NAME
ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0, ECDSA_SIG_new, ECDSA_SIG_free, ECDSA_size, ECDSA_sign, ECDSA_do_sign, ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex, ECDSA_do_sign_ex - low level elliptic curve digital signature algorithm (ECDSA) functions
SYNOPSIS
#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);
Deprecated since OpenSSL 3.0, can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see int ECDSA_size(const EC_KEY *eckey);
int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
EC_KEY *eckey);
int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen,
const unsigned char *sig, int siglen, EC_KEY *eckey);
int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
const ECDSA_SIG *sig, EC_KEY* eckey);
ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
const BIGNUM *kinv, const BIGNUM *rp,
EC_KEY *eckey);
int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
int ECDSA_sign_ex(int type, const unsigned char *dgst, int dgstlen,
unsigned char *sig, unsigned int *siglen,
const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey);
ECDSA_SIG is an opaque structure consisting of two BIGNUMs for the r and s value of an ECDSA signature (see X9.62 or FIPS 186-2). ECDSA_SIG_new() allocates an empty ECDSA_SIG structure. Note: before OpenSSL 1.1.0 the: the r and s components were initialised. ECDSA_SIG_free() frees the ECDSA_SIG structure sig. ECDSA_SIG_get0() returns internal pointers the r and s values contained in sig and stores them in *pr and *ps, respectively. The pointer pr or ps can be NULL, in which case the corresponding value is not returned. The values r, s can also be retrieved separately by the corresponding function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively. The r and s values can be set by calling ECDSA_SIG_set0() and passing the new values for r and s as parameters to the function. Calling this function transfers the memory management of the values to the ECDSA_SIG object, and therefore the values that have been passed in should not be freed directly after this function has been called. See d2i_ECDSA_SIG(3) for information about encoding and decoding ECDSA signatures to/from DER. All of the functions described below are deprecated. Applications should use the higher level EVP interface such as EVP_DigestVerifyInit(3) instead. ECDSA_size() returns the maximum length of a DER encoded ECDSA signature created with the private EC key eckey. To obtain the actual signature size use RETURN VALUES
ECDSA_SIG_new() returns NULL if the allocation fails. ECDSA_SIG_set0() returns 1 on success or 0 on failure. ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value, or NULL if it is unset. ECDSA_size() returns the maximum length signature or 0 on error. ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful or 0 on error. ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated ECDSA_SIG structure or NULL on error. ECDSA_verify() and ECDSA_do_verify() return 1 for a valid signature, 0 for an invalid signature and -1 on error. The error codes can be obtained by EXAMPLES
Creating an ECDSA signature of a given SHA-256 hash value using the named curve prime256v1 (aka P-256). First step: create an EC_KEY object (note: this part is not ECDSA specific) Second step: compute the ECDSA signature of a SHA-256 hash value using ECDSA_do_sign(): or using ECDSA_sign(): Third step: verify the created ECDSA signature using ECDSA_do_verify(): or using ECDSA_verify(): and finally evaluate the return value: ANSI X9.62, US Federal Information Processing Standard FIPS 186-2 (Digital Signature Standard, DSS) EVP_DigestSignInit(3), EVP_PKEY_sign(3) d2i_ECDSA_SIG(3) The ECDSA_size(), ECDSA_sign(), ECDSA_do_sign(), ECDSA_verify(), ECDSA_do_verify(), ECDSA_sign_setup(), ECDSA_sign_ex() and ECDSA_do_sign_ex() functions were deprecated in OpenSSL 3.0. Copyright 2004-2020 The OpenSSL Project Authors. All Rights Reserved. Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.DESCRIPTION
int ret;
ECDSA_SIG *sig;
EC_KEY *eckey;
eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
if (eckey == NULL)
/* error */
if (EC_KEY_generate_key(eckey) == 0)
/* error */
sig = ECDSA_do_sign(digest, 32, eckey);
if (sig == NULL)
/* error */
unsigned char *buffer, *pp;
int buf_len;
buf_len = ECDSA_size(eckey);
buffer = OPENSSL_malloc(buf_len);
pp = buffer;
if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
/* error */
ret = ECDSA_do_verify(digest, 32, sig, eckey);
ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
if (ret == 1)
/* signature ok */
else if (ret == 0)
/* incorrect signature */
else
/* error */CONFORMING TO
SEE ALSO
HISTORY
COPYRIGHT