Edit File: SHA256.3
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "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 .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #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); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" Applications should use the higher level functions \&\fBEVP_DigestInit\fR\|(3) etc. instead of calling the hash functions directly. .PP \&\s-1SHA\-1\s0 (Secure Hash Algorithm) is a cryptographic hash function with a 160 bit output. .PP \&\s-1\fBSHA1\s0()\fR computes the \s-1SHA\-1\s0 message digest of the \fBn\fR bytes at \fBd\fR and places it in \fBmd\fR (which must have space for \&\s-1SHA_DIGEST_LENGTH\s0 == 20 bytes of output). If \fBmd\fR is \s-1NULL,\s0 the digest is placed in a static array. Note: setting \fBmd\fR to \s-1NULL\s0 is \fBnot thread safe\fR. .PP The following functions may be used if the message is not completely stored in memory: .PP \&\fBSHA1_Init()\fR initializes a \fB\s-1SHA_CTX\s0\fR structure. .PP \&\fBSHA1_Update()\fR can be called repeatedly with chunks of the message to be hashed (\fBlen\fR bytes at \fBdata\fR). .PP \&\fBSHA1_Final()\fR places the message digest in \fBmd\fR, which must have space for \s-1SHA_DIGEST_LENGTH\s0 == 20 bytes of output, and erases the \fB\s-1SHA_CTX\s0\fR. .PP 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\fR object instead of \fB\s-1SHA_CTX\s0\fR. \s-1SHA384\s0 and \s-1SHA512\s0 use \fB\s-1SHA512_CTX\s0\fR. The buffer \fBmd\fR 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-1\fBSHA1\s0()\fR function above, the \&\s-1\fBSHA224\s0()\fR, \s-1\fBSHA256\s0()\fR, \s-1\fBSHA384\s0()\fR and \s-1\fBSHA512\s0()\fR functions are not thread safe if \&\fBmd\fR is \s-1NULL.\s0 .PP The predecessor of \s-1SHA\-1, SHA,\s0 is also implemented, but it should be used only when backward compatibility is required. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\s-1\fBSHA1\s0()\fR, \s-1\fBSHA224\s0()\fR, \s-1\fBSHA256\s0()\fR, \s-1\fBSHA384\s0()\fR and \s-1\fBSHA512\s0()\fR return a pointer to the hash value. .PP \&\fBSHA1_Init()\fR, \fBSHA1_Update()\fR and \fBSHA1_Final()\fR and equivalent \s-1SHA224, SHA256, SHA384\s0 and \s-1SHA512\s0 functions return 1 for success, 0 otherwise. .SH "CONFORMING TO" .IX Header "CONFORMING TO" \&\s-1US\s0 Federal Information Processing Standard \s-1FIPS PUB 180\-4\s0 (Secure Hash Standard), \&\s-1ANSI X9.30\s0 .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBripemd\fR\|(3), \fBhmac\fR\|(3), \fBEVP_DigestInit\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\s-1\fBSHA1\s0()\fR, \fBSHA1_Init()\fR, \fBSHA1_Update()\fR and \fBSHA1_Final()\fR are available in all versions of SSLeay and OpenSSL.