FFXIVLauncher-Netmaui

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// NOTE: This file is copy-pasted almost *as-is* from the previous work `Aither.Crypto`
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//       hence currently it does not follow XL's naming convetions.
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//       
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//       It's totally okay to change this. But for now, this is what it is atm.
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// ReSharper disable InconsistentNaming
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using System;
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namespace XIVLauncher.Common.Encryption.BlockCipher
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{
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    public sealed class Ecb<T> : IBlockMode where T : IBlockCipher
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    {
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        private T m_cipher;
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        public Ecb(T cipher)
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        {
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            m_cipher = cipher;
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        }
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        private void AssertSliceLength(ReadOnlySpan<byte> input, ReadOnlySpan<byte> output)
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        {
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            if (input.Length > output.Length)
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            {
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                throw new ArgumentException("The output slice must be larger than the input.", nameof(output));
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            }
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            var blockSize = m_cipher.BlockSize;
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            if (input.Length % blockSize != 0)
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            {
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                throw new ArgumentException("The length of the input slice must be divisible by the block length.",
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                    nameof(input));
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            }
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        }
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        public void Encrypt(ReadOnlySpan<byte> input, Span<byte> output)
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        {
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            AssertSliceLength(input, output);
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            unsafe
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            {
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                fixed (byte* pInput = input)
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                fixed (byte* pOutput = output)
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                {
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                    for (var i = 0; i < input.Length; i += m_cipher.BlockSize)
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                    {
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                        m_cipher.EncryptBlockUnsafe(pInput + i, pOutput + i);
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                    }
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                }
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            }
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        }
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        public void Decrypt(ReadOnlySpan<byte> input, Span<byte> output)
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        {
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            AssertSliceLength(input, output);
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            unsafe
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            {
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                fixed (byte* pInput = input)
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                fixed (byte* pOutput = output)
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                {
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                    for (var i = 0; i < input.Length; i += m_cipher.BlockSize)
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                    {
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                        m_cipher.DecryptBlockUnsafe(pInput + i, pOutput + i);
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                    }
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                }
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            }
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        }
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    }
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}
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// ReSharper restore InconsistentNaming
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