Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / DSA_sign.3
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124.\" ========================================================================
125.\"
126.IX Title "DSA_sign 3"
e3261593 127.TH DSA_sign 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
984263bc 132.SH "NAME"
74dab6c2 133DSA_sign, DSA_sign_setup, DSA_verify \- DSA signatures
984263bc 134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 1
137\& #include <openssl/dsa.h>
e257b235 138\&
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139\& int DSA_sign(int type, const unsigned char *dgst, int len,
140\& unsigned char *sigret, unsigned int *siglen, DSA *dsa);
e257b235 141\&
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142\& int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp,
143\& BIGNUM **rp);
e257b235 144\&
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145\& int DSA_verify(int type, const unsigned char *dgst, int len,
146\& unsigned char *sigbuf, int siglen, DSA *dsa);
147.Ve
148.SH "DESCRIPTION"
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149.IX Header "DESCRIPTION"
150\&\fIDSA_sign()\fR computes a digital signature on the \fBlen\fR byte message
151digest \fBdgst\fR using the private key \fBdsa\fR and places its \s-1ASN\s0.1 \s-1DER\s0
984263bc 152encoding at \fBsigret\fR. The length of the signature is places in
8b0cefbb 153*\fBsiglen\fR. \fBsigret\fR must point to DSA_size(\fBdsa\fR) bytes of memory.
984263bc 154.PP
8b0cefbb 155\&\fIDSA_sign_setup()\fR may be used to precompute part of the signing
e257b235 156operation in case signature generation is time-critical. It expects
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157\&\fBdsa\fR to contain \s-1DSA\s0 parameters. It places the precomputed values
158in newly allocated \fB\s-1BIGNUM\s0\fRs at *\fBkinvp\fR and *\fBrp\fR, after freeing
159the old ones unless *\fBkinvp\fR and *\fBrp\fR are \s-1NULL\s0. These values may
160be passed to \fIDSA_sign()\fR in \fBdsa\->kinv\fR and \fBdsa\->r\fR.
161\&\fBctx\fR is a pre-allocated \fB\s-1BN_CTX\s0\fR or \s-1NULL\s0.
984263bc 162.PP
8b0cefbb 163\&\fIDSA_verify()\fR verifies that the signature \fBsigbuf\fR of size \fBsiglen\fR
984263bc 164matches a given message digest \fBdgst\fR of size \fBlen\fR.
8b0cefbb 165\&\fBdsa\fR is the signer's public key.
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166.PP
167The \fBtype\fR parameter is ignored.
168.PP
8b0cefbb 169The \s-1PRNG\s0 must be seeded before \fIDSA_sign()\fR (or \fIDSA_sign_setup()\fR)
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170is called.
171.SH "RETURN VALUES"
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172.IX Header "RETURN VALUES"
173\&\fIDSA_sign()\fR and \fIDSA_sign_setup()\fR return 1 on success, 0 on error.
174\&\fIDSA_verify()\fR returns 1 for a valid signature, 0 for an incorrect
984263bc 175signature and \-1 on error. The error codes can be obtained by
8b0cefbb 176\&\fIERR_get_error\fR\|(3).
984263bc 177.SH "CONFORMING TO"
74dab6c2 178.IX Header "CONFORMING TO"
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179\&\s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 186 (Digital Signature
180Standard, \s-1DSS\s0), \s-1ANSI\s0 X9.30
181.SH "SEE ALSO"
74dab6c2 182.IX Header "SEE ALSO"
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183\&\fIdsa\fR\|(3), \fIERR_get_error\fR\|(3), \fIrand\fR\|(3),
184\&\fIDSA_do_sign\fR\|(3)
185.SH "HISTORY"
984263bc 186.IX Header "HISTORY"
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187\&\fIDSA_sign()\fR and \fIDSA_verify()\fR are available in all versions of SSLeay.
188\&\fIDSA_sign_setup()\fR was added in SSLeay 0.8.