【发布时间】：2015-06-27 15:34:03
【问题描述】：
我正在尝试在 C 中复制一个散列函数以用于现有的散列和盐数据库。但是，一旦我减少了 PHP 获取 sha256 哈希的方式以及 c 获取哈希的方式，我就无法获得相同的哈希值。
我已经查看了很多在 C 中获取相同哈希的方法，但我无法完全弄清楚 C 代码有什么问题。 C 代码有效，但输出不一样。
这是我的 PHP 代码的基础，它需要密码并使用单个空格作为盐，其余代码只是可视化并查看输出：
<?php
$salt = ' ';
$password = 'password';
$temp1 = hash_hmac('sha256', $salt, $password, true);
echo "======================\r\n<br>";
echo "password [${password}]\r\n<br>";
echo "salt [${salt}]\r\n<br>";
echo "======================\r\n<br>";
echo gettype($temp1) . "\r\n<br>";
echo "each char as dechex(ord(x))\r\n<br>";
for ($i = 0; $i < strlen($temp1); ++$i) {
$x = dechex(ord($temp1[$i]));
echo "[$x] ";
}
echo "-------------------------\r\n<br>";
echo "base64_encode\r\n<br>";
echo base64_encode($temp1)."\r\n<br>"; ?>
和输出
======================
password [password]
salt [ ]
======================
string
each char as dechex(ord(x))
[52] [33] [c] [6b] [2f] [b6] [22] [cd] [bb] [73] [93] [c2] [5c] [be] [6c] [f4] [d3] [a6] [26] [cc] [ef] [aa] [9] [5e] [e0] [93] [33] [8] [83] [8d] [9] [63] -------------------------
base64_encode
UjMMay+2Is27c5PCXL5s9NOmJszvqgle4JMzCIONCWM=
我正在使用的 C，这是我能找到的最简单的示例。我只是想获得相同的哈希输出。它不必使用这种方法。我还包括了我正在使用的 base64 包含函数以防万一：
#include <string.h>
#include <stdio.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <openssl/pem.h>
#include <openssl/hmac.h>
#define PBKDF2_DIGEST_LENGTH SHA256_DIGEST_LENGTH
#define PBKDF2_SALT_PREFIX ""
#define PBKDF2_SALT_PREFIX_LENGTH strlen(PBKDF2_SALT_PREFIX)
#define PBKDF2_PRF_ALGORITHM_OLD EVP_sha512()
#define PBKDF2_DIGEST_LENGTH_OLD SHA512_DIGEST_LENGTH
#define PBKDF2_SALT_LENGTH 32
#define PBKDF2_RESULT_LENGTH PBKDF2_SALT_PREFIX_LENGTH + (2 * PBKDF2_DIGEST_LENGTH) + PBKDF2_SALT_LENGTH + 2
#define PBKDF2_ROUNDS 1000
#define PBKDF2_PRF_ALGORITHM EVP_sha256()
char *base64encode (const void *b64_encode_this, int encode_this_many_bytes){
BIO *b64_bio, *mem_bio; //Declares two OpenSSL BIOs: a base64 filter and a memory BIO.
BUF_MEM *mem_bio_mem_ptr; //Pointer to a "memory BIO" structure holding our base64 data.
b64_bio = BIO_new(BIO_f_base64()); //Initialize our base64 filter BIO.
mem_bio = BIO_new(BIO_s_mem()); //Initialize our memory sink BIO.
BIO_push(b64_bio, mem_bio); //Link the BIOs by creating a filter-sink BIO chain.
BIO_set_flags(b64_bio, BIO_FLAGS_BASE64_NO_NL); //No newlines every 64 characters or less.
BIO_write(b64_bio, b64_encode_this, encode_this_many_bytes); //Records base64 encoded data.
BIO_flush(b64_bio); //Flush data. Necessary for b64 encoding, because of pad characters.
BIO_get_mem_ptr(mem_bio, &mem_bio_mem_ptr); //Store address of mem_bio's memory structure.
BIO_set_close(mem_bio, BIO_NOCLOSE); //Permit access to mem_ptr after BIOs are destroyed.
BIO_free_all(b64_bio); //Destroys all BIOs in chain, starting with b64 (i.e. the 1st one).
BUF_MEM_grow(mem_bio_mem_ptr, (*mem_bio_mem_ptr).length + 1); //Makes space for end null.
(*mem_bio_mem_ptr).data[(*mem_bio_mem_ptr).length] = '\0'; //Adds null-terminator to tail.
return (*mem_bio_mem_ptr).data; //Returns base-64 encoded data. (See: "buf_mem_st" struct).
}
int main(void)
{
static unsigned char hb[PBKDF2_DIGEST_LENGTH];
static unsigned char hashBlock[PBKDF2_DIGEST_LENGTH];
char *password = "password";
char *salt = " ";
int passes = 1;
PKCS5_PBKDF2_HMAC(password, strlen(password), salt, strlen(salt) , passes, PBKDF2_PRF_ALGORITHM, PBKDF2_DIGEST_LENGTH, hb);
unsigned int i = 0;
printf("printf hex\n");
while(i<32)
{
printf("[%x] ", hb[i]);
++i;
}
printf("\n\n");
printf("base-64 encode\n");
printf("%s \n", base64encode(hb, 32));
return 0;
}
C产生的输出，基本上是为了可视化输出：
./pbkdf2_hack
printf hex
[f8] [8b] [fe] [58] [64] [f8] [a] [ef] [c0] [da] [b2] [97] [42] [ce] [b3] [83] [67] [85] [a5] [f2] [c8] [94] [7b] [2d] [82] [5d] [8a] [a5] [c0] [46] [9a] [24]
base-64 encode
+Iv+WGT4Cu/A2rKXQs6zg2eFpfLIlHstgl2KpcBGmiQ=
编译，以防这里需要有所不同：
gcc pbkdf2_example.c -lcrypto -o pbkdf2_example
【问题讨论】：