Complete the implementation of the AES algorithm operating in ECB mode, partially implemented by the attached code. The class must be capable of both encrypting and decrypting a plain text into a cipher text and back when the same key is passed to the encrypt$()$ and decrypt$()$ methods. AES is a block cipher that operates on bytes directly, so your code should be capable of encrypting any string of Unicode characters and decrypting back to identical Unicode.

import java.util.Arrays;

public class AES $\{$

public final Integer$[]$ keyLengths $=\{128,192,256\}$;

private int$[]$ key;

private static final HashMap RC $=$ new HashMap;

static $\{$

RC$.$put$(1,0$x$01$L$)$;

RC$.$put$(2,0$x$02$L$)$;

RC$.$put$(3,0$x$04$L$)$;

RC$.$put$(4,0$x$080$L$)$;

RC$.$put$(5,0$x$10$L$)$;

RC$.$put$(6,0$x$20$L$)$;

RC$.$put$(7,0$x$40$L$)$;

RC$.$put$(8,0$x$80$L$)$;

RC$.$put$(9,0$x$1$BL$)$;

RC$.$put$(10,0$x$36$L$)$;

$\}$

public AES$()$

$\{$

int index $=($int$)($Math$.$random$()*$ keyLengths.length$)$;

genKey$($keyLengths$[$index$])$;

$\}$

public AES$($int keyLength$)$

$\{$

genKey$($keyLength$)$;

$\}$

public int getRandomLength$()$

$\{$

int index $=($int$)($Math$.$random$()*$ keyLengths.length$)$;

return keyLengths$[$index$]$;

$\}$

private void genKey$($int keyLength$)$

$\{$

key $=$ new int$[$keyLength $/8]$;

for $($int i $=0$; i $$ key.length; i$++)$

$\{$

key$[$i$]=$ randByte$()$;

$\}$

$\}$

private int$[]$ keySchedule$()$

$\{$

int N $=$ key.length $/4$;

int R $=$ key.length $/4+7$;

int WLen $=4*$R;

int$[]$ W $=$ new int$[$WLen$*4]$;

for $($int i $=0$; i $$ WLen; i$++)$

$\{$

if $($i $$ N$)$

$\{$

int$[]$ word $=$ getKeyWord$($i$)$;

for $($int j $=0$; j $<mtext\; id="EditorElement\_767628"></mtext><mn\; id="EditorElement\_767629">4</mn>$; j$++)$

$\{$

W$[4+$i$+$j$]=$ word$[$j$]$;

$\}$

$\}$ else if $($i $>=$N && i $\%$ N $==0)$

$\{$

int$[]$ word $=$ new int$[4]$;

for $($int j $=0$; j $<mtext\; id="EditorElement\_767786"></mtext><mn\; id="EditorElement\_767787">4</mn>$; j$++)$

$\{$

word$[$j$]=$ W$[4*($i$-1)+$j$]$;

$\}$

word $=$ rotWord$($word$)$;

for $($int j $=0$; j $<mtext\; id="EditorElement\_767900"></mtext><mn\; id="EditorElement\_767901">4</mn>$; j$++)$

$\{$

word$[$j$]=$ SBox.encrypt$($word$[$j$])$;

$\}$

W$[4*$i$]=$ W$[4*($i$-$N$)]^$ word$[0]^$ RC$.$get$($i$/$N$)$

for $($int j $=1$; j $<mtext\; id="EditorElement\_768045"></mtext><mn\; id="EditorElement\_768046">4</mn>$; j$++)$

$\{$

W$[4*$i$+$j$]=$ W$[4*($i$-$N$)+$j$]^$ word$[$j$]$;

$\}$

$\}$ else if $($i $>=$ N && N $>6$ && i $\%$ N $==4)$

$\{$

int$[]$ word $=$ new int$[4]$;

for $($int j $=0$; j $<mtext\; id="EditorElement\_768229"></mtext><mn\; id="EditorElement\_768230">4</mn>$; j$++)$

$\{$

word$[$j$]=$ W$[4*($i$-1)+$j$]$;

$\}$

for $($int j $=0$; j $<mtext\; id="EditorElement\_768314"></mtext><mn\; id="EditorElement\_768315">4</mn>$; j$++)$

$\{$

word$[$j$]=$ SBox.encrypt$($word$[$j$])$;

$\}$

for $($int j $=0$; j $<mtext\; id="EditorElement\_768413"></mtext><mn\; id="EditorElement\_768414">4</mn>$; j$++)$

$\{$

W$[4*$i$+$j$]=$ W$[4*($i$-$N$)+$j$]^$ word$[$j$]$;

$\{$ else

$\{$

int$[]$ word $=$ new int$[4]$;

for $($int j $=0$; j $<mtext\; id="EditorElement\_768564"></mtext><mn\; id="EditorElement\_768565">4</mn>$; j$++)$

$\{$

word$[$j$]=$ W$[4*($i$-1)+$j$]$;

$\}$

for $($int j $=0$; j $<mtext\; id="EditorElement\_768654"></mtext><mn\; id="EditorElement\_768655">4</mn>$; j$++)$

$\{$

W$[4*$i$+$j$]=$ W$[4*($i$-$N$)+$j$]^$ word$[$j$]$;

$\}$

$\}$

$\}$

return W;

$\}$

private int$[]$ getKeyWord$($int index$)$

$\{$

int$[]$ word $=$ new int$[4]$;

for $($int i $=0$; i $<mtext\; id="EditorElement\_768892"></mtext><mn\; id="EditorElement\_768893">4</mn>$; i$++)$

$\{$

word$[$i$]=$ key$[4*$index $+$i$]$;

$\}$

return word;

$\}$

private int$[]$ rotWord$($int$[]$ word$)$

$\{$

int$[]$ rot $=$ new int$[4]$;

rot$[0]=$ word$[1]$;

rot$[1]=$ word$[2]$;

rot$[2]=$ word$[3]$;

rot$[3]=$ word$[0]$;

return rot;

$\}$

prvate int randByte$()$

$\{$

return $($int$)($Math$.$random$()*256)$;

$\}$

public String encrypt$($String plaintext$)$

$\{$

return cipher$($plaintext$,$ true$)$;

$\}$

public String decrypt$($String cipherText$)$

$\{$

return cipher$($cipherText$,$ false$)$;

$\}$

private String cipher$($String inText, boolean mode$)$

$\{$

char$[]$ charArray $=$ inText.toCharArray$()$;

char$[][]$ block $=$ new char$[4][4]$;

StringBuilder outText $=$ new StringBuilder$()$;

int index $=0$;

while$(!$getBlock$($block$,$ charArray, index$))$

$\{$

outText.append$($cipherBlock$($block$,$ mode$))$;

index $+=16$;

$\}$

return outText.toString$()$;

$\}$

private boolean getBlock$($char$[][]$ block, char$[]$ chars, int index$)$

$\{$

boolean lastBlock $=$ false;

for $($int col $=0$; col $<mtext\; id="EditorElement\_770012"></mtext><mn\; id="EditorElement\_770013">4</mn>$; col$++)$

$\{$

for $($int row $=0$; row $<mtext\; id="EditorElement\_770068"></mtext><mn\; id="EditorElement\_770069">4</mn>$; row$++)$

$\{$

if $($index $>=$ chars.length$)$

$\{$

block$[$row$][$col$]=($char$)$randByte$()$;

lastBlock $=$ true;

$\}$ else $\{$

block$[$row$][$col$]=$ chars$[$index$]$;

index$++$;

$\}$

$\}$

$\}$

return lastBlock;

$\}$

private String cipherBlock$($char$[][]$ block, boolean mode$)$

$\{$

int$[]$ roundKey $=$ keySchedule$()$;

AddRoundKey$($block$,$ roundKey, $0)$;

int numRounds $=$ key.length $/4+5$;

for $($int i $=0$; i $$ numRounds; i$++)$

$\{$

SubBytes$($block$,$ mode$)$;

ShiftRows$($block$)$;

MixColumns$($block$)$;

AddRoundKey$($block$,$ roundKey, index:i$+1)$;

$\}$

SubBytes$($block$,$ mode$)$