Merge branch 'vendor/OPENSSL'
[dragonfly.git] / secure / lib / libcrypto / man / DSA_sign.3
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129.\" ========================================================================
130.\"
131.IX Title "DSA_sign 3"
18ed9402 132.TH DSA_sign 3 "2008-09-27" "0.9.8i" "OpenSSL"
984263bc 133.SH "NAME"
74dab6c2 134DSA_sign, DSA_sign_setup, DSA_verify \- DSA signatures
984263bc 135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/dsa.h>
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139.Ve
140.PP
141.Vb 2
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142\& int DSA_sign(int type, const unsigned char *dgst, int len,
143\& unsigned char *sigret, unsigned int *siglen, DSA *dsa);
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144.Ve
145.PP
146.Vb 2
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147\& int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp,
148\& BIGNUM **rp);
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149.Ve
150.PP
151.Vb 2
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152\& int DSA_verify(int type, const unsigned char *dgst, int len,
153\& unsigned char *sigbuf, int siglen, DSA *dsa);
154.Ve
155.SH "DESCRIPTION"
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156.IX Header "DESCRIPTION"
157\&\fIDSA_sign()\fR computes a digital signature on the \fBlen\fR byte message
158digest \fBdgst\fR using the private key \fBdsa\fR and places its \s-1ASN\s0.1 \s-1DER\s0
984263bc 159encoding at \fBsigret\fR. The length of the signature is places in
8b0cefbb 160*\fBsiglen\fR. \fBsigret\fR must point to DSA_size(\fBdsa\fR) bytes of memory.
984263bc 161.PP
8b0cefbb 162\&\fIDSA_sign_setup()\fR may be used to precompute part of the signing
aac4ff6f 163operation in case signature generation is time\-critical. It expects
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164\&\fBdsa\fR to contain \s-1DSA\s0 parameters. It places the precomputed values
165in newly allocated \fB\s-1BIGNUM\s0\fRs at *\fBkinvp\fR and *\fBrp\fR, after freeing
166the old ones unless *\fBkinvp\fR and *\fBrp\fR are \s-1NULL\s0. These values may
167be passed to \fIDSA_sign()\fR in \fBdsa\->kinv\fR and \fBdsa\->r\fR.
168\&\fBctx\fR is a pre-allocated \fB\s-1BN_CTX\s0\fR or \s-1NULL\s0.
984263bc 169.PP
8b0cefbb 170\&\fIDSA_verify()\fR verifies that the signature \fBsigbuf\fR of size \fBsiglen\fR
984263bc 171matches a given message digest \fBdgst\fR of size \fBlen\fR.
8b0cefbb 172\&\fBdsa\fR is the signer's public key.
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173.PP
174The \fBtype\fR parameter is ignored.
175.PP
8b0cefbb 176The \s-1PRNG\s0 must be seeded before \fIDSA_sign()\fR (or \fIDSA_sign_setup()\fR)
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177is called.
178.SH "RETURN VALUES"
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179.IX Header "RETURN VALUES"
180\&\fIDSA_sign()\fR and \fIDSA_sign_setup()\fR return 1 on success, 0 on error.
181\&\fIDSA_verify()\fR returns 1 for a valid signature, 0 for an incorrect
984263bc 182signature and \-1 on error. The error codes can be obtained by
8b0cefbb 183\&\fIERR_get_error\fR\|(3).
984263bc 184.SH "CONFORMING TO"
74dab6c2 185.IX Header "CONFORMING TO"
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186\&\s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 186 (Digital Signature
187Standard, \s-1DSS\s0), \s-1ANSI\s0 X9.30
188.SH "SEE ALSO"
74dab6c2 189.IX Header "SEE ALSO"
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190\&\fIdsa\fR\|(3), \fIERR_get_error\fR\|(3), \fIrand\fR\|(3),
191\&\fIDSA_do_sign\fR\|(3)
192.SH "HISTORY"
984263bc 193.IX Header "HISTORY"
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194\&\fIDSA_sign()\fR and \fIDSA_verify()\fR are available in all versions of SSLeay.
195\&\fIDSA_sign_setup()\fR was added in SSLeay 0.8.