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Support for Encrypted Files/Medias

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Wizou 2022-10-07 03:00:57 +02:00
parent c6adeb1f31
commit f22990cb58
9 changed files with 143 additions and 37 deletions
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79
src/Encryption.cs
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@ -4,6 +4,7 @@ using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
@ -14,9 +15,9 @@ namespace WTelegram
{
internal static class Encryption
{
internal static readonly RNGCryptoServiceProvider RNG = new();
private static readonly Dictionary<long, RSAPublicKey> PublicKeys = new();
private static readonly Aes AesECB = Aes.Create();
internal static readonly RNGCryptoServiceProvider RNG = new();
internal static readonly Aes AesECB = Aes.Create();
static Encryption()
{
@ -295,25 +296,23 @@ j4WcDuXc2CTHgH8gFTNhp/Y8/SpDOhvn9QIDAQAB
return AES_IGE_EncryptDecrypt(input, aes_key, aes_iv, encrypt);
}
private static byte[] AES_IGE_EncryptDecrypt(Span<byte> input, byte[] aes_key, byte[] aes_iv, bool encrypt)
internal static byte[] AES_IGE_EncryptDecrypt(Span<byte> input, byte[] aes_key, byte[] aes_iv, bool encrypt)
{
if (input.Length % 16 != 0) throw new ApplicationException("AES_IGE input size not divisible by 16");
// code adapted from PHP implementation found at https://mgp25.com/AESIGE/
var output = new byte[input.Length];
var xPrev = aes_iv.AsSpan(encrypt ? 16 : 0, 16);
var yPrev = aes_iv.AsSpan(encrypt ? 0 : 16, 16);
using var aesCrypto = encrypt ? AesECB.CreateEncryptor(aes_key, null) : AesECB.CreateDecryptor(aes_key, null);
byte[] yXOR = new byte[16];
for (int i = 0; i < input.Length; i += 16)
var output = new byte[input.Length];
var prevBytes = (byte[])aes_iv.Clone();
var span = MemoryMarshal.Cast<byte, long>(input);
var sout = MemoryMarshal.Cast<byte, long>(output);
var prev = MemoryMarshal.Cast<byte, long>(prevBytes);
if (!encrypt) { (prev[2], prev[0]) = (prev[0], prev[2]); (prev[3], prev[1]) = (prev[1], prev[3]); }
for (int i = 0, count = input.Length / 8; i < count;)
{
for (int j = 0; j < 16; j++)
yXOR[j] = (byte)(input[i + j] ^ yPrev[j]);
aesCrypto.TransformBlock(yXOR, 0, 16, output, i);
for (int j = 0; j < 16; j++)
output[i + j] ^= xPrev[j];
xPrev = input.Slice(i, 16);
yPrev = output.AsSpan(i, 16);
sout[i] = span[i] ^ prev[0]; sout[i + 1] = span[i + 1] ^ prev[1];
aesCrypto.TransformBlock(output, i * 8, 16, output, i * 8);
prev[0] = sout[i] ^= prev[2]; prev[1] = sout[i + 1] ^= prev[3];
prev[2] = span[i++]; prev[3] = span[i++];
}
return output;
}
@ -526,4 +525,52 @@ j4WcDuXc2CTHgH8gFTNhp/Y8/SpDOhvn9QIDAQAB
}
#endif
}
public class AES_IGE_Stream : Helpers.IndirectStream
{
private readonly ICryptoTransform aesCrypto;
private readonly byte[] prevBytes;
public AES_IGE_Stream(Stream stream, DecryptedMessageMedia media) : this(stream, media.SizeKeyIV) { }
public AES_IGE_Stream(Stream innerStream, (int size, byte[] key, byte[] iv) t) : this(innerStream, t.key, t.iv) { ContentLength = t.size; }
public AES_IGE_Stream(Stream stream, byte[] key, byte[] iv, bool encrypt = false) : base(stream)
{
aesCrypto = encrypt ? Encryption.AesECB.CreateEncryptor(key, null) : Encryption.AesECB.CreateDecryptor(key, null);
if (encrypt) prevBytes = (byte[])iv.Clone();
else { prevBytes = new byte[32]; Array.Copy(iv, 0, prevBytes, 16, 16); Array.Copy(iv, 16, prevBytes, 0, 16); }
}
public override int Read(byte[] buffer, int offset, int count)
{
count = _innerStream.Read(buffer, offset, count);
if (count == 0) return 0;
Process(buffer, offset, count);
if (ContentLength.HasValue && _innerStream.Position == _innerStream.Length)
return count - (int)(_innerStream.Position - ContentLength.Value);
return count;
}
public override void Write(byte[] buffer, int offset, int count)
{
Process(buffer, offset, count);
if (ContentLength.HasValue && _innerStream.Position + count > ContentLength)
count -= (int)(_innerStream.Position + count - ContentLength.Value);
_innerStream.Write(buffer, offset, count);
}
public void Process(byte[] buffer, int offset, int count)
{
count = (count + 15) & ~15;
var span = MemoryMarshal.Cast<byte, long>(buffer.AsSpan(offset, count));
var prev = MemoryMarshal.Cast<byte, long>(prevBytes);
for (offset = 0, count /= 8; offset < count;)
{
prev[0] ^= span[offset]; prev[1] ^= span[offset + 1];
aesCrypto.TransformBlock(prevBytes, 0, 16, prevBytes, 0);
prev[0] ^= prev[2]; prev[1] ^= prev[3];
prev[2] = span[offset]; prev[3] = span[offset + 1];
span[offset++] = prev[0]; span[offset++] = prev[1];
}
}
}
}