NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

       #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    [Toc]    [Back]

       SHA-1 (Secure Hash  Algorithm)  is  a  cryptographic  hash
       function with a 160-bit output.

       The  SHA1()  function 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 can be used if the message is  not
       completely stored in memory:

       The  SHA1_Init() function initializes a SHA_CTX structure.

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

       The SHA1_Final() function 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, such
       as EVP_DigestInit(), 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    [Toc]    [Back]

       The SHA1() function returns a pointer to the hash value.

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

HISTORY    [Toc]    [Back]

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

       SHA conforms to US Federal Information Processing Standard
       FIPS  PUB 180 (Secure Hash Standard). SHA-1 conforms to US
       Federal Information Processing  Standard  FIPS  PUB  180-1
       (Secure Hash Standard), ANSI X9.30

SEE ALSO    [Toc]    [Back]

       Functions: ripemd(3), hmac(3), EVP_DigestInit(3)



                                                           SHA(3)