mirror of
https://github.com/kwsch/PKHeX
synced 2024-11-23 12:33:06 +00:00
fc754b346b
[Language Reference](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-10.0/file-scoped-namespaces) Updates all the files, one less level of indentation. Some small changes were made to API surfaces, renaming `PKM pkm` -> `PKM pk`, and `LegalityAnalysis.pkm` -> `LegalityAnalysis.Entity`
74 lines
2.5 KiB
C#
74 lines
2.5 KiB
C#
using System;
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using static System.Buffers.Binary.BinaryPrimitives;
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namespace PKHeX.Core;
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/// <summary>
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/// Genius Sonority's logic for <see cref="GameVersion.XD"/> and <see cref="GameVersion.BATREV"/> encryption.
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/// </summary>
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public static class GeniusCrypto
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{
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public static void ReadKeys(ReadOnlySpan<byte> input, Span<ushort> keys)
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{
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for (int i = 0; i < keys.Length; i++)
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keys[i] = ReadUInt16BigEndian(input[(i * 2)..]);
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}
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public static void Decrypt(ReadOnlySpan<byte> input, Span<byte> output, Span<ushort> keys)
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{
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if (keys.Length != 4)
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throw new ArgumentOutOfRangeException(nameof(keys));
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int i = 0;
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do
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{
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foreach (var key in keys)
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{
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ushort value = ReadUInt16BigEndian(input[i..]);
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value -= key;
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WriteUInt16BigEndian(output[i..], value);
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i += 2;
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}
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AdvanceKeys(keys);
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} while (i != input.Length);
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}
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public static void Encrypt(ReadOnlySpan<byte> input, Span<byte> output, Span<ushort> keys)
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{
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if (keys.Length != 4)
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throw new ArgumentOutOfRangeException(nameof(keys));
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int i = 0;
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do
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{
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foreach (var key in keys)
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{
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ushort value = ReadUInt16BigEndian(input[i..]);
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value += key;
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WriteUInt16BigEndian(output[i..], value);
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i += 2;
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}
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AdvanceKeys(keys);
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} while (i != input.Length);
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}
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private static void AdvanceKeys(Span<ushort> keys)
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{
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var k3 = keys[3] + 0x13;
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var k2 = keys[2] + 0x17;
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var k1 = keys[1] + 0x29;
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var k0 = keys[0] + 0x43;
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// Rotate 4bit groups across the diagonal [ / ] after biasing each u16 (no overflow):
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// 0123 FB73
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// 4567 EA62
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// 89AB becomes D951
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// CDEF C840
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// We can leave our intermediary types as int as the bit-masks remove any overflow.
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keys[3] = (ushort)(((k0 >> 12) & 0xf) | ((k1 >> 8) & 0xf0) | ((k2 >> 4) & 0xf00) | ( k3 & 0xf000));
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keys[2] = (ushort)(((k0 >> 08) & 0xf) | ((k1 >> 4) & 0xf0) | ( k2 & 0xf00) | ((k3 << 04) & 0xf000));
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keys[1] = (ushort)(((k0 >> 04) & 0xf) | ( k1 & 0xf0) | ((k2 << 4) & 0xf00) | ((k3 << 08) & 0xf000));
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keys[0] = (ushort)(( k0 & 0xf) | ((k1 << 4) & 0xf0) | ((k2 << 8) & 0xf00) | ((k3 << 12) & 0xf000));
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}
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}
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