mirror of https://github.com/openssl/openssl
187 lines
6.4 KiB
Plaintext
187 lines
6.4 KiB
Plaintext
=pod
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=head1 NAME
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ECDSA_size, ECDSA_sign, ECDSA_do_sign,
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ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex,
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ECDSA_do_sign_ex - deprecated low-level elliptic curve digital signature algorithm
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(ECDSA) functions
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=head1 SYNOPSIS
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#include <openssl/ecdsa.h>
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The following functions have been deprecated since OpenSSL 3.0, and can be
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hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
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see L<openssl_user_macros(7)>:
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int ECDSA_size(const EC_KEY *eckey);
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int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
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unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
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ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
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EC_KEY *eckey);
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int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen,
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const unsigned char *sig, int siglen, EC_KEY *eckey);
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int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
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const ECDSA_SIG *sig, EC_KEY* eckey);
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ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
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const BIGNUM *kinv, const BIGNUM *rp,
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EC_KEY *eckey);
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int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
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int ECDSA_sign_ex(int type, const unsigned char *dgst, int dgstlen,
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unsigned char *sig, unsigned int *siglen,
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const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey);
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=head1 DESCRIPTION
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See L<ECDSA_SIG_new(3)> for a description of the B<ECDSA_SIG> object.
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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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All of the functions described below are deprecated. Applications should
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use the higher level B<EVP> interface such as L<EVP_DigestSignInit(3)>
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or L<EVP_DigestVerifyInit(3)> instead.
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ECDSA_size() returns the maximum length of a DER encoded ECDSA signature
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created with the private EC key I<eckey>. To obtain the actual signature
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size use L<EVP_PKEY_sign(3)> with a NULL I<sig> parameter.
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ECDSA_sign() computes a digital signature of the I<dgstlen> bytes hash value
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I<dgst> using the private EC key I<eckey>. The DER encoded signatures is
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stored in I<sig> and its length is returned in I<sig_len>. Note: I<sig> must
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point to ECDSA_size(eckey) bytes of memory. The parameter I<type> is currently
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ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with I<kinv>
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and I<rp> set to NULL.
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ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned
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as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign()
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is a wrapper function for ECDSA_do_sign_ex() with I<kinv> and I<rp> set to
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NULL.
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ECDSA_verify() verifies that the signature in I<sig> of size I<siglen> is a
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valid ECDSA signature of the hash value I<dgst> of size I<dgstlen> using the
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public key I<eckey>. The parameter I<type> is ignored.
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ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
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presented in the form of a pointer to an B<ECDSA_SIG> structure.
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The remaining functions utilise the internal I<kinv> and I<r> values used
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during signature computation. Most applications will never need to call these
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and some external ECDSA ENGINE implementations may not support them at all if
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either I<kinv> or I<r> is not NULL.
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ECDSA_sign_setup() may be used to precompute parts of the signing operation.
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I<eckey> is the private EC key and I<ctx> is a pointer to B<BN_CTX> structure
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(or NULL). The precomputed values or returned in I<kinv> and I<rp> and can be
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used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex().
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ECDSA_sign_ex() computes a digital signature of the I<dgstlen> bytes hash value
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I<dgst> using the private EC key I<eckey> and the optional pre-computed values
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I<kinv> and I<rp>. The DER encoded signature is stored in I<sig> and its
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length is returned in I<sig_len>. Note: I<sig> must point to ECDSA_size(eckey)
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bytes of memory. The parameter I<type> is ignored.
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ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is
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returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error).
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=head1 RETURN VALUES
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ECDSA_size() returns the maximum length signature or 0 on error.
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ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful
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or 0 on error.
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ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
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B<ECDSA_SIG> structure or NULL on error.
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ECDSA_verify() and ECDSA_do_verify() return 1 for a valid
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signature, 0 for an invalid signature and -1 on error.
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The error codes can be obtained by L<ERR_get_error(3)>.
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=head1 EXAMPLES
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Creating an ECDSA signature of a given SHA-256 hash value using the
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named curve prime256v1 (aka P-256).
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This example uses deprecated functionality. See L</DESCRIPTION>.
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First step: create an EC_KEY object (note: this part is B<not> ECDSA
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specific)
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int ret;
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ECDSA_SIG *sig;
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EC_KEY *eckey;
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eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
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if (eckey == NULL)
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/* error */
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if (EC_KEY_generate_key(eckey) == 0)
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/* error */
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Second step: compute the ECDSA signature of a SHA-256 hash value
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using ECDSA_do_sign():
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sig = ECDSA_do_sign(digest, 32, eckey);
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if (sig == NULL)
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/* error */
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or using ECDSA_sign():
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unsigned char *buffer, *pp;
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int buf_len;
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buf_len = ECDSA_size(eckey);
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buffer = OPENSSL_malloc(buf_len);
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pp = buffer;
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if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
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/* error */
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Third step: verify the created ECDSA signature using ECDSA_do_verify():
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ret = ECDSA_do_verify(digest, 32, sig, eckey);
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or using ECDSA_verify():
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ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
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and finally evaluate the return value:
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if (ret == 1)
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/* signature ok */
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else if (ret == 0)
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/* incorrect signature */
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else
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/* error */
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=head1 CONFORMING TO
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ANSI X9.62, US Federal Information Processing Standard FIPS186-2
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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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=head1 HISTORY
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All functionality described here was deprecated in OpenSSL 3.0.
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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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