md5.pod revision 59191 
1=pod
2
3=head1 NAME
4
5MD2, MD5, MD2_Init, MD2_Update, MD2_Final, MD5_Init, MD5_Update,
6MD5_Final - MD2 and MD5 hash functions
7
8=head1 SYNOPSIS
9
10 #include <openssl/md2.h>
11
12 unsigned char *MD2(const unsigned char *d, unsigned long n,
13                  unsigned char *md);
14
15 void MD2_Init(MD2_CTX *c);
16 void MD2_Update(MD2_CTX *c, const unsigned char *data,
17                  unsigned long len);
18 void MD2_Final(unsigned char *md, MD2_CTX *c);
19
20
21 #include <openssl/md5.h>
22
23 unsigned char *MD5(const unsigned char *d, unsigned long n,
24                  unsigned char *md);
25
26 void MD5_Init(MD5_CTX *c);
27 void MD5_Update(MD5_CTX *c, const void *data,
28                  unsigned long len);
29 void MD5_Final(unsigned char *md, MD5_CTX *c);
30
31=head1 DESCRIPTION
32
33MD2 and MD5 are cryptographic hash functions with a 128 bit output.
34
35MD2() and MD5() compute the MD2 and MD5 message digest of the B<n>
36bytes at B<d> and place it in B<md> (which must have space for
37MD2_DIGEST_LENGTH == MD5_DIGEST_LENGTH == 16 bytes of output). If
38B<md> is NULL, the digest is placed in a static array.
39
40The following functions may be used if the message is not completely
41stored in memory:
42
43MD2_Init() initializes a B<MD2_CTX> structure.
44
45MD2_Update() can be called repeatedly with chunks of the message to
46be hashed (B<len> bytes at B<data>).
47
48MD2_Final() places the message digest in B<md>, which must have space
49for MD2_DIGEST_LENGTH == 16 bytes of output, and erases the B<MD2_CTX>.
50
51MD5_Init(), MD5_Update() and MD5_Final() are analogous using an
52B<MD5_CTX> structure.
53
54Applications should use the higher level functions
55L<EVP_DigestInit(3)|EVP_DigestInit(3)>
56etc. instead of calling the hash functions directly.
57
58=head1 NOTE
59
60MD2 and MD5 are recommended only for compatibility with existing
61applications. In new applications, SHA-1 or RIPEMD-160 should be
62preferred.
63
64=head1 RETURN VALUES
65
66MD2() and MD5() return pointers to the hash value. 
67
68MD2_Init(), MD2_Update() MD2_Final(), MD5_Init(), MD5_Update() and
69MD5_Final() do not return values.
70
71=head1 CONFORMING TO
72
73RFC 1319, RFC 1321
74
75=head1 SEE ALSO
76
77L<sha(3)|sha(3)>, L<ripemd(3)|ripemd(3)>, L<EVP_DigestInit(3)|EVP_DigestInit(3)>
78
79=head1 HISTORY
80
81MD2(), MD2_Init(), MD2_Update() MD2_Final(), MD5(), MD5_Init(),
82MD5_Update() and MD5_Final() are available in all versions of SSLeay
83and OpenSSL.
84
85=cut
86