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sha256.cpp
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sha256.cpp
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/*
* SHA-256
* Implementation derived from LibTomCrypt (Tom St Denis)
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
*/
#include <string.h>
#include "sha256.h"
#include "internal.h"
namespace sphincs_plus {
const unsigned SHA256_FINALCOUNT_SIZE = 8;
const unsigned NUM_ROUNDS = 64;
static const unsigned long K[NUM_ROUNDS] = {
0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL, 0x3956c25bUL,
0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL, 0xd807aa98UL, 0x12835b01UL,
0x243185beUL, 0x550c7dc3UL, 0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL,
0xc19bf174UL, 0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL, 0x983e5152UL,
0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL, 0xc6e00bf3UL, 0xd5a79147UL,
0x06ca6351UL, 0x14292967UL, 0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL,
0x53380d13UL, 0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL, 0xd192e819UL,
0xd6990624UL, 0xf40e3585UL, 0x106aa070UL, 0x19a4c116UL, 0x1e376c08UL,
0x2748774cUL, 0x34b0bcb5UL, 0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL,
0x682e6ff3UL, 0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
};
/* Various logical functions */
/* Rotate x right by rot bits */
static uint32_t RORc(uint32_t x, int rot) {
rot &= 31; if (rot == 0) return x;
unsigned long right = ((x&0xFFFFFFFFUL)>>rot );
unsigned long left = ((x&0xFFFFFFFFUL)<<(32-rot) );
return (right|left) & 0xFFFFFFFFUL;
}
#define Ch(x,y,z) (z ^ (x & (y ^ z)))
#define Maj(x,y,z) (((x | y) & z) | (x & y))
#define S(x, n) RORc((x),(n))
#define R(x, n) (((x)&0xFFFFFFFFUL)>>(n))
#define Sigma0(x) (S(x, 2) ^ S(x, 13) ^ S(x, 22))
#define Sigma1(x) (S(x, 6) ^ S(x, 11) ^ S(x, 25))
#define Gamma0(x) (S(x, 7) ^ S(x, 18) ^ R(x, 3))
#define Gamma1(x) (S(x, 17) ^ S(x, 19) ^ R(x, 10))
void SHA256_CTX::compress(const void *buf) {
uint32_t S0, S1, S2, S3, S4, S5, S6, S7, W[NUM_ROUNDS], t0, t1, t;
unsigned i;
const unsigned char *p;
/* copy state into S */
S0 = h[0];
S1 = h[1];
S2 = h[2];
S3 = h[3];
S4 = h[4];
S5 = h[5];
S6 = h[6];
S7 = h[7];
/*
* We've been asked to perform the hash computation on this 512-bit string.
* SHA256 interprets that as an array of 16 bigendian 32 bit numbers; copy
* it, and convert it into 16 unsigned long's of the CPU's native format
*/
p = static_cast<const unsigned char *>(buf);
for (i=0; i<16; i++) {
W[i] = bytes_to_ull(p, 4);
p += 4;
}
/* fill W[16..63] */
for (i = 16; i < NUM_ROUNDS; i++) {
W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];
}
/* Compress */
#define RND(a,b,c,d,e,f,g,h,i) \
t0 = h + Sigma1(e) + Ch(e, f, g) + K[i] + W[i]; \
t1 = Sigma0(a) + Maj(a, b, c); \
d += t0; \
h = t0 + t1;
for (i = 0; i < NUM_ROUNDS; ++i) {
RND(S0,S1,S2,S3,S4,S5,S6,S7,i);
t = S7; S7 = S6; S6 = S5; S5 = S4;
S4 = S3; S3 = S2; S2 = S1; S1 = S0; S0 = t;
}
#undef RND
/* feedback */
h[0] += S0;
h[1] += S1;
h[2] += S2;
h[3] += S3;
h[4] += S4;
h[5] += S5;
h[6] += S6;
h[7] += S7;
}
void SHA256_CTX::init(void) {
count = 0;
num = 0;
h[0] = 0x6A09E667UL;
h[1] = 0xBB67AE85UL;
h[2] = 0x3C6EF372UL;
h[3] = 0xA54FF53AUL;
h[4] = 0x510E527FUL;
h[5] = 0x9B05688CUL;
h[6] = 0x1F83D9ABUL;
h[7] = 0x5BE0CD19UL;
}
void SHA256_CTX::init_from_intermediate(const sha256_state init,
unsigned int start_count) {
memcpy( h, init, 8 * sizeof(uint32_t) );
count = 8 * start_count; // SHA256_CTX keeps a bit count
num = 0; // Intermediates always start at a block boundary
}
void SHA256_CTX::update(const void *src, uint64_t input_count)
{
const unsigned char *p = static_cast<const unsigned char*>(src);
count += 8 * input_count;
while (input_count) {
unsigned int this_step = 64 - num;
if (this_step > input_count) this_step = input_count;
const unsigned char *this_block;
if (this_step == 64) {
this_block = p; // The entire block comes directly from the data
// stream. Compress it without copying
} else {
memcpy( &data[num], p, this_step );
if (this_step + num < 64) {
num += this_step;
break;
}
this_block = data; // We had to assemble this block in the
// data buffer - compress it from there
}
p += this_step;
input_count -= this_step;
num = 0;
compress( this_block );
}
}
/*
* Add padding and return the message digest.
*/
void SHA256_CTX::final(unsigned char *digest)
{
unsigned char finalcount[SHA256_FINALCOUNT_SIZE];
ull_to_bytes(finalcount, SHA256_FINALCOUNT_SIZE, count);
update("\200", 1);
if (num > 56) {
update("\0\0\0\0\0\0\0\0", 8);
}
memset( data + num, 0, 56 - num );
num = 56;
update(finalcount, SHA256_FINALCOUNT_SIZE); /* Should cause a compress */
/*
* The final state is an array of uint32_t's; place them as a series
* of bigendian 4-byte words onto the output
*/
for (unsigned i=0; i<8; i++) {
u32_to_bytes( digest + 4*i, h[i] );
}
}
void SHA256_CTX::export_intermediate(sha256_state intermediate) {
memcpy( intermediate, h, 8 * sizeof(uint32_t) );
}
} /* namespace sphincs_plus */