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sys/hashes/sha256: extract common code
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@PeterKietzmann
PeterKietzmann committed Jun 8, 2020
1 parent d4e90d3 commit 852c58b
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200 changes: 10 additions & 190 deletions sys/hashes/sha256.c
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Original file line number Diff line number Diff line change
Expand Up @@ -49,143 +49,8 @@
#include <assert.h>

#include "hashes/sha256.h"
#include "hashes/sha2xx_common.h"

#ifdef __BIG_ENDIAN__
/* Copy a vector of big-endian uint32_t into a vector of bytes */
#define be32enc_vect memcpy

/* Copy a vector of bytes into a vector of big-endian uint32_t */
#define be32dec_vect memcpy

#else /* !__BIG_ENDIAN__ */

/*
* 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(void *dst_, const void *src_, size_t len)
{
if ((uintptr_t)dst_ % sizeof(uint32_t) == 0 &&
(uintptr_t)src_ % sizeof(uint32_t) == 0) {
uint32_t *dst = dst_;
const uint32_t *src = src_;
for (size_t i = 0; i < len / 4; i++) {
dst[i] = __builtin_bswap32(src[i]);
}
}
else {
uint8_t *dst = dst_;
const uint8_t *src = src_;
for (size_t i = 0; i < len; i += 4) {
dst[i] = src[i + 3];
dst[i + 1] = src[i + 2];
dst[i + 2] = src[i + 1];
dst[i + 3] = 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.
*/
#define be32dec_vect be32enc_vect

#endif /* __BYTE_ORDER__ != __ORDER_BIG_ENDIAN__ */

/* 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))

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,
};

/*
* 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];

/* 1. Prepare message schedule W. */
be32dec_vect(W, block, 64);
for (int 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. */
for (int i = 0; i < 64; ++i) {
uint32_t e = S[(68 - i) % 8], f = S[(69 - i) % 8];
uint32_t g = S[(70 - i) % 8], h = S[(71 - i) % 8];
uint32_t t0 = h + S1(e) + Ch(e, f, g) + W[i] + K[i];

uint32_t a = S[(64 - i) % 8], b = S[(65 - i) % 8];
uint32_t c = S[(66 - i) % 8], d = S[(67 - i) % 8];
uint32_t t1 = S0(a) + Maj(a, b, c);

S[(67 - i) % 8] = d + t0;
S[(71 - i) % 8] = t0 + t1;
}

/* 4. Mix local working variables into global state */
for (int i = 0; i < 8; i++) {
state[i] += S[i];
}
}

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,
};

/* Add padding and terminating bit-count. */
static void sha256_pad(sha256_context_t *ctx)
{
/*
* Convert length to a vector of bytes -- we do this now rather
* than later because the length will change after we pad.
*/
unsigned char len[8];

be32enc_vect(len, ctx->count, 8);

/* Add 1--64 bytes so that the resulting length is 56 mod 64 */
uint32_t r = (ctx->count[1] >> 3) & 0x3f;
uint32_t 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 initialization. Begins a SHA-256 operation. */
void sha256_init(sha256_context_t *ctx)
Expand All @@ -207,45 +72,7 @@ void sha256_init(sha256_context_t *ctx)
/* Add bytes into the hash */
void sha256_update(sha256_context_t *ctx, const void *data, size_t len)
{
/* Number of bytes left in the buffer from previous updates */
uint32_t r = (ctx->count[1] >> 3) & 0x3f;

/* Convert the length into a number of bits */
uint32_t bitlen1 = ((uint32_t) len) << 3;
uint32_t bitlen0 = ((uint32_t) len) >> 29;

/* Update number of bits */
if ((ctx->count[1] += bitlen1) < bitlen1) {
ctx->count[0]++;
}

ctx->count[0] += bitlen0;

/* Handle the case where we don't need to perform any transforms */
if (len < 64 - r) {
if (len > 0) {
memcpy(&ctx->buf[r], data, len);
}
return;
}

/* Finish the current block */
const unsigned char *src = data;

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);
sha2xx_update(ctx, data, len);
}

/*
Expand All @@ -254,14 +81,7 @@ void sha256_update(sha256_context_t *ctx, const void *data, size_t len)
*/
void sha256_final(sha256_context_t *ctx, void *dst)
{
/* Add padding */
sha256_pad(ctx);

/* Write the hash */
be32enc_vect(dst, ctx->state, 32);

/* Clear the context state */
memset((void *) ctx, 0, sizeof(*ctx));
sha2xx_final(ctx, dst, SHA256_DIGEST_LENGTH);
}

void *sha256(const void *data, size_t len, void *digest)
Expand All @@ -274,7 +94,7 @@ void *sha256(const void *data, size_t len, void *digest)
}

sha256_init(&c);
sha256_update(&c, data, len);
sha2xx_update(&c, data, len);
sha256_final(&c, digest);

return digest;
Expand Down Expand Up @@ -312,20 +132,20 @@ void hmac_sha256_init(hmac_context_t *ctx, const void *key, size_t key_length)
* tmp = hash(i_key_pad CONCAT message)
*/
sha256_init(&ctx->c_in);
sha256_update(&ctx->c_in, i_key_pad, SHA256_INTERNAL_BLOCK_SIZE);
sha2xx_update(&ctx->c_in, i_key_pad, SHA256_INTERNAL_BLOCK_SIZE);

/*
* Initiate calculation of the outer hash
* result = hash(o_key_pad CONCAT tmp)
*/
sha256_init(&ctx->c_out);
sha256_update(&ctx->c_out, o_key_pad, SHA256_INTERNAL_BLOCK_SIZE);
sha2xx_update(&ctx->c_out, o_key_pad, SHA256_INTERNAL_BLOCK_SIZE);

}

void hmac_sha256_update(hmac_context_t *ctx, const void *data, size_t len)
{
sha256_update(&ctx->c_in, data, len);
sha2xx_update(&ctx->c_in, data, len);
}

void hmac_sha256_final(hmac_context_t *ctx, void *digest)
Expand All @@ -339,7 +159,7 @@ void hmac_sha256_final(hmac_context_t *ctx, void *digest)
}

sha256_final(&ctx->c_in, tmp);
sha256_update(&ctx->c_out, tmp, SHA256_DIGEST_LENGTH);
sha2xx_update(&ctx->c_out, tmp, SHA256_DIGEST_LENGTH);
sha256_final(&ctx->c_out, digest);
}

Expand Down Expand Up @@ -367,7 +187,7 @@ static inline void sha256_inplace(unsigned char element[SHA256_DIGEST_LENGTH])
sha256_context_t ctx;

sha256_init(&ctx);
sha256_update(&ctx, element, SHA256_DIGEST_LENGTH);
sha2xx_update(&ctx, element, SHA256_DIGEST_LENGTH);
sha256_final(&ctx, element);
}

Expand Down Expand Up @@ -419,7 +239,7 @@ void *sha256_chain_with_waypoints(const void *seed,
for (size_t i = 1; i < elements; ++i) {
sha256_context_t ctx;
sha256_init(&ctx);
sha256_update(&ctx, waypoints[(i - 1)].element, SHA256_DIGEST_LENGTH);
sha2xx_update(&ctx, waypoints[(i - 1)].element, SHA256_DIGEST_LENGTH);
sha256_final(&ctx, waypoints[i].element);
waypoints[i].index = i;
}
Expand Down
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