ECDSA_sign (3)
Leading comments
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NAME
ECDSA_SIG_new, ECDSA_SIG_free, i2d_ECDSA_SIG, d2i_ECDSA_SIG, ECDSA_size, ECDSA_sign_setup, ECDSA_sign, ECDSA_sign_ex, ECDSA_verify, ECDSA_do_sign, ECDSA_do_sign_ex, ECDSA_do_verify - Elliptic Curve Digital Signature AlgorithmSYNOPSIS
#include <openssl/ecdsa.h> ECDSA_SIG* ECDSA_SIG_new(void); void ECDSA_SIG_free(ECDSA_SIG *sig); int i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp); ECDSA_SIG* d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp, long len); ECDSA_SIG* ECDSA_do_sign(const unsigned char *dgst, int dgst_len, 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_do_verify(const unsigned char *dgst, int dgst_len, const ECDSA_SIG *sig, EC_KEY* eckey); int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp); int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen, unsigned char *sig, unsigned int *siglen, EC_KEY *eckey); 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); int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen, const unsigned char *sig, int siglen, EC_KEY *eckey); int ECDSA_size(const EC_KEY *eckey); const ECDSA_METHOD* ECDSA_OpenSSL(void); void ECDSA_set_default_method(const ECDSA_METHOD *meth); const ECDSA_METHOD* ECDSA_get_default_method(void); int ECDSA_set_method(EC_KEY *eckey,const ECDSA_METHOD *meth); int ECDSA_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func, CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func); int ECDSA_set_ex_data(EC_KEY *d, int idx, void *arg); void* ECDSA_get_ex_data(EC_KEY *d, int idx);
DESCRIPTION
The
struct { BIGNUM *r; BIGNUM *s; } ECDSA_SIG;
ECDSA_SIG_new() allocates a new
ECDSA_SIG_free() frees the
i2d_ECDSA_SIG() creates the
d2i_ECDSA_SIG() decodes a
ECDSA_size() returns the maximum length of a
ECDSA_sign_setup() may be used to precompute parts of the signing operation. eckey is the private
ECDSA_sign() is wrapper function for ECDSA_sign_ex with kinv and rp set to
ECDSA_sign_ex() computes a digital signature of the dgstlen bytes hash value dgst using the private
ECDSA_verify() verifies that the signature in sig of size siglen is a valid
ECDSA_do_sign() is wrapper function for ECDSA_do_sign_ex with kinv and rp set to
ECDSA_do_sign_ex() computes a digital signature of the dgst_len bytes hash value dgst using the private key eckey and the optional pre-computed values kinv and rp. The signature is returned in a newly allocated
ECDSA_do_verify() verifies that the signature sig is a valid
RETURN VALUES
ECDSA_size() returns the maximum length signature or 0 on error.ECDSA_sign_setup() and ECDSA_sign() return 1 if successful or 0 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 aFirst step: create a
int ret; ECDSA_SIG *sig; EC_KEY *eckey; eckey = EC_KEY_new_by_curve_name(NID_secp192k1); if (eckey == NULL) { /* error */ } if (!EC_KEY_generate_key(eckey)) { /* error */ }
Second step: compute the
sig = ECDSA_do_sign(digest, 20, 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); { /* error */ }
Third step: verify the created
ret = ECDSA_do_verify(digest, 20, sig, eckey);
or using ECDSA_verify
ret = ECDSA_verify(0, digest, 20, buffer, buf_len, eckey);
and finally evaluate the return value:
if (ret == -1) { /* error */ } else if (ret == 0) { /* incorrect signature */ } else /* ret == 1 */ { /* signature ok */ }