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.\" ========================================================================
.\"
.IX Title "DSA_do_sign 3"
.TH DSA_do_sign 3 "2019-12-20" "1.0.2u" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
DSA_do_sign, DSA_do_verify \- raw DSA signature operations
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dsa.h>
\&
\& DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
\&
\& int DSA_do_verify(const unsigned char *dgst, int dgst_len,
\&             DSA_SIG *sig, DSA *dsa);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBDSA_do_sign()\fR computes a digital signature on the \fBlen\fR byte message
digest \fBdgst\fR using the private key \fBdsa\fR and returns it in a
newly allocated \fB\s-1DSA_SIG\s0\fR structure.
.PP
\&\fBDSA_sign_setup\fR\|(3) may be used to precompute part
of the signing operation for each signature in case signature generation
is time-critical.
.PP
\&\fBDSA_do_verify()\fR verifies that the signature \fBsig\fR matches a given
message digest \fBdgst\fR of size \fBlen\fR.  \fBdsa\fR is the signer's public
key.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBDSA_do_sign()\fR returns the signature, \s-1NULL\s0 on error.  \fBDSA_do_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 "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBdsa\fR\|(3), \fBERR_get_error\fR\|(3), \fBrand\fR\|(3),
\&\fBDSA_SIG_new\fR\|(3),
\&\fBDSA_sign\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fBDSA_do_sign()\fR and \fBDSA_do_verify()\fR were added in OpenSSL 0.9.3.