MD5 HMAC与OpenSSL

Question

我试图使用OpenSSL生成MD5 HMAC并且大部分代码都是借用的.生成的hmac不正确:

#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <syslog.h>
#include <string.h>

#include <openssl/engine.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main() 
{
  unsigned char* key = (unsigned char*) "2012121220121212201212122012121220121212201212122012121220121212";
  unsigned char* data = (unsigned char*) "johndoejohndoejohndoejohndoejohndoejohndoejohndoejohndoejohndoejohndoejohndoejohndoe";
  unsigned char* expected = (unsigned char*) "abcd1d87dca34f334786307d0da4fcbd";
  unsigned char* result;
  // unsigned int result_len = 16;
  unsigned int result_len = 16;
  int i;
  static char res_hexstring[32];

  // result = HMAC(EVP_sha256(), key, 4, data, 28, NULL, NULL);
  result = HMAC(EVP_md5(), key, 32, data, 28, NULL, NULL);
  for (i = 0; i < result_len; i++) {
    sprintf(&(res_hexstring[i * 2]), "%02x", result[i]);
  }

  if (strcmp((char*) res_hexstring, (char*) expected) == 0) {
    printf("Test ok, result length %d\n", result_len);
  } else {
    printf("Got %s instead of %s\n", res_hexstring, expected);
  }
}

生成的哈希是不正确的.我希望得到一些反馈,或者有人指出我正确的方向.

Answer 1

HMAC的第三和第五个参数是错误的.您必须传递密钥的长度和数据的长度.在您的示例中,这分别是64和84,而不是32和28.

所以:

-    result = HMAC(EVP_md5(), key, 32, data, 28, NULL, NULL);                                                                                                                                                                         
+    result = HMAC(EVP_md5(), key, 64, data, 84, NULL, NULL); 

通过这种修改,它似乎工作正常.