Would rather use P's and Q's rather than binary

PsAndQs.java

package in.kyle.api;

/**
 * P = 0
 * Q = 1
 */
public class PsAndQs {
    
    private static final byte[] BIT_MASKS =
            new byte[]{0b1000000, 0b1000000, 0b100000, 0b10000, 0b1000, 0b100, 0b10, 0b1};
    
    public static String encode(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        
        for (byte b : bytes) {
            for (byte mask : BIT_MASKS) {
                if ((b & mask) == mask) {
                    sb.append("q");
                } else {
                    sb.append("p");
                }
            }
        }
        
        return sb.toString();
    }
    
    public static byte[] decode(String encodedString) {
        char[] chars = encodedString.toCharArray();
        
        if (chars.length % 8 != 0) {
            throw new IllegalArgumentException("Invalid input string, not % 8, " + chars.length);
        }
        
        byte[] bytes = new byte[chars.length / 8];
        
        for (int i = 0; i < chars.length; i += 8) {
            byte value = 0;
            for (int j = 0; j < 8; j++) {
                if (chars[i + j] == 'q') {
                    value |= BIT_MASKS[j];
                }
            }
            
            bytes[i / 8] = value;
        }
        
        return bytes;
    }
}