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Encryption class public + TL Methods/Helpers

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Wizou 2025-10-31 00:14:48 +01:00
parent 48d005b605
commit 2e95576be5
3 changed files with 74 additions and 27 deletions
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44
src/Encryption.cs
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@ -94,7 +94,7 @@ namespace WTelegram
if (serverDHparams is not ServerDHParamsOk serverDHparamsOk) throw new WTException("not server_DH_params_ok");
if (serverDHparamsOk.nonce != nonce) throw new WTException("Nonce mismatch");
if (serverDHparamsOk.server_nonce != resPQ.server_nonce) throw new WTException("Server Nonce mismatch");
var (tmp_aes_key, tmp_aes_iv) = ConstructTmpAESKeyIV(resPQ.server_nonce, pqInnerData.new_nonce);
var (tmp_aes_key, tmp_aes_iv) = ConstructTmpAESKeyIV(sha1, resPQ.server_nonce, pqInnerData.new_nonce);
var answer = AES_IGE_EncryptDecrypt(serverDHparamsOk.encrypted_answer, tmp_aes_key, tmp_aes_iv, false);
using var answerReader = new BinaryReader(new MemoryStream(answer));
@ -163,26 +163,26 @@ namespace WTelegram
session.AuthKey = authKey;
session.Salt = BinaryPrimitives.ReadInt64LittleEndian(pqInnerData.new_nonce.raw) ^ BinaryPrimitives.ReadInt64LittleEndian(resPQ.server_nonce.raw);
session.OldSalt = session.Salt;
}
(byte[] key, byte[] iv) ConstructTmpAESKeyIV(TL.Int128 server_nonce, Int256 new_nonce)
{
byte[] tmp_aes_key = new byte[32], tmp_aes_iv = new byte[32];
sha1.TransformBlock(new_nonce, 0, 32, null, 0);
sha1.TransformFinalBlock(server_nonce, 0, 16);
sha1.Hash.CopyTo(tmp_aes_key, 0); // tmp_aes_key := SHA1(new_nonce + server_nonce)
sha1.Initialize();
sha1.TransformBlock(server_nonce, 0, 16, null, 0);
sha1.TransformFinalBlock(new_nonce, 0, 32);
Array.Copy(sha1.Hash, 0, tmp_aes_key, 20, 12); // + SHA1(server_nonce, new_nonce)[0:12]
Array.Copy(sha1.Hash, 12, tmp_aes_iv, 0, 8); // tmp_aes_iv != SHA1(server_nonce, new_nonce)[12:8]
sha1.Initialize();
sha1.TransformBlock(new_nonce, 0, 32, null, 0);
sha1.TransformFinalBlock(new_nonce, 0, 32);
sha1.Hash.CopyTo(tmp_aes_iv, 8); // + SHA(new_nonce + new_nonce)
Array.Copy(new_nonce, 0, tmp_aes_iv, 28, 4); // + new_nonce[0:4]
sha1.Initialize();
return (tmp_aes_key, tmp_aes_iv);
}
public static (byte[] key, byte[] iv) ConstructTmpAESKeyIV(SHA1 sha1, TL.Int128 server_nonce, Int256 new_nonce)
{
byte[] tmp_aes_key = new byte[32], tmp_aes_iv = new byte[32];
sha1.TransformBlock(new_nonce, 0, 32, null, 0);
sha1.TransformFinalBlock(server_nonce, 0, 16);
sha1.Hash.CopyTo(tmp_aes_key, 0); // tmp_aes_key := SHA1(new_nonce + server_nonce)
sha1.Initialize();
sha1.TransformBlock(server_nonce, 0, 16, null, 0);
sha1.TransformFinalBlock(new_nonce, 0, 32);
Array.Copy(sha1.Hash, 0, tmp_aes_key, 20, 12); // + SHA1(server_nonce, new_nonce)[0:12]
Array.Copy(sha1.Hash, 12, tmp_aes_iv, 0, 8); // tmp_aes_iv != SHA1(server_nonce, new_nonce)[12:8]
sha1.Initialize();
sha1.TransformBlock(new_nonce, 0, 32, null, 0);
sha1.TransformFinalBlock(new_nonce, 0, 32);
sha1.Hash.CopyTo(tmp_aes_iv, 8); // + SHA(new_nonce + new_nonce)
Array.Copy(new_nonce, 0, tmp_aes_iv, 28, 4); // + new_nonce[0:4]
sha1.Initialize();
return (tmp_aes_key, tmp_aes_iv);
}
internal static void CheckGoodPrime(BigInteger p, int g)
@ -278,7 +278,7 @@ j4WcDuXc2CTHgH8gFTNhp/Y8/SpDOhvn9QIDAQAB
-----END RSA PUBLIC KEY-----");
}
internal static byte[] EncryptDecryptMessage(Span<byte> input, bool encrypt, int x, byte[] authKey, byte[] msgKey, int msgKeyOffset, SHA256 sha256)
public static byte[] EncryptDecryptMessage(Span<byte> input, bool encrypt, int x, byte[] authKey, byte[] msgKey, int msgKeyOffset, SHA256 sha256)
{
// first, construct AES key & IV
byte[] aes_key = new byte[32], aes_iv = new byte[32];
@ -299,7 +299,7 @@ j4WcDuXc2CTHgH8gFTNhp/Y8/SpDOhvn9QIDAQAB
return AES_IGE_EncryptDecrypt(input, aes_key, aes_iv, encrypt);
}
internal static byte[] AES_IGE_EncryptDecrypt(Span<byte> input, byte[] aes_key, byte[] aes_iv, bool encrypt)
public static byte[] AES_IGE_EncryptDecrypt(Span<byte> input, byte[] aes_key, byte[] aes_iv, bool encrypt)
{
if (input.Length % 16 != 0) throw new WTException("AES_IGE input size not divisible by 16");