BasicSymmetricCipherBCrypt.cs

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using System;
using System.Security.Cryptography;
using Internal.NativeCrypto;
 
namespace Internal.Cryptography;
 
internal sealed class BasicSymmetricCipherBCrypt : Internal.Cryptography.BasicSymmetricCipher
{
    private readonly bool _encrypting;
 
    private Internal.NativeCrypto.SafeKeyHandle _hKey;
 
    private byte[] _currentIv;
 
    public BasicSymmetricCipherBCrypt(Internal.NativeCrypto.SafeAlgorithmHandle algorithm, CipherMode cipherMode, int blockSizeInBytes, int paddingSizeInBytes, byte[] key, bool ownsParentHandle, byte[] iv, bool encrypting)
        : base(cipherMode.GetCipherIv(iv), blockSizeInBytes, paddingSizeInBytes)
    {
        _encrypting = encrypting;
        if (base.IV != null)
        {
            _currentIv = new byte[base.IV.Length];
        }
        _hKey = global::Interop.BCrypt.BCryptImportKey(algorithm, key);
        if (ownsParentHandle)
        {
            _hKey.SetParentHandle(algorithm);
        }
        Reset();
    }
 
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            Internal.NativeCrypto.SafeKeyHandle hKey = _hKey;
            _hKey = null;
            hKey?.Dispose();
            byte[] currentIv = _currentIv;
            _currentIv = null;
            if (currentIv != null)
            {
                Array.Clear(currentIv);
            }
        }
        base.Dispose(disposing);
    }
 
    public override int Transform(ReadOnlySpan<byte> input, Span<byte> output)
    {
        int num = 0;
        if (input.Overlaps(output, out var elementOffset) && elementOffset != 0)
        {
            byte[] array = System.Security.Cryptography.CryptoPool.Rent(output.Length);
            try
            {
                num = BCryptTransform(input, array);
                array.AsSpan(0, num).CopyTo(output);
            }
            finally
            {
                System.Security.Cryptography.CryptoPool.Return(array, num);
            }
        }
        else
        {
            num = BCryptTransform(input, output);
        }
        if (num != input.Length)
        {
            throw new CryptographicException(System.SR.Cryptography_UnexpectedTransformTruncation);
        }
        return num;
        int BCryptTransform(ReadOnlySpan<byte> input, Span<byte> output)
        {
            if (!_encrypting)
            {
                return global::Interop.BCrypt.BCryptDecrypt(_hKey, input, _currentIv, output);
            }
            return global::Interop.BCrypt.BCryptEncrypt(_hKey, input, _currentIv, output);
        }
    }
 
    public override int TransformFinal(ReadOnlySpan<byte> input, Span<byte> output)
    {
        int result = 0;
        if (input.Length != 0)
        {
            result = Transform(input, output);
        }
        Reset();
        return result;
    }
 
    private void Reset()
    {
        if (base.IV != null)
        {
            Buffer.BlockCopy(base.IV, 0, _currentIv, 0, base.IV.Length);
        }
    }
}