xref: /freebsd/secure/lib/libcrypto/man/man3/SHA256_Init.3 (revision 1719886f6d08408b834d270c59ffcfd821c8f63a)
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Title "SHA256_INIT 3ossl"
SHA256_INIT 3ossl "2023-09-19" "3.0.11" "OpenSSL"
For nroff, turn off justification. Always turn off hyphenation; it makes
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"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"
Header "SYNOPSIS" .Vb 1 #include <openssl/sha.h> \& unsigned char *SHA1(const unsigned char *data, size_t count, unsigned char *md_buf); unsigned char *SHA224(const unsigned char *data, size_t count, unsigned char *md_buf); unsigned char *SHA256(const unsigned char *data, size_t count, unsigned char *md_buf); unsigned char *SHA384(const unsigned char *data, size_t count, unsigned char *md_buf); unsigned char *SHA512(const unsigned char *data, size_t count, unsigned char *md_buf); .Ve

The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining \s-1OPENSSL_API_COMPAT\s0 with a suitable version value, see openssl_user_macros\|(7):

.Vb 3 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); \& 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); \& 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); \& 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); \& 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); .Ve

"DESCRIPTION"
Header "DESCRIPTION" All of the functions described on this page except for \s-1SHA1\s0(), \s-1SHA224\s0(), \s-1SHA256\s0(), \s-1SHA384\s0() and \s-1SHA512\s0() are deprecated. Applications should instead use EVP_DigestInit_ex\|(3), EVP_DigestUpdate\|(3) and EVP_DigestFinal_ex\|(3), or the quick one-shot function EVP_Q_digest\|(3). \s-1SHA1\s0(), \s-1SHA224\s0(), \s-1SHA256\s0(), \s-1SHA384\s0(), and \s-1SHA256\s0() can continue to be used. They can also be replaced by, e.g.,

.Vb 1 (EVP_Q_digest(d, n, md, NULL, NULL, "SHA256", NULL) ? md : NULL) .Ve

\s-1SHA-1\s0 (Secure Hash Algorithm) is a cryptographic hash function with a 160 bit output.

\s-1SHA1\s0() computes the \s-1SHA-1\s0 message digest of the n bytes at d and places it in md (which must have space for \s-1SHA_DIGEST_LENGTH\s0 == 20 bytes of output). If md is \s-1NULL,\s0 the digest is placed in a static array. Note: setting md to \s-1NULL\s0 is not thread safe.

The following functions may be used if the message is not completely stored in memory:

\fBSHA1_Init() initializes a \s-1SHA_CTX\s0 structure.

\fBSHA1_Update() can be called repeatedly with chunks of the message to be hashed (len bytes at data).

\fBSHA1_Final() places the message digest in md, which must have space for \s-1SHA_DIGEST_LENGTH\s0 == 20 bytes of output, and erases the \s-1SHA_CTX\s0.

The \s-1SHA224, SHA256, SHA384\s0 and \s-1SHA512\s0 families of functions operate in the same way as for the \s-1SHA1\s0 functions. Note that \s-1SHA224\s0 and \s-1SHA256\s0 use a \fB\s-1SHA256_CTX\s0 object instead of \s-1SHA_CTX\s0. \s-1SHA384\s0 and \s-1SHA512\s0 use \s-1SHA512_CTX\s0. The buffer md must have space for the output from the \s-1SHA\s0 variant being used (defined by \s-1SHA224_DIGEST_LENGTH, SHA256_DIGEST_LENGTH, SHA384_DIGEST_LENGTH\s0 and \s-1SHA512_DIGEST_LENGTH\s0). Also note that, as for the \s-1SHA1\s0() function above, the \s-1SHA224\s0(), \s-1SHA256\s0(), \s-1SHA384\s0() and \s-1SHA512\s0() functions are not thread safe if \fBmd is \s-1NULL.\s0

"RETURN VALUES"
Header "RETURN VALUES" \s-1SHA1\s0(), \s-1SHA224\s0(), \s-1SHA256\s0(), \s-1SHA384\s0() and \s-1SHA512\s0() return a pointer to the hash value.

\fBSHA1_Init(), SHA1_Update() and SHA1_Final() and equivalent \s-1SHA224, SHA256, SHA384\s0 and \s-1SHA512\s0 functions return 1 for success, 0 otherwise.

"CONFORMING TO"
Header "CONFORMING TO" \s-1US\s0 Federal Information Processing Standard \s-1FIPS PUB 180-4\s0 (Secure Hash Standard), \s-1ANSI X9.30\s0
"SEE ALSO"
Header "SEE ALSO" \fBEVP_Q_digest\|(3), \fBEVP_DigestInit\|(3)
"HISTORY"
Header "HISTORY" All of these functions except SHA*() were deprecated in OpenSSL 3.0.
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.