diff --git a/libraries/Crypto/AESCommon.cpp b/libraries/Crypto/AESCommon.cpp
index cf52f0af..e583b3b9 100644
--- a/libraries/Crypto/AESCommon.cpp
+++ b/libraries/Crypto/AESCommon.cpp
@@ -31,9 +31,15 @@
  * AES192, or AES256 to create an AES block cipher with a specific
  * key size.
  *
+ * \note This AES implementation does not have constant cache behaviour due
+ * to the use of table lookups.  It may not be safe to use this implementation
+ * in an environment where the attacker can observe the timing of encryption
+ * and decryption operations.  Unless AES compatibility is required,
+ * it is recommended that the ChaCha stream cipher be used instead.
+ *
  * Reference: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
  *
- * \sa AES128, AES192, AES256
+ * \sa ChaCha, AES128, AES192, AES256
  */
 
 // AES S-box (http://en.wikipedia.org/wiki/Rijndael_S-box)
diff --git a/libraries/Crypto/Arcfour.cpp b/libraries/Crypto/Arcfour.cpp
index 61db4bbc..65159628 100644
--- a/libraries/Crypto/Arcfour.cpp
+++ b/libraries/Crypto/Arcfour.cpp
@@ -30,6 +30,7 @@
  * \note While fast and small on 8-bit platforms, Arcfour is a very weak
  * algorithm when used incorrectly.  Security can be improved slightly using
  * drop() and good key generation.  Never reuse the same key with Arcfour.
+ * ChaCha will almost always be a better option than Arcfour.
  *
  * The default key size is 128 bits, but any key size between 40 and
  * 256 bits (5 to 32 bytes) can be used with setKey().
@@ -41,7 +42,7 @@
  *
  * Reference: http://en.wikipedia.org/wiki/RC4
  *
- * \sa Cipher
+ * \sa ChaCha
  */
 
 /**
diff --git a/libraries/Crypto/ChaCha.cpp b/libraries/Crypto/ChaCha.cpp
new file mode 100644
index 00000000..836fdc72
--- /dev/null
+++ b/libraries/Crypto/ChaCha.cpp
@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "ChaCha.h"
+#include "Crypto.h"
+#include "RotateUtil.h"
+#include "EndianUtil.h"
+#include <string.h>
+
+/**
+ * \class ChaCha ChaCha.h <ChaCha.h>
+ * \brief ChaCha stream cipher.
+ *
+ * ChaCha is a stream cipher that takes a key, an 8-byte nonce/IV, and a
+ * counter and hashes them to generate a keystream to XOR with the plaintext.
+ * Variations on the ChaCha cipher use 8, 12, or 20 rounds of hashing
+ * operations with either 128-bit or 256-bit keys.
+ *
+ * Reference: http://cr.yp.to/chacha.html
+ */
+
+/**
+ * \brief Constructs a new ChaCha stream cipher.
+ *
+ * \param numRounds Number of encryption rounds to use; usually 8, 12, or 20.
+ */
+ChaCha::ChaCha(uint8_t numRounds)
+    : rounds(numRounds)
+    , posn(64)
+{
+}
+
+ChaCha::~ChaCha()
+{
+    clean(block);
+    clean(stream);
+}
+
+size_t ChaCha::keySize() const
+{
+    // Default key size is 128-bit, but any key size is allowed.
+    return 16;
+}
+
+size_t ChaCha::ivSize() const
+{
+    // We return 8 but we also support 12-byte nonces in setIV().
+    return 8;
+}
+
+/**
+ * \fn uint8_t ChaCha::numRounds() const
+ * \brief Returns the number of encryption rounds; usually 8, 12, or 20.
+ *
+ * \sa setNumRounds()
+ */
+
+/**
+ * \fn void ChaCha::setNumRounds(uint8_t numRounds)
+ * \brief Sets the number of encryption rounds.
+ *
+ * \param numRounds The number of encryption rounds; usually 8, 12, or 20.
+ *
+ * \sa numRounds()
+ */
+
+bool ChaCha::setKey(const uint8_t *key, size_t len)
+{
+    static const char tag128[] = "expand 16-byte k";
+    static const char tag256[] = "expand 32-byte k";
+    if (len <= 16) {
+        memcpy(block, tag128, 16);
+        memcpy(block + 16, key, len);
+        memcpy(block + 32, key, len);
+        if (len < 16) {
+            memset(block + 16 + len, 0, 16 - len);
+            memset(block + 32 + len, 0, 16 - len);
+        }
+    } else {
+        if (len > 32)
+            len = 32;
+        memcpy(block, tag256, 16);
+        memcpy(block + 16, key, len);
+        if (len < 32)
+            memset(block + 16 + len, 0, 32 - len);
+    }
+    posn = 64;
+    return true;
+}
+
+bool ChaCha::setIV(const uint8_t *iv, size_t len)
+{
+    // From draft-nir-cfrg-chacha20-poly1305-04.txt, we can use either
+    // 64-bit or 96-bit nonces.  The 96-bit nonce consists of the high
+    // word of the counter prepended to a regular 64-bit nonce for ChaCha.
+    if (len == 8) {
+        memset(block + 48, 0, 8);
+        memcpy(block + 56, iv, len);
+        posn = 64;
+        return true;
+    } else if (len == 12) {
+        memset(block + 48, 0, 4);
+        memcpy(block + 52, iv, len);
+        posn = 64;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+/**
+ * \brief Sets the starting counter for encryption.
+ *
+ * \param counter A 4-byte or 8-byte value to use for the starting counter
+ * instead of the default value of zero.
+ * \param len The length of the counter, which must be 4 or 8.
+ * \return Returns false if \a len is not 4 or 8.
+ *
+ * This function must be called after setIV() and before the first call
+ * to encrypt().  It is used to specify a different starting value than
+ * zero for the counter portion of the hash input.
+ *
+ * \sa setIV()
+ */
+bool ChaCha::setCounter(const uint8_t *counter, size_t len)
+{
+    // Normally both the IV and the counter are 8 bytes in length.
+    // However, if the IV was 12 bytes, then a 4 byte counter can be used.
+    if (len == 4 || len == 8) {
+        memcpy(block + 48, counter, len);
+        posn = 64;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+void ChaCha::encrypt(uint8_t *output, const uint8_t *input, size_t len)
+{
+    while (len > 0) {
+        if (posn >= 64) {
+            // Generate a new encrypted counter block.
+            hashCore((uint32_t *)stream, (const uint32_t *)block, rounds);
+            posn = 0;
+
+            // Increment the counter, taking care not to reveal
+            // any timing information about the starting value.
+            // We iterate through the entire counter region even
+            // if we could stop earlier because a byte is non-zero.
+            uint16_t temp = 1;
+            uint8_t index = 48;
+            while (index < 56) {
+                temp += block[index];
+                block[index] = (uint8_t)temp;
+                temp >>= 8;
+                ++index;
+            }
+        }
+        uint8_t templen = 64 - posn;
+        if (templen > len)
+            templen = len;
+        len -= templen;
+        while (templen > 0) {
+            *output++ = *input++ ^ stream[posn++];
+            --templen;
+        }
+    }
+}
+
+void ChaCha::decrypt(uint8_t *output, const uint8_t *input, size_t len)
+{
+    encrypt(output, input, len);
+}
+
+void ChaCha::clear()
+{
+    clean(block);
+    clean(stream);
+    posn = 64;
+}
+
+// On AVR it is faster to rotate left by 16 bits and then right by 4 bits
+// one at a time than to rotate left by 12 bits in a single step.
+#define leftRotate12(a) \
+    (__extension__ ({ \
+        uint32_t temp = (a); \
+        temp = (temp << 16) | (temp >> 16); \
+        temp = rightRotate(temp, 1); \
+        temp = rightRotate(temp, 1); \
+        temp = rightRotate(temp, 1); \
+        rightRotate(temp, 1); \
+    }))
+
+// Perform a ChaCha quarter round operation.
+#define quarterRound(a, b, c, d)    \
+    do { \
+        uint32_t _b = (b); \
+        uint32_t _a = (a) + _b; \
+        uint32_t _d = leftRotate((d) ^ _a, 16); \
+        uint32_t _c = (c) + _d; \
+        _b = leftRotate12(_b ^ _c); \
+        _a += _b; \
+        (d) = _d = leftRotate(_d ^ _a, 8); \
+        _c += _d; \
+        (a) = _a; \
+        (b) = leftRotate7(_b ^ _c); \
+        (c) = _c; \
+    } while (0)
+
+/**
+ * \brief Executes the ChaCha hash core on an input memory block.
+ *
+ * \param output Output memory block, must be at least 16 words in length
+ * and must not overlap with \a input.
+ * \param input Input memory block, must be at least 16 words in length.
+ * \param rounds Number of ChaCha rounds to perform; usually 8, 12, or 20.
+ *
+ * This function is provided for the convenience of applications that need
+ * access to the ChaCha hash core without the higher-level processing that
+ * turns the core into a stream cipher.
+ */
+void ChaCha::hashCore(uint32_t *output, const uint32_t *input, uint8_t rounds)
+{
+    uint8_t posn;
+
+    // Copy the input buffer to the output prior to the first round
+    // and convert from little-endian to host byte order.
+    for (posn = 0; posn < 16; ++posn)
+        output[posn] = le32toh(input[posn]);
+
+    // Perform the ChaCha rounds in sets of two.
+    for (; rounds >= 2; rounds -= 2) {
+        // Column round.
+        quarterRound(output[0], output[4], output[8],  output[12]);
+        quarterRound(output[1], output[5], output[9],  output[13]);
+        quarterRound(output[2], output[6], output[10], output[14]);
+        quarterRound(output[3], output[7], output[11], output[15]);
+
+        // Diagonal round.
+        quarterRound(output[0], output[5], output[10], output[15]);
+        quarterRound(output[1], output[6], output[11], output[12]);
+        quarterRound(output[2], output[7], output[8],  output[13]);
+        quarterRound(output[3], output[4], output[9],  output[14]);
+    }
+
+    // Add the original input to the final output, convert back to
+    // little-endian, and return the result.
+    for (posn = 0; posn < 16; ++posn)
+        output[posn] = htole32(output[posn] + le32toh(input[posn]));
+}
diff --git a/libraries/Crypto/ChaCha.h b/libraries/Crypto/ChaCha.h
new file mode 100644
index 00000000..21a140f1
--- /dev/null
+++ b/libraries/Crypto/ChaCha.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef CRYPTO_CHACHA_h
+#define CRYPTO_CHACHA_h
+
+#include "Cipher.h"
+
+class ChaCha : public Cipher
+{
+public:
+    explicit ChaCha(uint8_t numRounds = 20);
+    virtual ~ChaCha();
+
+    size_t keySize() const;
+    size_t ivSize() const;
+
+    uint8_t numRounds() const { return rounds; }
+    void setNumRounds(uint8_t numRounds) { rounds = numRounds; }
+
+    bool setKey(const uint8_t *key, size_t len);
+    bool setIV(const uint8_t *iv, size_t len);
+    bool setCounter(const uint8_t *counter, size_t len);
+
+    void encrypt(uint8_t *output, const uint8_t *input, size_t len);
+    void decrypt(uint8_t *output, const uint8_t *input, size_t len);
+
+    void clear();
+
+    static void hashCore(uint32_t *output, const uint32_t *input, uint8_t rounds);
+
+private:
+    uint8_t block[64];
+    uint8_t stream[64];
+    uint8_t rounds;
+    uint8_t posn;
+};
+
+#endif
diff --git a/libraries/Crypto/EndianUtil.h b/libraries/Crypto/EndianUtil.h
new file mode 100644
index 00000000..58ba1804
--- /dev/null
+++ b/libraries/Crypto/EndianUtil.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef CRYPTO_ENDIANUTIL_H
+#define CRYPTO_ENDIANUTIL_H
+
+#include <inttypes.h>
+
+// CPU is assumed to be little endian.   Edit this file if you
+// need to port this library to a big endian CPU.
+
+#define htole32(x)  (x)
+#define le32toh(x)  (x)
+#define htobe32(x)  \
+    (__extension__ ({ \
+        uint32_t _temp = (x); \
+        ((_temp >> 24) & 0x000000FF) | \
+        ((_temp >>  8) & 0x0000FF00) | \
+        ((_temp <<  8) & 0x00FF0000) | \
+        ((_temp << 24) & 0xFF000000); \
+    }))
+#define be32toh(x)  (htobe32((x)))
+
+#endif
diff --git a/libraries/Crypto/RotateUtil.h b/libraries/Crypto/RotateUtil.h
new file mode 100644
index 00000000..c0b2cdc4
--- /dev/null
+++ b/libraries/Crypto/RotateUtil.h
@@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef CRYPTO_ROTATEUTIL_H
+#define CRYPTO_ROTATEUTIL_H
+
+#include <inttypes.h>
+
+// Rotation functions that are optimised for best performance on AVR.
+// The most efficient rotations are where the number of bits is 1 or a
+// multiple of 8, so we compose the efficient rotations to produce all
+// other rotation counts of interest.  All macros below assume arguments
+// of 32 bits in size.
+
+// Generic left rotate - best performance when "bits" is 1 or a multiple of 8.
+#define leftRotate(a, bits) \
+    (__extension__ ({ \
+        uint32_t _temp = (a); \
+        (_temp << (bits)) | (_temp >> (32 - (bits))); \
+    }))
+
+// Generic right rotate - best performance when "bits" is 1 or a multiple of 8.
+#define rightRotate(a, bits) \
+    (__extension__ ({ \
+        uint32_t _temp = (a); \
+        (_temp >> (bits)) | (_temp << (32 - (bits))); \
+    }))
+
+// Left rotate by 1.
+#define leftRotate1(a)  (leftRotate((a), 1))
+
+// Left rotate by 2.
+#define leftRotate2(a)  (leftRotate(leftRotate((a), 1), 1))
+
+// Left rotate by 3.
+#define leftRotate3(a)  (leftRotate(leftRotate(leftRotate((a), 1), 1), 1))
+
+// Left rotate by 4.
+#define leftRotate4(a)  (leftRotate(leftRotate(leftRotate(leftRotate((a), 1), 1), 1), 1))
+
+// Left rotate by 5: Rotate left by 8, then right by 3.
+#define leftRotate5(a)  (rightRotate(rightRotate(rightRotate(leftRotate((a), 8), 1), 1), 1))
+
+// Left rotate by 6: Rotate left by 8, then right by 2.
+#define leftRotate6(a)  (rightRotate(rightRotate(leftRotate((a), 8), 1), 1))
+
+// Left rotate by 7: Rotate left by 8, then right by 1.
+#define leftRotate7(a)  (rightRotate(leftRotate((a), 8), 1))
+
+// Left rotate by 8.
+#define leftRotate8(a)  (leftRotate((a), 8))
+
+// Left rotate by 9: Rotate left by 8, then left by 1.
+#define leftRotate9(a)  (leftRotate(leftRotate((a), 8), 1))
+
+// Left rotate by 10: Rotate left by 8, then left by 2.
+#define leftRotate10(a) (leftRotate(leftRotate(leftRotate((a), 8), 1), 1))
+
+// Left rotate by 11: Rotate left by 8, then left by 3.
+#define leftRotate11(a) (leftRotate(leftRotate(leftRotate(leftRotate((a), 8), 1), 1), 1))
+
+// Left rotate by 12: Rotate left by 8, then left by 4.
+#define leftRotate12(a) (leftRotate(leftRotate(leftRotate(leftRotate(leftRotate((a), 8), 1), 1), 1), 1))
+
+// Left rotate by 13: Rotate left by 16, then right by 3.
+#define leftRotate13(a) (rightRotate(rightRotate(rightRotate(leftRotate((a), 16), 1), 1), 1))
+
+// Left rotate by 14: Rotate left by 16, then right by 2.
+#define leftRotate14(a) (rightRotate(rightRotate(leftRotate((a), 16), 1), 1))
+
+// Left rotate by 15: Rotate left by 16, then right by 1.
+#define leftRotate15(a) (rightRotate(leftRotate((a), 16), 1))
+
+// Left rotate by 16.
+#define leftRotate16(a) (leftRotate((a), 16))
+
+// Left rotate by 17: Rotate left by 16, then left by 1.
+#define leftRotate17(a) (leftRotate(leftRotate((a), 16), 1))
+
+// Left rotate by 18: Rotate left by 16, then left by 2.
+#define leftRotate18(a) (leftRotate(leftRotate(leftRotate((a), 16), 1), 1))
+
+// Left rotate by 19: Rotate left by 16, then left by 3.
+#define leftRotate19(a) (leftRotate(leftRotate(leftRotate(leftRotate((a), 16), 1), 1), 1))
+
+// Left rotate by 20: Rotate left by 16, then left by 4.
+#define leftRotate20(a) (leftRotate(leftRotate(leftRotate(leftRotate(leftRotate((a), 16), 1), 1), 1), 1))
+
+// Left rotate by 21: Rotate left by 24, then right by 3.
+#define leftRotate21(a) (rightRotate(rightRotate(rightRotate(leftRotate((a), 24), 1), 1), 1))
+
+// Left rotate by 22: Rotate left by 24, then right by 2.
+#define leftRotate22(a) (rightRotate(rightRotate(leftRotate((a), 24), 1), 1))
+
+// Left rotate by 23: Rotate left by 24, then right by 1.
+#define leftRotate23(a) (rightRotate(leftRotate((a), 24), 1))
+
+// Left rotate by 24.
+#define leftRotate24(a) (leftRotate((a), 24))
+
+// Left rotate by 25: Rotate left by 24, then left by 1.
+#define leftRotate25(a) (leftRotate(leftRotate((a), 24), 1))
+
+// Left rotate by 26: Rotate left by 24, then left by 2.
+#define leftRotate26(a) (leftRotate(leftRotate(leftRotate((a), 24), 1), 1))
+
+// Left rotate by 27: Rotate left by 24, then left by 3.
+#define leftRotate27(a) (leftRotate(leftRotate(leftRotate(leftRotate((a), 24), 1), 1), 1))
+
+// Left rotate by 28: Rotate right by 4.
+#define leftRotate28(a) (rightRotate(rightRotate(rightRotate(rightRotate((a), 1), 1), 1), 1))
+
+// Left rotate by 29: Rotate right by 3.
+#define leftRotate29(a) (rightRotate(rightRotate(rightRotate((a), 1), 1), 1))
+
+// Left rotate by 30: Rotate right by 2.
+#define leftRotate30(a) (rightRotate(rightRotate((a), 1), 1))
+
+// Left rotate by 31: Rotate right by 1.
+#define leftRotate31(a) (rightRotate((a), 1))
+
+// Define the right rotations in terms of left rotations.
+#define rightRotate1(a)  (leftRotate31((a)))
+#define rightRotate2(a)  (leftRotate30((a)))
+#define rightRotate3(a)  (leftRotate29((a)))
+#define rightRotate4(a)  (leftRotate28((a)))
+#define rightRotate5(a)  (leftRotate27((a)))
+#define rightRotate6(a)  (leftRotate26((a)))
+#define rightRotate7(a)  (leftRotate25((a)))
+#define rightRotate8(a)  (leftRotate24((a)))
+#define rightRotate9(a)  (leftRotate23((a)))
+#define rightRotate10(a) (leftRotate22((a)))
+#define rightRotate11(a) (leftRotate21((a)))
+#define rightRotate12(a) (leftRotate20((a)))
+#define rightRotate13(a) (leftRotate19((a)))
+#define rightRotate14(a) (leftRotate18((a)))
+#define rightRotate15(a) (leftRotate17((a)))
+#define rightRotate16(a) (leftRotate16((a)))
+#define rightRotate17(a) (leftRotate15((a)))
+#define rightRotate18(a) (leftRotate14((a)))
+#define rightRotate19(a) (leftRotate13((a)))
+#define rightRotate20(a) (leftRotate12((a)))
+#define rightRotate21(a) (leftRotate11((a)))
+#define rightRotate22(a) (leftRotate10((a)))
+#define rightRotate23(a) (leftRotate9((a)))
+#define rightRotate24(a) (leftRotate8((a)))
+#define rightRotate25(a) (leftRotate7((a)))
+#define rightRotate26(a) (leftRotate6((a)))
+#define rightRotate27(a) (leftRotate5((a)))
+#define rightRotate28(a) (leftRotate4((a)))
+#define rightRotate29(a) (leftRotate3((a)))
+#define rightRotate30(a) (leftRotate2((a)))
+#define rightRotate31(a) (leftRotate1((a)))
+
+#endif
diff --git a/libraries/Crypto/examples/TestChaCha/TestChaCha.ino b/libraries/Crypto/examples/TestChaCha/TestChaCha.ino
new file mode 100644
index 00000000..ba0ccd8e
--- /dev/null
+++ b/libraries/Crypto/examples/TestChaCha/TestChaCha.ino
@@ -0,0 +1,375 @@
+/*
+ * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+This example runs tests on the ChaCha implementation to verify correct behaviour.
+*/
+
+#include <Crypto.h>
+#include <ChaCha.h>
+#include <string.h>
+
+#define MAX_PLAINTEXT_SIZE  64
+#define MAX_CIPHERTEXT_SIZE 64
+
+struct TestVector
+{
+    const char *name;
+    byte key[32];
+    size_t keySize;
+    uint8_t rounds;
+    byte plaintext[MAX_PLAINTEXT_SIZE];
+    byte ciphertext[MAX_CIPHERTEXT_SIZE];
+    byte iv[8];
+    byte counter[8];
+    size_t size;
+};
+
+// Use the test vectors from section 9 of the Salsa20 specification,
+// http://cr.yp.to/snuffle/spec.pdf, but modify the ciphertext to
+// the expected output from ChaCha20/12/8.  Unfortunately the ChaCha
+// specification doesn't contain test vectors - these were generated
+// using the reference implementation from http://cr.yp.to/chacha.html.
+
+static TestVector const testVectorChaCha20_128 = {
+    .name        = "ChaCha20 128-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16},
+    .keySize     = 16,
+    .rounds      = 20,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0x1C, 0x91, 0xE7, 0x99, 0x71, 0xC0, 0x1C, 0x2A,
+                    0xEC, 0xE9, 0x24, 0x35, 0xB1, 0x6E, 0xBF, 0xFD,
+                    0x33, 0x05, 0xCC, 0x17, 0x24, 0x9D, 0x66, 0xA7,
+                    0xA0, 0xCA, 0xB8, 0x36, 0x03, 0xA6, 0x9D, 0x93,
+                    0x9A, 0x4C, 0x10, 0x40, 0xD9, 0x2A, 0x86, 0x78,
+                    0x3A, 0xAD, 0x71, 0x87, 0x55, 0x9F, 0x5B, 0x9A,
+                    0x68, 0x52, 0xA0, 0xAD, 0x59, 0xAE, 0x04, 0x10,
+                    0x25, 0x74, 0x5C, 0x05, 0x62, 0x78, 0xF4, 0x8A},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+static TestVector const testVectorChaCha20_256 = {
+    .name        = "ChaCha20 256-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+                    201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
+                    211, 212, 213, 214, 215, 216},
+    .keySize     = 32,
+    .rounds      = 20,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0x2A, 0x7E, 0x73, 0xC2, 0x2A, 0xE5, 0xCF, 0x4E,
+                    0x21, 0x75, 0xB1, 0x26, 0x38, 0x3F, 0x60, 0x84,
+                    0x11, 0x25, 0xFC, 0xAD, 0xFD, 0x16, 0x54, 0xF2,
+                    0xD7, 0x8C, 0x5D, 0x49, 0x8D, 0x96, 0xBE, 0x15,
+                    0xC9, 0x00, 0x12, 0x09, 0x14, 0x43, 0x2D, 0x6D,
+                    0x64, 0x33, 0x88, 0xA6, 0x16, 0x39, 0x86, 0xFD,
+                    0xD8, 0x85, 0x4D, 0x76, 0x42, 0xEC, 0x0A, 0x0C,
+                    0x8A, 0xF2, 0x99, 0x2E, 0x54, 0xAE, 0xB4, 0xD9},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+static TestVector const testVectorChaCha12_128 = {
+    .name        = "ChaCha12 128-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16},
+    .keySize     = 16,
+    .rounds      = 12,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0xCB, 0xC1, 0xCF, 0x63, 0xE8, 0xD0, 0x62, 0x83,
+                    0xFC, 0x12, 0x87, 0x8C, 0x62, 0x09, 0x5B, 0xF8,
+                    0x84, 0x93, 0x30, 0xC6, 0xE6, 0x26, 0x87, 0x99,
+                    0xB0, 0xD9, 0xC1, 0xE1, 0xD7, 0x58, 0xCA, 0x05,
+                    0xFE, 0x46, 0x40, 0xD1, 0xDC, 0x14, 0x68, 0x3C,
+                    0xFF, 0x25, 0xF7, 0x70, 0x5F, 0xBF, 0x37, 0xC5,
+                    0x29, 0x8F, 0x3C, 0x55, 0x74, 0xDF, 0xF7, 0x49,
+                    0x8D, 0xD8, 0xE9, 0xBA, 0x5D, 0xF1, 0x9F, 0xA5},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+static TestVector const testVectorChaCha12_256 = {
+    .name        = "ChaCha12 256-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+                    201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
+                    211, 212, 213, 214, 215, 216},
+    .keySize     = 32,
+    .rounds      = 12,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0xB8, 0x49, 0xD4, 0x70, 0xE0, 0xFF, 0x57, 0x12,
+                    0x95, 0xBF, 0xD9, 0xCD, 0x26, 0xFD, 0x4D, 0x6E,
+                    0x70, 0xA2, 0xBC, 0x58, 0x63, 0xF6, 0x2C, 0xC3,
+                    0xC7, 0x1C, 0x9B, 0x1A, 0x54, 0xDC, 0xF9, 0xF8,
+                    0xFD, 0x59, 0xEA, 0xC9, 0xC3, 0x10, 0xA1, 0xDE,
+                    0xD1, 0x53, 0x84, 0xD6, 0x8D, 0xC6, 0x61, 0x09,
+                    0x2E, 0x62, 0x14, 0xC5, 0x77, 0x4B, 0x6B, 0x5B,
+                    0x0D, 0x35, 0xE6, 0x17, 0x41, 0x51, 0xA6, 0xA4},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+static TestVector const testVectorChaCha8_128 = {
+    .name        = "ChaCha8 128-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16},
+    .keySize     = 16,
+    .rounds      = 8,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0x76, 0x42, 0x84, 0xB4, 0x87, 0x1F, 0x54, 0xAE,
+                    0x33, 0xBF, 0x79, 0x3C, 0xE2, 0x78, 0x5B, 0x4D,
+                    0xE7, 0x90, 0xF3, 0x8C, 0xB8, 0xF4, 0xA1, 0x56,
+                    0x87, 0x8B, 0x54, 0x06, 0xBE, 0x5A, 0x1B, 0x1C,
+                    0x30, 0x31, 0xD3, 0xCD, 0x90, 0x34, 0xC8, 0x93,
+                    0x2C, 0x0A, 0x5E, 0xC9, 0x4A, 0x1A, 0x66, 0x4C,
+                    0x28, 0x94, 0xA9, 0x61, 0xBB, 0xB4, 0xF0, 0x2D,
+                    0x59, 0x73, 0x9F, 0xC9, 0xF1, 0xF0, 0x66, 0x05},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+static TestVector const testVectorChaCha8_256 = {
+    .name        = "ChaCha8 256-bit",
+    .key         = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+                    201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
+                    211, 212, 213, 214, 215, 216},
+    .keySize     = 32,
+    .rounds      = 8,
+    .plaintext   = {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, 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, 0x00, 0x00},
+    .ciphertext  = {0x38, 0x0F, 0x75, 0xD6, 0x32, 0xF8, 0xBB, 0x2C,
+                    0x44, 0x81, 0xF4, 0x27, 0x90, 0xB8, 0xAA, 0xE3,
+                    0x09, 0xD1, 0xB9, 0x55, 0xC2, 0xF5, 0x85, 0x27,
+                    0xBB, 0x8F, 0x43, 0x00, 0x68, 0x2B, 0x2A, 0x1B,
+                    0x7A, 0xC1, 0x5B, 0xC3, 0xA3, 0xFF, 0x29, 0xC9,
+                    0xD2, 0x95, 0x98, 0xF6, 0x3C, 0xAC, 0x9B, 0x2C,
+                    0xA3, 0xF1, 0x40, 0x1E, 0xFA, 0x7C, 0xAC, 0xA3,
+                    0xB1, 0x61, 0x27, 0x50, 0xBB, 0x03, 0x24, 0x36},
+    .iv          = {101,102,103,104,105,106,107,108},
+    .counter     = {109, 110, 111, 112, 113, 114, 115, 116},
+    .size        = 64
+};
+
+ChaCha chacha;
+
+byte buffer[128];
+
+bool testCipher_N(ChaCha *cipher, const struct TestVector *test, size_t inc)
+{
+    byte output[MAX_CIPHERTEXT_SIZE];
+    size_t posn, len;
+
+    cipher->clear();
+    if (!cipher->setKey(test->key, test->keySize)) {
+        Serial.print("setKey ");
+        return false;
+    }
+    if (!cipher->setIV(test->iv, cipher->ivSize())) {
+        Serial.print("setIV ");
+        return false;
+    }
+    if (!cipher->setCounter(test->counter, 8)) {
+        Serial.print("setCounter ");
+        return false;
+    }
+
+    memset(output, 0xBA, sizeof(output));
+
+    for (posn = 0; posn < test->size; posn += inc) {
+        len = test->size - posn;
+        if (len > inc)
+            len = inc;
+        cipher->encrypt(output + posn, test->plaintext + posn, len);
+    }
+
+    if (memcmp(output, test->ciphertext, test->size) != 0) {
+        Serial.print(output[0], HEX);
+        Serial.print("->");
+        Serial.print(test->ciphertext[0], HEX);
+        return false;
+    }
+
+    cipher->setKey(test->key, test->keySize);
+    cipher->setIV(test->iv, cipher->ivSize());
+    cipher->setCounter(test->counter, 8);
+
+    for (posn = 0; posn < test->size; posn += inc) {
+        len = test->size - posn;
+        if (len > inc)
+            len = inc;
+        cipher->decrypt(output + posn, test->ciphertext + posn, len);
+    }
+
+    if (memcmp(output, test->plaintext, test->size) != 0)
+        return false;
+
+    return true;
+}
+
+void testCipher(ChaCha *cipher, const struct TestVector *test)
+{
+    bool ok;
+
+    Serial.print(test->name);
+    Serial.print(" ... ");
+
+    cipher->setNumRounds(test->rounds);
+
+    ok  = testCipher_N(cipher, test, test->size);
+    ok &= testCipher_N(cipher, test, 1);
+    ok &= testCipher_N(cipher, test, 2);
+    ok &= testCipher_N(cipher, test, 5);
+    ok &= testCipher_N(cipher, test, 8);
+    ok &= testCipher_N(cipher, test, 13);
+    ok &= testCipher_N(cipher, test, 16);
+
+    if (ok)
+        Serial.println("Passed");
+    else
+        Serial.println("Failed");
+}
+
+void perfCipherEncrypt(ChaCha *cipher, const struct TestVector *test)
+{
+    unsigned long start;
+    unsigned long elapsed;
+    int count;
+
+    Serial.print(test->name);
+    Serial.print(" Encrypt ... ");
+
+    cipher->setNumRounds(test->rounds);
+    cipher->setKey(test->key, test->keySize);
+    cipher->setIV(test->iv, cipher->ivSize());
+    start = micros();
+    for (count = 0; count < 500; ++count) {
+        cipher->encrypt(buffer, buffer, sizeof(buffer));
+    }
+    elapsed = micros() - start;
+
+    Serial.print(elapsed / (sizeof(buffer) * 500.0));
+    Serial.print("us per byte, ");
+    Serial.print((sizeof(buffer) * 500.0 * 1000000.0) / elapsed);
+    Serial.println(" bytes per second");
+}
+
+void perfCipherDecrypt(ChaCha *cipher, const struct TestVector *test)
+{
+    unsigned long start;
+    unsigned long elapsed;
+    int count;
+
+    Serial.print(test->name);
+    Serial.print(" Decrypt ... ");
+
+    cipher->setNumRounds(test->rounds);
+    cipher->setKey(test->key, test->keySize);
+    cipher->setIV(test->iv, cipher->ivSize());
+    start = micros();
+    for (count = 0; count < 500; ++count) {
+        cipher->decrypt(buffer, buffer, sizeof(buffer));
+    }
+    elapsed = micros() - start;
+
+    Serial.print(elapsed / (sizeof(buffer) * 500.0));
+    Serial.print("us per byte, ");
+    Serial.print((sizeof(buffer) * 500.0 * 1000000.0) / elapsed);
+    Serial.println(" bytes per second");
+}
+
+void perfCipher(ChaCha *cipher, const struct TestVector *test)
+{
+    perfCipherEncrypt(cipher, test);
+    perfCipherDecrypt(cipher, test);
+}
+
+void setup()
+{
+    Serial.begin(9600);
+
+    Serial.println();
+
+    Serial.println("Test Vectors:");
+    testCipher(&chacha, &testVectorChaCha20_128);
+    testCipher(&chacha, &testVectorChaCha20_256);
+    testCipher(&chacha, &testVectorChaCha12_128);
+    testCipher(&chacha, &testVectorChaCha12_256);
+    testCipher(&chacha, &testVectorChaCha8_128);
+    testCipher(&chacha, &testVectorChaCha8_256);
+
+    Serial.println();
+
+    Serial.println("Performance Tests:");
+    perfCipher(&chacha, &testVectorChaCha20_128);
+    perfCipher(&chacha, &testVectorChaCha20_256);
+    perfCipher(&chacha, &testVectorChaCha12_128);
+    perfCipher(&chacha, &testVectorChaCha12_256);
+    perfCipher(&chacha, &testVectorChaCha8_128);
+    perfCipher(&chacha, &testVectorChaCha8_256);
+}
+
+void loop()
+{
+}