text: /*
   * EAP server/peer: EAP-pwd shared definitions
   * Copyright (c) 2009, Dan Harkins <dharkins@lounge.org>
   *
   * This software may be distributed under the terms of the BSD license.
   * See README for more details.
   */
  
  #ifndef EAP_PWD_COMMON_H
  #define EAP_PWD_COMMON_H
  
  #include <openssl/bn.h>
  #include <openssl/sha.h>
  #include <openssl/ec.h>
  #include <openssl/evp.h>
  #include <openssl/hmac.h>
  
  /*
   * definition of a finite cyclic group
   * TODO: support one based on a prime field
   */
  typedef struct group_definition_ {
  	u16 group_num;
  	EC_GROUP *group;
  	EC_POINT *pwe;
  	BIGNUM *order;
  	BIGNUM *prime;
  } EAP_PWD_group;
  
  /*
   * EAP-pwd header, included on all payloads
   * L(1 bit) | M(1 bit) | exch(6 bits) | total_length(if L is set)
   */
  #define EAP_PWD_HDR_SIZE                1
  
  #define EAP_PWD_OPCODE_ID_EXCH          1
  #define EAP_PWD_OPCODE_COMMIT_EXCH      2
  #define EAP_PWD_OPCODE_CONFIRM_EXCH     3
  #define EAP_PWD_GET_LENGTH_BIT(x)       ((x) & 0x80)
  #define EAP_PWD_SET_LENGTH_BIT(x)       ((x) |= 0x80)
  #define EAP_PWD_GET_MORE_BIT(x)         ((x) & 0x40)
  #define EAP_PWD_SET_MORE_BIT(x)         ((x) |= 0x40)
  #define EAP_PWD_GET_EXCHANGE(x)         ((x) & 0x3f)
  #define EAP_PWD_SET_EXCHANGE(x,y)       ((x) |= (y))
  
  /* EAP-pwd-ID payload */
  struct eap_pwd_id {
  	be16 group_num;
  	u8 random_function;
  #define EAP_PWD_DEFAULT_RAND_FUNC       1
  	u8 prf;
  #define EAP_PWD_DEFAULT_PRF             1
  	u8 token[4];
  	u8 prep;
  #define EAP_PWD_PREP_NONE               0
  #define EAP_PWD_PREP_MS                 1
  	u8 identity[0];     /* length inferred from payload */
  } STRUCT_PACKED;
  
  /* common routines */
  int compute_password_element(EAP_PWD_group *, u16, u8 *, int, u8 *, int, u8 *,
  			     int, u8 *);
  int compute_keys(EAP_PWD_group *, BN_CTX *, BIGNUM *, BIGNUM *, BIGNUM *,
  		 u8 *, u8 *, u32 *, u8 *, u8 *);
  void H_Init(HMAC_CTX *);
  void H_Update(HMAC_CTX *, const u8 *, int);
  void H_Final(HMAC_CTX *, u8 *);
  
  #endif  /* EAP_PWD_COMMON_H */
  