Add support for PKCSv1_5_NoOID signatures

[cipherboy]

This assumes a pre-hashed input has been provided to Vault, but we do not write the hash's OID into the signature stream. This allows us to generate the alternative PKCSv1_5_NoOID signature type rather than the existing PKCSv1_5_DERnull signature type we presently use.

These are specified in RFC 3447 Section 9.2.

Signed-off-by: Alexander Scheel <[email protected]>

---

I've not figured out how to test this independently with PyCryptography or OpenSSL... I'm not sure its really supported in their PKCS#1v1.5 APIs.

This fails on my system, since OpenSSL can't map none to a valid EVP_md algorithm:

#!/usr/bin/python3

import base64
import cryptography
import cryptography.hazmat
import cryptography.hazmat.primitives
import cryptography.hazmat.primitives.asymmetric
import cryptography.hazmat.primitives.asymmetric.padding
import cryptography.hazmat.primitives.asymmetric.utils
import cryptography.hazmat.primitives.hashes
import cryptography.hazmat.primitives.serialization

data = base64.b64decode("P8m2iUWdc4+MiKOkiqnjNUIBa3pAUuABqqU2/KdIE8s=")
sig = base64.b64decode("ipSuAuEoD6KOErYNApazvBGa+FQ1mXWdQYt7HbtZhWDz3XUayrOP9dGBa4yP1YuHs5svwjPa+rrv0pxUGmCNXBT4A8U7pc4f/OEzFhKTpqLd/PUAxP/attKATVJ8zHf/7B5s4db9hdAkBc3amHA4lgnYQLxb6DbyCwMeH2wPs4xuR3KLaZPGEDQhjb3ahjYwkEzuhlFzGFu2q01M+Ez5aLLXZiTczV6gZ6dkkPGR9NManG5Fi6AD9g21198dICKfeU9FnP4fAK65hYWDfe3Tphp+FPCmb8Tgtij30nFAnk/Ni1HAnyHoaqei7DL19WL1loqD0RvzfIekdhQYmvdcfg==")
pub = b"""-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1wUu+Ks0pYD/lkSJYTb6
n9sXIll058PmnCaugl7gATQ7KbJv6ZTu9GpbM1j0hIU3sCfEjEZh2Xld9B9mLXb5
qUZp4dkyztQZs/w20A3EQgH+EjBVyfFEH/TdAU97z80QCy2Hrq7rSOCIFf5oQoYe
m+qMLz2VTxDN+ve9emiPypXeWCfo7XGapXkZkocRTh5qL3wbuUH1nLgJaYU6J8Vv
6PhTQgV1ZcPf4hqcYMeRBHDQOEMj5VezdzVHzFC6mBaRMZTzTpWZS8ps8pNCCC73
hHmN9v8U2L/Ogli2phB23aP58Oh0RDj84L/KfG1YutMUiGtjAiRFDEdzL8QEbzUq
MQIDAQAB
-----END PUBLIC KEY-----"""

public_key = cryptography.hazmat.primitives.serialization.load_pem_public_key(pub)

class NoHash(cryptography.hazmat.primitives.hashes.HashAlgorithm):
    name = "none"
    digest_size = 32
    block_size = 0

print(len(sig), len(data), NoHash().digest_size, cryptography.hazmat.primitives.asymmetric.utils.Prehashed(NoHash()).digest_size)

ret = public_key.verify(
    sig,
    data,
    cryptography.hazmat.primitives.asymmetric.padding.PKCS1v15(),
    cryptography.hazmat.primitives.asymmetric.utils.Prehashed(NoHash()))

[cipherboy]

Hearing nothing else, I'm going ahead and merging. Thanks all!