The following functions have been deprecated since OpenSSL 3.0,
and can be hidden entirely by defining OPENSSL_API_COMPAT with a
suitable version value, see openssl_user_macros(7):
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);
DESCRIPTION¶
ECDSA_SIG is an opaque structure consisting of two BIGNUMs
for the r and s value of an ECDSA signature (see X9.62 or
FIPS186-2).
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.
Non-NULL r and s values can be set on the sig
by calling ECDSA_SIG_set0(). 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 by the
caller.
See i2d_ECDSA_SIG(3) and 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_DigestSignInit(3) or 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 EVP_PKEY_sign(3) with a NULL sig
parameter.
ECDSA_sign() computes a digital signature of the
dgstlen bytes hash value dgst using the private EC key
eckey. The DER encoded signatures is stored in sig and its
length is returned in sig_len. Note: sig must point to
ECDSA_size(eckey) bytes of memory. The parameter type is currently
ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex()
with kinv and rp set to NULL.
ECDSA_do_sign() is similar to ECDSA_sign() except
the signature is returned as a newly allocated ECDSA_SIG structure
(or NULL on error). ECDSA_do_sign() is a wrapper function for
ECDSA_do_sign_ex() with kinv and rp set to NULL.
ECDSA_verify() verifies that the signature in sig of
size siglen is a valid ECDSA signature of the hash value dgst
of size dgstlen using the public key eckey. The parameter
type is ignored.
ECDSA_do_verify() is similar to ECDSA_verify()
except the signature is presented in the form of a pointer to an
ECDSA_SIG structure.
The remaining functions utilise the internal kinv and
r values used during signature computation. Most applications will
never need to call these and some external ECDSA ENGINE implementations may
not support them at all if either kinv or r is not NULL.
ECDSA_sign_setup() may be used to precompute parts of the
signing operation. eckey is the private EC key and ctx is a
pointer to BN_CTX structure (or NULL). The precomputed values or
returned in kinv and rp and can be used in a later call to
ECDSA_sign_ex() or ECDSA_do_sign_ex().
ECDSA_sign_ex() computes a digital signature of the
dgstlen bytes hash value dgst using the private EC key
eckey and the optional pre-computed values kinv and rp.
The DER encoded signature is stored in sig and its length is returned
in sig_len. Note: sig must point to ECDSA_size(eckey) bytes of
memory. The parameter type is ignored.
ECDSA_do_sign_ex() is similar to ECDSA_sign_ex()
except the signature is returned as a newly allocated ECDSA_SIG
structure (or NULL on error).
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 ERR_get_error(3).
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)
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 */
Second step: compute the ECDSA signature of a SHA-256 hash value
using ECDSA_do_sign():
sig = ECDSA_do_sign(digest, 32, eckey);
if (sig == NULL)
/* error */
or using ECDSA_sign():
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 */
Third step: verify the created ECDSA signature using
ECDSA_do_verify():
ret = ECDSA_do_verify(digest, 32, sig, eckey);
or using ECDSA_verify():
ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
and finally evaluate the return value:
if (ret == 1)
/* signature ok */
else if (ret == 0)
/* incorrect signature */
/* error */
ANSI X9.62, US Federal Information Processing Standard FIPS186-2
(Digital Signature Standard, DSS)
SEE ALSO¶
EC_KEY_new(3), EVP_DigestSignInit(3),
EVP_DigestVerifyInit(3), EVP_PKEY_sign(3)
i2d_ECDSA_SIG(3), d2i_ECDSA_SIG(3)
HISTORY¶
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¶
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>.
