https://github.com/ruby/openssl/commit/85d6b7f192

Update the references to the file "LICENCE" with "COPYING".

The file LICENCE doesn't exist in ruby/ruby nor ruby/openssl. This has
been always the case since OpenSSL for Ruby 2 was merged to the ruby
tree as a standard library in 2003.

In OpenSSL for Ruby 2's CVS repository[1], the LICENCE file contained
an old version of the Ruby License, identical to the COPYING file that
was in Ruby's tree at that time (r4128[2]).

[1] http://cvs.savannah.gnu.org/viewvc/rubypki/ossl2/LICENCE?revision=1.1.1.1&view=markup
[2] https://github.com/ruby/ruby/blob/231247c010acba191b78ed2d1310c935e63ad919/COPYING

https://github.com/ruby/openssl/commit/5bccf07d04

Describe the behavior of OpenSSL::PKey::{DH,DSA,EC,RSA}#to_pem
and #to_der more clearly. They return a different result depending on
whether the pkey is a public or private key. This was not documented
adequately.

Also, suggest the use of OpenSSL::PKey::PKey#private_to_pem
and #public_to_pem instead, if possible.

https://github.com/ruby/openssl/commit/d22769af8f

https://github.com/ruby/openssl/commit/c0023822fe

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

We can use it to implement OpenSSL::PKey::PKey#initialize_copy. This
should work on all key types, not just DH/DSA/EC/RSA types.

https://github.com/ruby/openssl/commit/66cd8cbaaf

Allocate an EVP_PKEY when the content is ready: when #initialize
or #initialize_copy is called, rather than when a T_DATA is allocated.
This is more natural because the lower level API has been deprecated
and an EVP_PKEY is becoming the minimum unit of handling keys.

https://github.com/ruby/openssl/commit/74f6c61756

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

The low-level API that is used to implement #public_key is deprecated
in OpenSSL 3.0. It is actually very simple to implement in another way,
using existing methods only, in much shorter code. Let's do it.

While we are at it, the documentation is updated to recommend against
using #public_key. Now that OpenSSL::PKey::PKey implements public_to_der
method, there is no real use case for #public_key in newly written Ruby
programs.

https://github.com/ruby/openssl/commit/48a6c391ef

Use EVP_PKEY_print_private() instead of the low-level API *_print()
functions, such as RSA_print().

EVP_PKEY_print_*() family was added in OpenSSL 1.0.0.

Note that it falls back to EVP_PKEY_print_public() and
EVP_PKEY_print_params() as necessary. This is required for EVP_PKEY_DH
type for which _private() fails if the private component is not set in
the pkey object.

Since the new API works in the same way for all key types, we now
implement #to_text in the base class OpenSSL::PKey::PKey rather than in
each subclass.

https://github.com/ruby/openssl/commit/e0b4c56956