Encryption program returning weird string for encryption but correct string after decryption

Question

I am performing xor encryption in Java. It encrypts a byte array, converts it into a String, and then prints the String.

However, when I execute it, I get strange "boxes" in the output (Eclipse console).

The algorithm code:

for(int i = 0; i < messageArr.length; i++)
{
    encryptedMessage[i] = (byte) (messageArr[i]^codebookArr[i]);
}

String eMessage = new String(encryptedMessage);
return eMessage;

The main method:

String lMessage = e.xorEncrypt(message, codebook);
System.out.println("Encrypted message: " + lMessage);
String uMessage = e.xorEncrypt(lMessage, codebook);
System.out.println("Unencrypted message: " + uMessage);

When I run this code, it prints strange "boxes" for the encrypted string. However, when it decrypts the string, I receive the original output, showing that the encryption algorithm works.

Why do I receive the strange boxes for the encrypted output, but the correct string when I decrypt it?

You get boxes because they are not readable ascii characters — Deepesh Choudhary
– Deepesh Choudhary, Commented May 6, 2017 at 7:07
You're trying to transform arbitrary, binary bytes to a String, using the platform default encoding. You can't expect to get back only valid, printable characters. Not all byte sequences are valid character sequences in all encodings, and not all characters are printable. — JB Nizet
– JB Nizet, Commented May 6, 2017 at 7:08
Why do you expect something printable when you print the encrypted stuff? — Tom
– Tom, Commented May 6, 2017 at 7:08
Sure. Use Base64 encoding to transform the arbitrary byte array into a sequence of printable characters. — JB Nizet
– JB Nizet, Commented May 6, 2017 at 7:30

Community · Accepted Answer · 2017-05-23 12:26:06Z

1

You can use Base64 encoding after encryption (it is a best practice) so you don't get weird boxes and no special characters get lost in "travel".

A good reference:

Base64 Encoding in Java

You will get a string somewhat like this: b2xkIGNyb3cgbWVkaWNpbmUgc2hvdw==

edited May 23, 2017 at 12:26

CommunityBot

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answered May 6, 2017 at 7:21

didiz

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