src/libstrongswan/crypto/diffie_hellman.h

   1 /*
   2  * Copyright (C) 2010 Tobias Brunner
   3  * Copyright (C) 2005-2007 Martin Willi
   4  * Copyright (C) 2005 Jan Hutter
   5  * Hochschule fuer Technik Rapperswil
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation; either version 2 of the License, or (at your
  10  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  * for more details.
  16  */
  17
  18 /**
  19  * @defgroup diffie_hellman diffie_hellman
  20  * @{ @ingroup crypto
  21  */
  22
  23 #ifndef DIFFIE_HELLMAN_H_
  24 #define DIFFIE_HELLMAN_H_
  25
  26 typedef enum diffie_hellman_group_t diffie_hellman_group_t;
  27 typedef struct diffie_hellman_t diffie_hellman_t;
  28 typedef struct diffie_hellman_params_t diffie_hellman_params_t;
  29
  30 #include <library.h>
  31
  32 /**
  33  * Diffie-Hellman group.
  34  *
  35  * The modulus (or group) to use for a Diffie-Hellman calculation.
  36  * See IKEv2 RFC 3.3.2 and RFC 3526.
  37  *
  38  * ECP groups are defined in RFC 4753 and RFC 5114.
  39  */
  40 enum diffie_hellman_group_t {
  41         MODP_NONE     =  0,
  42         MODP_768_BIT  =  1,
  43         MODP_1024_BIT =  2,
  44         MODP_1536_BIT =  5,
  45         MODP_2048_BIT = 14,
  46         MODP_3072_BIT = 15,
  47         MODP_4096_BIT = 16,
  48         MODP_6144_BIT = 17,
  49         MODP_8192_BIT = 18,
  50         ECP_256_BIT   = 19,
  51         ECP_384_BIT   = 20,
  52         ECP_521_BIT   = 21,
  53         MODP_1024_160 = 22,
  54         MODP_2048_224 = 23,
  55         MODP_2048_256 = 24,
  56         ECP_192_BIT   = 25,
  57         ECP_224_BIT   = 26,
  58         /** insecure NULL diffie hellman group for testing, in PRIVATE USE */
  59         MODP_NULL = 1024,
  60         /** MODP group with custon generator, prime */
  61         MODP_CUSTOM = 1025,
  62 };
  63
  64 /**
  65  * enum name for diffie_hellman_group_t.
  66  */
  67 extern enum_name_t *diffie_hellman_group_names;
  68
  69 /**
  70  * Implementation of the Diffie-Hellman algorithm, as in RFC2631.
  71  */
  72 struct diffie_hellman_t {
  73
  74         /**
  75          * Returns the shared secret of this diffie hellman exchange.
  76          *
  77          * Space for returned secret is allocated and must be
  78          * freed by the caller.
  79          *
  80          * @param secret        shared secret will be written into this chunk
  81          * @return                      SUCCESS, FAILED if not both DH values are set
  82          */
  83         status_t (*get_shared_secret) (diffie_hellman_t *this, chunk_t *secret);
  84
  85         /**
  86          * Sets the public value of partner.
  87          *
  88          * Chunk gets cloned and can be destroyed afterwards.
  89          *
  90          * @param value         public value of partner
  91          */
  92         void (*set_other_public_value) (diffie_hellman_t *this, chunk_t value);
  93
  94         /**
  95          * Gets the own public value to transmit.
  96          *
  97          * Space for returned chunk is allocated and must be freed by the caller.
  98          *
  99          * @param value         public value of caller is stored at this location
 100          */
 101         void (*get_my_public_value) (diffie_hellman_t *this, chunk_t *value);
 102
 103         /**
 104          * Get the DH group used.
 105          *
 106          * @return                      DH group set in construction
 107          */
 108         diffie_hellman_group_t (*get_dh_group) (diffie_hellman_t *this);
 109
 110         /**
 111          * Destroys an diffie_hellman_t object.
 112          */
 113         void (*destroy) (diffie_hellman_t *this);
 114 };
 115
 116 /**
 117  * Parameters for a specific diffie hellman group.
 118  */
 119 struct diffie_hellman_params_t {
 120
 121         /**
 122          * The prime of the group
 123          */
 124         const chunk_t prime;
 125
 126         /**
 127          * Generator of the group
 128          */
 129         const chunk_t generator;
 130
 131         /**
 132          * Exponent length to use
 133          */
 134         size_t exp_len;
 135
 136         /**
 137          * Prime order subgroup; for MODP Groups 22-24
 138          */
 139         const chunk_t subgroup;
 140 };
 141
 142 /**
 143  * Get the parameters associated with the specified diffie hellman group.
 144  *
 145  * @param group                 DH group
 146  * @return                              The parameters or NULL, if the group is not supported
 147  */
 148 diffie_hellman_params_t *diffie_hellman_get_params(diffie_hellman_group_t group);
 149
 150 /**
 151  * Check if a given DH group is an ECDH group
 152  *
 153  * @param group                 group to check
 154  * @return                              TUE if group is an ECP group
 155  */
 156 bool diffie_hellman_group_is_ec(diffie_hellman_group_t group);
 157
 158 #endif /** DIFFIE_HELLMAN_H_ @}*/