signature_method.py

import oauth2 as oauth
import base64
from tlslite.utils import keyfactory

class SignatureMethod_RSA_SHA1(oauth.SignatureMethod):
    name = 'RSA-SHA1'
    def __init__(self, key_path):
      self.key_path = key_path

    def signing_base(self, request, consumer, token):
        if not hasattr(request, 'normalized_url') or request.normalized_url is None:
            raise ValueError("Base URL for request is not set.")

        sig = (
            oauth.escape(request.method),
            oauth.escape(request.normalized_url),
            oauth.escape(request.get_normalized_parameters()),
        )

        key = '%s&' % oauth.escape(consumer.secret)
        if token:
            key += oauth.escape(token.secret)
        raw = '&'.join(sig)
        return key, raw

    def sign(self, request, consumer, token):
        """Builds the base signature string."""
        key, raw = self.signing_base(request, consumer, token)

        with open(self.key_path, 'r') as f:
            data = f.read()
        privateKeyString = data.strip()

        privatekey = keyfactory.parsePrivateKey(privateKeyString)
        signature = privatekey.hashAndSign(raw)

        return base64.b64encode(signature)