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c99209264d
Fixes #19829 Examples added for setting/getting ECDSA SIG related r and s values Reviewed-by: Hugo Landau <hlandau@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/19936)
147 lines
4.2 KiB
Plaintext
147 lines
4.2 KiB
Plaintext
=pod
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=head1 NAME
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ECDSA_SIG_new, ECDSA_SIG_free,
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ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0
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- Functions for creating, destroying and manipulating ECDSA_SIG objects
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=head1 SYNOPSIS
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#include <openssl/ecdsa.h>
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ECDSA_SIG *ECDSA_SIG_new(void);
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void ECDSA_SIG_free(ECDSA_SIG *sig);
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void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps);
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const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig);
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const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig);
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int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s);
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=head1 DESCRIPTION
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B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the
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I<r> and I<s> value of an Elliptic Curve Digital Signature Algorithm (ECDSA) signature
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(see FIPS186-4 or X9.62).
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The B<ECDSA_SIG> object was mainly used by the deprecated low level functions described in
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L<ECDSA_sign(3)>, it is still required in order to be able to set or get the values of
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I<r> and I<s> into or from a signature. This is mainly used for testing purposes as shown
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in the L</EXAMPLES>.
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ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure.
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Note: before OpenSSL 1.1.0, the I<r> and I<s> components were initialised.
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ECDSA_SIG_free() frees the B<ECDSA_SIG> structure I<sig>.
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ECDSA_SIG_get0() returns internal pointers the I<r> and I<s> values contained
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in I<sig> and stores them in I<*pr> and I<*ps>, respectively.
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The pointer I<pr> or I<ps> can be NULL, in which case the corresponding value
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is not returned.
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The values I<r>, I<s> can also be retrieved separately by the corresponding
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function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively.
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Non-NULL I<r> and I<s> values can be set on the I<sig> by calling
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ECDSA_SIG_set0(). Calling this function transfers the memory management of the
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values to the B<ECDSA_SIG> object, and therefore the values that have been
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passed in should not be freed by the caller.
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See L<i2d_ECDSA_SIG(3)> and L<d2i_ECDSA_SIG(3)> for information about encoding
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and decoding ECDSA signatures to/from DER.
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=head1 RETURN VALUES
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ECDSA_SIG_new() returns NULL if the allocation fails.
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ECDSA_SIG_set0() returns 1 on success or 0 on failure.
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ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value,
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or NULL if it is unset.
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=head1 EXAMPLES
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Extract signature I<r> and I<s> values from a ECDSA I<signature>
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of size I<signaturelen>:
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ECDSA_SIG *obj;
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const BIGNUM *r, *s;
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/* Load a signature into the ECDSA_SIG object */
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obj = d2i_ECDSA_SIG(NULL, &signature, signaturelen);
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if (obj == NULL)
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/* error */
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r = ECDSA_SIG_get0_r(obj);
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s = ECDSA_SIG_get0_s(obj);
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if (r == NULL || s == NULL)
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/* error */
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/* Use BN_bn2binpad() here to convert to r and s into byte arrays */
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/*
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* Do not try to access I<r> or I<s> after calling ECDSA_SIG_free(),
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* as they are both freed by this call.
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*/
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ECDSA_SIG_free(obj);
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Convert I<r> and I<s> byte arrays into an ECDSA_SIG I<signature> of
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size I<signaturelen>:
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ECDSA_SIG *obj = NULL;
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unsigned char *signature = NULL;
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size_t signaturelen;
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BIGNUM *rbn = NULL, *sbn = NULL;
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obj = ECDSA_SIG_new();
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if (obj == NULL)
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/* error */
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rbn = BN_bin2bn(r, rlen, NULL);
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sbn = BN_bin2bn(s, slen, NULL);
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if (rbn == NULL || sbn == NULL)
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/* error */
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if (!ECDSA_SIG_set0(obj, rbn, sbn))
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/* error */
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/* Set these to NULL since they are now owned by obj */
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rbn = sbn = NULL;
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signaturelen = i2d_ECDSA_SIG(obj, &signature);
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if (signaturelen <= 0)
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/* error */
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/*
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* This signature could now be passed to L<EVP_DigestVerify(3)>
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* or L<EVP_DigestVerifyFinal(3)>
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*/
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BN_free(rbn);
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BN_free(sbn);
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OPENSSL_free(signature);
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ECDSA_SIG_free(obj);
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=head1 CONFORMING TO
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ANSI X9.62,
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US Federal Information Processing Standard FIPS186-4
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(Digital Signature Standard, DSS)
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=head1 SEE ALSO
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L<EC_KEY_new(3)>,
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L<EVP_DigestSignInit(3)>,
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L<EVP_DigestVerifyInit(3)>,
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L<EVP_PKEY_sign(3)>
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L<i2d_ECDSA_SIG(3)>,
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L<d2i_ECDSA_SIG(3)>,
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L<ECDSA_sign(3)>
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=head1 COPYRIGHT
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Copyright 2004-2022 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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