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Source/Engine/Utilities/Encryption.cpp

@@ -0,0 +1,135 @@
+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#include "Encryption.h"
+#include "Engine/Platform/StringUtils.h"
+
+namespace
+{
+    const char* base64_chars =
+            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+            "abcdefghijklmnopqrstuvwxyz"
+            "0123456789+/";
+
+    bool is_base64(byte c)
+    {
+        return StringUtils::IsAlnum((char)c) || c == '+' || c == '/';
+    }
+
+    // @formatter:off
+    const int32 B64index[256] =
+    {
+        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  62, 63, 62, 62, 63,
+        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0,  0,  0,  0,  0,  0,
+        0,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14,
+        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0,  0,  0,  0,  63,
+        0,  26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
+        41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
+    };
+    // @formatter:on
+}
+
+void Encryption::EncryptBytes(byte* data, uint64 size)
+{
+    byte offset = 71;
+    for (uint64 i = 0; i < size; i++)
+    {
+        data[i] = (data[i] ^ (byte)i) + offset;
+        offset += 13;
+    }
+}
+
+void Encryption::DecryptBytes(byte* data, uint64 size)
+{
+    byte offset = 71;
+    for (uint64 i = 0; i < size; i++)
+    {
+        data[i] = data[i] - offset ^ (byte)i;
+        offset += 13;
+    }
+}
+
+int32 Encryption::Base64EncodeLength(int32 size)
+{
+    return (size + 2) / 3 * 4;
+}
+
+int32 Encryption::Base64DecodeLength(const char* encoded, int32 length)
+{
+    if (length == 0)
+        return 0;
+    const int32 pad1 = length % 4 || encoded[length - 1] == '=';
+    const int32 pad2 = pad1 && (length % 4 > 2 || encoded[length - 2] != '=');
+    const int32 last = (length - pad1) / 4 << 2;
+    return last / 4 * 3 + pad1 + pad2;
+}
+
+void Encryption::Base64Encode(const byte* bytes, int32 size, Array<char>& encoded)
+{
+    encoded.Resize(Base64EncodeLength(size));
+    Base64Encode(bytes, size, encoded.Get());
+}
+
+void Encryption::Base64Encode(const byte* bytes, int32 size, char* encoded)
+{
+    int32 i;
+    for (i = 0; i < size - 2; i += 3)
+    {
+        *encoded++ = base64_chars[bytes[i] >> 2 & 0x3F];
+        *encoded++ = base64_chars[(bytes[i] & 0x3) << 4 | (int32)(bytes[i + 1] & 0xF0) >> 4];
+        *encoded++ = base64_chars[(bytes[i + 1] & 0xF) << 2 | (int32)(bytes[i + 2] & 0xC0) >> 6];
+        *encoded++ = base64_chars[bytes[i + 2] & 0x3F];
+    }
+    if (i < size)
+    {
+        *encoded++ = base64_chars[bytes[i] >> 2 & 0x3F];
+        if (i == size - 1)
+        {
+            *encoded++ = base64_chars[((bytes[i] & 0x3) << 4)];
+            *encoded++ = '=';
+        }
+        else
+        {
+            *encoded++ = base64_chars[(bytes[i] & 0x3) << 4 | (int32)(bytes[i + 1] & 0xF0) >> 4];
+            *encoded++ = base64_chars[((bytes[i + 1] & 0xF) << 2)];
+        }
+        *encoded = '=';
+    }
+}
+
+void Encryption::Base64Decode(const char* encoded, int32 length, Array<byte>& output)
+{
+    output.Clear();
+    if (length == 0)
+        return;
+    output.Resize(Base64DecodeLength(encoded, length));
+    Base64Decode(encoded, length, output.Get());
+}
+
+void Encryption::Base64Decode(const char* encoded, int32 length, byte* output)
+{
+    if (length == 0)
+        return;
+    int32 j = 0;
+    const int32 pad1 = length % 4 || encoded[length - 1] == '=', pad2 = pad1 && (length % 4 > 2 || encoded[length - 2] != '=');
+    const int32 last = (length - pad1) / 4 << 2;
+    byte* str = output;
+    for (int32 i = 0; i < last; i += 4)
+    {
+        int32 n = B64index[encoded[i]] << 18 | B64index[encoded[i + 1]] << 12 | B64index[encoded[i + 2]] << 6 | B64index[encoded[i + 3]];
+        str[j++] = n >> 16;
+        str[j++] = n >> 8 & 0xFF;
+        str[j++] = n & 0xFF;
+    }
+    if (pad1)
+    {
+        int32 n = B64index[encoded[last]] << 18 | B64index[encoded[last + 1]] << 12;
+        str[j++] = n >> 16;
+        if (pad2)
+        {
+            n |= B64index[encoded[last + 2]] << 6;
+            str[j] = n >> 8 & 0xFF;
+        }
+    }
+}