| =pod |
| |
| =head1 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 |
| |
| =head1 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); |
| |
| The following functions have been deprecated since OpenSSL 3.0, and can be |
| hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, |
| see L<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); |
| |
| =head1 DESCRIPTION |
| |
| B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the |
| I<r> and I<s> value of an ECDSA signature (see X9.62 or FIPS186-2). |
| |
| ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure. Note: before |
| OpenSSL 1.1.0 the: the I<r> and I<s> components were initialised. |
| |
| ECDSA_SIG_free() frees the B<ECDSA_SIG> structure I<sig>. |
| |
| ECDSA_SIG_get0() returns internal pointers the I<r> and I<s> values contained |
| in I<sig> and stores them in I<*pr> and I<*ps>, respectively. |
| The pointer I<pr> or I<ps> can be NULL, in which case the corresponding value |
| is not returned. |
| |
| The values I<r>, I<s> can also be retrieved separately by the corresponding |
| function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively. |
| |
| Non-NULL I<r> and I<s> values can be set on the I<sig> by calling |
| ECDSA_SIG_set0(). Calling this function transfers the memory management of the |
| values to the B<ECDSA_SIG> object, and therefore the values that have been |
| passed in should not be freed by the caller. |
| |
| See L<i2d_ECDSA_SIG(3)> and L<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 B<EVP> interface such as L<EVP_DigestSignInit(3)> |
| or L<EVP_DigestVerifyInit(3)> instead. |
| |
| ECDSA_size() returns the maximum length of a DER encoded ECDSA signature |
| created with the private EC key I<eckey>. To obtain the actual signature |
| size use L<EVP_PKEY_sign(3)> with a NULL I<sig> parameter. |
| |
| ECDSA_sign() computes a digital signature of the I<dgstlen> bytes hash value |
| I<dgst> using the private EC key I<eckey>. The DER encoded signatures is |
| stored in I<sig> and its length is returned in I<sig_len>. Note: I<sig> must |
| point to ECDSA_size(eckey) bytes of memory. The parameter I<type> is currently |
| ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with I<kinv> |
| and I<rp> set to NULL. |
| |
| ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned |
| as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign() |
| is a wrapper function for ECDSA_do_sign_ex() with I<kinv> and I<rp> set to |
| NULL. |
| |
| ECDSA_verify() verifies that the signature in I<sig> of size I<siglen> is a |
| valid ECDSA signature of the hash value I<dgst> of size I<dgstlen> using the |
| public key I<eckey>. The parameter I<type> is ignored. |
| |
| ECDSA_do_verify() is similar to ECDSA_verify() except the signature is |
| presented in the form of a pointer to an B<ECDSA_SIG> structure. |
| |
| The remaining functions utilise the internal I<kinv> and I<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 I<kinv> or I<r> is not NULL. |
| |
| ECDSA_sign_setup() may be used to precompute parts of the signing operation. |
| I<eckey> is the private EC key and I<ctx> is a pointer to B<BN_CTX> structure |
| (or NULL). The precomputed values or returned in I<kinv> and I<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 I<dgstlen> bytes hash value |
| I<dgst> using the private EC key I<eckey> and the optional pre-computed values |
| I<kinv> and I<rp>. The DER encoded signature is stored in I<sig> and its |
| length is returned in I<sig_len>. Note: I<sig> must point to ECDSA_size(eckey) |
| bytes of memory. The parameter I<type> is ignored. |
| |
| ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is |
| returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error). |
| |
| =head1 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 |
| B<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 L<ERR_get_error(3)>. |
| |
| =head1 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 B<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 */ |
| else |
| /* error */ |
| |
| =head1 CONFORMING TO |
| |
| ANSI X9.62, US Federal Information Processing Standard FIPS186-2 |
| (Digital Signature Standard, DSS) |
| |
| =head1 SEE ALSO |
| |
| L<EC_KEY_new(3)>, |
| L<EVP_DigestSignInit(3)>, |
| L<EVP_DigestVerifyInit(3)>, |
| L<EVP_PKEY_sign(3)> |
| L<i2d_ECDSA_SIG(3)>, |
| L<d2i_ECDSA_SIG(3)> |
| |
| =head1 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. |
| |
| =head1 COPYRIGHT |
| |
| Copyright 2004-2021 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 |
| L<https://www.openssl.org/source/license.html>. |
| |
| =cut |