NetBSD/lib/libcrypto/man/openssl_sha.3

.\"	$NetBSD: openssl_sha.3,v 1.1 2001/04/12 10:45:50 itojun Exp $
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.\" ======================================================================
.\"
.IX Title "sha 3"
.TH sha 3 "0.9.6a" "2000-07-22" "OpenSSL"
.UC
.SH "NAME"
\&\s-1SHA1\s0, SHA1_Init, SHA1_Update, SHA1_Final \- Secure Hash Algorithm
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/sha.h>
.Ve
.Vb 2
\& unsigned char *SHA1(const unsigned char *d, unsigned long n,
\&                  unsigned char *md);
.Ve
.Vb 4
\& void SHA1_Init(SHA_CTX *c);
\& void SHA1_Update(SHA_CTX *c, const void *data,
\&                  unsigned long len);
\& void SHA1_Final(unsigned char *md, SHA_CTX *c);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\s-1SHA-1\s0 (Secure Hash Algorithm) is a cryptographic hash function with a
160 bit output.
.PP
\&\fISHA1()\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.
.PP
The following functions may be used if the message is not completely
stored in memory:
.PP
\&\fISHA1_Init()\fR initializes a \fB\s-1SHA_CTX\s0\fR structure.
.PP
\&\fISHA1_Update()\fR can be called repeatedly with chunks of the message to
be hashed (\fBlen\fR bytes at \fBdata\fR).
.PP
\&\fISHA1_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
Applications should use the higher level functions
EVP_DigestInit(3)
etc. instead of calling the hash functions directly.
.PP
The predecessor of \s-1SHA-1\s0, \s-1SHA\s0, is also implemented, but it should be
used only when backward compatibility is required.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fISHA1()\fR returns a pointer to the hash value. 
.PP
\&\fISHA1_Init()\fR, \fISHA1_Update()\fR and \fISHA1_Final()\fR do not return values.
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
\&\s-1SHA:\s0 \s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 \s-1PUB\s0 180 (Secure Hash
Standard),
\&\s-1SHA-1:\s0 \s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 \s-1PUB\s0 180\-1 (Secure Hash
Standard),
\&\s-1ANSI\s0 X9.30
.SH "SEE ALSO"
.IX Header "SEE ALSO"
openssl_ripemd(3), openssl_hmac(3), EVP_DigestInit(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fISHA1()\fR, \fISHA1_Init()\fR, \fISHA1_Update()\fR and \fISHA1_Final()\fR are available in all
versions of SSLeay and OpenSSL.