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.\" ========================================================================
.\"
.IX Title "ECDSA_SIG_NEW 3"
.TH ECDSA_SIG_NEW 3 "2023-08-01" "3.0.10" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
ECDSA_SIG_new, ECDSA_SIG_free,
ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0
\&\- Functions for creating, destroying and manipulating ECDSA_SIG objects
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ecdsa.h>
\&
\& ECDSA_SIG *ECDSA_SIG_new(void);
\& void ECDSA_SIG_free(ECDSA_SIG *sig);
\& void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps);
\& const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig);
\& const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig);
\& int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fB\s-1ECDSA_SIG\s0\fR is an opaque structure consisting of two BIGNUMs for the
\&\fIr\fR and \fIs\fR value of an Elliptic Curve Digital Signature Algorithm (\s-1ECDSA\s0) signature
(see \s-1FIPS186\-4\s0 or X9.62).
The \fB\s-1ECDSA_SIG\s0\fR object was mainly used by the deprecated low level functions described in
\&\fBECDSA_sign\fR\|(3), it is still required in order to be able to set or get the values of
\&\fIr\fR and \fIs\fR into or from a signature. This is mainly used for testing purposes as shown
in the \*(L"\s-1EXAMPLES\*(R"\s0.
.PP
\&\fBECDSA_SIG_new()\fR allocates an empty \fB\s-1ECDSA_SIG\s0\fR structure.
Note: before OpenSSL 1.1.0, the \fIr\fR and \fIs\fR components were initialised.
.PP
\&\fBECDSA_SIG_free()\fR frees the \fB\s-1ECDSA_SIG\s0\fR structure \fIsig\fR.
.PP
\&\fBECDSA_SIG_get0()\fR returns internal pointers the \fIr\fR and \fIs\fR values contained
in \fIsig\fR and stores them in \fI*pr\fR and \fI*ps\fR, respectively.
The pointer \fIpr\fR or \fIps\fR can be \s-1NULL,\s0 in which case the corresponding value
is not returned.
.PP
The values \fIr\fR, \fIs\fR can also be retrieved separately by the corresponding
function \fBECDSA_SIG_get0_r()\fR and \fBECDSA_SIG_get0_s()\fR, respectively.
.PP
Non-NULL \fIr\fR and \fIs\fR values can be set on the \fIsig\fR by calling
\&\fBECDSA_SIG_set0()\fR. Calling this function transfers the memory management of the
values to the \fB\s-1ECDSA_SIG\s0\fR object, and therefore the values that have been
passed in should not be freed by the caller.
.PP
See \fBi2d_ECDSA_SIG\fR\|(3) and \fBd2i_ECDSA_SIG\fR\|(3) for information about encoding
and decoding \s-1ECDSA\s0 signatures to/from \s-1DER.\s0
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBECDSA_SIG_new()\fR returns \s-1NULL\s0 if the allocation fails.
.PP
\&\fBECDSA_SIG_set0()\fR returns 1 on success or 0 on failure.
.PP
\&\fBECDSA_SIG_get0_r()\fR and \fBECDSA_SIG_get0_s()\fR return the corresponding value,
or \s-1NULL\s0 if it is unset.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
Extract signature \fIr\fR and \fIs\fR values from a \s-1ECDSA\s0 \fIsignature\fR
of size \fIsignaturelen\fR:
.PP
.Vb 2
\& ECDSA_SIG *obj;
\& const BIGNUM *r, *s;
\&
\& /* Load a signature into the ECDSA_SIG object */
\& obj = d2i_ECDSA_SIG(NULL, &signature, signaturelen);
\& if (obj == NULL)
\&     /* error */
\&
\& r = ECDSA_SIG_get0_r(obj);
\& s = ECDSA_SIG_get0_s(obj);
\& if (r == NULL || s == NULL)
\&     /* error */
\&
\& /* Use BN_bn2binpad() here to convert to r and s into byte arrays */
\&
\& /*
\&  * Do not try to access I<r> or I<s> after calling ECDSA_SIG_free(),
\&  * as they are both freed by this call.
\&  */
\& ECDSA_SIG_free(obj);
.Ve
.PP
Convert \fIr\fR and \fIs\fR byte arrays into an \s-1ECDSA_SIG\s0 \fIsignature\fR of
size \fIsignaturelen\fR:
.PP
.Vb 4
\& ECDSA_SIG *obj = NULL;
\& unsigned char *signature = NULL;
\& size_t signaturelen;
\& BIGNUM *rbn = NULL, *sbn = NULL;
\&
\& obj = ECDSA_SIG_new();
\& if (obj == NULL)
\&     /* error */
\& rbn = BN_bin2bn(r, rlen, NULL);
\& sbn = BN_bin2bn(s, slen, NULL);
\& if (rbn == NULL || sbn == NULL)
\&     /* error */
\&
\& if (!ECDSA_SIG_set0(obj, rbn, sbn))
\&     /* error */
\& /* Set these to NULL since they are now owned by obj */
\& rbn = sbn = NULL;
\&
\& signaturelen = i2d_ECDSA_SIG(obj, &signature);
\& if (signaturelen <= 0)
\&     /* error */
\&
\& /*
\&  * This signature could now be passed to L<EVP_DigestVerify(3)>
\&  * or L<EVP_DigestVerifyFinal(3)>
\&  */
\&
\& BN_free(rbn);
\& BN_free(sbn);
\& OPENSSL_free(signature);
\& ECDSA_SIG_free(obj);
.Ve
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
\&\s-1ANSI X9.62,
US\s0 Federal Information Processing Standard \s-1FIPS186\-4\s0
(Digital Signature Standard, \s-1DSS\s0)
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBEC_KEY_new\fR\|(3),
\&\fBEVP_DigestSignInit\fR\|(3),
\&\fBEVP_DigestVerifyInit\fR\|(3),
\&\fBEVP_PKEY_sign\fR\|(3)
\&\fBi2d_ECDSA_SIG\fR\|(3),
\&\fBd2i_ECDSA_SIG\fR\|(3),
\&\fBECDSA_sign\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2004\-2022 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (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>.