Manual Pages for UNIX Operating System command usage for man HMAC_CTX_init

OpenSSL                                            hmac(3openssl)



NNNNAAAAMMMMEEEE
     HMAC, HMAC_CTX_init, HMAC_Init, HMAC_Init_ex, HMAC_Update,
     HMAC_Final, HMAC_CTX_cleanup, HMAC_cleanup - HMAC message
     authentication code

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      unsigned char *HMAC(const EVP_MD *evp_md, const void *key,
                    int key_len, const unsigned char *d, int n,
                    unsigned char *md, unsigned int *md_len);

      void HMAC_CTX_init(HMAC_CTX *ctx);

      void HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
                    const EVP_MD *md);
      void HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len,
                        const EVP_MD *md, ENGINE *impl);
      void HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len);
      void HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len);

      void HMAC_CTX_cleanup(HMAC_CTX *ctx);
      void HMAC_cleanup(HMAC_CTX *ctx);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     HMAC is a MAC (message authentication code), i.e. a keyed
     hash function used for message authentication, which is
     based on a hash function.

     HMAC() computes the message authentication code of the nnnn
     bytes at dddd using the hash function eeeevvvvpppp_mmmmdddd and the key kkkkeeeeyyyy
     which is kkkkeeeeyyyy_lllleeeennnn bytes long.

     It places the result in mmmmdddd (which must have space for the
     output of the hash function, which is no more than
     EEEEVVVVPPPP_MMMMAAAAXXXX_MMMMDDDD_SSSSIIIIZZZZEEEE bytes).  If mmmmdddd is NULL, the digest is placed
     in a static array.  The size of the output is placed in
     mmmmdddd_lllleeeennnn, unless it is NNNNUUUULLLLLLLL.

     eeeevvvvpppp_mmmmdddd can be EVP_sha1(), EVP_ripemd160() etc.

     HMAC_CTX_init() initialises a HHHHMMMMAAAACCCC_CCCCTTTTXXXX before first use. It
     must be called.

     HMAC_CTX_cleanup() erases the key and other data from the
     HHHHMMMMAAAACCCC_CCCCTTTTXXXX and releases any associated resources. It must be
     called when an HHHHMMMMAAAACCCC_CCCCTTTTXXXX is no longer required.

     HMAC_cleanup() is an alias for HMAC_CTX_cleanup() included
     for back compatibility with 0.9.6b, it is deprecated.




12/Oct/2010            Last change: 0.9.8o                      1






OpenSSL                                            hmac(3openssl)



     The following functions may be used if the message is not
     completely stored in memory:

     HMAC_Init() initializes a HHHHMMMMAAAACCCC_CCCCTTTTXXXX structure to use the hash
     function eeeevvvvpppp_mmmmdddd and the key kkkkeeeeyyyy which is kkkkeeeeyyyy_lllleeeennnn bytes long.
     It is deprecated and only included for backward
     compatibility with OpenSSL 0.9.6b.

     HMAC_Init_ex() initializes or reuses a HHHHMMMMAAAACCCC_CCCCTTTTXXXX structure to
     use the function eeeevvvvpppp_mmmmdddd and key kkkkeeeeyyyy. Either can be NULL, in
     which case the existing one will be reused. HMAC_CTX_init()
     must have been called before the first use of an HHHHMMMMAAAACCCC_CCCCTTTTXXXX in
     this function. NNNN....BBBB.... HHHHMMMMAAAACCCC_IIIInnnniiiitttt(((()))) hhhhaaaadddd tttthhhhiiiissss uuuunnnnddddooooccccuuuummmmeeeennnntttteeeedddd
     bbbbeeeehhhhaaaavvvviiiioooouuuurrrr iiiinnnn pppprrrreeeevvvviiiioooouuuussss vvvveeeerrrrssssiiiioooonnnnssss ooooffff OOOOppppeeeennnnSSSSSSSSLLLL ---- ffffaaaaiiiilllluuuurrrreeee ttttoooo
     sssswwwwiiiittttcccchhhh ttttoooo HHHHMMMMAAAACCCC_IIIInnnniiiitttt_eeeexxxx(((()))) iiiinnnn pppprrrrooooggggrrrraaaammmmssss tttthhhhaaaatttt eeeexxxxppppeeeecccctttt iiiitttt wwwwiiiillllllll
     ccccaaaauuuusssseeee tttthhhheeeemmmm ttttoooo ssssttttoooopppp wwwwoooorrrrkkkkiiiinnnngggg.

     HMAC_Update() can be called repeatedly with chunks of the
     message to be authenticated (lllleeeennnn bytes at ddddaaaattttaaaa).

     HMAC_Final() places the message authentication code in mmmmdddd,
     which must have space for the hash function output.

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     HMAC() returns a pointer to the message authentication code.

     HMAC_CTX_init(), HMAC_Init_ex(), HMAC_Update(), HMAC_Final()
     and HMAC_CTX_cleanup() do not return values.

CCCCOOOONNNNFFFFOOOORRRRMMMMIIIINNNNGGGG TTTTOOOO
     RFC 2104

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     sha(3), evp(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     HMAC(), HMAC_Init(), HMAC_Update(), HMAC_Final() and
     HMAC_cleanup() are available since SSLeay 0.9.0.

     HMAC_CTX_init(), HMAC_Init_ex() and HMAC_CTX_cleanup() are
     available since OpenSSL 0.9.7.














12/Oct/2010            Last change: 0.9.8o                      2