. */ + be32dec_vect(W, block, 64); + for (i = 16; i < 64; i++) + W[i] = s1(W[i - 2]) + W[i - 7] + s0(W[i - 15]) + W[i - 16]; + + /* 2. Initialize working variables. */ + memcpy(S, state, 32); + + /* 3. Mix. */ + RNDr(S, W, 0, 0x428a2f98); + RNDr(S, W, 1, 0x71374491); + RNDr(S, W, 2, 0xb5c0fbcf); + RNDr(S, W, 3, 0xe9b5dba5); + RNDr(S, W, 4, 0x3956c25b); + RNDr(S, W, 5, 0x59f111f1); + RNDr(S, W, 6, 0x923f82a4); + RNDr(S, W, 7, 0xab1c5ed5); + RNDr(S, W, 8, 0xd807aa98); + RNDr(S, W, 9, 0x12835b01); + RNDr(S, W, 10, 0x243185be); + RNDr(S, W, 11, 0x550c7dc3); + RNDr(S, W, 12, 0x72be5d74); + RNDr(S, W, 13, 0x80deb1fe); + RNDr(S, W, 14, 0x9bdc06a7); + RNDr(S, W, 15, 0xc19bf174); + RNDr(S, W, 16, 0xe49b69c1); + RNDr(S, W, 17, 0xefbe4786); + RNDr(S, W, 18, 0x0fc19dc6); + RNDr(S, W, 19, 0x240ca1cc); + RNDr(S, W, 20, 0x2de92c6f); + RNDr(S, W, 21, 0x4a7484aa); + RNDr(S, W, 22, 0x5cb0a9dc); + RNDr(S, W, 23, 0x76f988da); + RNDr(S, W, 24, 0x983e5152); + RNDr(S, W, 25, 0xa831c66d); + RNDr(S, W, 26, 0xb00327c8); + RNDr(S, W, 27, 0xbf597fc7); + RNDr(S, W, 28, 0xc6e00bf3); + RNDr(S, W, 29, 0xd5a79147); + RNDr(S, W, 30, 0x06ca6351); + RNDr(S, W, 31, 0x14292967); + RNDr(S, W, 32, 0x27b70a85); + RNDr(S, W, 33, 0x2e1b2138); + RNDr(S, W, 34, 0x4d2c6dfc); + RNDr(S, W, 35, 0x53380d13); + RNDr(S, W, 36, 0x650a7354); + RNDr(S, W, 37, 0x766a0abb); + RNDr(S, W, 38, 0x81c2c92e); + RNDr(S, W, 39, 0x92722c85); + RNDr(S, W, 40, 0xa2bfe8a1); + RNDr(S, W, 41, 0xa81a664b); + RNDr(S, W, 42, 0xc24b8b70); + RNDr(S, W, 43, 0xc76c51a3); + RNDr(S, W, 44, 0xd192e819); + RNDr(S, W, 45, 0xd6990624); + RNDr(S, W, 46, 0xf40e3585); + RNDr(S, W, 47, 0x106aa070); + RNDr(S, W, 48, 0x19a4c116); + RNDr(S, W, 49, 0x1e376c08); + RNDr(S, W, 50, 0x2748774c); + RNDr(S, W, 51, 0x34b0bcb5); + RNDr(S, W, 52, 0x391c0cb3); + RNDr(S, W, 53, 0x4ed8aa4a); + RNDr(S, W, 54, 0x5b9cca4f); + RNDr(S, W, 55, 0x682e6ff3); + RNDr(S, W, 56, 0x748f82ee); + RNDr(S, W, 57, 0x78a5636f); + RNDr(S, W, 58, 0x84c87814); + RNDr(S, W, 59, 0x8cc70208); + RNDr(S, W, 60, 0x90befffa); + RNDr(S, W, 61, 0xa4506ceb); + RNDr(S, W, 62, 0xbef9a3f7); + RNDr(S, W, 63, 0xc67178f2); + + /* 4. Mix local working variables into global state */ + for (i = 0; i < 8; i++) + state[i] += S[i]; + + /* Clean the stack. */ + memset(W, 0, 256); + memset(S, 0, 32); + t0 = t1 = 0; +} + +static unsigned char PAD[64] = { + 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 +}; + +/* SHA-256 initialization. Begins a SHA-256 operation. */ +static void +SHA256_Init(SHA256_CTX * ctx) +{ + + /* Zero bits processed so far */ + ctx->count[0] = ctx->count[1] = 0; + + /* Magic initialization constants */ + ctx->state[0] = 0x6A09E667; + ctx->state[1] = 0xBB67AE85; + ctx->state[2] = 0x3C6EF372; + ctx->state[3] = 0xA54FF53A; + ctx->state[4] = 0x510E527F; + ctx->state[5] = 0x9B05688C; + ctx->state[6] = 0x1F83D9AB; + ctx->state[7] = 0x5BE0CD19; +} + +/* Add bytes into the hash */ +static void +SHA256_Update(SHA256_CTX * ctx, const void *in, size_t len) +{ + uint32_t bitlen[2]; + uint32_t r; + const unsigned char *src = in; + + /* Number of bytes left in the buffer from previous updates */ + r = (ctx->count[1] >> 3) & 0x3f; + + /* Convert the length into a number of bits */ + bitlen[1] = ((uint32_t)len) << 3; + bitlen[0] = (uint32_t)(len >> 29); + + /* Update number of bits */ + if ((ctx->count[1] += bitlen[1]) < bitlen[1]) + ctx->count[0]++; + ctx->count[0] += bitlen[0]; + + /* Handle the case where we don't need to perform any transforms */ + if (len < 64 - r) { + memcpy(&ctx->buf[r], src, len); + return; + } + + /* Finish the current block */ + memcpy(&ctx->buf[r], src, 64 - r); + SHA256_Transform(ctx->state, ctx->buf); + src += 64 - r; + len -= 64 - r; + + /* Perform complete blocks */ + while (len >= 64) { + SHA256_Transform(ctx->state, src); + src += 64; + len -= 64; + } + + /* Copy left over data into buffer */ + memcpy(ctx->buf, src, len); +} + +/* Add padding and terminating bit-count. */ +static void +SHA256_Pad(SHA256_CTX * ctx) +{ + unsigned char len[8]; + uint32_t r, plen; + + /* + * Convert length to a vector of bytes -- we do this now rather + * than later because the length will change after we pad. + */ + be32enc_vect(len, ctx->count, 8); + + /* Add 1--64 bytes so that the resulting length is 56 mod 64 */ + r = (ctx->count[1] >> 3) & 0x3f; + plen = (r < 56) ? (56 - r) : (120 - r); + SHA256_Update(ctx, PAD, (size_t)plen); + + /* Add the terminating bit-count */ + SHA256_Update(ctx, len, 8); +} + +/* + * SHA-256 finalization. Pads the input data, exports the hash value, + * and clears the context state. + */ +static void +SHA256_Final(unsigned char digest[32], SHA256_CTX * ctx) +{ + + /* Add padding */ + SHA256_Pad(ctx); + + /* Write the hash */ + be32enc_vect(digest, ctx->state, 32); + + /* Clear the context state */ + memset((void *)ctx, 0, sizeof(*ctx)); +} + +/* Initialize an HMAC-SHA256 operation with the given key. */ +static void +HMAC_SHA256_Init(HMAC_SHA256_CTX * ctx, const void * _K, size_t Klen) +{ + unsigned char pad[64]; + unsigned char khash[32]; + const unsigned char * K = _K; + size_t i; + + /* If Klen > 64, the key is really SHA256(K). */ + if (Klen > 64) { + SHA256_Init(&ctx->ictx); + SHA256_Update(&ctx->ictx, K, Klen); + SHA256_Final(khash, &ctx->ictx); + K = khash; + Klen = 32; + } + + /* Inner SHA256 operation is SHA256(K xor [block of 0x36] || data). */ + SHA256_Init(&ctx->ictx); + memset(pad, 0x36, 64); + for (i = 0; i < Klen; i++) + pad[i] ^= K[i]; + SHA256_Update(&ctx->ictx, pad, 64); + + /* Outer SHA256 operation is SHA256(K xor [block of 0x5c] || hash). */ + SHA256_Init(&ctx->octx); + memset(pad, 0x5c, 64); + for (i = 0; i < Klen; i++) + pad[i] ^= K[i]; + SHA256_Update(&ctx->octx, pad, 64); + + /* Clean the stack. */ + memset(khash, 0, 32); +} + +/* Add bytes to the HMAC-SHA256 operation. */ +static void +HMAC_SHA256_Update(HMAC_SHA256_CTX * ctx, const void *in, size_t len) +{ + + /* Feed data to the inner SHA256 operation. */ + SHA256_Update(&ctx->ictx, in, len); +} + +/* Finish an HMAC-SHA256 operation. */ +static void +HMAC_SHA256_Final(unsigned char digest[32], HMAC_SHA256_CTX * ctx) +{ + unsigned char ihash[32]; + + /* Finish the inner SHA256 operation. */ + SHA256_Final(ihash, &ctx->ictx); + + /* Feed the inner hash to the outer SHA256 operation. */ + SHA256_Update(&ctx->octx, ihash, 32); + + /* Finish the outer SHA256 operation. */ + SHA256_Final(digest, &ctx->octx); + + /* Clean the stack. */ + memset(ihash, 0, 32); +} + +/** + * PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, c, buf, dkLen): + * Compute PBKDF2(passwd, salt, c, dkLen) using HMAC-SHA256 as the PRF, and + * write the output to buf. The value dkLen must be at most 32 * (2^32 - 1). + */ +static void +PBKDF2_SHA256(const uint8_t * passwd, size_t passwdlen, const uint8_t * salt, + size_t saltlen, uint64_t c, uint8_t * buf, size_t dkLen) +{ + HMAC_SHA256_CTX PShctx, hctx; + size_t i; + uint8_t ivec[4]; + uint8_t U[32]; + uint8_t T[32]; + uint64_t j; + int k; + size_t clen; + + /* Compute HMAC state after processing P and S. */ + HMAC_SHA256_Init(&PShctx, passwd, passwdlen); + HMAC_SHA256_Update(&PShctx, salt, saltlen); + + /* Iterate through the blocks. */ + for (i = 0; i * 32 < dkLen; i++) { + /* Generate INT(i + 1). */ + be32enc(ivec, (uint32_t)(i + 1)); + + /* Compute U_1 = PRF(P, S || INT(i)). */ + memcpy(&hctx, &PShctx, sizeof(HMAC_SHA256_CTX)); + HMAC_SHA256_Update(&hctx, ivec, 4); + HMAC_SHA256_Final(U, &hctx); + + /* T_i = U_1 ... */ + memcpy(T, U, 32); + + for (j = 2; j <= c; j++) { + /* Compute U_j. */ + HMAC_SHA256_Init(&hctx, passwd, passwdlen); + HMAC_SHA256_Update(&hctx, U, 32); + HMAC_SHA256_Final(U, &hctx); + + /* ... xor U_j ... */ + for (k = 0; k < 32; k++) + T[k] ^= U[k]; + } + + /* Copy as many bytes as necessary into buf. */ + clen = dkLen - i * 32; + if (clen > 32) + clen = 32; + memcpy(&buf[i * 32], T, clen); + } + + /* Clean PShctx, since we never called _Final on it. */ + memset(&PShctx, 0, sizeof(HMAC_SHA256_CTX)); +} + +#endif |