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
#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);
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.
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).
DH_new(3),
ERR_get_error(3),
RAND_bytes(3),
DH_free(3)
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 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>.