c++ - C中的一种方式哈希函数

Question

有没有什么方法可以计算 C 编程中的单向哈希，它返回结果哈希值的字节数组.. 谢谢..

Answer 1

您可以为此使用 Lib。例如 libgcrypt。

看看这里。这与您在这里提出的问题几乎相同。

对于 libgcrypt11-dev 包 (gcrypt.h)

#include <gcrypt.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv){

  /* Test for arg string */
  if ( argc < 2 ){
    fprintf( stderr, "Usage: %s <string>\n", argv[0] );
    exit( 1 );
  }

  /* Length of message to encrypt */
  int msg_len = strlen( argv[1] );

  /* Length of resulting sha1 hash - gcry_md_get_algo_dlen
   * returns digest lenght for an algo */
  int hash_len = gcry_md_get_algo_dlen( GCRY_MD_SHA1 );

  /* output sha1 hash - this will be binary data */
  unsigned char hash[ hash_len ];

  /* output sha1 hash - converted to hex representation
   * 2 hex digits for every byte + 1 for trailing \0 */
  char *out = (char *) malloc( sizeof(char) * ((hash_len*2)+1) );
  char *p = out;

  /* calculate the SHA1 digest. This is a bit of a shortcut function
   * most gcrypt operations require the creation of a handle, etc. */
  gcry_md_hash_buffer( GCRY_MD_SHA1, hash, argv[1], msg_len );

  /* Convert each byte to its 2 digit ascii
   * hex representation and place in out */
  int i;
  for ( i = 0; i < hash_len; i++, p += 2 ) {
    snprintf ( p, 3, "%02x", hash[i] );
  }

  printf( "%s\n", out );
  free( out );

}