1=pod
2
3=head1 NAME
4
5SHA1, SHA1_Init, SHA1_Update, SHA1_Final, SHA224, SHA224_Init, SHA224_Update,
6SHA224_Final, SHA256, SHA256_Init, SHA256_Update, SHA256_Final, SHA384,
7SHA384_Init, SHA384_Update, SHA384_Final, SHA512, SHA512_Init, SHA512_Update,
8SHA512_Final - Secure Hash Algorithm
9
10=head1 SYNOPSIS
11
12 #include <openssl/sha.h>
13
14 int SHA1_Init(SHA_CTX *c);
15 int SHA1_Update(SHA_CTX *c, const void *data, size_t len);
16 int SHA1_Final(unsigned char *md, SHA_CTX *c);
17 unsigned char *SHA1(const unsigned char *d, size_t n,
18      unsigned char *md);
19
20 int SHA224_Init(SHA256_CTX *c);
21 int SHA224_Update(SHA256_CTX *c, const void *data, size_t len);
22 int SHA224_Final(unsigned char *md, SHA256_CTX *c);
23 unsigned char *SHA224(const unsigned char *d, size_t n,
24      unsigned char *md);
25
26 int SHA256_Init(SHA256_CTX *c);
27 int SHA256_Update(SHA256_CTX *c, const void *data, size_t len);
28 int SHA256_Final(unsigned char *md, SHA256_CTX *c);
29 unsigned char *SHA256(const unsigned char *d, size_t n,
30      unsigned char *md);
31
32 int SHA384_Init(SHA512_CTX *c);
33 int SHA384_Update(SHA512_CTX *c, const void *data, size_t len);
34 int SHA384_Final(unsigned char *md, SHA512_CTX *c);
35 unsigned char *SHA384(const unsigned char *d, size_t n,
36      unsigned char *md);
37
38 int SHA512_Init(SHA512_CTX *c);
39 int SHA512_Update(SHA512_CTX *c, const void *data, size_t len);
40 int SHA512_Final(unsigned char *md, SHA512_CTX *c);
41 unsigned char *SHA512(const unsigned char *d, size_t n,
42      unsigned char *md);
43
44=head1 DESCRIPTION
45
46Applications should use the higher level functions
47L<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead of calling the hash
48functions directly.
49
50SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
51160 bit output.
52
53SHA1() computes the SHA-1 message digest of the B<n>
54bytes at B<d> and places it in B<md> (which must have space for
55SHA_DIGEST_LENGTH == 20 bytes of output). If B<md> is NULL, the digest
56is placed in a static array. Note: setting B<md> to NULL is B<not thread safe>.
57
58The following functions may be used if the message is not completely
59stored in memory:
60
61SHA1_Init() initializes a B<SHA_CTX> structure.
62
63SHA1_Update() can be called repeatedly with chunks of the message to
64be hashed (B<len> bytes at B<data>).
65
66SHA1_Final() places the message digest in B<md>, which must have space
67for SHA_DIGEST_LENGTH == 20 bytes of output, and erases the B<SHA_CTX>.
68
69The SHA224, SHA256, SHA384 and SHA512 families of functions operate in the
70same way as for the SHA1 functions. Note that SHA224 and SHA256 use a
71B<SHA256_CTX> object instead of B<SHA_CTX>. SHA384 and SHA512 use B<SHA512_CTX>.
72The buffer B<md> must have space for the output from the SHA variant being used
73(defined by SHA224_DIGEST_LENGTH, SHA256_DIGEST_LENGTH, SHA384_DIGEST_LENGTH and
74SHA512_DIGEST_LENGTH). Also note that, as for the SHA1() function above, the
75SHA224(), SHA256(), SHA384() and SHA512() functions are not thread safe if
76B<md> is NULL.
77
78The predecessor of SHA-1, SHA, is also implemented, but it should be
79used only when backward compatibility is required.
80
81=head1 RETURN VALUES
82
83SHA1(), SHA224(), SHA256(), SHA384() and SHA512() return a pointer to the hash
84value. 
85
86SHA1_Init(), SHA1_Update() and SHA1_Final() and equivalent SHA224, SHA256,
87SHA384 and SHA512 functions return 1 for success, 0 otherwise.
88
89=head1 CONFORMING TO
90
91US Federal Information Processing Standard FIPS PUB 180-4 (Secure Hash
92Standard),
93ANSI X9.30
94
95=head1 SEE ALSO
96
97L<ripemd(3)|ripemd(3)>, L<hmac(3)|hmac(3)>, L<EVP_DigestInit(3)|EVP_DigestInit(3)>
98
99=head1 HISTORY
100
101SHA1(), SHA1_Init(), SHA1_Update() and SHA1_Final() are available in all
102versions of SSLeay and OpenSSL.
103
104=cut
105