RFC-2104, HMAC algo. with SHA256

From: mklooptbd (mklooptbd@yahoo.com)
Date: 03/31/03

  • Next message: Mok-Kong Shen: "Re: Q: One-way functions" 
    From: mklooptbd@yahoo.com (mklooptbd)
Date: 31 Mar 2003 01:48:10 -0800

    Hello, I've read the RFC-2104 specs and there is one thing I couldn't
    find (maybe missed it), I've put my question prepended with --?>:
    after the key initialization proccess (padding etc.).

    Thanks a bunch.

    --!> this comes directly from the RFC paper, example with MD5

    MD5Init(&context); /* init context for 1st
                                                  * pass */
    MD5Update(&context, k_ipad, 64) /* start with inner pad */
    --?>Does the next line mean I do it every pass in the loop
    --?>(for every 512 bytes for sha256),
    --?>because data isn't short, or only once?
    MD5Update(&context, text, text_len); /* then text of datagram */
    MD5Final(digest, &context); /* finish up 1st pass */
    /*
    * perform outer MD5
    */
    MD5Init(&context); /* init context for 2nd
                                          * pass */
    --?>The following 2 lines are probably done once?
    MD5Update(&context, k_opad, 64); /* start with outer pad */
    MD5Update(&context, digest, 16); /* then results of 1st
                                                  * hash */
    MD5Final(digest, &context); /* finish up 2nd pass */

  • Next message: Mok-Kong Shen: "Re: Q: One-way functions"