functions added: verify_signature, address_from_pubkey

this seems to support developers experience: simple SigVerify and independent address from public key generation

crypto.py

@@ -268,4 +268,16 @@ def sign(privateKey, message):
     return base58.b58encode(curve.calculateSignature(random64, base58.b58decode(privateKey), message))
 
 def id(message):
-    return base58.b58encode(hashlib.sha256(message).digest())
+    return base58.b58encode(hashlib.sha256(message).digest())
+
+def verify_signature(pub_key, message, signature):
+    """ all of the arguments are expected in a string format """
+    return curve.verifySignature(base58.b58decode(pub_key), message.encode(), base58.b58decode(signature)) == 0
+
+def address_from_pubkey(public_key):
+    """ public key is expected as a string """
+    pubKey = base58.b58decode(public_key)
+    unhashedAddress = chr(1) + str(pw.CHAIN_ID) + pw.crypto.hashChain(pubKey)[0:20]
+    addressHash = pw.crypto.hashChain(pw.crypto.str2bytes(unhashedAddress))[0:4]
+    address = base58.b58encode(pw.crypto.str2bytes(unhashedAddress + addressHash))
+    return address