5 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 Algorithm
9 #include <openssl/ecdsa.h>
11 ECDSA_SIG* ECDSA_SIG_new(void);
12 void ECDSA_SIG_free(ECDSA_SIG *sig);
13 int i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp);
14 ECDSA_SIG* d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp,
17 ECDSA_SIG* ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
19 ECDSA_SIG* ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
20 const BIGNUM *kinv, const BIGNUM *rp,
22 int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
23 const ECDSA_SIG *sig, EC_KEY* eckey);
24 int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx,
25 BIGNUM **kinv, BIGNUM **rp);
26 int ECDSA_sign(int type, const unsigned char *dgst,
27 int dgstlen, unsigned char *sig,
28 unsigned int *siglen, EC_KEY *eckey);
29 int ECDSA_sign_ex(int type, const unsigned char *dgst,
30 int dgstlen, unsigned char *sig,
31 unsigned int *siglen, const BIGNUM *kinv,
32 const BIGNUM *rp, EC_KEY *eckey);
33 int ECDSA_verify(int type, const unsigned char *dgst,
34 int dgstlen, const unsigned char *sig,
35 int siglen, EC_KEY *eckey);
36 int ECDSA_size(const EC_KEY *eckey);
38 const ECDSA_METHOD* ECDSA_OpenSSL(void);
39 void ECDSA_set_default_method(const ECDSA_METHOD *meth);
40 const ECDSA_METHOD* ECDSA_get_default_method(void);
41 int ECDSA_set_method(EC_KEY *eckey,const ECDSA_METHOD *meth);
45 The B<ECDSA_SIG> structure consists of two BIGNUMs for the
46 r and s value of a ECDSA signature (see X9.62 or FIPS 186-2).
54 ECDSA_SIG_new() allocates a new B<ECDSA_SIG> structure (note: this
55 function also allocates the BIGNUMs) and initialize it.
57 ECDSA_SIG_free() frees the B<ECDSA_SIG> structure B<sig>.
59 i2d_ECDSA_SIG() creates the DER encoding of the ECDSA signature
60 B<sig> and writes the encoded signature to B<*pp> (note: if B<pp>
61 is NULL B<i2d_ECDSA_SIG> returns the expected length in bytes of
62 the DER encoded signature). B<i2d_ECDSA_SIG> returns the length
63 of the DER encoded signature (or 0 on error).
65 d2i_ECDSA_SIG() decodes a DER encoded ECDSA signature and returns
66 the decoded signature in a newly allocated B<ECDSA_SIG> structure.
67 B<*sig> points to the buffer containing the DER encoded signature
70 ECDSA_size() returns the maximum length of a DER encoded
71 ECDSA signature created with the private EC key B<eckey>.
73 ECDSA_sign_setup() may be used to precompute parts of the
74 signing operation. B<eckey> is the private EC key and B<ctx>
75 is a pointer to B<BN_CTX> structure (or NULL). The precomputed
76 values or returned in B<kinv> and B<rp> and can be used in a
77 later call to B<ECDSA_sign_ex> or B<ECDSA_do_sign_ex>.
79 ECDSA_sign() is wrapper function for ECDSA_sign_ex with B<kinv>
80 and B<rp> set to NULL.
82 ECDSA_sign_ex() computes a digital signature of the B<dgstlen> bytes
83 hash value B<dgst> using the private EC key B<eckey> and the optional
84 pre-computed values B<kinv> and B<rp>. The DER encoded signatures is
85 stored in B<sig> and it's length is returned in B<sig_len>. Note: B<sig>
86 must point to B<ECDSA_size> bytes of memory. The parameter B<type>
89 ECDSA_verify() verifies that the signature in B<sig> of size
90 B<siglen> is a valid ECDSA signature of the hash value
91 B<dgst> of size B<dgstlen> using the public key B<eckey>.
92 The parameter B<type> is ignored.
94 ECDSA_do_sign() is wrapper function for ECDSA_do_sign_ex with B<kinv>
95 and B<rp> set to NULL.
97 ECDSA_do_sign_ex() computes a digital signature of the B<dgst_len>
98 bytes hash value B<dgst> using the private key B<eckey> and the
99 optional pre-computed values B<kinv> and B<rp>. The signature is
100 returned in a newly allocated B<ECDSA_SIG> structure (or NULL on error).
102 ECDSA_do_verify() verifies that the signature B<sig> is a valid
103 ECDSA signature of the hash value B<dgst> of size B<dgst_len>
104 using the public key B<eckey>.
108 ECDSA_size() returns the maximum length signature or 0 on error.
110 ECDSA_sign_setup() and ECDSA_sign() return 1 if successful or 0
113 ECDSA_verify() and ECDSA_do_verify() return 1 for a valid
114 signature, 0 for an invalid signature and -1 on error.
115 The error codes can be obtained by L<ERR_get_error(3)>.
119 Creating a ECDSA signature of given SHA-1 hash value using the
120 named curve secp192k1.
122 First step: create a EC_KEY object (note: this part is B<not> ECDSA
128 eckey = EC_KEY_new_by_curve_name(NID_secp192k1);
133 if (!EC_KEY_generate_key(eckey))
138 Second step: compute the ECDSA signature of a SHA-1 hash value
139 using B<ECDSA_do_sign>
141 sig = ECDSA_do_sign(digest, 20, eckey);
147 or using B<ECDSA_sign>
149 unsigned char *buffer, *pp;
151 buf_len = ECDSA_size(eckey);
152 buffer = OPENSSL_malloc(buf_len);
154 if (!ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey);
159 Third step: verify the created ECDSA signature using B<ECDSA_do_verify>
161 ret = ECDSA_do_verify(digest, 20, sig, eckey);
163 or using B<ECDSA_verify>
165 ret = ECDSA_verify(0, digest, 20, buffer, buf_len, eckey);
167 and finally evaluate the return value:
175 /* incorrect signature */
184 ANSI X9.62, US Federal Information Processing Standard FIPS 186-2
185 (Digital Signature Standard, DSS)