SYNOPSIS

#include <openssl/sha.h>
unsigned char *SHA1(const unsigned char *d, unsigned long n,
unsigned char *md);
int SHA1_Init(SHA_CTX *c);
int SHA1_Update(SHA_CTX *c, const void *data,
unsigned long len);
int 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() return 1 for success, 0 otherwise.

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

HISTORY

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