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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.

       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>.

1.1.1a				  2018-11-20			SHA256_INIT(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | CONFORMING TO | SEE ALSO | COPYRIGHT

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