Add Support for secp256k1 algorithms (AKA ES256K)

[jimmyjames]

Changes

This replaces #428 to add support for the secp256k1 algorithm. The only changes from that original PR are the ones requested on the review:

• Remove the addition of a deprecated method
• Whitespace fixes

It also removes the README txt file.

For review purposes, see the commits for this PR; the changes to the original PR have been captured as separate commits.

References

#428

Testing

• This change adds test coverage
• This change has been tested on the latest version of Java or why not

How to create a secp256k1 key to be used with ES256K algorithm:

Generate the key

openssl ecparam -genkey -name secp256k1 -out KEY.pem -text

• The file is split into 2 parts a curve specification (EC PARAMETERS) and the key value
• This format is not suitable to be read by the PermUtils PEM reader so we have to convert it into PCKS8 format:

openssl pkcs8 -topk8 -inform PEM -outform PEM -nocrypt -in KEY.pem -out ec256k-key.private.pem

The public key is then calculated as follows:

openssl ec -pubout -in KEY.pem -out ec256k-key-public.pem

How to get DER signature:

ECDSAAlgorithm algorithm256 = (ECDSAAlgorithm) Algorithm.ECDSA256((ECPublicKey) readPublicKeyFromFile(PUBLIC_KEY_FILE_256K, "EC"), (ECPrivateKey) readPrivateKeyFromFile(PRIVATE_KEY_FILE_256K, "EC"));
String[] parts = ES256K_JWT.split("\\.");

byte[] derSignature = algorithm256.JOSEToDER(Base64.decodeBase64(parts[2]));
String jwt=parts[0]+"."+parts[1]+"."+Base64.encodeBase64URLSafeString(derSignature);

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors

[lbalmaceda]

weird formatting?

[jimmyjames]

Pushed a commit to fix running the formatter.

[lbalmaceda]

might be good to run the formatter shortcut option+command+L to update all these changes

Suggested change

	String signed = JWT.create().sign(Algorithm.ECDSA256K(publicKey, privateKey) );
	String signed = JWT.create().sign(Algorithm.ECDSA256K(publicKey, privateKey));

[jimmyjames]

Yes, added a commit to do just that.

[lbalmaceda]

I prefer the other approach but this is a test so it's fine. However, try running the import organizer shortcut control+option+O

[jimmyjames]

Fixed.

[lbalmaceda]

Good to merge 👍