HMAC-MD5

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yosi izaq
2001-05-21
2002-05-14
  • yosi izaq

    yosi izaq - 2001-05-21

    Hello , I am trying to use your lib to acivate HMAC-MD5 . I do a
        hmacmd5Reset(&param) ;
        hmacmd5Update(&param,(const unsigned char*) "abcdefg",8) ;
        hmacmd5Digest(&param,digest);
    code sequence and I get strange results (data vactor is included in the digest ) .
    I use this key :
    uint32 key[8] ={0x12,0x34,0x56,0x78,0x9a,0xbc,0xde,0xef} ;

    Could anyone please tell me what I'm doing wrong ?
    An alternative would be an example of HMAC_MD5 test.

    TIA

     
    • Bob Deblier

      Bob Deblier - 2001-06-24

      Yo-yo,

      You must pass the key as an array of real 32-bit values, not as an array of 32-bit values containing only 8-bit values; what's more: in the code sample above you don't use the key at all!

      Try something like this instead:

      uint32 key[2] = { 0x12345678, 0x9abcdef }; /* 64 bits */
      uint32 digest[4]; /* 128 bits */

      hmacParam param;

      hmacmd5Setup(&param, key, 64);
      /* you don't need to reset after a setup */
      hmacmd5Update(&param, (const unsigned char*) "abcdefg", 8);
      hmacmd5Digest(&param, &digest);

      This should produce the result you desire.

       
    • Anthony Stramaglia

      Hi,

      As yo-yo was doing, I am also trying to write something using hmac-md5.

      I coded my project successfully in Perl using some hmac-md5 Perl modules, but Perl runs too slowly and I want to recode it in C.

      I have experience with very basic C/C++ programming, and even so, it's been a while. So I'm a little confused as to what to use.

      Basically I'm looking to follow this procedure:

      Read a binary file upon which a key will be used to create an hmac-md5 digest. File is small so it can fit into an array.

      Read a an ASCII text file containing a key or phrase to use as the hmac-md5 key.

      Output should be a 32-character hex text ASCII hash code.

      What functions would I use from hmac-md5 and how would I send the data to them and get the hash to print out?

      I tried using the suggested code in the previous reply to yo-yo but I'm at a loss at this point.

      Any help is appreciated!

       
      • Bob Deblier

        Bob Deblier - 2002-05-10

        See the previous example code to digest your data, once you've read it (in binary format).

        After computing the digest with the md5Digest function, you can print the 32-byte hexdump of the digest with:

        mp32println(4, digest);

         
    • Anthony Stramaglia

      Hi,

      Thanks for the info. However, I tried compiling a small program based on exactly the above code example.

      I used the following compiler lines:

      gcc -DHAVE_CONFIG_H -I. -I. -I.. -I..  -DOPTIMIZE_I586  -O3 -mpentium -march=pentium -fomit-frame-pointer -c cryptest.c

      and

      /bin/sh ../libtool --mode=link gcc  -O3 -mpentium -march=pentium -fomit-frame-pointer  -o cryptest  cryptest.o ../libbeecrypt.la -lrt -lpthread

      and I get the following warnings:

      cryptest.c: In function `main':
      cryptest.c:31: warning: passing arg 1 of `hmacmd5Setup' from incompatible pointer type
      cryptest.c:33: warning: passing arg 1 of `hmacmd5Update' from incompatible pointer type
      cryptest.c:34: warning: passing arg 1 of `hmacmd5Digest' from incompatible pointer type
      cryptest.c:34: warning: passing arg 2 of `hmacmd5Digest' from incompatible pointer type

      The program compiles and links properly, but when I run it, I get a segfault:

      [root@thorne tests]# ./cryptest
      67452301efcdab8998badcfe10325476
      Segmentation fault

      Promising, but still not as I like it :)

      Any ideas what I should do to fix?

      Thanks,
      Anthony

       
      • Anthony Stramaglia

        Ok I think I figured it out.

        The declaration needs to be hmacmd5Param param
        not just hmacParam, since we're doing it for md5.

        Also, hmacmd5Digest(&param, &digest) caused one remaining pointer warning. Changing it to hmacmd5Digest(&param, digest) fixed that.

        Now I get a hash with no segfaults.

        -Anthony

         

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