LibCrypto: Implement GCM mode

Libraries/LibCrypto/Authentication/GHash.cpp

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2020, Ali Mohammad Pur <ali.mpfard@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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.
+ *
+ * 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.
+ */
+
+#include <AK/MemoryStream.h>
+#include <AK/Types.h>
+#include <AK/Vector.h>
+#include <LibCrypto/Authentication/GHash.h>
+#include <LibCrypto/BigInt/UnsignedBigInteger.h>
+
+namespace {
+
+static u32 to_u32(const u8* b)
+{
+    return AK::convert_between_host_and_big_endian(*(const u32*)b);
+}
+
+static void to_u8s(u8* b, const u32* w)
+{
+    for (auto i = 0; i < 4; ++i) {
+        auto& e = *((u32*)(b + i * 4));
+        e = AK::convert_between_host_and_big_endian(w[i]);
+    }
+}
+
+}
+
+namespace Crypto {
+namespace Authentication {
+
+GHash::TagType GHash::process(ReadonlyBytes aad, ReadonlyBytes cipher)
+{
+    u32 tag[4] { 0, 0, 0, 0 };
+
+    auto transform_one = [&](auto& buf) {
+        size_t i = 0;
+        for (; i < buf.size(); i += 16) {
+            if (i + 16 <= buf.size()) {
+                for (auto j = 0; j < 4; ++j) {
+                    tag[j] ^= to_u32(buf.offset(i + j * 4));
+                }
+                galois_multiply(tag, m_key, tag);
+            }
+        }
+
+        if (i > buf.size()) {
+            static u8 buffer[16];
+            Bytes buffer_bytes { buffer, 16 };
+            OutputMemoryStream stream { buffer_bytes };
+            stream.write(buf.slice(i - 16));
+            stream.fill_to_end(0);
+
+            for (auto j = 0; j < 4; ++j) {
+                tag[j] ^= to_u32(buffer_bytes.offset(j * 4));
+            }
+            galois_multiply(tag, m_key, tag);
+        }
+    };
+
+    transform_one(aad);
+    transform_one(cipher);
+
+    auto aad_bits = 8 * (u64)aad.size();
+    auto cipher_bits = 8 * (u64)cipher.size();
+
+    auto high = [](u64 value) -> u32 { return value >> 32; };
+    auto low = [](u64 value) -> u32 { return value & 0xffffffff; };
+
+#ifdef GHASH_PROCESS_DEBUG
+    dbg() << "AAD bits: " << high(aad_bits) << " : " << low(aad_bits);
+    dbg() << "Cipher bits: " << high(cipher_bits) << " : " << low(cipher_bits);
+
+    dbg() << "Tag bits: " << tag[0] << " : " << tag[1] << " : " << tag[2] << " : " << tag[3];
+#endif
+
+    tag[0] ^= high(aad_bits);
+    tag[1] ^= low(aad_bits);
+    tag[2] ^= high(cipher_bits);
+    tag[3] ^= low(cipher_bits);
+
+#ifdef GHASH_PROCESS_DEBUG
+    dbg() << "Tag bits: " << tag[0] << " : " << tag[1] << " : " << tag[2] << " : " << tag[3];
+#endif
+
+    galois_multiply(tag, m_key, tag);
+
+    TagType digest;
+    to_u8s(digest.data, tag);
+
+    return digest;
+}
+
+/// Galois Field multiplication using <x^127 + x^7 + x^2 + x + 1>.
+/// Note that x, y, and z are strictly BE.
+void galois_multiply(u32 (&z)[4], const u32 (&_x)[4], const u32 (&_y)[4])
+{
+    u32 x[4] { _x[0], _x[1], _x[2], _x[3] };
+    u32 y[4] { _y[0], _y[1], _y[2], _y[3] };
+    __builtin_memset(z, 0, sizeof(z));
+
+    for (ssize_t i = 127; i > -1; --i) {
+        if ((y[3 - (i / 32)] >> (i % 32)) & 1) {
+            z[0] ^= x[0];
+            z[1] ^= x[1];
+            z[2] ^= x[2];
+            z[3] ^= x[3];
+        }
+        auto a0 = x[0] & 1;
+        x[0] >>= 1;
+        auto a1 = x[1] & 1;
+        x[1] >>= 1;
+        x[1] |= a0 << 31;
+        auto a2 = x[2] & 1;
+        x[2] >>= 1;
+        x[2] |= a1 << 31;
+        auto a3 = x[3] & 1;
+        x[3] >>= 1;
+        x[3] |= a2 << 31;
+
+        if (a3)
+            x[0] ^= 0xe1000000;
+    }
+}
+
+}
+}