SHA 的实现

android open 的代码

#ifndef _EMBEDDED_SHA_H_
#define _EMBEDDED_SHA_H_

#include <inttypes.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef struct SHA_CTX {
uint64_t count;
uint8_t buf[64];
uint32_t state[5];
} SHA_CTX;

void SHA_init(SHA_CTX *ctx);
void SHA_update(SHA_CTX *ctx, const void* data, int len);
const uint8_t* SHA_final(SHA_CTX *ctx);

/* Convenience method. Returns digest parameter value. */
const uint8_t* SHA(const void *data, int len, uint8_t *digest);

#define SHA_DIGEST_SIZE 20

#ifdef __cplusplus
}
#endif

#endif

#include "sha.h"

#define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))

static void SHA1_transform(SHA_CTX *ctx) {
uint32_t W[80];
uint32_t A, B, C, D, E;
uint8_t *p = ctx->buf;
int t;

for(t = 0; t < 16; ++t) {
uint32_t tmp = *p++ << 24;
tmp |= *p++ << 16;
tmp |= *p++ << 8;
tmp |= *p++;
W[t] = tmp;
}

for(; t < 80; t++) {
W[t] = rol(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
}

A = ctx->state[0];
B = ctx->state[1];
C = ctx->state[2];
D = ctx->state[3];
E = ctx->state[4];

for(t = 0; t < 80; t++) {
uint32_t tmp = rol(5,A) + E + W[t];

if (t < 20)
tmp += (D^(B&(C^D))) + 0x5A827999;
else if ( t < 40)
tmp += (B^C^D) + 0x6ED9EBA1;
else if ( t < 60)
tmp += ((B&C)|(D&(B|C))) + 0x8F1BBCDC;
else
tmp += (B^C^D) + 0xCA62C1D6;

E = D;
D = C;
C = rol(30,B);
B = A;
A = tmp;
}

ctx->state[0] += A;
ctx->state[1] += B;
ctx->state[2] += C;
ctx->state[3] += D;
ctx->state[4] += E;
}

void SHA_init(SHA_CTX *ctx) {
ctx->state[0] = 0x67452301;
ctx->state[1] = 0xEFCDAB89;
ctx->state[2] = 0x98BADCFE;
ctx->state[3] = 0x10325476;
ctx->state[4] = 0xC3D2E1F0;
ctx->count = 0;
}

void SHA_update(SHA_CTX *ctx, const void *data, int len) {
int i = ctx->count % sizeof(ctx->buf);
const uint8_t* p = (const uint8_t*)data;

ctx->count += len;

while (len--) {
ctx->buf[i++] = *p++;
if (i == sizeof(ctx->buf)) {
SHA1_transform(ctx);
i = 0;
}
}
}
const uint8_t *SHA_final(SHA_CTX *ctx) {
uint8_t *p = ctx->buf;
uint64_t cnt = ctx->count * 8;
int i;

SHA_update(ctx, (uint8_t*)"/x80", 1);
while ((ctx->count % sizeof(ctx->buf)) != (sizeof(ctx->buf) - 8)) {
SHA_update(ctx, (uint8_t*)"/0", 1);
}
for (i = 0; i < 8; ++i) {
uint8_t tmp = cnt >> ((7 - i) * 8);
SHA_update(ctx, &tmp, 1);
}

for (i = 0; i < 5; i++) {
uint32_t tmp = ctx->state[i];
*p++ = tmp >> 24;
*p++ = tmp >> 16;
*p++ = tmp >> 8;
*p++ = tmp >> 0;
}

return ctx->buf;
}

/* Convenience function */
const uint8_t* SHA(const void *data, int len, uint8_t *digest) {
const uint8_t *p;
int i;
SHA_CTX ctx;
SHA_init(&ctx);
SHA_update(&ctx, data, len);
p = SHA_final(&ctx);
for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
digest[i] = *p++;
}
return digest;
}

更多相关文章

随机推荐