python pycrypto pyopenssl sign data from private key

sign.py

def sign(private_key_loc, policyText):
    '''
    param: private_key_loc Path to your private key
    param: package PolicyText to be signed
    return: base64 encoded signature
    '''
    from Crypto.PublicKey import RSA 
    from Crypto.Signature import PKCS1_v1_5 
    from Crypto.Hash import SHA256
    from OpenSSL import crypto
    from base64 import b64encode, b64decode
    key = open(private_key_loc, "rb").read()
    p12 = crypto.load_pkcs12(key, "notasecret")
    pem = crypto.dump_privatekey(crypto.FILETYPE_PEM, p12.get_privatekey())
    rsakey = RSA.importKey(pem) 
    signer = PKCS1_v1_5.new(rsakey) 
    digest = SHA256.new() 
    # It's being assumed the data is plain text, so it's encoded before updating the digest 
    digest.update(b64encode(policyText)) 
    sign = signer.sign(digest) 
    verifier = PKCS1_v1_5.new(rsakey.publickey())
    verified = verifier.verify(digest, sign)
    print verified
    return b64encode(sign)

def signUsingJson(json_loc, policyText):
    '''
    param: private_key_loc Path to your private JSON key
    param: package PolicyText to be signed
    return: base64 encoded signature
    '''
    from oauth2client.service_account import ServiceAccountCredentials
    from base64 import b64encode, b64decode
    creds = ServiceAccountCredentials.from_json_keyfile_name(json_loc)
    # It's being assumed the data is plain text, so it's encoded before updating the digest 
    signature = creds.sign_blob(b64encode(policyText))[1]
    return b64encode(signature)