50 lines
1.4 KiB
C#
50 lines
1.4 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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using System.Numerics;
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using Glove;
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namespace SockScape.Encryption {
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class StreamCipher {
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private readonly byte[] Key = new byte[Encryption.Key.KeySizeBytes];
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private readonly byte[] State = new byte[256];
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public StreamCipher(BigInteger key) {
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int i = 0, j = 0;
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State = State.Select(x => (byte)i++).ToArray();
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Array.Copy(key.ToByteArray(), Key, Key.Length);
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for(i = 0; i < State.Length; ++i) {
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j = (j + State[i] + Key[i % Key.Length]) % 256;
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Utils.Swap(ref State[i], ref State[j]);
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}
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GenerateStream(1024);
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}
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private byte[] GenerateStream(long length) {
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var stream = new byte[length];
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int i = 0, j = 0;
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for(long x = 0; x < length; ++x) {
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i = (i + 1) % 256;
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j = (j + State[i]) % 256;
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Utils.Swap(ref State[i], ref State[j]);
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stream[x] = State[(State[i] + State[j]) % 256];
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}
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return stream;
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}
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public byte[] Parse(byte[] data) {
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var stream = GenerateStream(data.LongLength);
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for(long i = 0; i < data.LongLength; ++i)
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data[i] ^= stream[i];
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return data;
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}
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}
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}
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