new commands: signmessage and verifymessage.

client/wallet.py

@@ -17,8 +17,7 @@
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 
-import sys, base64, os, re, hashlib, socket, getpass, copy, operator, ast, random
-from decimal import Decimal
+import sys, base64, os, re, hashlib, copy, operator, ast
 
 try:
     import ecdsa  
@@ -151,7 +150,6 @@ def int_to_hex(i, length=1):
     return s.decode('hex')[::-1].encode('hex')
 
 
-
 # AES
 EncodeAES = lambda secret, s: base64.b64encode(aes.encryptData(secret,s))
 DecodeAES = lambda secret, e: aes.decryptData(secret, base64.b64decode(e))
@@ -343,11 +341,73 @@ class Wallet:
 
         pk = number_to_string(secexp,order)
         return pk
+
+    def sign_message(self, address, message, password):
+        private_key = ecdsa.SigningKey.from_string( self.get_private_key2(address, password), curve = SECP256k1 )
+        public_key = private_key.get_verifying_key()
+        signature = private_key.sign_digest( Hash( message ), sigencode = ecdsa.util.sigencode_string )
+        assert public_key.verify_digest( signature, Hash( message ), sigdecode = ecdsa.util.sigdecode_string)
+        for i in range(4):
+            sig = base64.b64encode( chr(27+i) + signature )
+            if self.verify_message( address, sig, message):
+                return sig
+        else:
+            raise BaseException("error: cannot sign message")
+        
             
-            
-    def verify_message(self, signing_address, signature, message):
-        """ recover public key from signature; """
-        pass
+    def verify_message(self, address, signature, message):
+        """ See http://www.secg.org/download/aid-780/sec1-v2.pdf for the math """
+        
+        from ecdsa import numbertheory, ellipticcurve, util
+        import msqr
+        curve = curve_secp256k1
+        G = generator_secp256k1
+        order = G.order()
+
+        sig = base64.b64decode(signature)
+        if len(sig) != 65: raise BaseException("error")
+        recid = ord(sig[0]) - 27
+        # print "recid", recid
+
+        # extract r,s from signature
+        r,s = util.sigdecode_string(sig[1:], order)
+
+        # 1.1
+        x = r + (recid/2) * order
+
+        # 1.3
+        alpha = ( x * x * x  + curve.a() * x + curve.b() ) % curve.p()
+        beta = msqr.modular_sqrt(alpha, curve.p())
+        y = beta if (beta - recid) % 2 == 0 else curve.p() - beta
+
+        # 1.4 the constructor checks that nR is at infinity
+        try:
+            R = ellipticcurve.Point(curve, x, y, order)
+        except:
+            print "not in curve"
+            return False
+
+        # 1.5 compute e from message:
+        h = Hash(message)
+        e = string_to_number(h)
+        minus_e = -e % order
+
+        # 1.6 compute Q = r^-1 (sR - eG)
+        inv_r = numbertheory.inverse_mod(r,order)
+        Q = inv_r * ( s * R + minus_e * G )
+        public_key = ecdsa.VerifyingKey.from_public_point( Q, curve = SECP256k1 )
+
+        # check that Q is the public key
+        try:
+            public_key.verify_digest( sig[1:], h, sigdecode = ecdsa.util.sigdecode_string)
+        except:
+            print "wrong key"
+            return False
+
+        # check that we get the original signing address
+        addr = public_key_to_bc_address( '04'.decode('hex') + public_key.to_string() )
+        # print addr
+        return address == addr
     
 
     def create_new_address2(self, for_change):