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.

The predecessor of SHA-1, SHA, is also implemented, but it should be used only when backward compatibility is required.

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 2000-2016 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>.