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POjava basic encryption program
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  1. POjava basic encryption program
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    copied!<p>I'm trying to make a basic encryption program that used random numbers to encrypt the whole alphabet, encrypt a user submitted phrase and then decrypt it back to the original phrase but I am finding it very hard. Can anyone help point out my mistakes please! It shouldn't code two letters to the same letter, ie a and b shouldn't ever be both matched to c.</p> <pre><code>public class MainClass { public static final int ALPHASIZE = 26; public static final char[] Lalpha = { 'a','b','c','d','e','f','g','h','i','j','k','l', 'm','n','o','p','q','r','s','t','u','v','w','x','y','z' }; public static final char[] Ualpha = {'A','B','C','D','E','F','G','H','I','J','K','L', 'M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z', }; protected static char[] encryptU = new char[ALPHASIZE]; protected static int[] decrypt = new int[ALPHASIZE]; protected static char[] encryptL = new char[ALPHASIZE]; Random rgenerator = new Random(); public MainClass(){ int randNum = rgenerator.nextInt(ALPHASIZE); for(int i=0; i&lt;ALPHASIZE ; i++) { //makes sure that it won't assign a letter to itself or to one that has already been assigned do { randNum = rgenerator.nextInt(26); } while (randNum%26==0 &amp;&amp;Arrays.asList(encryptU).contains(Ualpha[randNum])); encryptU[i] = Ualpha[randNum]; encryptL[i] = Lalpha[randNum]; decrypt[i] = randNum; } } public String encrypt(String secret) { System.out.println(Arrays.toString(encryptU)); int position = 0; char[] mess = secret.toCharArray(); for(int i = 0 ; i&lt;mess.length;i++) { if(Character.isUpperCase(mess[i])) { for(int j = 0; j &lt; encryptU.length; j++) { if(mess[i]==Ualpha[j]) { position = j; } mess[i] = encryptU[position]; } } if(Character.isLowerCase(mess[i])) { for(int j = 0; j &lt; encryptU.length; j++) { if(mess[i]==Lalpha[j]) { position = j; } mess[i] = encryptL[position]; } } } return new String(mess); } public String decrypt(String secret) { char[] mess = secret.toCharArray(); for(int i = 0 ; i&lt;mess.length;i++) { if(Character.isUpperCase(mess[i])) { for(int j = 0; j&lt;ALPHASIZE; j++){ if(mess[i]==encryptU[j]){ mess[i] = Ualpha[j]; } } } if(Character.isLowerCase(mess[i])) { for(int j = 0; j&lt;ALPHASIZE; j++){ if(mess[i]==encryptL[j]){ mess[i] = Lalpha[j]; } } } } return new String(mess); } } </code></pre>
 

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