159191Skris=pod
259191Skris
359191Skris=head1 NAME
459191Skris
559191SkrisMDC2, MDC2_Init, MDC2_Update, MDC2_Final - MDC2 hash function
659191Skris
759191Skris=head1 SYNOPSIS
859191Skris
959191Skris #include <openssl/mdc2.h>
1059191Skris
1159191Skris unsigned char *MDC2(const unsigned char *d, unsigned long n,
1259191Skris                  unsigned char *md);
1359191Skris
14167612Ssimon int MDC2_Init(MDC2_CTX *c);
15167612Ssimon int MDC2_Update(MDC2_CTX *c, const unsigned char *data,
1659191Skris                  unsigned long len);
17167612Ssimon int MDC2_Final(unsigned char *md, MDC2_CTX *c);
1859191Skris
1959191Skris=head1 DESCRIPTION
2059191Skris
2159191SkrisMDC2 is a method to construct hash functions with 128 bit output from
2259191Skrisblock ciphers.  These functions are an implementation of MDC2 with
2359191SkrisDES.
2459191Skris
2559191SkrisMDC2() computes the MDC2 message digest of the B<n>
2659191Skrisbytes at B<d> and places it in B<md> (which must have space for
2759191SkrisMDC2_DIGEST_LENGTH == 16 bytes of output). If B<md> is NULL, the digest
2859191Skrisis placed in a static array.
2959191Skris
3059191SkrisThe following functions may be used if the message is not completely
3159191Skrisstored in memory:
3259191Skris
3359191SkrisMDC2_Init() initializes a B<MDC2_CTX> structure.
3459191Skris
3559191SkrisMDC2_Update() can be called repeatedly with chunks of the message to
3659191Skrisbe hashed (B<len> bytes at B<data>).
3759191Skris
3859191SkrisMDC2_Final() places the message digest in B<md>, which must have space
3959191Skrisfor MDC2_DIGEST_LENGTH == 16 bytes of output, and erases the B<MDC2_CTX>.
4059191Skris
4159191SkrisApplications should use the higher level functions
4259191SkrisL<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead of calling the
4359191Skrishash functions directly.
4459191Skris
4559191Skris=head1 RETURN VALUES
4659191Skris
4759191SkrisMDC2() returns a pointer to the hash value. 
4859191Skris
49167612SsimonMDC2_Init(), MDC2_Update() and MDC2_Final() return 1 for success, 0 otherwise.
5059191Skris
5159191Skris=head1 CONFORMING TO
5259191Skris
5359191SkrisISO/IEC 10118-2, with DES
5459191Skris
5559191Skris=head1 SEE ALSO
5659191Skris
5759191SkrisL<sha(3)|sha(3)>, L<EVP_DigestInit(3)|EVP_DigestInit(3)>
5859191Skris
5959191Skris=head1 HISTORY
6059191Skris
6159191SkrisMDC2(), MDC2_Init(), MDC2_Update() and MDC2_Final() are available since
6259191SkrisSSLeay 0.8.
6359191Skris
6459191Skris=cut
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