Use pointMult instead of arithmetic.privtopub

pointMult is faster than the pure python arithmetic.privtopub

Additionally in makeCryptor the call to a.privtopub could have just simply be changed to call the local privToPub but then privkey would have been dehexified twice (once in makeCryptor, then again in privToPub) and privToPub would have hexified its result only for makeCryptor to immediately dehexify it. This sort of unnecessary hexifying/dehexifying seems to occur throughout PyBitmessage.

src/highlevelcrypto.py

@@ -1,9 +1,10 @@
 import pyelliptic
 from pyelliptic import arithmetic as a, OpenSSL
 def makeCryptor(privkey):
-  privkey_bin = '\x02\xca\x00 '+a.changebase(privkey,16,256,minlen=32)
-  pubkey = a.changebase(a.privtopub(privkey),16,256,minlen=65)[1:]
-  pubkey_bin = '\x02\xca\x00 '+pubkey[:32]+'\x00 '+pubkey[32:]
+  private_key = a.changebase(privkey, 16, 256, minlen=32)
+  public_key = pointMult(private_key)
+  privkey_bin = '\x02\xca\x00\x20' + private_key
+  pubkey_bin = '\x02\xca\x00\x20' + public_key[1:-32] + '\x00\x20' + pubkey[-32:]
   cryptor = pyelliptic.ECC(curve='secp256k1',privkey=privkey_bin,pubkey=pubkey_bin)
   return cryptor
 def hexToPubkey(pubkey):
@@ -15,7 +16,9 @@ def makePubCryptor(pubkey):
   return pyelliptic.ECC(curve='secp256k1',pubkey=pubkey_bin)
 # Converts hex private key into hex public key
 def privToPub(privkey):
-  return a.privtopub(privkey)
+  private_key = a.changebase(privkey, 16, 256, minlen=32)
+  public_key = pointMult(private_key)
+  return public_key.encode('hex')
 # Encrypts message with hex public key
 def encrypt(msg,hexPubkey):
   return pyelliptic.ECC(curve='secp256k1').encrypt(msg,hexToPubkey(hexPubkey))