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DH_generate_parameters(3)           OpenSSL          DH_generate_parameters(3)



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

LIBRARY
       libcrypto, -lcrypto

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
       needed, use DH_check().  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 has been determined to not being an odd prime.
           Note that the lack of this bit doesn't guarantee that p is a prime.

       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.

       If 0 is returned or *codes is set to a nonzero value the supplied
       parameters should not be used for Diffie-Hellman operations otherwise
       the security properties of the key exchange are not guaranteed.

       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
       All of these functions were deprecated in OpenSSL 3.0.

       DH_generate_parameters() was deprecated in OpenSSL 0.9.8; use
       DH_generate_parameters_ex() instead.

COPYRIGHT
       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

       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>.



3.0.12                            2023-10-25         DH_generate_parameters(3)