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      1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      2  * All rights reserved.
      3  *
      4  * This package is an SSL implementation written
      5  * by Eric Young (eay (at) cryptsoft.com).
      6  * The implementation was written so as to conform with Netscapes SSL.
      7  *
      8  * This library is free for commercial and non-commercial use as long as
      9  * the following conditions are aheared to.  The following conditions
     10  * apply to all code found in this distribution, be it the RC4, RSA,
     11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
     12  * included with this distribution is covered by the same copyright terms
     13  * except that the holder is Tim Hudson (tjh (at) cryptsoft.com).
     14  *
     15  * Copyright remains Eric Young's, and as such any Copyright notices in
     16  * the code are not to be removed.
     17  * If this package is used in a product, Eric Young should be given attribution
     18  * as the author of the parts of the library used.
     19  * This can be in the form of a textual message at program startup or
     20  * in documentation (online or textual) provided with the package.
     21  *
     22  * Redistribution and use in source and binary forms, with or without
     23  * modification, are permitted provided that the following conditions
     24  * are met:
     25  * 1. Redistributions of source code must retain the copyright
     26  *    notice, this list of conditions and the following disclaimer.
     27  * 2. Redistributions in binary form must reproduce the above copyright
     28  *    notice, this list of conditions and the following disclaimer in the
     29  *    documentation and/or other materials provided with the distribution.
     30  * 3. All advertising materials mentioning features or use of this software
     31  *    must display the following acknowledgement:
     32  *    "This product includes cryptographic software written by
     33  *     Eric Young (eay (at) cryptsoft.com)"
     34  *    The word 'cryptographic' can be left out if the rouines from the library
     35  *    being used are not cryptographic related :-).
     36  * 4. If you include any Windows specific code (or a derivative thereof) from
     37  *    the apps directory (application code) you must include an acknowledgement:
     38  *    "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)"
     39  *
     40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
     41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     50  * SUCH DAMAGE.
     51  *
     52  * The licence and distribution terms for any publically available version or
     53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
     54  * copied and put under another distribution licence
     55  * [including the GNU Public Licence.] */
     56 
     57 #ifndef OPENSSL_HEADER_DH_H
     58 #define OPENSSL_HEADER_DH_H
     59 
     60 #include <openssl/base.h>
     61 
     62 #include <openssl/ex_data.h>
     63 #include <openssl/thread.h>
     64 
     65 #if defined(__cplusplus)
     66 extern "C" {
     67 #endif
     68 
     69 
     70 // DH contains functions for performing Diffie-Hellman key agreement in
     71 // multiplicative groups.
     72 
     73 
     74 // Allocation and destruction.
     75 
     76 // DH_new returns a new, empty DH object or NULL on error.
     77 OPENSSL_EXPORT DH *DH_new(void);
     78 
     79 // DH_free decrements the reference count of |dh| and frees it if the reference
     80 // count drops to zero.
     81 OPENSSL_EXPORT void DH_free(DH *dh);
     82 
     83 // DH_up_ref increments the reference count of |dh| and returns one.
     84 OPENSSL_EXPORT int DH_up_ref(DH *dh);
     85 
     86 
     87 // Properties.
     88 
     89 // DH_get0_key sets |*out_pub_key| and |*out_priv_key|, if non-NULL, to |dh|'s
     90 // public and private key, respectively. If |dh| is a public key, the private
     91 // key will be set to NULL.
     92 OPENSSL_EXPORT void DH_get0_key(const DH *dh, const BIGNUM **out_pub_key,
     93                                 const BIGNUM **out_priv_key);
     94 
     95 // DH_set0_key sets |dh|'s public and private key to the specified values. If
     96 // NULL, the field is left unchanged. On success, it takes ownership of each
     97 // argument and returns one. Otherwise, it returns zero.
     98 OPENSSL_EXPORT int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
     99 
    100 // DH_get0_pqg sets |*out_p|, |*out_q|, and |*out_g|, if non-NULL, to |dh|'s p,
    101 // q, and g parameters, respectively.
    102 OPENSSL_EXPORT void DH_get0_pqg(const DH *dh, const BIGNUM **out_p,
    103                                 const BIGNUM **out_q, const BIGNUM **out_g);
    104 
    105 // DH_set0_pqg sets |dh|'s p, q, and g parameters to the specified values.  If
    106 // NULL, the field is left unchanged. On success, it takes ownership of each
    107 // argument and returns one. Otherwise, it returns zero. |q| may be NULL, but
    108 // |p| and |g| must either be specified or already configured on |dh|.
    109 OPENSSL_EXPORT int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);
    110 
    111 
    112 // Standard parameters.
    113 
    114 // BN_get_rfc3526_prime_1536 sets |*ret| to the 1536-bit MODP group from RFC
    115 // 3526 and returns |ret|. If |ret| is NULL then a fresh |BIGNUM| is allocated
    116 // and returned. It returns NULL on allocation failure.
    117 OPENSSL_EXPORT BIGNUM *BN_get_rfc3526_prime_1536(BIGNUM *ret);
    118 
    119 
    120 // Parameter generation.
    121 
    122 #define DH_GENERATOR_2 2
    123 #define DH_GENERATOR_5 5
    124 
    125 // DH_generate_parameters_ex generates a suitable Diffie-Hellman group with a
    126 // prime that is |prime_bits| long and stores it in |dh|. The generator of the
    127 // group will be |generator|, which should be |DH_GENERATOR_2| unless there's a
    128 // good reason to use a different value. The |cb| argument contains a callback
    129 // function that will be called during the generation. See the documentation in
    130 // |bn.h| about this. In addition to the callback invocations from |BN|, |cb|
    131 // will also be called with |event| equal to three when the generation is
    132 // complete.
    133 OPENSSL_EXPORT int DH_generate_parameters_ex(DH *dh, int prime_bits,
    134                                              int generator, BN_GENCB *cb);
    135 
    136 
    137 // Diffie-Hellman operations.
    138 
    139 // DH_generate_key generates a new, random, private key and stores it in
    140 // |dh|. It returns one on success and zero on error.
    141 OPENSSL_EXPORT int DH_generate_key(DH *dh);
    142 
    143 // DH_compute_key calculates the shared key between |dh| and |peers_key| and
    144 // writes it as a big-endian integer into |out|, which must have |DH_size|
    145 // bytes of space. It returns the number of bytes written, or a negative number
    146 // on error.
    147 OPENSSL_EXPORT int DH_compute_key(uint8_t *out, const BIGNUM *peers_key,
    148                                   DH *dh);
    149 
    150 
    151 // Utility functions.
    152 
    153 // DH_size returns the number of bytes in the DH group's prime.
    154 OPENSSL_EXPORT int DH_size(const DH *dh);
    155 
    156 // DH_num_bits returns the minimum number of bits needed to represent the
    157 // absolute value of the DH group's prime.
    158 OPENSSL_EXPORT unsigned DH_num_bits(const DH *dh);
    159 
    160 #define DH_CHECK_P_NOT_PRIME 0x01
    161 #define DH_CHECK_P_NOT_SAFE_PRIME 0x02
    162 #define DH_CHECK_UNABLE_TO_CHECK_GENERATOR 0x04
    163 #define DH_CHECK_NOT_SUITABLE_GENERATOR 0x08
    164 #define DH_CHECK_Q_NOT_PRIME 0x10
    165 #define DH_CHECK_INVALID_Q_VALUE 0x20
    166 #define DH_CHECK_INVALID_J_VALUE 0x40
    167 
    168 // These are compatibility defines.
    169 #define DH_NOT_SUITABLE_GENERATOR DH_CHECK_NOT_SUITABLE_GENERATOR
    170 #define DH_UNABLE_TO_CHECK_GENERATOR DH_CHECK_UNABLE_TO_CHECK_GENERATOR
    171 
    172 // DH_check checks the suitability of |dh| as a Diffie-Hellman group. and sets
    173 // |DH_CHECK_*| flags in |*out_flags| if it finds any errors. It returns one if
    174 // |*out_flags| was successfully set and zero on error.
    175 //
    176 // Note: these checks may be quite computationally expensive.
    177 OPENSSL_EXPORT int DH_check(const DH *dh, int *out_flags);
    178 
    179 #define DH_CHECK_PUBKEY_TOO_SMALL 0x1
    180 #define DH_CHECK_PUBKEY_TOO_LARGE 0x2
    181 #define DH_CHECK_PUBKEY_INVALID 0x4
    182 
    183 // DH_check_pub_key checks the suitability of |pub_key| as a public key for the
    184 // DH group in |dh| and sets |DH_CHECK_PUBKEY_*| flags in |*out_flags| if it
    185 // finds any errors. It returns one if |*out_flags| was successfully set and
    186 // zero on error.
    187 OPENSSL_EXPORT int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key,
    188                                     int *out_flags);
    189 
    190 // DHparams_dup allocates a fresh |DH| and copies the parameters from |dh| into
    191 // it. It returns the new |DH| or NULL on error.
    192 OPENSSL_EXPORT DH *DHparams_dup(const DH *dh);
    193 
    194 
    195 // ASN.1 functions.
    196 
    197 // DH_parse_parameters decodes a DER-encoded DHParameter structure (PKCS #3)
    198 // from |cbs| and advances |cbs|. It returns a newly-allocated |DH| or NULL on
    199 // error.
    200 OPENSSL_EXPORT DH *DH_parse_parameters(CBS *cbs);
    201 
    202 // DH_marshal_parameters marshals |dh| as a DER-encoded DHParameter structure
    203 // (PKCS #3) and appends the result to |cbb|. It returns one on success and zero
    204 // on error.
    205 OPENSSL_EXPORT int DH_marshal_parameters(CBB *cbb, const DH *dh);
    206 
    207 
    208 // ex_data functions.
    209 //
    210 // See |ex_data.h| for details.
    211 
    212 OPENSSL_EXPORT int DH_get_ex_new_index(long argl, void *argp,
    213                                        CRYPTO_EX_unused *unused,
    214                                        CRYPTO_EX_dup *dup_unused,
    215                                        CRYPTO_EX_free *free_func);
    216 OPENSSL_EXPORT int DH_set_ex_data(DH *d, int idx, void *arg);
    217 OPENSSL_EXPORT void *DH_get_ex_data(DH *d, int idx);
    218 
    219 
    220 // Deprecated functions.
    221 
    222 // DH_generate_parameters behaves like |DH_generate_parameters_ex|, which is
    223 // what you should use instead. It returns NULL on error, or a newly-allocated
    224 // |DH| on success. This function is provided for compatibility only.
    225 OPENSSL_EXPORT DH *DH_generate_parameters(int prime_len, int generator,
    226                                           void (*callback)(int, int, void *),
    227                                           void *cb_arg);
    228 
    229 // d2i_DHparams parses an ASN.1, DER encoded Diffie-Hellman parameters structure
    230 // from |len| bytes at |*inp|. If |ret| is not NULL then, on exit, a pointer to
    231 // the result is in |*ret|. Note that, even if |*ret| is already non-NULL on
    232 // entry, it will not be written to. Rather, a fresh |DH| is allocated and the
    233 // previous one is freed.
    234 //
    235 // On successful exit, |*inp| is advanced past the DER structure. It
    236 // returns the result or NULL on error.
    237 //
    238 // Use |DH_parse_parameters| instead.
    239 OPENSSL_EXPORT DH *d2i_DHparams(DH **ret, const unsigned char **inp, long len);
    240 
    241 // i2d_DHparams marshals |in| to an ASN.1, DER structure. If |outp| is not NULL
    242 // then the result is written to |*outp| and |*outp| is advanced just past the
    243 // output. It returns the number of bytes in the result, whether written or
    244 // not, or a negative value on error.
    245 //
    246 // Use |DH_marshal_parameters| instead.
    247 OPENSSL_EXPORT int i2d_DHparams(const DH *in, unsigned char **outp);
    248 
    249 
    250 struct dh_st {
    251   BIGNUM *p;
    252   BIGNUM *g;
    253   BIGNUM *pub_key;   // g^x mod p
    254   BIGNUM *priv_key;  // x
    255 
    256   // priv_length contains the length, in bits, of the private value. If zero,
    257   // the private value will be the same length as |p|.
    258   unsigned priv_length;
    259 
    260   CRYPTO_MUTEX method_mont_p_lock;
    261   BN_MONT_CTX *method_mont_p;
    262 
    263   // Place holders if we want to do X9.42 DH
    264   BIGNUM *q;
    265   BIGNUM *j;
    266   unsigned char *seed;
    267   int seedlen;
    268   BIGNUM *counter;
    269 
    270   int flags;
    271   CRYPTO_refcount_t references;
    272   CRYPTO_EX_DATA ex_data;
    273 };
    274 
    275 
    276 #if defined(__cplusplus)
    277 }  // extern C
    278 
    279 extern "C++" {
    280 
    281 namespace bssl {
    282 
    283 BORINGSSL_MAKE_DELETER(DH, DH_free)
    284 
    285 }  // namespace bssl
    286 
    287 }  // extern C++
    288 
    289 #endif
    290 
    291 #define DH_R_BAD_GENERATOR 100
    292 #define DH_R_INVALID_PUBKEY 101
    293 #define DH_R_MODULUS_TOO_LARGE 102
    294 #define DH_R_NO_PRIVATE_VALUE 103
    295 #define DH_R_DECODE_ERROR 104
    296 #define DH_R_ENCODE_ERROR 105
    297 
    298 #endif  // OPENSSL_HEADER_DH_H
    299