clamp static method
Implementation
static void clamp(Uint8List key) {
key[3] &= R_MASK_HIGH_4;
key[7] &= R_MASK_HIGH_4;
key[11] &= R_MASK_HIGH_4;
key[15] &= R_MASK_HIGH_4;
key[4] &= R_MASK_LOW_2;
key[8] &= R_MASK_LOW_2;
key[12] &= R_MASK_LOW_2;
}