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DH_GENERATE_PARAMETERS(3ossl) OpenSSL DH_GENERATE_PARAMETERS(3ossl) 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 SYNOPSIS #include <openssl/dh.h> The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7): 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); The following functions have been deprecated since OpenSSL 0.9.8, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7): DH *DH_generate_parameters(int prime_len, int generator, void (*callback)(int, int, void *), void *cb_arg); DESCRIPTION All of the functions described on this page are deprecated. Applications should instead use EVP_PKEY_check(3), EVP_PKEY_public_check(3), EVP_PKEY_private_check(3) and EVP_PKEY_param_check(3). DH_generate_parameters_ex() generates Diffie-Hellman parameters that can be shared among a group of users, and stores them in the provided DH 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. prime_len is the length in bits of the safe prime to be generated. generator is a small number > 1, typically 2 or 5. A callback function may be used to provide feedback about the progress of the key generation. If cb is not NULL, it will be called as described in BN_generate_prime(3) while a random prime number is generated, and when a prime has been found, BN_GENCB_call(cb, 3, 0) is called. See BN_generate_prime_ex(3) 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 BN_generate_prime(3) for information on the old-style callback. DH_check_params() confirms that the p and g are likely enough to be valid. This is a lightweight check, if a more thorough check is DH_NOT_SUITABLE_GENERATOR The generator g is not suitable. Note that the lack of this bit doesn't guarantee that g is suitable, unless p is known to be a strong prime. DH_MODULUS_TOO_SMALL The modulus is too small. DH_MODULUS_TOO_LARGE The modulus is too large. DH_check() confirms that the Diffie-Hellman parameters dh are valid. The value of *codes is updated with any problems found. If *codes is zero then no problems were found, otherwise the following bits may be set: DH_CHECK_P_NOT_PRIME The parameter p is not prime. DH_CHECK_P_NOT_SAFE_PRIME The parameter p is not a safe prime and no q value is present. DH_UNABLE_TO_CHECK_GENERATOR The generator g cannot be checked for suitability. DH_NOT_SUITABLE_GENERATOR The generator g is not suitable. DH_CHECK_Q_NOT_PRIME The parameter q is not prime. DH_CHECK_INVALID_Q_VALUE The parameter q is invalid. DH_CHECK_INVALID_J_VALUE The parameter j is invalid. 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. 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 ERR_get_error(3). SEE ALSO DH_new(3), ERR_get_error(3), RAND_bytes(3), DH_free(3) HISTORY Licensed under the Apache License 2.0 (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 <https://www.openssl.org/source/license.html>. 3.0.11 2023-09-19 DH_GENERATE_PARAMETERS(3ossl)