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  * ECC Brainpool groups are defined in RFC 6954.
  40  */
  41 enum diffie_hellman_group_t {
  42         MODP_NONE     =  0,
  43         MODP_768_BIT  =  1,
  44         MODP_1024_BIT =  2,
  45         MODP_1536_BIT =  5,
  46         MODP_2048_BIT = 14,
  47         MODP_3072_BIT = 15,
  48         MODP_4096_BIT = 16,
  49         MODP_6144_BIT = 17,
  50         MODP_8192_BIT = 18,
  51         ECP_256_BIT   = 19,
  52         ECP_384_BIT   = 20,
  53         ECP_521_BIT   = 21,
  54         MODP_1024_160 = 22,
  55         MODP_2048_224 = 23,
  56         MODP_2048_256 = 24,
  57         ECP_192_BIT   = 25,
  58         ECP_224_BIT   = 26,
  59         ECP_224_BP    = 27,
  60         ECP_256_BP    = 28,
  61         ECP_384_BP    = 29,
  62         ECP_512_BP    = 30,
  63         /** insecure NULL diffie hellman group for testing, in PRIVATE USE */
  64         MODP_NULL = 1024,
  65         /** MODP group with custom generator/prime */
  66         /** Parameters defined by IEEE 1363.1, in PRIVATE USE */
  67         NTRU_112_BIT = 1030,
  68         NTRU_128_BIT = 1031,
  69         NTRU_192_BIT = 1032,
  70         NTRU_256_BIT = 1033,
  71         /** internally used DH group with additional parameters g and p, outside
  72          * of PRIVATE USE (i.e. IKEv2 DH group range) so it can't be negotiated */
  73         MODP_CUSTOM = 65536,
  74 };
  75
  76 /**
  77  * enum name for diffie_hellman_group_t.
  78  */
  79 extern enum_name_t *diffie_hellman_group_names;
  80
  81 /**
  82  * Implementation of the Diffie-Hellman algorithm, as in RFC2631.
  83  */
  84 struct diffie_hellman_t {
  85
  86         /**
  87          * Returns the shared secret of this diffie hellman exchange.
  88          *
  89          * Space for returned secret is allocated and must be freed by the caller.
  90          *
  91          * @param secret        shared secret will be written into this chunk
  92          * @return                      TRUE if shared secret computed successfully
  93          */
  94         bool (*get_shared_secret)(diffie_hellman_t *this, chunk_t *secret)
  95                 __attribute__((warn_unused_result));
  96
  97         /**
  98          * Sets the public value of partner.
  99          *
 100          * Chunk gets cloned and can be destroyed afterwards.
 101          *
 102          * @param value         public value of partner
 103          */
 104         void (*set_other_public_value) (diffie_hellman_t *this, chunk_t value);
 105
 106         /**
 107          * Gets the own public value to transmit.
 108          *
 109          * Space for returned chunk is allocated and must be freed by the caller.
 110          *
 111          * @param value         public value of caller is stored at this location
 112          */
 113         void (*get_my_public_value) (diffie_hellman_t *this, chunk_t *value);
 114
 115         /**
 116          * Get the DH group used.
 117          *
 118          * @return                      DH group set in construction
 119          */
 120         diffie_hellman_group_t (*get_dh_group) (diffie_hellman_t *this);
 121
 122         /**
 123          * Destroys a diffie_hellman_t object.
 124          */
 125         void (*destroy) (diffie_hellman_t *this);
 126 };
 127
 128 /**
 129  * Parameters for a specific diffie hellman group.
 130  */
 131 struct diffie_hellman_params_t {
 132
 133         /**
 134          * The prime of the group
 135          */
 136         const chunk_t prime;
 137
 138         /**
 139          * Generator of the group
 140          */
 141         const chunk_t generator;
 142
 143         /**
 144          * Exponent length to use
 145          */
 146         size_t exp_len;
 147
 148         /**
 149          * Prime order subgroup; for MODP Groups 22-24
 150          */
 151         const chunk_t subgroup;
 152 };
 153
 154 /**
 155  * Initialize diffie hellman parameters during startup.
 156  */
 157 void diffie_hellman_init();
 158
 159 /**
 160  * Get the parameters associated with the specified diffie hellman group.
 161  *
 162  * Before calling this method, use diffie_hellman_init() to initialize the
 163  * DH group table. This is usually done by library_init().
 164  *
 165  * @param group                 DH group
 166  * @return                              The parameters or NULL, if the group is not supported
 167  */
 168 diffie_hellman_params_t *diffie_hellman_get_params(diffie_hellman_group_t group);
 169
 170 /**
 171  * Check if a given DH group is an ECDH group
 172  *
 173  * @param group                 group to check
 174  * @return                              TUE if group is an ECP group
 175  */
 176 bool diffie_hellman_group_is_ec(diffie_hellman_group_t group);
 177
 178 #endif /** DIFFIE_HELLMAN_H_ @}*/