Add support for JDK 22-native edec key support

[mattrpav]

Description

Currently, elliptical curve key support is available through a 3rd party library that is seemingly unmaintained (latest release 2018).

JDK 22 add support for edec keys natively

Motivation

Remove reliance on 3rd-party library, use JDK-default key for up-and-comming ssh key format

Alternatives considered

No response

Additional context

No response

JDK 22 support:
ref: https://javaalmanac.io/jdk/22/apidiff/21/

3rd party library:

<dependency>
  <groupId>net.i2p.crypto</groupId>
  <artifactId>eddsa</artifactId>
  <optional>true</optional>
  <scope>provided</scope>
</dependency>

[tomaswolf]

Actually ed25519 is supported as of Java 15. Bouncy Castle also supports it.

Unfortunately, changing the current implementation so that it would work with any of these is not possible without API breaks. It's also a lot of work.

[jsoo1]

Does #639 solve this in a non-api-breaking way?

[basil]

This seems challenging given that MINA needs a way to recover the public key associated with a given private key in GenericOpenSSHEd25519PrivateKeyEntryDecoder#decodePrivateKey, something which is supported out-of-the-box by org.bouncycastle.jcajce.provider.asymmetric.edec.BC15EdDSAPrivateKey and net.i2p.crypto.eddsa.EdDSAPrivateKey but not by sun.security.ec.ed.EdDSAPrivateKeyImpl.

[pflaska]

I have already experimented with JDK support, but I can't recall all the details. I do remember that the basic functionality was working. I added a new module, sshd-jdk-ed25519, with its pom.xml built using Java 15 or higher. If this module is on the classpath, the JDK implementation takes precedence. This work was done during the development of version 2.14, but currently, there are merge conflicts. This was all before support for Bouncycastle's Ed25519 was introduced.

If you're interested, the prototype can be viewed here:
master...pflaska:mina-sshd:pflaska/master/jdk-ed25519

[mattrpav]

@pflaska a rebase should be able to clear most of the merge commit issues.

If you squash the commits and make a PR, I'm happy to comment and help test.

1. This should be removed too / or converted to a logger line:

..sshd/common/signature/AbstractSignature.java

System.out.println("Signature: " + bytesToHex(sig));

2. Would there be some other runtime exception possibly missed by changing this catch?
   master...pflaska:mina-sshd:pflaska/master/jdk-ed25519#diff-0d70c12c05d7851c7eb77953ff9abe05b1797200acb6ca6345e9fae7fc773df3R287

[pflaska]

I rebased my branch, and it compiles again. However, the rebase changes require careful review, as both my modifications and #639 provide support in their own ways. I need to adjust my JDK-15 support to work correctly with the current master.

[tomaswolf]

Done in branch dev_3.0.0 for milestone 3.0.0-M2.