mirror of
https://github.com/openssl/openssl.git
synced 2024-12-14 12:34:02 +08:00
Add ECDSA documentation.
Submitted by: Nils Larsch
This commit is contained in:
parent
ee3a47a994
commit
5075521e75
232
doc/crypto/ecdsa.pod
Normal file
232
doc/crypto/ecdsa.pod
Normal file
@ -0,0 +1,232 @@
|
||||
=pod
|
||||
|
||||
=head1 NAME
|
||||
|
||||
ecdsa - Elliptic Curve Digital Signature Algorithm
|
||||
|
||||
=head1 SYNOPSIS
|
||||
|
||||
#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_DATA* ECDSA_DATA_new(void);
|
||||
ECDSA_DATA* ECDSA_DATA_new_method(ENGINE *eng);
|
||||
void ECDSA_DATA_free(ECDSA_DATA *data);
|
||||
ECDSA_DATA* ecdsa_check(EC_KEY *eckey);
|
||||
|
||||
ECDSA_SIG* ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
|
||||
EC_KEY *eckey);
|
||||
int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
|
||||
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_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);
|
||||
|
||||
=head1 DESCRIPTION
|
||||
|
||||
The B<ECDSA_SIG> structure consists of two BIGNUMs for the
|
||||
r and s value of a ECDSA signature (see X9.62 or FIPS 186-2).
|
||||
|
||||
struct
|
||||
{
|
||||
BIGNUM *r;
|
||||
BIGNUM *s;
|
||||
} ECDSA_SIG;
|
||||
|
||||
ECDSA_SIG_new() allocates a new B<ECDSA_SIG> structure (note: this
|
||||
function also allocates the BIGNUMs) and initialize it.
|
||||
|
||||
ECDSA_SIG_free() frees the B<ECDSA_SIG> structure B<sig>.
|
||||
|
||||
i2d_ECDSA_SIG() creates the DER encoding of the ECDSA signature
|
||||
B<sig> and writes the encoded signature to B<*pp> (note: if B<pp>
|
||||
is NULL B<i2d_ECDSA_SIG> returns the expected length in bytes of
|
||||
the DER encoded signature). B<i2d_ECDSA_SIG> returns the length
|
||||
of the DER encoded signature (or 0 on error).
|
||||
|
||||
d2i_ECDSA_SIG() decodes a DER encoded ECDSA signature and returns
|
||||
the decoded signature in a newly allocated B<ECDSA_SIG> structure.
|
||||
B<*sig> points to the buffer containing the DER encoded signature
|
||||
of size B<len>.
|
||||
|
||||
The B<ECDSA_DATA> structure extends the B<EC_KEY_METH_DATA>
|
||||
structure with ECDSA specific data.
|
||||
|
||||
struct
|
||||
{
|
||||
/* EC_KEY_METH_DATA part */
|
||||
int (*init)(EC_KEY *);
|
||||
void (*finish)(EC_KEY *);
|
||||
/* method (ECDSA) specific part */
|
||||
BIGNUM *kinv; /* signing pre-calc */
|
||||
BIGNUM *r; /* signing pre-calc */
|
||||
...
|
||||
}
|
||||
ECDSA_DATA;
|
||||
|
||||
B<kinv> and B<r> are used to store precomputed values (see
|
||||
B<ECDSA_sign_setup>).
|
||||
|
||||
ECDSA_DATA_new() returns a newly allocated and initialized
|
||||
B<ECDSA_DATA> structure (or NULL on error).
|
||||
|
||||
ECDSA_DATA_free() frees the B<ECDSA_DATA> structure B<data>.
|
||||
|
||||
ecdsa_check() returns the pointer to the B<ECDSA_DATA>
|
||||
structure in B<EC_KEY-E<gt>meth_data> (if B<EC_KEY-E<gt>meth_data>
|
||||
is not a pointer to a B<ECDSA_DATA> structure then the old
|
||||
data is freed and a new B<ECDSA_DATA> structure is allocated
|
||||
using B<ECDSA_DATA_new>).
|
||||
|
||||
ECDSA_size() returns the maximum length of a DER encoded
|
||||
ECDSA signature created with the private EC key B<eckey>.
|
||||
|
||||
ECDSA_sign_setup() may be used to precompute parts of the
|
||||
signing operation. B<eckey> is the private EC key and B<ctx>
|
||||
is a pointer to B<BN_CTX> structure (or NULL). The precomputed
|
||||
values or returned in B<kinv> and B<rp> and can be used in a
|
||||
later call to B<ECDSA_sign> or B<ECDSA_do_sign> when placed in
|
||||
B<ECDSA_DATA-E<gt>kinv> and B<ECDSA_DATA-E<gt>r>.
|
||||
|
||||
ECDSA_sign() computes a digital signature of the B<dgstlen> bytes
|
||||
hash value B<dgst> using the private EC key B<eckey> and places
|
||||
the DER encoding of the created signature in B<sig>. The length
|
||||
of the created signature is returned in B<sig_len>. Note: B<sig>
|
||||
must point to B<ECDSA_size> bytes of memory. The parameter B<type>
|
||||
is ignored.
|
||||
|
||||
ECDSA_verify() verifies that the signature in B<sig> of size
|
||||
B<siglen> is a valid ECDSA signature of the hash value
|
||||
value B<dgst> of size B<dgstlen> using the public key B<eckey>.
|
||||
The parameter B<type> is ignored.
|
||||
|
||||
ECDSA_do_sign() computes a digital signature of the B<dgst_len>
|
||||
bytes hash value B<dgst> using the private key B<eckey> and
|
||||
returns the signature in a newly allocated B<ECDSA_SIG> structure
|
||||
(or NULL on error).
|
||||
|
||||
ECDSA_do_verify() verifies that the signature B<sig> is a valid
|
||||
ECDSA signature of the hash value B<dgst> of size B<dgst_len>
|
||||
using the public key B<eckey>.
|
||||
|
||||
=head1 RETURN VALUES
|
||||
|
||||
ECDSA_size() returns the maximum length signature or 0 on error.
|
||||
|
||||
ECDSA_sign_setup() and ECDSA_sign() return 1 if successful or -1
|
||||
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)|ERR_get_error(3)>.
|
||||
|
||||
=head1 EXAMPLES
|
||||
|
||||
Creating a ECDSA signature of given SHA-1 hash value using the
|
||||
named curve secp192k1.
|
||||
|
||||
First step: create a EC_KEY object (note: this part is B<not> ECDSA
|
||||
specific)
|
||||
|
||||
int ret;
|
||||
ECDSA_SIG *sig;
|
||||
EC_KEY *eckey = EC_KEY_new();
|
||||
if (eckey == NULL)
|
||||
{
|
||||
/* error */
|
||||
}
|
||||
key->group = EC_GROUP_new_by_nid(NID_secp192k1);
|
||||
if (key->group == NULL)
|
||||
{
|
||||
/* error */
|
||||
}
|
||||
if (!EC_KEY_generate_key(eckey))
|
||||
{
|
||||
/* error */
|
||||
}
|
||||
|
||||
Second step: compute the ECDSA signature of a SHA-1 hash value
|
||||
using B<ECDSA_do_sign>
|
||||
|
||||
sig = ECDSA_do_sign(digest, 20, eckey);
|
||||
if (sig == NULL)
|
||||
{
|
||||
/* error */
|
||||
}
|
||||
|
||||
or using B<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 ECDSA signature using B<ECDSA_do_verify>
|
||||
|
||||
ret = ECDSA_do_verify(digest, 20, sig, eckey);
|
||||
|
||||
or using B<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 */
|
||||
}
|
||||
|
||||
=head1 CONFORMING TO
|
||||
|
||||
ANSI X9.62, US Federal Information Processing Standard FIPS 186-2
|
||||
(Digital Signature Standard, DSS)
|
||||
|
||||
=head1 SEE ALSO
|
||||
|
||||
L<dsa(3)|dsa(3)>, L<rsa(3)|rsa(3)>
|
||||
|
||||
=head1 HISTORY
|
||||
|
||||
The ecdsa implementation was first introduced in OpenSSL 0.9.8
|
||||
|
||||
=head1 AUTHOR
|
||||
|
||||
Nils Larsch for the OpenSSL project (http://www.openssl.org).
|
||||
|
||||
=cut
|
Loading…
Reference in New Issue
Block a user