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/* Copyright (c) 2016-2018 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "buffer.h"
#include "hash-method.h"
#include "hmac.h"
#include "pkcs5.h"
#include <stdint.h>
#include <arpa/inet.h>
static
int pkcs5_pbkdf1(const struct hash_method *hash,
const unsigned char *password, size_t password_len,
const unsigned char *salt, size_t salt_len,
unsigned int iter, uint32_t length,
buffer_t *result)
{
if (length < 1 ||
length > hash->digest_size) return -1;
if (iter < 1) return -1;
unsigned char dk[hash->digest_size];
unsigned char ctx[hash->context_size];
hash->init(ctx);
hash->loop(ctx, password, password_len);
hash->loop(ctx, salt, salt_len);
hash->result(ctx, dk);
length--;
for(;length>0;length--) {
hash->init(ctx);
hash->loop(ctx, dk, hash->digest_size);
hash->result(ctx, dk);
}
buffer_append(result, dk, hash->digest_size);
return 0;
}
static
int pkcs5_pbkdf2(const struct hash_method *hash,
const unsigned char *password, size_t password_len,
const unsigned char *salt, size_t salt_len,
unsigned int iter, uint32_t length,
buffer_t *result)
{
if (length < 1 || iter < 1) return -1;
size_t l = (length + hash->digest_size - 1)/hash->digest_size; /* same as ceil(length/hash->digest_size) */
unsigned char dk[l * hash->digest_size];
unsigned char *block;
struct hmac_context hctx;
unsigned int c,i,t;
unsigned char U_c[hash->digest_size];
for(t = 0; t < l; t++) {
block = &(dk[t*hash->digest_size]);
/* U_1 = PRF(Password, Salt|| INT_BE32(Block_Number)) */
c = htonl(t+1);
hmac_init(&hctx, password, password_len, hash);
hmac_update(&hctx, salt, salt_len);
hmac_update(&hctx, &c, sizeof(c));
hmac_final(&hctx, U_c);
/* block = U_1 ^ .. ^ U_iter */
memcpy(block, U_c, hash->digest_size);
/* U_c = PRF(Password, U_c-1) */
for(c = 1; c < iter; c++) {
hmac_init(&hctx, password, password_len, hash);
hmac_update(&hctx, U_c, hash->digest_size);
hmac_final(&hctx, U_c);
for(i = 0; i < hash->digest_size; i++)
block[i] ^= U_c[i];
}
}
buffer_append(result, dk, length);
return 0;
}
int pkcs5_pbkdf(enum pkcs5_pbkdf_mode mode, const struct hash_method *hash,
const unsigned char *password, size_t password_len,
const unsigned char *salt, size_t salt_len,
unsigned int iterations, uint32_t dk_len,
buffer_t *result)
{
if (mode == PKCS5_PBKDF1)
return pkcs5_pbkdf1(hash,password,password_len,
salt,salt_len,iterations,dk_len,result);
else if (mode == PKCS5_PBKDF2)
return pkcs5_pbkdf2(hash,password,password_len,
salt,salt_len,iterations,dk_len,result);
i_unreached();
}
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