We use dh2048_ffdhe2048.pem file (DH 2048 bits) instead of dh1024.pem file in
both non-FIPS and FIPS cases. Because the following command fails to generate
the pem file with 1024 bits. And the OpenSSL FIPS 140-2 security policy
document explains the DH public keys are allowed from 2048 bits.[1]

```
$ OPENSSL_CONF=/home/jaruga/.local/openssl-3.3.0-dev-fips-debug-1aa08644ec/ssl/openssl_fips.cnf \
  /home/jaruga/.local/openssl-3.3.0-dev-fips-debug-1aa08644ec/bin/openssl \
  dhparam -out dh1024.pem 1024
Generating DH parameters, 1024 bit long safe prime
dhparam: Generating DH key parameters failed
```

The dh2048_ffdhe2048.pem file was created by the following command with the
OpenSSL FIPS configuration file. The logic to generate the DH pem file is
different between non-FIPS and FIPS cases. In FIPS, it seems that the command
always returns the text defined as ffdhe2048 in the FFDHE groups in RFC 7919
unlike non-FIPS.[2]

As the generated pem file is a normal and valid PKCS#3-style group parameter, we
use the file for the non-FIPS case too.

```
$ OPENSSL_CONF=/home/jaruga/.local/openssl-3.3.0-dev-fips-debug-1aa08644ec/ssl/openssl_fips.cnf \
  /home/jaruga/.local/openssl-3.3.0-dev-fips-debug-1aa08644ec/bin/openssl \
  dhparam -out dh2048_ffdhe2048.pem 2048
```

Note that the hard-coded PEM-encoded string in the `test_DHparams` is
intentional to avoid modifying the content unintentionally.

* [1] https://www.openssl.org/source/ - OpenSSL 3.0.8 FIPS 140-2 security
  policy document page 25, Table 10 – Public Keys - DH Public
  - DH (2048/3072/4096/6144/8192) public key agreement key
* [2] RFC7919 - Appendix A.1: ffdhe2048
  https://www.rfc-editor.org/rfc/rfc7919#appendix-A.1

OpenSSL 3.0 made EVP_PKEY immutable. This means we can only have a const
pointer of the low level struct and the following methods can no longer
be provided when linked against OpenSSL 3.0:

 - OpenSSL::PKey::RSA#set_key
 - OpenSSL::PKey::RSA#set_factors
 - OpenSSL::PKey::RSA#set_crt_params
 - OpenSSL::PKey::DSA#set_pqg
 - OpenSSL::PKey::DSA#set_key
 - OpenSSL::PKey::DH#set_pqg
 - OpenSSL::PKey::DH#set_key
 - OpenSSL::PKey::EC#group=
 - OpenSSL::PKey::EC#private_key=
 - OpenSSL::PKey::EC#public_key=

There is no direct replacement for this functionality at the moment.
I plan to introduce a wrapper around EVP_PKEY_fromdata(), which takes
all key components at once to construct an EVP_PKEY.

https://github.com/ruby/openssl/commit/6848d2d969

OpenSSL::PKey::DH#generate_key! will not work on OpenSSL 3.0 because
keys are made immutable. Users should use OpenSSL::PKey.generate_key
instead.

https://github.com/ruby/openssl/commit/8ee6a582c7

It uses deprecated PKey::{RSA,DSA,DH}#set_* methods, which will not
work with OpenSSL 3.0. The same can easily be achieved using
PKey#public_to_der regardless of the key kind.

https://github.com/ruby/openssl/commit/7b66eaa2db

Use EVP_PKEY_param_check() instead of DH_check() if available. Also,
use EVP_PKEY_public_check() instead of EC_KEY_check_key().

EVP_PKEY_*check() is part of the EVP API and is meant to replace those
low-level functions. They were added by OpenSSL 1.1.1. It is currently
not provided by LibreSSL.

https://github.com/ruby/openssl/commit/797e9f8e08

Implement PKey::DH.new(size, gen), PKey::DH.generate(size, gen), and
PKey::DH#generate_key! using PKey.generate_parameters and .generate_key
instead of the low level DH functions.

Note that the EVP interface can enforce additional restrictions - for
example, DH key shorter than 2048 bits is no longer accepted by default
in OpenSSL 3.0. The test code is updated accordingly.

https://github.com/ruby/openssl/commit/c2e9b16f0b

Add OpenSSL::PKey::PKey#derive as the wrapper for EVP_PKEY_CTX_derive().
This is useful for pkey types that we don't have dedicated classes, such
as X25519.

https://github.com/ruby/openssl/commit/28f0059bea

Try PEM_read_bio_Parameters(). Only PEM format is supported at the
moment since corresponding d2i_* functions are not provided by OpenSSL.

https://github.com/ruby/openssl/commit/867e5c021b

https://github.com/ruby/openssl/commit/c4374ff041

Import the master branch of ruby/openssl for preparing to release openssl-2.2.0