SHA256_INIT(3)                               OpenSSL                               SHA256_INIT(3)



NAME
       SHA1, SHA1_Init, SHA1_Update, SHA1_Final, SHA224, SHA224_Init, SHA224_Update,
       SHA224_Final, SHA256, SHA256_Init, SHA256_Update, SHA256_Final, SHA384, SHA384_Init,
       SHA384_Update, SHA384_Final, SHA512, SHA512_Init, SHA512_Update, SHA512_Final - Secure
       Hash Algorithm

SYNOPSIS
        #include <openssl/sha.h>

        int SHA1_Init(SHA_CTX *c);
        int SHA1_Update(SHA_CTX *c, const void *data, size_t len);
        int SHA1_Final(unsigned char *md, SHA_CTX *c);
        unsigned char *SHA1(const unsigned char *d, size_t n,
                            unsigned char *md);

        int SHA224_Init(SHA256_CTX *c);
        int SHA224_Update(SHA256_CTX *c, const void *data, size_t len);
        int SHA224_Final(unsigned char *md, SHA256_CTX *c);
        unsigned char *SHA224(const unsigned char *d, size_t n,
                              unsigned char *md);

        int SHA256_Init(SHA256_CTX *c);
        int SHA256_Update(SHA256_CTX *c, const void *data, size_t len);
        int SHA256_Final(unsigned char *md, SHA256_CTX *c);
        unsigned char *SHA256(const unsigned char *d, size_t n,
                              unsigned char *md);

        int SHA384_Init(SHA512_CTX *c);
        int SHA384_Update(SHA512_CTX *c, const void *data, size_t len);
        int SHA384_Final(unsigned char *md, SHA512_CTX *c);
        unsigned char *SHA384(const unsigned char *d, size_t n,
                              unsigned char *md);

        int SHA512_Init(SHA512_CTX *c);
        int SHA512_Update(SHA512_CTX *c, const void *data, size_t len);
        int SHA512_Final(unsigned char *md, SHA512_CTX *c);
        unsigned char *SHA512(const unsigned char *d, size_t n,
                              unsigned char *md);

DESCRIPTION
       Applications should use the higher level functions EVP_DigestInit(3) etc. instead of
       calling the hash functions directly.

       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. Note: setting md to NULL is not thread safe.

       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.

       The SHA224, SHA256, SHA384 and SHA512 families of functions operate in the same way as for
       the SHA1 functions. Note that SHA224 and SHA256 use a SHA256_CTX object instead of
       SHA_CTX. SHA384 and SHA512 use SHA512_CTX.  The buffer md must have space for the output
       from the SHA variant being used (defined by SHA224_DIGEST_LENGTH, SHA256_DIGEST_LENGTH,
       SHA384_DIGEST_LENGTH and SHA512_DIGEST_LENGTH). Also note that, as for the SHA1() function
       above, the SHA224(), SHA256(), SHA384() and SHA512() functions are not thread safe if md
       is NULL.

RETURN VALUES
       SHA1(), SHA224(), SHA256(), SHA384() and SHA512() return a pointer to the hash value.

       SHA1_Init(), SHA1_Update() and SHA1_Final() and equivalent SHA224, SHA256, SHA384 and
       SHA512 functions return 1 for success, 0 otherwise.

CONFORMING TO
       US Federal Information Processing Standard FIPS PUB 180-4 (Secure Hash Standard), ANSI
       X9.30

SEE ALSO
       EVP_DigestInit(3)

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.



1.1.1l                                      2021-08-24                             SHA256_INIT(3)