XTEA: add extended TEA encryption

Makefile.am

@@ -27,6 +27,8 @@ UTIL_FILES   =		\
     coord/store.hpp	\
     crypto/tea.cpp	\
     crypto/tea.hpp	\
+    crypto/xtea.cpp	\
+    crypto/xtea.hpp	\
     crypto/arc4.cpp	\
     crypto/arc4.hpp	\
     debug.cpp   	\
@@ -267,6 +269,7 @@ TEST_BIN = 			\
     test/colour			\
     test/crypto/arc4		\
     test/crypto/tea		\
+    test/crypto/xtea		\
     test/extent			\
     test/fixed			\
     test/float			\

crypto/xtea.cpp

@@ -0,0 +1,89 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "xtea.hpp"
+
+using util::crypto::XTEA;
+
+
+///////////////////////////////////////////////////////////////////////////////
+static const uint32_t MAGIC = 0x9E3779B9;
+
+// each iteration performs two feistel rounds, for a total of 64
+static const unsigned ITERATIONS = 32;
+
+
+///////////////////////////////////////////////////////////////////////////////
+XTEA::XTEA (key_t _key):
+    m_key (_key)
+{ }
+
+
+//-----------------------------------------------------------------------------
+void
+XTEA::encrypt (uint32_t *restrict dst, const uint32_t *restrict src, size_t count)
+{
+    if (count % 2)
+        throw std::invalid_argument ("XTEA requires even data count");
+
+    auto last = src + count;
+
+    while (src < last) {
+        uint32_t sum = 0;
+        uint32_t v0 = src[0];
+        uint32_t v1 = src[1];
+
+        for (unsigned i = 0; i < ITERATIONS; ++i) {
+            v0  += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + m_key[sum & 3]);
+            sum += MAGIC;
+            v1  += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + m_key[(sum >> 11) & 3]);
+        }
+
+        dst[0] = v0;
+        dst[1] = v1;
+
+        src += 2;
+        dst += 2;
+    }
+}
+
+
+//-----------------------------------------------------------------------------
+void
+XTEA::decrypt (uint32_t *restrict dst, const uint32_t *restrict src, size_t count)
+{
+    if (count % 2)
+        throw std::invalid_argument ("XTEA requires even data count");
+
+    auto last = src + count;
+
+    while (src < last) {
+        uint32_t sum = ITERATIONS * MAGIC;
+        uint32_t v0 = src[0];
+        uint32_t v1 = src[1];
+
+        for (unsigned i = 0; i < ITERATIONS; ++i) {
+            v1  -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + m_key[(sum >> 11) & 3]);
+            sum -= MAGIC;
+            v0  -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + m_key[sum & 3]);
+        }
+
+        dst[0] = v0;
+        dst[1] = v1;
+
+        src += 2;
+    }
+}

crypto/xtea.hpp

@@ -0,0 +1,40 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_TEA_HPP
+#define __UTIL_TEA_HPP
+
+#include <array>
+#include <cstdint>
+#include <cstddef>
+
+namespace util { namespace crypto {
+    // http://en.wikipedia.org/wiki/XTEA
+    class XTEA {
+    public:
+        using key_t = std::array<uint32_t,4>;
+
+        XTEA (key_t);
+
+        void encrypt (uint32_t *restrict dst, const uint32_t *restrict src, size_t count);
+        void decrypt (uint32_t *restrict dst, const uint32_t *restrict src, size_t count);
+
+    private:
+        key_t m_key;
+    };
+} }
+
+#endif

test/crypto/xtea.cpp

@@ -0,0 +1,65 @@
+#include "tap.hpp"
+#include "crypto/xtea.hpp"
+#include "types.hpp"
+
+int
+main ()
+{
+    // test vectors from 'TeaCrypt', by Logan J. Drews.
+    struct {
+        std::array<uint32_t,4> key;
+        std::array<uint32_t,2> dec;
+        std::array<uint32_t,2> enc;
+    } TESTS[] = {
+        {
+            {0x00000000, 0x00000000, 0x00000000, 0x00000000},
+            {0x00000000, 0x00000000},
+            {0xDEE9D4D8, 0xF7131ED9},
+        },
+
+        {
+            {0x00000000, 0x00000000, 0x00000000, 0x00000000},
+            {0x01020304, 0x05060708},
+            {0x065C1B89, 0x75C6A816},
+        },
+
+        {
+            {0x00112233, 0x44556677, 0x8899AABB, 0xCCDDEEFF},
+            {0x01020304, 0x05060708},
+            {0xDCDD7ACD, 0xC1584B79},
+
+        },
+
+        {
+            {0x00112233, 0x44556677, 0x8899AABB, 0xCCDDEEFF},
+            {0x01234567, 0x89ABCDEF},
+            {0xB8BF2821, 0x622B5B30},
+        },
+    };
+
+    util::TAP::logger tap;
+
+    for (size_t i = 0; i < elems (TESTS); ++i) {
+        const auto &t = TESTS[i];
+        util::crypto::XTEA gen (t.key);
+
+        std::array<uint32_t,2> enc, dec;
+
+        gen.encrypt (enc.data (), t.dec.data (), t.dec.size ());
+        gen.decrypt (dec.data (), t.enc.data (), t.enc.size ());
+
+        {
+            std::ostringstream os;
+            os << "TEA_enc " << i;
+            tap.expect (enc == t.enc, os.str ());
+        }
+
+        {
+            std::ostringstream os;
+            os << "TEA_dec " << i;
+            tap.expect (dec == t.dec, os.str ());
+        }
+    }
+
+    return tap.status ();
+}