private void OpenKey(IntPtr algorithm, byte[] key, int effectiveKeyLength)
{
_ctx = Interop.Crypto.EvpCipherCreate(
algorithm,
ref MemoryMarshal.GetReference(key.AsSpan()),
key.Length * 8,
effectiveKeyLength,
ref MemoryMarshal.GetReference(IV.AsSpan()),
_encrypting ? 1 : 0);
Interop.Crypto.CheckValidOpenSslHandle(_ctx);
// OpenSSL will happily do PKCS#7 padding for us, but since we support padding modes
// that it doesn't (PaddingMode.Zeros) we'll just always pad the blocks ourselves.
CheckBoolReturn(Interop.Crypto.EvpCipherCtxSetPadding(_ctx, 0));
}