/* crypto/dh/dh.h */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#ifndef HEADER_DH_H
#define HEADER_DH_H

#include <openssl/e_os2.h>

#ifdef OPENSSL_NO_DH
#error DH is disabled.
#endif

#ifndef OPENSSL_NO_BIO
#include <openssl/bio.h>
#endif
#include <openssl/ossl_typ.h>
#ifndef OPENSSL_NO_DEPRECATED
#include <openssl/bn.h>
#endif
	
#ifndef OPENSSL_DH_MAX_MODULUS_BITS
# define OPENSSL_DH_MAX_MODULUS_BITS	10000
#endif

#define DH_FLAG_CACHE_MONT_P     0x01
#define DH_FLAG_NO_EXP_CONSTTIME 0x02 /* new with 0.9.7h; the built-in DH
                                       * implementation now uses constant time
                                       * modular exponentiation for secret exponents
                                       * by default. This flag causes the
                                       * faster variable sliding window method to
                                       * be used for all exponents.
                                       */

#ifdef  __cplusplus
extern "C" {
#endif

/* Already defined in ossl_typ.h */
/* typedef struct dh_st DH; */
/* typedef struct dh_method DH_METHOD; */

struct dh_method
	{
	const char *name;
	/* Methods here */
	int (*generate_key)(DH *dh);
	int (*compute_key)(unsigned char *key,const BIGNUM *pub_key,DH *dh);
	int (*bn_mod_exp)(const DH *dh, BIGNUM *r, const BIGNUM *a,
				const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,
				BN_MONT_CTX *m_ctx); /* Can be null */

	int (*init)(DH *dh);
	int (*finish)(DH *dh);
	int flags;
	char *app_data;
	/* If this is non-NULL, it will be used to generate parameters */
	int (*generate_params)(DH *dh, int prime_len, int generator, BN_GENCB *cb);
	};

struct dh_st
	{
	/* This first argument is used to pick up errors when
	 * a DH is passed instead of a EVP_PKEY */
	int pad;
	int version;
	BIGNUM *p;
	BIGNUM *g;
	long length; /* optional */
	BIGNUM *pub_key;	/* g^x */
	BIGNUM *priv_key;	/* x */

	int flags;
	BN_MONT_CTX *method_mont_p;
	/* Place holders if we want to do X9.42 DH */
	BIGNUM *q;
	BIGNUM *j;
	unsigned char *seed;
	int seedlen;
	BIGNUM *counter;

	int references;
	CRYPTO_EX_DATA ex_data;
	const DH_METHOD *meth;
	ENGINE *engine;
	};

#define DH_GENERATOR_2		2
/* #define DH_GENERATOR_3	3 */
#define DH_GENERATOR_5		5

/* DH_check error codes */
#define DH_CHECK_P_NOT_PRIME		0x01
#define DH_CHECK_P_NOT_SAFE_PRIME	0x02
#define DH_UNABLE_TO_CHECK_GENERATOR	0x04
#define DH_NOT_SUITABLE_GENERATOR	0x08

/* DH_check_pub_key error codes */
#define DH_CHECK_PUBKEY_TOO_SMALL	0x01
#define DH_CHECK_PUBKEY_TOO_LARGE	0x02

/* primes p where (p-1)/2 is prime too are called "safe"; we define
   this for backward compatibility: */
#define DH_CHECK_P_NOT_STRONG_PRIME	DH_CHECK_P_NOT_SAFE_PRIME

#define DHparams_dup(x) ASN1_dup_of_const(DH,i2d_DHparams,d2i_DHparams,x)
#define d2i_DHparams_fp(fp,x) (DH *)ASN1_d2i_fp((char *(*)())DH_new, \
		(char *(*)())d2i_DHparams,(fp),(unsigned char **)(x))
#define i2d_DHparams_fp(fp,x) ASN1_i2d_fp(i2d_DHparams,(fp), \
		(unsigned char *)(x))
#define d2i_DHparams_bio(bp,x) ASN1_d2i_bio_of(DH,DH_new,d2i_DHparams,bp,x)
#define i2d_DHparams_bio(bp,x) ASN1_i2d_bio_of_const(DH,i2d_DHparams,bp,x)

const DH_METHOD *DH_OpenSSL(void);

void DH_set_default_method(const DH_METHOD *meth);
const DH_METHOD *DH_get_default_method(void);
int DH_set_method(DH *dh, const DH_METHOD *meth);
DH *DH_new_method(ENGINE *engine);

DH *	DH_new(void);
void	DH_free(DH *dh);
int	DH_up_ref(DH *dh);
int	DH_size(const DH *dh);
int DH_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
	     CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func);
int DH_set_ex_data(DH *d, int idx, void *arg);
void *DH_get_ex_data(DH *d, int idx);

/* Deprecated version */
#ifndef OPENSSL_NO_DEPRECATED
DH *	DH_generate_parameters(int prime_len,int generator,
		void (*callback)(int,int,void *),void *cb_arg);
#endif /* !defined(OPENSSL_NO_DEPRECATED) */

/* New version */
int	DH_generate_parameters_ex(DH *dh, int prime_len,int generator, BN_GENCB *cb);

int	DH_check(const DH *dh,int *codes);
int	DH_check_pub_key(const DH *dh,const BIGNUM *pub_key, int *codes);
int	DH_generate_key(DH *dh);
int	DH_compute_key(unsigned char *key,const BIGNUM *pub_key,DH *dh);
DH *	d2i_DHparams(DH **a,const unsigned char **pp, long length);
int	i2d_DHparams(const DH *a,unsigned char **pp);
#ifndef OPENSSL_NO_FP_API
int	DHparams_print_fp(FILE *fp, const DH *x);
#endif
#ifndef OPENSSL_NO_BIO
int	DHparams_print(BIO *bp, const DH *x);
#else
int	DHparams_print(char *bp, const DH *x);
#endif

/* BEGIN ERROR CODES */
/* The following lines are auto generated by the script mkerr.pl. Any changes
 * made after this point may be overwritten when the script is next run.
 */
void ERR_load_DH_strings(void);

/* Error codes for the DH functions. */

/* Function codes. */
#define DH_F_COMPUTE_KEY				 102
#define DH_F_DHPARAMS_PRINT				 100
#define DH_F_DHPARAMS_PRINT_FP				 101
#define DH_F_DH_BUILTIN_GENPARAMS			 106
#define DH_F_DH_NEW_METHOD				 105
#define DH_F_GENERATE_KEY				 103
#define DH_F_GENERATE_PARAMETERS			 104

/* Reason codes. */
#define DH_R_BAD_GENERATOR				 101
#define DH_R_INVALID_PUBKEY				 102
#define DH_R_MODULUS_TOO_LARGE				 103
#define DH_R_NO_PRIVATE_VALUE				 100

#ifdef  __cplusplus
}
#endif
#endif