Add documentation for the -no_alt_chains option for various apps, as well as

[openssl.git] / doc / crypto / sha.pod

diff --git a/doc/crypto/sha.pod b/doc/crypto/sha.pod
index c1d40e97dc2e5ed379c6f03006d98b7ce6abd79d..4c1ab7102289971f47aa55d44eb0f59a90af2bac 100644 (file)
--- a/doc/crypto/sha.pod
+++ b/doc/crypto/sha.pod
@@ -2,35 +2,64 @@
 
 =head1 NAME
 
-sha - Secure Hash Algorithm
+SHA1, SHA1_Init, SHA1_Update, SHA1_Final - Secure Hash Algorithm
 
 =head1 SYNOPSIS
 
  #include <openssl/sha.h>
 
  unsigned char *SHA1(const unsigned char *d, unsigned long n,
-                     unsigned char *md);
+                  unsigned char *md);
 
- void SHA1_Init(SHA_CTX *c);
- void SHA1_Update(SHA_CTX *c, const unsigned char *data,
+ int SHA1_Init(SHA_CTX *c);
+ int SHA1_Update(SHA_CTX *c, const void *data,
                   unsigned long len);
- void SHA1_Final(unsigned char *md, SHA_CTX *c);
+ int SHA1_Final(unsigned char *md, SHA_CTX *c);
 
 =head1 DESCRIPTION
 
 SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
 160 bit output.
 
+SHA1() computes the SHA-1 message digest of the B<n>
+bytes at B<d> and places it in B<md> (which must have space for
+SHA_DIGEST_LENGTH == 20 bytes of output). If B<md> is NULL, the digest
+is placed in a static array.
+
+The following functions may be used if the message is not completely
+stored in memory:
+
+SHA1_Init() initializes a B<SHA_CTX> structure.
+
+SHA1_Update() can be called repeatedly with chunks of the message to
+be hashed (B<len> bytes at B<data>).
+
+SHA1_Final() places the message digest in B<md>, which must have space
+for SHA_DIGEST_LENGTH == 20 bytes of output, and erases the B<SHA_CTX>.
+
+Applications should use the higher level functions
+L<EVP_DigestInit(3)|EVP_DigestInit(3)>
+etc. instead of calling the hash functions directly.
+
 The predecessor of SHA-1, SHA, is also implemented, but it should be
 used only when backward compatibility is required.
 
+=head1 RETURN VALUES
+
+SHA1() returns a pointer to the hash value. 
+
+SHA1_Init(), SHA1_Update() and SHA1_Final() return 1 for success, 0 otherwise.
+
 =head1 CONFORMING TO
 
-US Federal Information Processing Standard FIPS 180 (Secure Hash
-Standard), ANSI X9.30
+SHA: US Federal Information Processing Standard FIPS PUB 180 (Secure Hash
+Standard),
+SHA-1: US Federal Information Processing Standard FIPS PUB 180-1 (Secure Hash
+Standard),
+ANSI X9.30
 
 =head1 SEE ALSO
 
-L<ripemd(3)|ripemd(3)>, L<SHA1(3)|SHA1(3)>, L<SHA1_Init(3)|SHA1_Init(3)>
+L<EVP_DigestInit(3)|EVP_DigestInit(3)>
 
 =cut