try to support pkcs8 v2 format pem file for EdDSA

[Myse1f]

Try to fix #280.

RFC5958 shows that pkcs8 v2 has the format:

OneAsymmetricKey ::= SEQUENCE {
       version                   Version,
       privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,
       privateKey                PrivateKey,
       attributes            [0] Attributes OPTIONAL,
       ...,
       [[2: publicKey        [1] PublicKey OPTIONAL ]],
       ...
}

There are maybe optional Attributes and Publickey after Privatekey. Thus it may not raise error when there are trailing data.

[Myse1f]

For ed25519 and ed448 in RFC5958, I think it should not raise error if something left after private key.

[tomato42]

Change looks good but there are few nits reported by codechecks, could you fix them?:

tox -e codechecks
GLOB sdist-make: /home/runner/work/python-ecdsa/python-ecdsa/setup.py
codechecks create: /home/runner/work/python-ecdsa/python-ecdsa/.tox/codechecks
codechecks installdeps: black==19.10b0, flake8
codechecks inst: /home/runner/work/python-ecdsa/python-ecdsa/.tox/.tmp/package/1/ecdsa-0.18.0b1+13.g8658d14.zip
codechecks installed: appdirs==1.4.4,attrs==21.4.0,black==19.10b0,click==8.0.3,ecdsa @ file:///home/runner/work/python-ecdsa/python-ecdsa/.tox/.tmp/package/1/ecdsa-0.18.0b1%2B13.g8658d14.zip,flake8==4.0.1,mccabe==0.6.1,pathspec==0.9.0,pycodestyle==2.8.0,pyflakes==2.4.0,regex==2021.11.10,six==1.16.0,toml==0.10.2,typed-ast==1.5.1
codechecks run-test-pre: PYTHONHASHSEED='3772385342'
codechecks run-test: commands[0] | flake8 setup.py speed.py src
src/ecdsa/keys.py:1127:1: W293 blank line contains whitespace
src/ecdsa/keys.py:1128:76: W291 trailing whitespace
src/ecdsa/keys.py:1129:70: W291 trailing whitespace
src/ecdsa/keys.py:1131:1: W293 blank line contains whitespace

[Myse1f]

Of course

Change looks good but there are few nits reported by codechecks, could you fix them?:

tox -e codechecks
GLOB sdist-make: /home/runner/work/python-ecdsa/python-ecdsa/setup.py
codechecks create: /home/runner/work/python-ecdsa/python-ecdsa/.tox/codechecks
codechecks installdeps: black==19.10b0, flake8
codechecks inst: /home/runner/work/python-ecdsa/python-ecdsa/.tox/.tmp/package/1/ecdsa-0.18.0b1+13.g8658d14.zip
codechecks installed: appdirs==1.4.4,attrs==21.4.0,black==19.10b0,click==8.0.3,ecdsa @ file:///home/runner/work/python-ecdsa/python-ecdsa/.tox/.tmp/package/1/ecdsa-0.18.0b1%2B13.g8658d14.zip,flake8==4.0.1,mccabe==0.6.1,pathspec==0.9.0,pycodestyle==2.8.0,pyflakes==2.4.0,regex==2021.11.10,six==1.16.0,toml==0.10.2,typed-ast==1.5.1
codechecks run-test-pre: PYTHONHASHSEED='3772385342'
codechecks run-test: commands[0] | flake8 setup.py speed.py src
src/ecdsa/keys.py:1127:1: W293 blank line contains whitespace
src/ecdsa/keys.py:1128:76: W291 trailing whitespace
src/ecdsa/keys.py:1129:70: W291 trailing whitespace
src/ecdsa/keys.py:1131:1: W293 blank line contains whitespace

[Myse1f]

Furthemore, I want to know if you have rough plan to release version 0.18.0. Then I could use the function for EdDSA.

[tomato42]

Furthemore, I want to know if you have rough plan to release version 0.18.0. Then I could use the function for EdDSA.

"when it's done", at the minimum, fixing the #268 and finishing #256 (adding interoperability testing with OpenSSL) needs to happen

[tomato42]

black part of codechecks is still failing, you should be able to fix it with tox -e codeformat

[Myse1f]

I think it should be fixed now.

[tomato42]

Yup, looks good. Thanks!