* Adding handshake patterns

* Adding token constants for handshake patterns

noise/constants.py

@@ -1,2 +1,12 @@
 class Empty:
     pass
+
+
+# Handshake pattern tokens
+TOKEN_E = 'e'
+TOKEN_S = 's'
+TOKEN_EE = 'ee'
+TOKEN_ES = 'es'
+TOKEN_SE = 'se'
+TOKEN_SS = 'ss'
+TOKEN_PSK = 'psk'

noise/patterns.py

@@ -0,0 +1,161 @@
+from noise.constants import TOKEN_E, TOKEN_S, TOKEN_EE, TOKEN_ES, TOKEN_SE, TOKEN_SS, TOKEN_PSK
+
+
+class Pattern(object):
+    """
+    TODO document
+    """
+    # As per specification, if both parties have pre-messages, the initiator is listed first. To reduce complexity,
+    # pre_messages shall be a list of two lists:
+    # the first for the initiator's pre-messages, the second for the responder
+    pre_messages = [
+        [],
+        []
+    ]
+    # TODO Comment
+    tokens = []
+
+
+# One-way patterns
+
+class PatternN(Pattern):
+    pre_messages = [
+        [],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES]
+    ]
+
+
+class PatternK(Pattern):
+    pre_messages = [
+        [TOKEN_S],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES, TOKEN_SS]
+    ]
+
+
+class PatternX(Pattern):
+    pre_messages = [
+        [],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES, TOKEN_S, TOKEN_SS]
+    ]
+
+
+# Interactive patterns
+
+class PatternNN(Pattern):
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE]
+    ]
+
+
+class PatternKN(Pattern):
+    pre_messages = [
+        [TOKEN_S],
+        []
+    ]
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE]
+    ]
+
+
+class PatternNK(Pattern):
+    pre_messages = [
+        [],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES],
+        [TOKEN_E, TOKEN_EE]
+    ]
+
+
+class PatternKK(Pattern):
+    pre_messages = [
+        [TOKEN_S],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES, TOKEN_SS],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE]
+    ]
+
+
+class PatternNX(Pattern):
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE, TOKEN_S, TOKEN_ES]
+    ]
+
+
+class PatternKX(Pattern):
+    pre_messages = [
+        [TOKEN_S],
+        []
+    ]
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE, TOKEN_S, TOKEN_ES]
+    ]
+
+
+class PatternXN(Pattern):
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE],
+        [TOKEN_S, TOKEN_SE]
+    ]
+
+
+class PatternIN(Pattern):
+    tokens = [
+        [TOKEN_E, TOKEN_S],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE]
+    ]
+
+
+class PatternXK(Pattern):
+    pre_messages = [
+        [],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES],
+        [TOKEN_E, TOKEN_EE],
+        [TOKEN_S, TOKEN_SE]
+    ]
+
+
+class PatternIK(Pattern):
+    pre_messages = [
+        [],
+        [TOKEN_S]
+    ]
+    tokens = [
+        [TOKEN_E, TOKEN_ES, TOKEN_S, TOKEN_SS],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE]
+    ]
+
+
+class PatternXX(Pattern):
+    tokens = [
+        [TOKEN_E],
+        [TOKEN_E, TOKEN_EE, TOKEN_S, TOKEN_ES],
+        [TOKEN_S, TOKEN_SE]
+    ]
+
+
+class PatternIX(Pattern):
+    tokens = [
+        [TOKEN_E, TOKEN_S],
+        [TOKEN_E, TOKEN_EE, TOKEN_SE, TOKEN_S, TOKEN_ES]
+    ]