SHA1(3)

     sha(3)                 0.9.6h (2000-02-25)                 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

     Page 1                                         (printed 1/19/103)

     sha(3)                 0.9.6h (2000-02-25)                 sha(3)

          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.

     Page 2                                         (printed 1/19/103)