private int GetLargestSymKeySize(SymmetricAlgorithm symAlg)
{
    KeySizes[] sizes = symAlg.LegalKeySizes;
    return sizes[sizes.Length - 1].MaxSize;
}
private int GetLargestAsymKeySize(AsymmetricAlgorithm asymAlg)
{
    KeySizes[] sizes = asymAlg.LegalKeySizes;
    return sizes[sizes.Length - 1].MaxSize;
}