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/*****************************************************************************
* Copyright (c) 2015-2020 IBM Corporation
* All rights reserved.
* This program and the accompanying materials
* are made available under the terms of the BSD License
* which accompanies this distribution, and is available at
* http://www.opensource.org/licenses/bsd-license.php
*
* Contributors:
* IBM Corporation - initial implementation
*****************************************************************************/
/*
* See: NIST standard for SHA-256 in FIPS PUB 180-4
*/
#include "byteorder.h"
#include "sha256.h"
#include "string.h"
typedef struct _sha256_ctx {
uint32_t h[8];
} sha256_ctx;
static inline uint32_t rotr(uint32_t x, uint8_t n)
{
return (x >> n) | (x << (32 - n));
}
static inline uint32_t Ch(uint32_t x, uint32_t y, uint32_t z)
{
return (x & y) | ((x ^ 0xffffffff) & z);
}
static inline uint32_t Maj(uint32_t x, uint32_t y, uint32_t z)
{
return (x & y) | (x & z) | (y & z);
}
static inline uint32_t sum0(uint32_t x)
{
return rotr(x, 2) ^ rotr(x, 13) ^ rotr(x, 22);
}
static inline uint32_t sum1(uint32_t x)
{
return rotr(x, 6) ^ rotr(x, 11) ^ rotr(x, 25);
}
static inline uint32_t sigma0(uint32_t x)
{
return rotr(x, 7) ^ rotr(x, 18) ^ (x >> 3);
}
static inline uint32_t sigma1(uint32_t x)
{
return rotr(x, 17) ^ rotr(x, 19) ^ (x >> 10);
}
static void sha256_block(uint32_t *w, sha256_ctx *ctx)
{
uint32_t t;
uint32_t a, b, c, d, e, f, g, h;
uint32_t T1, T2;
/*
* FIPS 180-4 4.2.2: SHA256 Constants
*/
static const uint32_t sha_ko[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
};
/*
* FIPS 180-4 6.2.2: step 1
*
* 0 <= i <= 15:
* W(t) = M(t)
* 16 <= i <= 63:
* W(t) = sigma1(W(t-2)) + W(t-7) + sigma0(W(t-15)) + W(t-16)
*/
/* w(0)..w(15) are in big endian format */
for (t = 0; t <= 15; t++)
w[t] = be32_to_cpu(w[t]);
for (t = 16; t <= 63; t++)
w[t] = sigma1(w[t-2]) + w[t-7] + sigma0(w[t-15]) + w[t-16];
/*
* step 2: a = H0, b = H1, c = H2, d = H3, e = H4, f = H5, g = H6, h = H7
*/
a = ctx->h[0];
b = ctx->h[1];
c = ctx->h[2];
d = ctx->h[3];
e = ctx->h[4];
f = ctx->h[5];
g = ctx->h[6];
h = ctx->h[7];
/*
* step 3: For i = 0 to 63:
* T1 = h + sum1(e) + Ch(e,f,g) + K(t) + W(t);
* T2 = sum0(a) + Maj(a,b,c)
* h = g; g = f; f = e; e = d + T1; d = c; c = b; b = a; a + T1 + T2
*/
for (t = 0; t <= 63; t++) {
T1 = h + sum1(e) + Ch(e, f, g) + sha_ko[t] + w[t];
T2 = sum0(a) + Maj(a, b, c);
h = g;
g = f;
f = e;
e = d + T1;
d = c;
c = b;
b = a;
a = T1 + T2;
}
/*
* step 4:
* H0 = a + H0, H1 = b + H1, H2 = c + H2, H3 = d + H3, H4 = e + H4
*/
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;
}
static void sha256_do(sha256_ctx *ctx, const uint8_t *data32, uint32_t length)
{
uint32_t offset;
uint16_t num;
uint32_t bits = 0;
uint32_t w[64];
uint64_t tmp;
/* treat data in 64-byte chunks */
for (offset = 0; length - offset >= 64; offset += 64) {
memcpy(w, data32 + offset, 64);
sha256_block((uint32_t *)w, ctx);
bits += (64 * 8);
}
/* last block with less than 64 bytes */
num = length - offset;
bits += (num << 3);
memcpy(w, data32 + offset, num);
/*
* FIPS 180-4 5.1: Padding the Message
*/
((uint8_t *)w)[num] = 0x80;
if (64 - (num + 1) > 0)
memset( &((uint8_t *)w)[num + 1], 0, 64 - (num + 1));
if (num >= 56) {
/* cannot append number of bits here */
sha256_block((uint32_t *)w, ctx);
memset(w, 0, 60);
}
/* write number of bits to end of block */
tmp = cpu_to_be64(bits);
memcpy(&w[14], &tmp, 8);
sha256_block(w, ctx);
/* need to switch result's endianness */
for (num = 0; num < 8; num++)
ctx->h[num] = cpu_to_be32(ctx->h[num]);
}
void sha256(const uint8_t *data, uint32_t length, uint8_t *hash)
{
sha256_ctx ctx = {
.h = {
/*
* FIPS 180-4: 6.2.1
* -> 5.3.3: initial hash value
*/
0x6a09e667,
0xbb67ae85,
0x3c6ef372,
0xa54ff53a,
0x510e527f,
0x9b05688c,
0x1f83d9ab,
0x5be0cd19
}
};
sha256_do(&ctx, data, length);
memcpy(hash, ctx.h, sizeof(ctx.h));
}
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