Adding a Python functional model of the ChaCha stream cipher.

1 files changed, 696 insertions, 0 deletions

diff --git a/src/model/python/chacha.py b/src/model/python/chacha.py
new file mode 100755
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+++ b/src/model/python/chacha.py
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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#=======================================================================
+#
+# chacha.py
+# ---------
+# Simple model of the ChaCha stream cipher. Used as a reference for
+# the HW implementation. The code follows the structure of the
+# HW implementation as much as possible.
+#
+#
+# Author: Joachim Strombergson
+# Copyright (c) 2011, NORDUnet A/S All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+# - Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+#
+# - Redistributions in binary form must reproduce the above copyright
+#   notice, this list of conditions and the following disclaimer in the
+#   documentation and/or other materials provided with the distribution.
+#
+# - Neither the name of the NORDUnet nor the names of its contributors may
+#   be used to endorse or promote products derived from this software
+#   without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+#=======================================================================
+
+#-------------------------------------------------------------------
+# Python module imports.
+#-------------------------------------------------------------------
+import sys
+
+
+#-------------------------------------------------------------------
+# Constants.
+#-------------------------------------------------------------------
+TAU   = [0x61707865, 0x3120646e, 0x79622d36, 0x6b206574]
+SIGMA = [0x61707865, 0x3320646e, 0x79622d32, 0x6b206574]
+
+
+#-------------------------------------------------------------------
+# ChaCha()
+#-------------------------------------------------------------------
+class ChaCha():
+
+    #---------------------------------------------------------------
+    # __init__()
+    #
+    # Given the key, iv initializes the state of the cipher.
+    # The number of rounds used can be set. By default 8 rounds
+    # are used. Accepts a list of either 16 or 32 bytes as key.
+    # Accepts a list of 8 bytes as IV.
+    #---------------------------------------------------------------
+    def __init__(self, key, iv, rounds = 8, verbose = 0):
+        self.state = [0] * 16
+        self.x = [0] * 16
+        self.rounds = rounds
+        self.verbose = verbose
+        self.set_key_iv(key, iv)
+
+
+    #---------------------------------------------------------------
+    # set_key_iv()
+    #
+    # Set key and iv. Basically reinitialize the cipher.
+    # This also resets the block counter.
+    #---------------------------------------------------------------
+    def set_key_iv(self, key, iv):
+        keyword0 = self._b2w(key[0:4])
+        keyword1 = self._b2w(key[4:8])
+        keyword2 = self._b2w(key[8:12])
+        keyword3 = self._b2w(key[12:16])
+
+        if len(key) == 16:
+            self.state[0]  = TAU[0]
+            self.state[1]  = TAU[1]
+            self.state[2]  = TAU[2]
+            self.state[3]  = TAU[3]
+            self.state[4]  = keyword0
+            self.state[5]  = keyword1
+            self.state[6]  = keyword2
+            self.state[7]  = keyword3
+            self.state[8]  = keyword0
+            self.state[9]  = keyword1
+            self.state[10] = keyword2
+            self.state[11] = keyword3
+
+        elif len(key) == 32:
+            keyword4 = self._b2w(key[16:20])
+            keyword5 = self._b2w(key[20:24])
+            keyword6 = self._b2w(key[24:28])
+            keyword7 = self._b2w(key[28:32])
+            self.state[0]  = SIGMA[0]
+            self.state[1]  = SIGMA[1]
+            self.state[2]  = SIGMA[2]
+            self.state[3]  = SIGMA[3]
+            self.state[4]  = keyword0
+            self.state[5]  = keyword1
+            self.state[6]  = keyword2
+            self.state[7]  = keyword3
+            self.state[8]  = keyword4
+            self.state[9]  = keyword5
+            self.state[10] = keyword6
+            self.state[11] = keyword7
+        else:
+            print("Key length of %d bits, is not supported." % (len(key) * 8))
+
+        # Common state init for both key lengths.
+        self.block_counter = [0, 0]
+        self.state[12] = self.block_counter[0]
+        self.state[13] = self.block_counter[1]
+        self.state[14] = self._b2w(iv[0:4])
+        self.state[15] = self._b2w(iv[4:8])
+
+        if self.verbose:
+            print("State after init:")
+            self._print_state()
+
+
+    #---------------------------------------------------------------
+    # next()
+    #
+    # Encyp/decrypt the next block. This also updates the
+    # internal state and increases the block counter.
+    #---------------------------------------------------------------
+    def next(self, data_in):
+        # Copy the current internal state to the temporary state x.
+        self.x = self.state[:]
+
+        if self.verbose:
+            print("State before round processing.")
+            self._print_state()
+
+        if self.verbose:
+            print("X before round processing:")
+            self._print_x()
+
+        # Update the internal state by performing
+        # (rounds / 2) double rounds.
+        for i in range(int(self.rounds / 2)):
+            if (self.verbose > 1):
+                print("Doubleround 0x%02x:" % i)
+            self._doubleround()
+            if (self.verbose > 1):
+                print("")
+
+        if self.verbose:
+            print("X after round processing:")
+            self._print_x()
+
+        # Update the internal state by adding the elements
+        # of the temporary state to the internal state.
+        self.state = [((self.state[i] + self.x[i]) & 0xffffffff) for i in range(16)]
+
+        if self.verbose:
+            print("State after round processing.")
+            self._print_state()
+
+        bytestate = []
+        for i in self.state:
+            bytestate += self._w2b(i)
+
+        # Create the data out words.
+        data_out = [data_in[i] ^ bytestate[i] for i in range(64)]
+
+        # Update the block counter.
+        self._inc_counter()
+
+        return data_out
+
+
+    #---------------------------------------------------------------
+    # _doubleround()
+    #
+    # Perform the two complete rounds that comprises the
+    # double round.
+    #---------------------------------------------------------------
+    def _doubleround(self):
+        if (self.verbose > 0):
+            print("Start of double round processing.")
+
+        self._quarterround(0, 4,  8, 12)
+        if (self.verbose > 1):
+            print("X after QR 0")
+            self._print_x()
+        self._quarterround(1, 5,  9, 13)
+        if (self.verbose > 1):
+            print("X after QR 1")
+            self._print_x()
+        self._quarterround(2, 6, 10, 14)
+        if (self.verbose > 1):
+            print("X after QR 2")
+            self._print_x()
+        self._quarterround(3, 7, 11, 15)
+        if (self.verbose > 1):
+            print("X after QR 3")
+            self._print_x()
+
+        self._quarterround(0, 5, 10, 15)
+        if (self.verbose > 1):
+            print("X after QR 4")
+            self._print_x()
+        self._quarterround(1, 6, 11, 12)
+        if (self.verbose > 1):
+            print("X after QR 5")
+            self._print_x()
+        self._quarterround(2, 7,  8, 13)
+        if (self.verbose > 1):
+            print("X after QR 6")
+            self._print_x()
+        self._quarterround(3, 4,  9, 14)
+        if (self.verbose > 1):
+            print("X after QR 7")
+            self._print_x()
+
+        if (self.verbose > 0):
+            print("End of double round processing.")
+
+
+    #---------------------------------------------------------------
+    #  _quarterround()
+    #
+    # Updates four elements in the state vector x given by
+    # their indices.
+    #---------------------------------------------------------------
+    def _quarterround(self, ai, bi, ci, di):
+        # Extract four elemenst from x using the qi tuple.
+        a, b, c, d = self.x[ai], self.x[bi], self.x[ci], self.x[di]
+
+        if (self.verbose > 1):
+            print("Indata to quarterround:")
+            print("X state indices:", ai, bi, ci, di)
+            print("a = 0x%08x, b = 0x%08x, c = 0x%08x, d = 0x%08x" %\
+                  (a, b, c, d))
+            print("")
+
+        a0 = (a + b) & 0xffffffff
+        d0 = d ^ a0
+        d1 = ((d0 << 16) + (d0 >> 16)) & 0xffffffff
+        c0 = (c + d1) & 0xffffffff
+        b0 = b ^ c0
+        b1 = ((b0 << 12) + (b0 >> 20)) & 0xffffffff
+        a1 = (a0 + b1) & 0xffffffff
+        d2 = d1 ^ a1
+        d3 = ((d2 << 8) + (d2 >> 24)) & 0xffffffff
+        c1 = (c0 + d3) & 0xffffffff
+        b2 = b1 ^ c1
+        b3 = ((b2 << 7) + (b2 >> 25)) & 0xffffffff
+
+        if (self.verbose > 2):
+            print("Intermediate values:")
+            print("a0 = 0x%08x, a1 = 0x%08x" % (a0, a1))
+            print("b0 = 0x%08x, b1 = 0x%08x, b2 = 0x%08x, b3 = 0x%08x" %\
+                  (b0, b1, b2, b3))
+            print("c0 = 0x%08x, c1 = 0x%08x" % (c0, c1))
+            print("d0 = 0x%08x, d1 = 0x%08x, d2 = 0x%08x, d3 = 0x%08x" %\
+                  (d0, d1, d2, d3))
+            print("")
+
+        a_prim = a1
+        b_prim = b3
+        c_prim = c1
+        d_prim = d3
+
+        if (self.verbose > 1):
+            print("Outdata from quarterround:")
+            print("a_prim = 0x%08x, b_prim = 0x%08x, c_prim = 0x%08x, d_prim = 0x%08x" %\
+                  (a_prim, b_prim, c_prim, d_prim))
+            print("")
+
+        # Update the four elemenst in x using the qi tuple.
+        self.x[ai], self.x[bi] = a_prim, b_prim
+        self.x[ci], self.x[di] = c_prim, d_prim
+
+
+    #---------------------------------------------------------------
+    # _inc_counter()
+    #
+    # Increase the 64 bit block counter.
+    #---------------------------------------------------------------
+    def _inc_counter(self):
+        self.block_counter[0] += 1 & 0xffffffff
+        if not (self.block_counter[0] % 0xffffffff):
+            self.block_counter[1] += 1 & 0xffffffff
+
+
+    #---------------------------------------------------------------
+    # _b2w()
+    #
+    # Given a list of four bytes returns the little endian
+    # 32 bit word representation of the bytes.
+    #---------------------------------------------------------------
+    def _b2w(self, bytes):
+        return (bytes[0] + (bytes[1] << 8)
+                + (bytes[2] << 16) + (bytes[3] << 24)) & 0xffffffff
+
+
+    #---------------------------------------------------------------
+    # _w2b()
+    #
+    # Given a 32-bit word returns a list of set of four bytes
+    # that is the little endian byte representation of the word.
+    #---------------------------------------------------------------
+    def _w2b(self, word):
+        return [(word & 0x000000ff), ((word & 0x0000ff00) >> 8),
+                ((word & 0x00ff0000) >> 16), ((word & 0xff000000) >> 24)]
+
+
+    #---------------------------------------------------------------
+    # _print_state()
+    #
+    # Print the internal state.
+    #---------------------------------------------------------------
+    def _print_state(self):
+        print(" 0: 0x%08x,  1: 0x%08x,  2: 0x%08x,  3: 0x%08x" %\
+              (self.state[0], self.state[1], self.state[2], self.state[3]))
+        print(" 4: 0x%08x,  5: 0x%08x,  6: 0x%08x,  7: 0x%08x" %\
+              (self.state[4], self.state[5], self.state[6], self.state[7]))
+        print(" 8: 0x%08x,  9: 0x%08x, 10: 0x%08x, 11: 0x%08x" %\
+              (self.state[8], self.state[9], self.state[10], self.state[11]))
+        print("12: 0x%08x, 13: 0x%08x, 14: 0x%08x, 15: 0x%08x" %\
+              (self.state[12], self.state[13], self.state[14], self.state[15]))
+        print("")
+
+
+    #---------------------------------------------------------------
+    # _print_x()
+    #
+    # Print the temporary state X.
+    #---------------------------------------------------------------
+    def _print_x(self):
+        print(" 0: 0x%08x,  1: 0x%08x,  2: 0x%08x,  3: 0x%08x" %\
+              (self.x[0], self.x[1], self.x[2], self.x[3]))
+        print(" 4: 0x%08x,  5: 0x%08x,  6: 0x%08x,  7: 0x%08x" %\
+              (self.x[4], self.x[5], self.x[6], self.x[7]))
+        print(" 8: 0x%08x,  9: 0x%08x, 10: 0x%08x, 11: 0x%08x" %\
+              (self.x[8], self.x[9], self.x[10], self.x[11]))
+        print("12: 0x%08x, 13: 0x%08x, 14: 0x%08x, 15: 0x%08x" %\
+              (self.x[12], self.x[13], self.x[14], self.x[15]))
+        print("")
+
+
+#-------------------------------------------------------------------
+# print_block()
+#
+# Print a given block (list) of bytes ordered in
+# rows of eight bytes.
+#-------------------------------------------------------------------
+def print_block(block):
+    for i in range(0, len(block), 8):
+        print("0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x" %\
+              (block[i], block[i+1], block[i+2], block[i+3],
+               block[i+4], block[i+5], block[i+6], block[i+7]))
+
+
+#-------------------------------------------------------------------
+# check_block()
+#
+# Compare the result block with the expected block and print
+# if the result for the given test case was correct or not.
+#-------------------------------------------------------------------
+def check_block(result, expected, test_case):
+    if result == expected:
+        print("SUCCESS: %s was correct." % test_case)
+    else:
+        print("ERROR: %s was not correct." % test_case)
+        print("Expected:")
+        print_block(expected)
+        print("")
+        print("Result:")
+        print_block(result)
+    print("")
+
+
+#-------------------------------------------------------------------
+# main()
+#
+# If executed tests the ChaCha class using known test vectors.
+#-------------------------------------------------------------------
+def main():
+    print("Testing the ChaCha Python model.")
+    print("--------------------------------")
+    print
+
+    # Testing with TC1-128-8.
+    # All zero inputs. IV all zero. 128 bit key, 8 rounds.
+    print("TC1-128-8: All zero inputs. 128 bit key, 8 rounds.")
+    key1 = [0x00] * 16
+    iv1  = [0x00] * 8
+    expected1 = [0xe2, 0x8a, 0x5f, 0xa4, 0xa6, 0x7f, 0x8c, 0x5d,
+                 0xef, 0xed, 0x3e, 0x6f, 0xb7, 0x30, 0x34, 0x86,
+                 0xaa, 0x84, 0x27, 0xd3, 0x14, 0x19, 0xa7, 0x29,
+                 0x57, 0x2d, 0x77, 0x79, 0x53, 0x49, 0x11, 0x20,
+                 0xb6, 0x4a, 0xb8, 0xe7, 0x2b, 0x8d, 0xeb, 0x85,
+                 0xcd, 0x6a, 0xea, 0x7c, 0xb6, 0x08, 0x9a, 0x10,
+                 0x18, 0x24, 0xbe, 0xeb, 0x08, 0x81, 0x4a, 0x42,
+                 0x8a, 0xab, 0x1f, 0xa2, 0xc8, 0x16, 0x08, 0x1b]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-128-8")
+    print
+
+
+    # Testing with TC1-128-12.
+    # All zero inputs. IV all zero. 128 bit key, 12 rounds.
+    print("TC1-128-12: All zero inputs. 128 bit key, 12 rounds.")
+    key1 = [0x00] * 16
+    iv1  = [0x00] * 8
+    expected1 = [0xe1, 0x04, 0x7b, 0xa9, 0x47, 0x6b, 0xf8, 0xff,
+                 0x31, 0x2c, 0x01, 0xb4, 0x34, 0x5a, 0x7d, 0x8c,
+                 0xa5, 0x79, 0x2b, 0x0a, 0xd4, 0x67, 0x31, 0x3f,
+                 0x1d, 0xc4, 0x12, 0xb5, 0xfd, 0xce, 0x32, 0x41,
+                 0x0d, 0xea, 0x8b, 0x68, 0xbd, 0x77, 0x4c, 0x36,
+                 0xa9, 0x20, 0xf0, 0x92, 0xa0, 0x4d, 0x3f, 0x95,
+                 0x27, 0x4f, 0xbe, 0xff, 0x97, 0xbc, 0x84, 0x91,
+                 0xfc, 0xef, 0x37, 0xf8, 0x59, 0x70, 0xb4, 0x50]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, rounds = 12, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-128-12")
+    print
+
+
+    # Testing with TC1-128-20.
+    # All zero inputs. IV all zero. 128 bit key, 20 rounds.
+    print("TC1-128-20: All zero inputs. 128 bit key, 20 rounds.")
+    key1 = [0x00] * 16
+    iv1  = [0x00] * 8
+    expected1 = [0x89, 0x67, 0x09, 0x52, 0x60, 0x83, 0x64, 0xfd,
+                 0x00, 0xb2, 0xf9, 0x09, 0x36, 0xf0, 0x31, 0xc8,
+                 0xe7, 0x56, 0xe1, 0x5d, 0xba, 0x04, 0xb8, 0x49,
+                 0x3d, 0x00, 0x42, 0x92, 0x59, 0xb2, 0x0f, 0x46,
+                 0xcc, 0x04, 0xf1, 0x11, 0x24, 0x6b, 0x6c, 0x2c,
+                 0xe0, 0x66, 0xbe, 0x3b, 0xfb, 0x32, 0xd9, 0xaa,
+                 0x0f, 0xdd, 0xfb, 0xc1, 0x21, 0x23, 0xd4, 0xb9,
+                 0xe4, 0x4f, 0x34, 0xdc, 0xa0, 0x5a, 0x10, 0x3f]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, rounds = 20, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-128-20")
+    print
+
+
+    # Testing with TC1-256-8.
+    # All zero inputs. IV all zero. 256 bit key, 8 rounds.
+    print("TC1-256-8: All zero inputs. 256 bit key, 8 rounds.")
+    key1 = [0x00] * 32
+    iv1  = [0x00] * 8
+    expected1 = [0x3e, 0x00, 0xef, 0x2f, 0x89, 0x5f, 0x40, 0xd6,
+                 0x7f, 0x5b, 0xb8, 0xe8, 0x1f, 0x09, 0xa5, 0xa1,
+                 0x2c, 0x84, 0x0e, 0xc3, 0xce, 0x9a, 0x7f, 0x3b,
+                 0x18, 0x1b, 0xe1, 0x88, 0xef, 0x71, 0x1a, 0x1e,
+                 0x98, 0x4c, 0xe1, 0x72, 0xb9, 0x21, 0x6f, 0x41,
+                 0x9f, 0x44, 0x53, 0x67, 0x45, 0x6d, 0x56, 0x19,
+                 0x31, 0x4a, 0x42, 0xa3, 0xda, 0x86, 0xb0, 0x01,
+                 0x38, 0x7b, 0xfd, 0xb8, 0x0e, 0x0c, 0xfe, 0x42]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-256-8")
+    print
+
+
+    # Testing with TC1-256-12.
+    # All zero inputs. IV all zero. 256 bit key, 12 rounds.
+    print("TC1-256-12: All zero inputs. 256 bit key, 12 rounds.")
+    key1 = [0x00] * 32
+    iv1  = [0x00] * 8
+    expected1 = [0x9b, 0xf4, 0x9a, 0x6a, 0x07, 0x55, 0xf9, 0x53,
+                 0x81, 0x1f, 0xce, 0x12, 0x5f, 0x26, 0x83, 0xd5,
+                 0x04, 0x29, 0xc3, 0xbb, 0x49, 0xe0, 0x74, 0x14,
+                 0x7e, 0x00, 0x89, 0xa5, 0x2e, 0xae, 0x15, 0x5f,
+                 0x05, 0x64, 0xf8, 0x79, 0xd2, 0x7a, 0xe3, 0xc0,
+                 0x2c, 0xe8, 0x28, 0x34, 0xac, 0xfa, 0x8c, 0x79,
+                 0x3a, 0x62, 0x9f, 0x2c, 0xa0, 0xde, 0x69, 0x19,
+                 0x61, 0x0b, 0xe8, 0x2f, 0x41, 0x13, 0x26, 0xbe]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, rounds = 12, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-256-12")
+    print
+
+
+    # Testing with TC1-256-20.
+    # All zero inputs. IV all zero. 256 bit key, 20 rounds.
+    print("TC1-256-20: All zero inputs. 256 bit key, 20 rounds.")
+    key1 = [0x00] * 32
+    iv1  = [0x00] * 8
+    expected1 = [0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90,
+                 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28,
+                 0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a,
+                 0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7,
+                 0xda, 0x41, 0x59, 0x7c, 0x51, 0x57, 0x48, 0x8d,
+                 0x77, 0x24, 0xe0, 0x3f, 0xb8, 0xd8, 0x4a, 0x37,
+                 0x6a, 0x43, 0xb8, 0xf4, 0x15, 0x18, 0xa1, 0x1c,
+                 0xc3, 0x87, 0xb6, 0x69, 0xb2, 0xee, 0x65, 0x86]
+    block1 = [0x00] * 64
+    cipher1 = ChaCha(key1, iv1, rounds = 20, verbose=0)
+    result1 = cipher1.next(block1)
+    check_block(result1, expected1, "TC1-256-20")
+    print
+
+
+    # Testing with TC2-128-8.
+    # Single bit set in key. IV all zero. 128 bit key.
+    print("TC2-128-8: One bit in key set. IV all zeros. 128 bit key, 8 rounds.")
+    key2 = [0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+    iv2  = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+    expected2 = [0x03, 0xa7, 0x66, 0x98, 0x88, 0x60, 0x5a, 0x07,
+                 0x65, 0xe8, 0x35, 0x74, 0x75, 0xe5, 0x86, 0x73,
+                 0xf9, 0x4f, 0xc8, 0x16, 0x1d, 0xa7, 0x6c, 0x2a,
+                 0x3a, 0xa2, 0xf3, 0xca, 0xf9, 0xfe, 0x54, 0x49,
+                 0xe0, 0xfc, 0xf3, 0x8e, 0xb8, 0x82, 0x65, 0x6a,
+                 0xf8, 0x3d, 0x43, 0x0d, 0x41, 0x09, 0x27, 0xd5,
+                 0x5c, 0x97, 0x2a, 0xc4, 0xc9, 0x2a, 0xb9, 0xda,
+                 0x37, 0x13, 0xe1, 0x9f, 0x76, 0x1e, 0xaa, 0x14]
+    block2 = [0x00] * 64
+    cipher2 = ChaCha(key2, iv2, verbose=0)
+    result2 = cipher2.next(block2)
+    check_block(result2, expected2, "TC2-128-8")
+    print
+
+
+    # Testing with TC2-256-8.
+    # Single bit set in key. IV all zero. 256 bit key.
+    print("TC2-256-8: One bit in key set. IV all zeros. 256 bit key, 8 rounds.")
+    key2 = [0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+    iv2  = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+    expected2 = [0xcf, 0x5e, 0xe9, 0xa0, 0x49, 0x4a, 0xa9, 0x61,
+                 0x3e, 0x05, 0xd5, 0xed, 0x72, 0x5b, 0x80, 0x4b,
+                 0x12, 0xf4, 0xa4, 0x65, 0xee, 0x63, 0x5a, 0xcc,
+                 0x3a, 0x31, 0x1d, 0xe8, 0x74, 0x04, 0x89, 0xea,
+                 0x28, 0x9d, 0x04, 0xf4, 0x3c, 0x75, 0x18, 0xdb,
+                 0x56, 0xeb, 0x44, 0x33, 0xe4, 0x98, 0xa1, 0x23,
+                 0x8c, 0xd8, 0x46, 0x4d, 0x37, 0x63, 0xdd, 0xbb,
+                 0x92, 0x22, 0xee, 0x3b, 0xd8, 0xfa, 0xe3, 0xc8]
+    block2 = [0x00] * 64
+    cipher2 = ChaCha(key2, iv2, verbose=0)
+    result2 = cipher2.next(block2)
+    check_block(result2, expected2, "TC2-256-8")
+    print
+
+
+    # Testing with TC3-128-8.
+    # All zero key. Single bit in IV set. 128 bit key.
+    print("TC3-128-8: All zero key. Single bit in IV set. 128 bit key, 8 rounds.")
+    key3 = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+    iv3  = [0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+
+    expected3 = [0x25, 0xf5, 0xbe, 0xc6, 0x68, 0x39, 0x16, 0xff,
+                 0x44, 0xbc, 0xcd, 0x12, 0xd1, 0x02, 0xe6, 0x92,
+                 0x17, 0x66, 0x63, 0xf4, 0xca, 0xc5, 0x3e, 0x71,
+                 0x95, 0x09, 0xca, 0x74, 0xb6, 0xb2, 0xee, 0xc8,
+                 0x5d, 0xa4, 0x23, 0x6f, 0xb2, 0x99, 0x02, 0x01,
+                 0x2a, 0xdc, 0x8f, 0x0d, 0x86, 0xc8, 0x18, 0x7d,
+                 0x25, 0xcd, 0x1c, 0x48, 0x69, 0x66, 0x93, 0x0d,
+                 0x02, 0x04, 0xc4, 0xee, 0x88, 0xa6, 0xab, 0x35]
+    block3 = [0x00] * 64
+    cipher3 = ChaCha(key3, iv3, verbose=0)
+    result3 = cipher3.next(block3)
+    check_block(result3, expected3, "TC3-128-8")
+    print
+
+
+    # Testing with TC4-128-8.
+    # All bits in key IV are set. 128 bit key, 8 rounds.
+    print("TC4-128-8: All bits in key IV are set. 128 bit key, 8 rounds.")
+    key4 = [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+            0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]
+    iv4  = [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]
+    expected4 = [0x22, 0x04, 0xd5, 0xb8, 0x1c, 0xe6, 0x62, 0x19,
+                 0x3e, 0x00, 0x96, 0x60, 0x34, 0xf9, 0x13, 0x02,
+                 0xf1, 0x4a, 0x3f, 0xb0, 0x47, 0xf5, 0x8b, 0x6e,
+                 0x6e, 0xf0, 0xd7, 0x21, 0x13, 0x23, 0x04, 0x16,
+                 0x3e, 0x0f, 0xb6, 0x40, 0xd7, 0x6f, 0xf9, 0xc3,
+                 0xb9, 0xcd, 0x99, 0x99, 0x6e, 0x6e, 0x38, 0xfa,
+                 0xd1, 0x3f, 0x0e, 0x31, 0xc8, 0x22, 0x44, 0xd3,
+                 0x3a, 0xbb, 0xc1, 0xb1, 0x1e, 0x8b, 0xf1, 0x2d]
+    block4 = [0x00] * 64
+    cipher4 = ChaCha(key4, iv4, verbose=0)
+    result4 = cipher4.next(block4)
+    check_block(result4, expected4, "TC4-128-8")
+    print
+
+
+    # Testing with TC5-128-8
+    print("TC5-128-8: Even bits set. 128 bit key, 8 rounds.")
+    key5 = [0x55] * 16
+    iv5  = [0x55] * 8
+    expected5 = [0xf0, 0xa2, 0x3b, 0xc3, 0x62, 0x70, 0xe1, 0x8e,
+                 0xd0, 0x69, 0x1d, 0xc3, 0x84, 0x37, 0x4b, 0x9b,
+                 0x2c, 0x5c, 0xb6, 0x01, 0x10, 0xa0, 0x3f, 0x56,
+                 0xfa, 0x48, 0xa9, 0xfb, 0xba, 0xd9, 0x61, 0xaa,
+                 0x6b, 0xab, 0x4d, 0x89, 0x2e, 0x96, 0x26, 0x1b,
+                 0x6f, 0x1a, 0x09, 0x19, 0x51, 0x4a, 0xe5, 0x6f,
+                 0x86, 0xe0, 0x66, 0xe1, 0x7c, 0x71, 0xa4, 0x17,
+                 0x6a, 0xc6, 0x84, 0xaf, 0x1c, 0x93, 0x19, 0x96]
+    block5 = [0x00] * 64
+    cipher5 = ChaCha(key5, iv5, verbose=0)
+    result5 = cipher5.next(block5)
+    check_block(result5, expected5, "TC5-128-8")
+    print
+
+
+    # Testing with TC6-128-8
+    print("TC6-128-8: Odd bits set. 128 bit key, 8 rounds.")
+    key6 = [0xaa] * 16
+    iv6  = [0xaa] * 8
+    expected6 = [0x31, 0x2d, 0x95, 0xc0, 0xbc, 0x38, 0xef, 0xf4,
+                 0x94, 0x2d, 0xb2, 0xd5, 0x0b, 0xdc, 0x50, 0x0a,
+                 0x30, 0x64, 0x1e, 0xf7, 0x13, 0x2d, 0xb1, 0xa8,
+                 0xae, 0x83, 0x8b, 0x3b, 0xea, 0x3a, 0x7a, 0xb0,
+                 0x38, 0x15, 0xd7, 0xa4, 0xcc, 0x09, 0xdb, 0xf5,
+                 0x88, 0x2a, 0x34, 0x33, 0xd7, 0x43, 0xac, 0xed,
+                 0x48, 0x13, 0x6e, 0xba, 0xb7, 0x32, 0x99, 0x50,
+                 0x68, 0x55, 0xc0, 0xf5, 0x43, 0x7a, 0x36, 0xc6]
+    block6 = [0x00] * 64
+    cipher6 = ChaCha(key6, iv6, verbose=0)
+    result6 = cipher6.next(block6)
+    check_block(result6, expected6, "TC6-128-8")
+    print
+
+
+    # Testing with TC7-128-8
+    print("TC7-128-8: Key and IV are increasing, decreasing patterns. 128 bit key, 8 rounds.")
+    key7 = [0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+            0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff]
+    iv7  = [0x0f, 0x1e, 0x2d, 0x3c, 0x4b, 0x59, 0x68, 0x77]
+    expected7 = [0xa7, 0xa6, 0xc8, 0x1b, 0xd8, 0xac, 0x10, 0x6e,
+                 0x8f, 0x3a, 0x46, 0xa1, 0xbc, 0x8e, 0xc7, 0x02,
+                 0xe9, 0x5d, 0x18, 0xc7, 0xe0, 0xf4, 0x24, 0x51,
+                 0x9a, 0xea, 0xfb, 0x54, 0x47, 0x1d, 0x83, 0xa2,
+                 0xbf, 0x88, 0x88, 0x61, 0x58, 0x6b, 0x73, 0xd2,
+                 0x28, 0xea, 0xaf, 0x82, 0xf9, 0x66, 0x5a, 0x5a,
+                 0x15, 0x5e, 0x86, 0x7f, 0x93, 0x73, 0x1b, 0xfb,
+                 0xe2, 0x4f, 0xab, 0x49, 0x55, 0x90, 0xb2, 0x31]
+    block7 = [0x00] * 64
+    cipher7 = ChaCha(key7, iv7, verbose=2)
+    result7 = cipher7.next(block7)
+    check_block(result7, expected7, "TC7-128-8")
+    print
+
+
+    # Testing with TC8-128-8
+    print("TC8-128-8: Random inputs. 128 bit key, 8 rounds.")
+    key8 = [0xc4, 0x6e, 0xc1, 0xb1, 0x8c, 0xe8, 0xa8, 0x78,
+            0x72, 0x5a, 0x37, 0xe7, 0x80, 0xdf, 0xb7, 0x35]
+    iv8  = [0x1a, 0xda, 0x31, 0xd5, 0xcf, 0x68, 0x82, 0x21]
+    expected8 = [0x6a, 0x87, 0x01, 0x08, 0x85, 0x9f, 0x67, 0x91,
+                 0x18, 0xf3, 0xe2, 0x05, 0xe2, 0xa5, 0x6a, 0x68,
+                 0x26, 0xef, 0x5a, 0x60, 0xa4, 0x10, 0x2a, 0xc8,
+                 0xd4, 0x77, 0x00, 0x59, 0xfc, 0xb7, 0xc7, 0xba,
+                 0xe0, 0x2f, 0x5c, 0xe0, 0x04, 0xa6, 0xbf, 0xbb,
+                 0xea, 0x53, 0x01, 0x4d, 0xd8, 0x21, 0x07, 0xc0,
+                 0xaa, 0x1c, 0x7c, 0xe1, 0x1b, 0x7d, 0x78, 0xf2,
+                 0xd5, 0x0b, 0xd3, 0x60, 0x2b, 0xbd, 0x25, 0x94]
+    block8 = [0x00] * 64
+    cipher8 = ChaCha(key8, iv8, verbose=0)
+    result8 = cipher8.next(block8)
+    check_block(result8, expected8, "TC8-128-8")
+    print
+
+
+#-------------------------------------------------------------------
+# __name__
+# Python thingy which allows the file to be run standalone as
+# well as parsed from within a Python interpreter.
+#-------------------------------------------------------------------
+if __name__=="__main__":
+    # Run the main function.
+    sys.exit(main())
+
+#=======================================================================
+# EOF chacha.py
+#=======================================================================