text: /* 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
  
  #ifdef OPENSSL_NO_DH
  #error DH is disabled.
  #endif
  
  #ifndef OPENSSL_NO_BIO
  #include <openssl/bio.h>
  #endif
  #include <openssl/bn.h>
  #include <openssl/crypto.h>
  #include <openssl/ossl_typ.h>
  	
  #define DH_FLAG_CACHE_MONT_P	0x01
  
  #ifdef  __cplusplus
  extern "C" {
  #endif
  
  typedef struct dh_st DH;
  
  typedef 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;
  } DH_METHOD;
  
  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;
  	char *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
  
  /* 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) (DH *)ASN1_dup((int (*)())i2d_DHparams, \
  		(char *(*)())d2i_DHparams,(char *)(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) (DH *)ASN1_d2i_bio((char *(*)())DH_new, \
  		(char *(*)())d2i_DHparams,(bp),(unsigned char **)(x))
  #ifdef  __cplusplus
  #define i2d_DHparams_bio(bp,x) ASN1_i2d_bio((int (*)())i2d_DHparams,(bp), \
  		(unsigned char *)(x))
  #else
  #define i2d_DHparams_bio(bp,x) ASN1_i2d_bio(i2d_DHparams,(bp), \
  		(unsigned char *)(x))
  #endif
  
  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);
  DH *	DH_generate_parameters(int prime_len,int generator,
  		void (*callback)(int,int,void *),void *cb_arg);
  int	DH_check(const DH *dh,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_DHPARAMS_PRINT				 100
  #define DH_F_DHPARAMS_PRINT_FP				 101
  #define DH_F_DH_COMPUTE_KEY				 102
  #define DH_F_DH_GENERATE_KEY				 103
  #define DH_F_DH_GENERATE_PARAMETERS			 104
  #define DH_F_DH_NEW_METHOD				 105
  
  /* Reason codes. */
  #define DH_R_BAD_GENERATOR				 101
  #define DH_R_NO_PRIVATE_VALUE				 100
  
  #ifdef  __cplusplus
  }
  #endif
  #endif
  