=pod =head1 NAME DH_generate_parameters_ex, DH_generate_parameters, DH_check, DH_check_params, DH_check_ex, DH_check_params_ex, DH_check_pub_key_ex - generate and check Diffie-Hellman parameters =head1 SYNOPSIS #include int DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb); int DH_check(DH *dh, int *codes); int DH_check_params(DH *dh, int *codes); int DH_check_ex(const DH *dh); int DH_check_params_ex(const DH *dh); int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key); Deprecated: #if OPENSSL_API_COMPAT < 0x00908000L DH *DH_generate_parameters(int prime_len, int generator, void (*callback)(int, int, void *), void *cb_arg); #endif =head1 DESCRIPTION DH_generate_parameters_ex() generates Diffie-Hellman parameters that can be shared among a group of users, and stores them in the provided B structure. The pseudo-random number generator must be seeded before calling it. The parameters generated by DH_generate_parameters_ex() should not be used in signature schemes. B is the length in bits of the safe prime to be generated. B is a small number E 1, typically 2 or 5. A callback function may be used to provide feedback about the progress of the key generation. If B is not B, it will be called as described in L while a random prime number is generated, and when a prime has been found, B is called. See L for information on the BN_GENCB_call() function. DH_generate_parameters() is similar to DH_generate_prime_ex() but expects an old-style callback function; see L for information on the old-style callback. DH_check_params() confirms that the B

and B are likely enough to be valid. This is a lightweight check, if a more thorough check is needed, use DH_check(). The value of B<*codes> is updated with any problems found. If B<*codes> is zero then no problems were found, otherwise the following bits may be set: =over 4 =item DH_CHECK_P_NOT_PRIME The parameter B

has been determined to not being an odd prime. Note that the lack of this bit doesn't guarantee that B

is a prime. =item DH_NOT_SUITABLE_GENERATOR The generator B is not suitable. Note that the lack of this bit doesn't guarantee that B is suitable, unless B

is known to be a strong prime. =back DH_check() confirms that the Diffie-Hellman parameters B are valid. The value of B<*codes> is updated with any problems found. If B<*codes> is zero then no problems were found, otherwise the following bits may be set: =over 4 =item DH_CHECK_P_NOT_PRIME The parameter B

is not prime. =item DH_CHECK_P_NOT_SAFE_PRIME The parameter B

is not a safe prime and no B value is present. =item DH_UNABLE_TO_CHECK_GENERATOR The generator B cannot be checked for suitability. =item DH_NOT_SUITABLE_GENERATOR The generator B is not suitable. =item DH_CHECK_Q_NOT_PRIME The parameter B is not prime. =item DH_CHECK_INVALID_Q_VALUE The parameter B is invalid. =item DH_CHECK_INVALID_J_VALUE The parameter B is invalid. =back DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to DH_check() and DH_check_params() respectively, but the error reasons are added to the thread's error queue instead of provided as return values from the function. =head1 RETURN VALUES DH_generate_parameters_ex(), DH_check() and DH_check_params() return 1 if the check could be performed, 0 otherwise. DH_generate_parameters() returns a pointer to the DH structure or NULL if the parameter generation fails. DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() return 1 if the check is successful, 0 for failed. The error codes can be obtained by L. =head1 SEE ALSO L, L, L, L =head1 HISTORY DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use DH_generate_parameters_ex() instead. =head1 COPYRIGHT Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L. =cut