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dsa(3)				    OpenSSL				dsa(3)

NAME
       dsa - Digital Signature Algorithm

SYNOPSIS
	#include <openssl/dsa.h>
	#include <openssl/engine.h>

	DSA *  DSA_new(void);
	void   DSA_free(DSA *dsa);

	int    DSA_size(const DSA *dsa);

	DSA *  DSA_generate_parameters(int bits, unsigned char *seed,
		       int seed_len, int *counter_ret, unsigned	long *h_ret,
		       void (*callback)(int, int, void *), void	*cb_arg);

	DH *   DSA_dup_DH(const	DSA *r);

	int    DSA_generate_key(DSA *dsa);

	int    DSA_sign(int dummy, const unsigned char *dgst, int len,
		       unsigned	char *sigret, unsigned int *siglen, DSA	*dsa);
	int    DSA_sign_setup(DSA *dsa,	BN_CTX *ctx, BIGNUM **kinvp,
		       BIGNUM **rp);
	int    DSA_verify(int dummy, const unsigned char *dgst,	int len,
		       const unsigned char *sigbuf, int	siglen,	DSA *dsa);

	void DSA_set_default_method(const DSA_METHOD *meth);
	const DSA_METHOD *DSA_get_default_method(void);
	int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
	DSA *DSA_new_method(ENGINE *engine);
	const DSA_METHOD *DSA_OpenSSL(void);

	int DSA_get_ex_new_index(long argl, char *argp,	int (*new_func)(),
		    int	(*dup_func)(), void (*free_func)());
	int DSA_set_ex_data(DSA	*d, int	idx, char *arg);
	char *DSA_get_ex_data(DSA *d, int idx);

	DSA_SIG	*DSA_SIG_new(void);
	void   DSA_SIG_free(DSA_SIG *a);
	int    i2d_DSA_SIG(const DSA_SIG *a, unsigned char **pp);
	DSA_SIG	*d2i_DSA_SIG(DSA_SIG **v, unsigned char	**pp, long length);

	DSA_SIG	*DSA_do_sign(const unsigned char *dgst,	int dlen, DSA *dsa);
	int    DSA_do_verify(const unsigned char *dgst,	int dgst_len,
		    DSA_SIG *sig, DSA *dsa);

	DSA *  d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length);
	DSA *  d2i_DSAPrivateKey(DSA **a, unsigned char	**pp, long length);
	DSA *  d2i_DSAparams(DSA **a, unsigned char **pp, long length);
	int    i2d_DSAPublicKey(const DSA *a, unsigned char **pp);
	int    i2d_DSAPrivateKey(const DSA *a, unsigned	char **pp);
	int    i2d_DSAparams(const DSA *a,unsigned char	**pp);

	int    DSAparams_print(BIO *bp,	const DSA *x);
	int    DSAparams_print_fp(FILE *fp, const DSA *x);
	int    DSA_print(BIO *bp, const	DSA *x,	int off);
	int    DSA_print_fp(FILE *bp, const DSA	*x, int	off);

DESCRIPTION
       These functions implement the Digital Signature Algorithm (DSA).	 The
       generation of shared DSA	parameters is described	in
       DSA_generate_parameters(3); DSA_generate_key(3) describes how to
       generate	a signature key. Signature generation and verification are
       described in DSA_sign(3).

       The DSA structure consists of several BIGNUM components.

	struct
	       {
	       BIGNUM *p;	       // prime	number (public)
	       BIGNUM *q;	       // 160-bit subprime, q |	p-1 (public)
	       BIGNUM *g;	       // generator of subgroup	(public)
	       BIGNUM *priv_key;       // private key x
	       BIGNUM *pub_key;	       // public key y = g^x
	       // ...
	       }
	DSA;

       In public keys, priv_key	is NULL.

       Note that DSA keys may use non-standard DSA_METHOD implementations,
       either directly or by the use of	ENGINE modules.	In some	cases (eg. an
       ENGINE providing	support	for hardware-embedded keys), these BIGNUM
       values will not be used by the implementation or	may be used for
       alternative data	storage. For this reason, applications should
       generally avoid using DSA structure elements directly and instead use
       API functions to	query or modify	keys.

CONFORMING TO
       US Federal Information Processing Standard FIPS 186 (Digital Signature
       Standard, DSS), ANSI X9.30

SEE ALSO
       bn(3), dh(3), err(3), rand(3), rsa(3), sha(3), engine(3), DSA_new(3),
       DSA_size(3), DSA_generate_parameters(3),	DSA_dup_DH(3),
       DSA_generate_key(3), DSA_sign(3), DSA_set_method(3),
       DSA_get_ex_new_index(3),	RSA_print(3)

1.0.1e				  2013-02-11				dsa(3)

NAME | SYNOPSIS | DESCRIPTION | CONFORMING TO | SEE ALSO

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