5 ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0,
6 ECDSA_SIG_new, ECDSA_SIG_free, i2d_ECDSA_SIG, d2i_ECDSA_SIG, ECDSA_size,
7 ECDSA_sign, ECDSA_do_sign, ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup,
8 ECDSA_sign_ex, ECDSA_do_sign_ex - low level elliptic curve digital signature
9 algorithm (ECDSA) functions
13 #include <openssl/ecdsa.h>
15 ECDSA_SIG *ECDSA_SIG_new(void);
16 void ECDSA_SIG_free(ECDSA_SIG *sig);
17 void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps);
18 const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig);
19 const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig);
20 int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s);
21 int i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp);
22 ECDSA_SIG *d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp, long len);
23 int ECDSA_size(const EC_KEY *eckey);
25 int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
26 unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
27 ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
30 int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen,
31 const unsigned char *sig, int siglen, EC_KEY *eckey);
32 int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
33 const ECDSA_SIG *sig, EC_KEY* eckey);
35 ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
36 const BIGNUM *kinv, const BIGNUM *rp,
38 int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
39 int ECDSA_sign_ex(int type, const unsigned char *dgst, int dgstlen,
40 unsigned char *sig, unsigned int *siglen,
41 const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey);
45 Note: these functions provide a low level interface to ECDSA. Most
46 applications should use the higher level B<EVP> interface such as
47 L<EVP_DigestSignInit(3)> or L<EVP_DigestVerifyInit(3)> instead.
49 B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the
50 B<r> and B<s> value of an ECDSA signature (see X9.62 or FIPS 186-2).
52 ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure. Note: before
53 OpenSSL 1.1.0 the: the B<r> and B<s> components were initialised.
55 ECDSA_SIG_free() frees the B<ECDSA_SIG> structure B<sig>.
57 ECDSA_SIG_get0() returns internal pointers the B<r> and B<s> values contained
58 in B<sig> and stores them in B<*pr> and B<*ps>, respectively.
59 The pointer B<pr> or B<ps> can be NULL, in which case the corresponding value
62 The values B<r>, B<s> can also be retrieved separately by the corresponding
63 function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively.
65 The B<r> and B<s> values can be set by calling ECDSA_SIG_set0() and passing the
66 new values for B<r> and B<s> as parameters to the function. Calling this
67 function transfers the memory management of the values to the ECDSA_SIG object,
68 and therefore the values that have been passed in should not be freed directly
69 after this function has been called.
71 i2d_ECDSA_SIG() creates the DER encoding of the ECDSA signature B<sig> and
72 writes the encoded signature to B<*pp> (note: if B<pp> is NULL i2d_ECDSA_SIG()
73 returns the expected length in bytes of the DER encoded signature).
74 i2d_ECDSA_SIG() returns the length of the DER encoded signature (or 0 on
77 d2i_ECDSA_SIG() decodes a DER encoded ECDSA signature and returns the decoded
78 signature in a newly allocated B<ECDSA_SIG> structure. B<*sig> points to the
79 buffer containing the DER encoded signature of size B<len>.
81 ECDSA_size() returns the maximum length of a DER encoded ECDSA signature
82 created with the private EC key B<eckey>.
84 ECDSA_sign() computes a digital signature of the B<dgstlen> bytes hash value
85 B<dgst> using the private EC key B<eckey>. The DER encoded signatures is
86 stored in B<sig> and its length is returned in B<sig_len>. Note: B<sig> must
87 point to ECDSA_size(eckey) bytes of memory. The parameter B<type> is currently
88 ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with B<kinv>
89 and B<rp> set to NULL.
91 ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned
92 as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign()
93 is a wrapper function for ECDSA_do_sign_ex() with B<kinv> and B<rp> set to
96 ECDSA_verify() verifies that the signature in B<sig> of size B<siglen> is a
97 valid ECDSA signature of the hash value B<dgst> of size B<dgstlen> using the
98 public key B<eckey>. The parameter B<type> is ignored.
100 ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
101 presented in the form of a pointer to an B<ECDSA_SIG> structure.
103 The remaining functions utilise the internal B<kinv> and B<r> values used
104 during signature computation. Most applications will never need to call these
105 and some external ECDSA ENGINE implementations may not support them at all if
106 either B<kinv> or B<r> is not B<NULL>.
108 ECDSA_sign_setup() may be used to precompute parts of the signing operation.
109 B<eckey> is the private EC key and B<ctx> is a pointer to B<BN_CTX> structure
110 (or NULL). The precomputed values or returned in B<kinv> and B<rp> and can be
111 used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex().
113 ECDSA_sign_ex() computes a digital signature of the B<dgstlen> bytes hash value
114 B<dgst> using the private EC key B<eckey> and the optional pre-computed values
115 B<kinv> and B<rp>. The DER encoded signature is stored in B<sig> and its
116 length is returned in B<sig_len>. Note: B<sig> must point to ECDSA_size(eckey)
117 bytes of memory. The parameter B<type> is ignored.
119 ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is
120 returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error).
124 ECDSA_SIG_new() returns NULL if the allocation fails.
126 ECDSA_SIG_set0() returns 1 on success or 0 on failure.
128 ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value,
129 or NULL if it is unset.
131 ECDSA_size() returns the maximum length signature or 0 on error.
133 ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful
136 ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
137 B<ECDSA_SIG> structure or NULL on error.
139 ECDSA_verify() and ECDSA_do_verify() return 1 for a valid
140 signature, 0 for an invalid signature and -1 on error.
141 The error codes can be obtained by L<ERR_get_error(3)>.
145 Creating an ECDSA signature of a given SHA-256 hash value using the
146 named curve prime256v1 (aka P-256).
148 First step: create an EC_KEY object (note: this part is B<not> ECDSA
155 eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
158 if (EC_KEY_generate_key(eckey) == 0)
161 Second step: compute the ECDSA signature of a SHA-256 hash value
162 using ECDSA_do_sign():
164 sig = ECDSA_do_sign(digest, 32, eckey);
168 or using ECDSA_sign():
170 unsigned char *buffer, *pp;
173 buf_len = ECDSA_size(eckey);
174 buffer = OPENSSL_malloc(buf_len);
176 if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
179 Third step: verify the created ECDSA signature using ECDSA_do_verify():
181 ret = ECDSA_do_verify(digest, 32, sig, eckey);
183 or using ECDSA_verify():
185 ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
187 and finally evaluate the return value:
192 /* incorrect signature */
198 ANSI X9.62, US Federal Information Processing Standard FIPS 186-2
199 (Digital Signature Standard, DSS)
204 L<EVP_DigestSignInit(3)>,
205 L<EVP_DigestVerifyInit(3)>
209 Copyright 2004-2018 The OpenSSL Project Authors. All Rights Reserved.
211 Licensed under the OpenSSL license (the "License"). You may not use
212 this file except in compliance with the License. You can obtain a copy
213 in the file LICENSE in the source distribution or at
214 L<https://www.openssl.org/source/license.html>.