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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" DSA_sign, DSA_sign_setup, DSA_verify \- DSA signatures .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/dsa.h> \& \& int DSA_sign(int type, const unsigned char *dgst, int len, \& unsigned char *sigret, unsigned int *siglen, DSA *dsa); \& \& int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp); \& \& int DSA_verify(int type, const unsigned char *dgst, int len, \& unsigned char *sigbuf, int siglen, DSA *dsa); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBDSA_sign()\fR computes a digital signature on the \fBlen\fR byte message digest \fBdgst\fR using the private key \fBdsa\fR and places its \s-1ASN.1 DER\s0 encoding at \fBsigret\fR. The length of the signature is places in *\fBsiglen\fR. \fBsigret\fR must point to DSA_size(\fBdsa\fR) bytes of memory. .PP \&\fBDSA_sign_setup()\fR is defined only for backward binary compatibility and should not be used. Since OpenSSL 1.1.0 the \s-1DSA\s0 type is opaque and the output of \&\fBDSA_sign_setup()\fR cannot be used anyway: calling this function will only cause overhead, and does not affect the actual signature (pre\-)computation. .PP \&\fBDSA_verify()\fR verifies that the signature \fBsigbuf\fR of size \fBsiglen\fR matches a given message digest \fBdgst\fR of size \fBlen\fR. \&\fBdsa\fR is the signer's public key. .PP The \fBtype\fR parameter is ignored. .PP The random generator must be seeded when \fBDSA_sign()\fR (or \fBDSA_sign_setup()\fR) is called. If the automatic seeding or reseeding of the OpenSSL \s-1CSPRNG\s0 fails due to external circumstances (see \s-1\fBRAND\s0\fR\|(7)), the operation will fail. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBDSA_sign()\fR and \fBDSA_sign_setup()\fR return 1 on success, 0 on error. \&\fBDSA_verify()\fR returns 1 for a valid signature, 0 for an incorrect signature and \-1 on error. The error codes can be obtained by \&\fBERR_get_error\fR\|(3). .SH "CONFORMING TO" .IX Header "CONFORMING TO" \&\s-1US\s0 Federal Information Processing Standard \s-1FIPS 186\s0 (Digital Signature Standard, \s-1DSS\s0), \s-1ANSI X9.30\s0 .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBDSA_new\fR\|(3), \fBERR_get_error\fR\|(3), \fBRAND_bytes\fR\|(3), \&\fBDSA_do_sign\fR\|(3), \&\s-1\fBRAND\s0\fR\|(7) .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2000\-2019 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (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>.