| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | DH_generate_parameters_ex, DH_generate_parameters,
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| 6 | DH_check, DH_check_params,
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| 7 | DH_check_ex, DH_check_params_ex, DH_check_pub_key_ex
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| 8 | - generate and check Diffie-Hellman
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| 9 | parameters
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| 10 |
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| 11 | =head1 SYNOPSIS
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| 12 |
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| 13 | #include <openssl/dh.h>
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| 14 |
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| 15 | int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb);
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| 16 |
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| 17 | int DH_check(DH *dh, int *codes);
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| 18 | int DH_check_params(DH *dh, int *codes);
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| 19 |
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| 20 | int DH_check_ex(const DH *dh);
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| 21 | int DH_check_params_ex(const DH *dh);
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| 22 | int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key);
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| 23 |
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| 24 | Deprecated:
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| 25 |
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| 26 | #if OPENSSL_API_COMPAT < 0x00908000L
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| 27 | DH *DH_generate_parameters(int prime_len, int generator,
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| 28 | void (*callback)(int, int, void *), void *cb_arg);
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| 29 | #endif
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| 30 |
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| 31 | =head1 DESCRIPTION
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| 32 |
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| 33 | DH_generate_parameters_ex() generates Diffie-Hellman parameters that can
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| 34 | be shared among a group of users, and stores them in the provided B<DH>
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| 35 | structure. The pseudo-random number generator must be
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| 36 | seeded before calling it.
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| 37 | The parameters generated by DH_generate_parameters_ex() should not be used in
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| 38 | signature schemes.
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| 39 |
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| 40 | B<prime_len> is the length in bits of the safe prime to be generated.
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| 41 | B<generator> is a small number E<gt> 1, typically 2 or 5.
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| 42 |
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| 43 | A callback function may be used to provide feedback about the progress
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| 44 | of the key generation. If B<cb> is not B<NULL>, it will be
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| 45 | called as described in L<BN_generate_prime(3)> while a random prime
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| 46 | number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)>
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| 47 | is called. See L<BN_generate_prime_ex(3)> for information on
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| 48 | the BN_GENCB_call() function.
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| 49 |
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| 50 | DH_generate_parameters() is similar to DH_generate_prime_ex() but
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| 51 | expects an old-style callback function; see
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| 52 | L<BN_generate_prime(3)> for information on the old-style callback.
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| 53 |
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| 54 | DH_check_params() confirms that the B<p> and B<g> are likely enough to
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| 55 | be valid.
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| 56 | This is a lightweight check, if a more thorough check is needed, use
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| 57 | DH_check().
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| 58 | The value of B<*codes> is updated with any problems found.
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| 59 | If B<*codes> is zero then no problems were found, otherwise the
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| 60 | following bits may be set:
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| 61 |
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| 62 | =over 4
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| 63 |
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| 64 | =item DH_CHECK_P_NOT_PRIME
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| 65 |
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| 66 | The parameter B<p> has been determined to not being an odd prime.
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| 67 | Note that the lack of this bit doesn't guarantee that B<p> is a
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| 68 | prime.
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| 69 |
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| 70 | =item DH_NOT_SUITABLE_GENERATOR
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| 71 |
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| 72 | The generator B<g> is not suitable.
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| 73 | Note that the lack of this bit doesn't guarantee that B<g> is
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| 74 | suitable, unless B<p> is known to be a strong prime.
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| 75 |
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| 76 | =back
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| 77 |
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| 78 | DH_check() confirms that the Diffie-Hellman parameters B<dh> are valid. The
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| 79 | value of B<*codes> is updated with any problems found. If B<*codes> is zero then
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| 80 | no problems were found, otherwise the following bits may be set:
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| 81 |
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| 82 | =over 4
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| 83 |
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| 84 | =item DH_CHECK_P_NOT_PRIME
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| 85 |
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| 86 | The parameter B<p> is not prime.
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| 87 |
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| 88 | =item DH_CHECK_P_NOT_SAFE_PRIME
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| 89 |
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| 90 | The parameter B<p> is not a safe prime and no B<q> value is present.
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| 91 |
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| 92 | =item DH_UNABLE_TO_CHECK_GENERATOR
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| 93 |
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| 94 | The generator B<g> cannot be checked for suitability.
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| 95 |
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| 96 | =item DH_NOT_SUITABLE_GENERATOR
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| 97 |
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| 98 | The generator B<g> is not suitable.
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| 99 |
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| 100 | =item DH_CHECK_Q_NOT_PRIME
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| 101 |
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| 102 | The parameter B<q> is not prime.
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| 103 |
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| 104 | =item DH_CHECK_INVALID_Q_VALUE
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| 105 |
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| 106 | The parameter B<q> is invalid.
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| 107 |
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| 108 | =item DH_CHECK_INVALID_J_VALUE
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| 109 |
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| 110 | The parameter B<j> is invalid.
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| 111 |
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| 112 | =back
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| 113 |
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| 114 | DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to
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| 115 | DH_check() and DH_check_params() respectively, but the error reasons are added
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| 116 | to the thread's error queue instead of provided as return values from the
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| 117 | function.
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| 118 |
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| 119 | =head1 RETURN VALUES
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| 120 |
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| 121 | DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1
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| 122 | if the check could be performed, 0 otherwise.
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| 123 |
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| 124 | DH_generate_parameters() returns a pointer to the DH structure or NULL if
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| 125 | the parameter generation fails.
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| 126 |
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| 127 | DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the
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| 128 | check is successful, 0 for failed.
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| 129 |
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| 130 | The error codes can be obtained by L<ERR_get_error(3)>.
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| 131 |
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| 132 | =head1 SEE ALSO
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| 133 |
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| 134 | L<DH_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>,
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| 135 | L<DH_free(3)>
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| 136 |
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| 137 | =head1 HISTORY
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| 138 |
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| 139 | DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use
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| 140 | DH_generate_parameters_ex() instead.
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| 141 |
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| 142 | =head1 COPYRIGHT
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| 143 |
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| 144 | Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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| 145 |
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| 146 | Licensed under the OpenSSL license (the "License"). You may not use
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| 147 | this file except in compliance with the License. You can obtain a copy
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| 148 | in the file LICENSE in the source distribution or at
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| 149 | L<https://www.openssl.org/source/license.html>.
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| 150 |
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| 151 | =cut
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