https://github.com/jaymine/Simple-Blockchain

Sign and verify.py

from Crypto.Hash import SHA256
from Crypto.Signature import PKCS1_v1_5
from Crypto.PublicKey import RSA

def sign (digest, privatekeyfile):
    private_key = False
    with open(privatekeyfile, "r") as private_key_file: # Read private key from file
        private_key = RSA.importKey(private_key_file.read())
    signer = PKCS1_v1_5.new(private_key) # Load private key and sign message
    return signer.sign(digest)

def verify (digest, signedBlockdata, publickeyfile):
    public_key = False
    with open(publickeyfile, "r") as public_key_file: # Load public key
        public_key = RSA.importKey(public_key_file.read())
    verifier = PKCS1_v1_5.new(public_key) # Verify message
    verified = verifier.verify(digest, signedBlockdata)
    assert verified, 'Signature verification failed'
    print 'Successfully verified message\n'