internal bool IsLegalKeySize(KeySizes[] legalKeys, int size)
 {
     foreach (KeySizes legalKeySize in legalKeys)
     {
         if (IsLegalKeySize(size, legalKeySize))
             return true;
     }
     return false;
 }
 internal bool IsLegalKeySize(int keySize, KeySizes keySizes)
 {
     int ks = keySize - keySizes.MinSize;
     bool result = ((ks >= 0) && (keySize <= keySizes.MaxSize));
     return ((keySizes.SkipSize == 0) ? result : (result && (ks % keySizes.SkipSize == 0)));
 }