1=pod
2
3=head1 NAME
4
5MD2, MD4, MD5, MD2_Init, MD2_Update, MD2_Final, MD4_Init, MD4_Update,
6MD4_Final, MD5_Init, MD5_Update, MD5_Final - MD2, MD4, 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 int MD2_Init(MD2_CTX *c);
16 int MD2_Update(MD2_CTX *c, const unsigned char *data,
17                  unsigned long len);
18 int MD2_Final(unsigned char *md, MD2_CTX *c);
19
20
21 #include <openssl/md4.h>
22
23 unsigned char *MD4(const unsigned char *d, unsigned long n,
24                  unsigned char *md);
25
26 int MD4_Init(MD4_CTX *c);
27 int MD4_Update(MD4_CTX *c, const void *data,
28                  unsigned long len);
29 int MD4_Final(unsigned char *md, MD4_CTX *c);
30
31
32 #include <openssl/md5.h>
33
34 unsigned char *MD5(const unsigned char *d, unsigned long n,
35                  unsigned char *md);
36
37 int MD5_Init(MD5_CTX *c);
38 int MD5_Update(MD5_CTX *c, const void *data,
39                  unsigned long len);
40 int MD5_Final(unsigned char *md, MD5_CTX *c);
41
42=head1 DESCRIPTION
43
44MD2, MD4, and MD5 are cryptographic hash functions with a 128 bit output.
45
46MD2(), MD4(), and MD5() compute the MD2, MD4, and MD5 message digest
47of the B<n> bytes at B<d> and place it in B<md> (which must have space
48for MD2_DIGEST_LENGTH == MD4_DIGEST_LENGTH == MD5_DIGEST_LENGTH == 16
49bytes of output). If B<md> is NULL, the digest is placed in a static
50array.
51
52The following functions may be used if the message is not completely
53stored in memory:
54
55MD2_Init() initializes a B<MD2_CTX> structure.
56
57MD2_Update() can be called repeatedly with chunks of the message to
58be hashed (B<len> bytes at B<data>).
59
60MD2_Final() places the message digest in B<md>, which must have space
61for MD2_DIGEST_LENGTH == 16 bytes of output, and erases the B<MD2_CTX>.
62
63MD4_Init(), MD4_Update(), MD4_Final(), MD5_Init(), MD5_Update(), and
64MD5_Final() are analogous using an B<MD4_CTX> and B<MD5_CTX> structure.
65
66Applications should use the higher level functions
67L<EVP_DigestInit(3)|EVP_DigestInit(3)>
68etc. instead of calling the hash functions directly.
69
70=head1 NOTE
71
72MD2, MD4, and MD5 are recommended only for compatibility with existing
73applications. In new applications, SHA-1 or RIPEMD-160 should be
74preferred.
75
76=head1 RETURN VALUES
77
78MD2(), MD4(), and MD5() return pointers to the hash value. 
79
80MD2_Init(), MD2_Update(), MD2_Final(), MD4_Init(), MD4_Update(),
81MD4_Final(), MD5_Init(), MD5_Update(), and MD5_Final() return 1 for
82success, 0 otherwise.
83
84=head1 CONFORMING TO
85
86RFC 1319, RFC 1320, RFC 1321
87
88=head1 SEE ALSO
89
90L<sha(3)|sha(3)>, L<ripemd(3)|ripemd(3)>, L<EVP_DigestInit(3)|EVP_DigestInit(3)>
91
92=head1 HISTORY
93
94MD2(), MD2_Init(), MD2_Update() MD2_Final(), MD5(), MD5_Init(),
95MD5_Update() and MD5_Final() are available in all versions of SSLeay
96and OpenSSL.
97
98MD4(), MD4_Init(), and MD4_Update() are available in OpenSSL 0.9.6 and
99above.
100
101=cut
102