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(KiriKiri): another encryption scheme.

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This commit is contained in:
morkt
2016-07-28 20:30:25 +04:00
parent 97a70d3fd4
commit 891b602a7f
2 changed files with 48 additions and 0 deletions
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46
ArcFormats/KiriKiri/CryptAlgorithms.cs
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@@ -24,6 +24,8 @@
//
using System;
using System.Collections.Generic;
using System.Linq;
using GameRes.Utility;
namespace GameRes.Formats.KiriKiri
@@ -696,4 +698,48 @@ namespace GameRes.Formats.KiriKiri
Decrypt (entry, offset, buffer, pos, count);
}
}
[Serializable]
public class AkabeiCrypt : ICrypt
{
private readonly uint m_seed;
public AkabeiCrypt (uint seed)
{
m_seed = seed;
}
public override byte Decrypt (Xp3Entry entry, long offset, byte value)
{
int key_pos = (int)offset & 0x1F;
var key = GetKey (entry.Hash).ElementAt (key_pos);
return (byte)(value ^ key);
}
public override void Decrypt (Xp3Entry entry, long offset, byte[] buffer, int pos, int count)
{
var key = GetKey (entry.Hash).ToArray();
int key_pos = (int)offset;
for (int i = 0; i < count; ++i)
{
buffer[pos+i] ^= key[key_pos++ & 0x1F];
}
}
public override void Encrypt (Xp3Entry entry, long offset, byte[] buffer, int pos, int count)
{
Decrypt (entry, offset, buffer, pos, count);
}
IEnumerable<byte> GetKey (uint hash)
{
hash = (hash ^ m_seed) & 0x7FFFFFFF;
hash = hash << 31 | hash;
for (int i = 0; i < 0x20; ++i)
{
yield return (byte)hash;
hash = (hash & 0xFFFFFFFE) << 23 | hash >> 8;
}
}
}
}