redhat man page for sha1

sha(3)								      OpenSSL								    sha(3)

NAME
       SHA1, SHA1_Init, SHA1_Update, SHA1_Final - Secure Hash Algorithm

SYNOPSIS
	#include <openssl/sha.h>

	unsigned char *SHA1(const unsigned char *d, unsigned long n,
			 unsigned char *md);

	void SHA1_Init(SHA_CTX *c);
	void SHA1_Update(SHA_CTX *c, const void *data,
			 unsigned long len);
	void SHA1_Final(unsigned char *md, SHA_CTX *c);

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 n bytes at d and places it in md (which must have space for SHA_DIGEST_LENGTH == 20 bytes
       of output). If 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 SHA_CTX structure.

       SHA1_Update() can be called repeatedly with chunks of the message to be hashed (len bytes at data).

       SHA1_Final() places the message digest in md, which must have space for SHA_DIGEST_LENGTH == 20 bytes of output, and erases the SHA_CTX.

       Applications should use the higher level functions 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.

RETURN VALUES
       SHA1() returns a pointer to the hash value.

       SHA1_Init(), SHA1_Update() and SHA1_Final() do not return values.

CONFORMING TO
       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

SEE ALSO
       ripemd(3), hmac(3), EVP_DigestInit(3)

HISTORY
       SHA1(), SHA1_Init(), SHA1_Update() and SHA1_Final() are available in all versions of SSLeay and OpenSSL.

0.9.7a								    2000-02-25								    sha(3)