Attempting to Call an Encryption Algorithm Generates NoSuchAlgorithmException

Question

When trying to compile the following code, I generate NoSuchAlgorithmException every time, regardless of what string I assign to the algorithm variable (AES, DESede, etc). The error is always thrown in the constructor, when I'm first trying to assign a value to the key, and for the life of me I can't manage to figure out what the issue is. I've included the entire file in the off chance that something is relevant, but the only problem area seems to be the constructor. If anyone is familiar with this issue and could point out where I'm going wrong, I'd be very grateful.

public class Seclib {


      private static String algorithm = "AES";
      private static Key key = null;
      private static Cipher cipher = null;

    public Seclib(){
        key = KeyGenerator.getInstance(algorithm).generateKey();
        cipher = Cipher.getInstance(algorithm);
    }

    public static String messageHash(String message) throws NoSuchAlgorithmException {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(message.getBytes());
        return md.digest(message.getBytes()).toString();
    }

    public static byte[] encryptMessage(String input) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] inputBytes = input.getBytes();
        return cipher.doFinal(inputBytes);
    }   

    private static String decrypt(byte[] encryptionBytes) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] recoveredBytes = 
        cipher.doFinal(encryptionBytes);
        String recovered = new String(recoveredBytes);
        return recovered;
    }   

    public static String initializeSecurityParameters(Scanner reader, int securityArray[]){

        int flagC = 0;
        int flagI = 0;
        int flagA = 0;

        String securityArrayString = "";

        String s;

        while(flagC == 0){

            System.out.println("Does this session require confidentiality? Y/N");
            System.out.println();
            s = reader.next();
            System.out.println();

            if(s.equals("Y") || s.equals("y") || s.equals("N") || s.equals("n")){

                if(s.equals("Y") || s.equals("y")){
                    securityArray[0] = 1;
                    flagC = 1;
                }else{
                    securityArray[0] = 0;
                    flagC = 2;
                }
            }

            if(flagC == 0){
                System.out.println("Invalid entry, must be one of Y,y,N,n");
                System.out.println();
            }
        }

        while(flagI == 0){

            System.out.println("Does this session require integrity? Y/N");
            System.out.println();
            s = reader.next();
            System.out.println();

            if(s.equals("Y") || s.equals("y") || s.equals("N") || s.equals("n")){
                flagI = 1;
                if(s.equals("Y") || s.equals("y")){
                    securityArray[1] = 1;
                    flagI = 1;
                }else{
                    securityArray[1] = 0;
                    flagI = 2;
                }
            }

            if(flagI == 0){
                System.out.println("Invalid entry, must be one of Y,y,N,n");
                System.out.println();
            }
        }

        while(flagA == 0){

            System.out.println("Does this session require authentication? Y/N");
            System.out.println();
            s = reader.next();
            System.out.println();

            if(s.equals("Y") || s.equals("y") || s.equals("N") || s.equals("n")){

                if(s.equals("Y") || s.equals("y")){
                    securityArray[2] = 1;
                    flagA = 1;
                }else{
                    securityArray[2] = 0;
                    flagA = 2;
                }
            }

            if(flagA == 0){
                System.out.println("Invalid entry, must be one of Y,y,N,n");
                System.out.println();
            }
        }

        //create security string

        for(int i = 0; i < 3; i++){
            securityArrayString = securityArrayString + String.valueOf(securityArray[i]);
        }

        //Use security array values to create key, etc based on need

        if(securityArray[0] == 1){
            System.out.println("C operations needed");
        }

        if(securityArray[1] == 1){
            System.out.println("I operations needed");
        }

        if(securityArray[2] == 1){
            System.out.println("A operations needed");
        }       

        return securityArrayString;
    }







}

Answer 1

Cipher's and KeyGenerator's getInstance() need different inputs:

key = KeyGenerator.getInstance("AES").generateKey();
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");