Base64: java.lang.IllegalArgumentException: Illegal character

Question

I'm trying to send a confirmation email after user registration. I'm using the JavaMail library for this purpose and the Java 8 Base64 util class.

I'm encoding user emails in the following way:

byte[] encodedEmail = Base64.getUrlEncoder().encode(user.getEmail().getBytes(StandardCharsets.UTF_8));
Multipart multipart = new MimeMultipart();
InternetHeaders headers = new InternetHeaders();
headers.addHeader("Content-type", "text/html; charset=UTF-8");
String confirmLink = "Complete your registration by clicking on following"+ "\n<a href='" + confirmationURL + encodedEmail + "'>link</a>";
MimeBodyPart link = new MimeBodyPart(headers,
confirmLink.getBytes("UTF-8"));
multipart.addBodyPart(link);

where confirmationURL is:

private final static String confirmationURL = "http://localhost:8080/project/controller?command=confirmRegistration&ID=";

And then decoding this in ConfirmRegistrationCommand in such way:

    String encryptedEmail = request.getParameter("ID");

    String decodedEmail = new String(Base64.getUrlDecoder().decode(encryptedEmail), StandardCharsets.UTF_8);

    RepositoryFactory repositoryFactory = RepositoryFactory
            .getFactoryByName(FactoryType.MYSQL_REPOSITORY_FACTORY);
    UserRepository userRepository = repositoryFactory.getUserRepository();
    User user = userRepository.find(decodedEmail);

    if (user.getEmail().equals(decodedEmail)) {
        user.setActiveStatus(true);
        return Path.WELCOME_PAGE;
    } else {
        return Path.ERROR_PAGE;
    }

And when I'm trying to decode:

http://localhost:8080/project/controller?command=confirmRegistration&ID=[B@6499375d

I'm getting java.lang.IllegalArgumentException: Illegal base64 character 5b.

I tried to use basic Encode/Decoder (not URL ones) with no success.

SOLVED:

The problem was the next - in the line:

 String confirmLink = "Complete your registration by clicking on following"+ "\n<a href='" + confirmationURL + encodedEmail + "'>link</a>";

I'm calling toString on an array of bytes, so I should do the following:

String encodedEmail = new String(Base64.getEncoder().encode(
                user.getEmail().getBytes(StandardCharsets.UTF_8)));

Thanks to Jon Skeet and ByteHamster.

Answer 1

Your encoded text is [B@6499375d. That is not Base64, something went wrong while encoding. That decoding code looks good.

Use this code to convert the byte[] to a String before adding it to the URL:

String encodedEmailString = new String(encodedEmail, "UTF-8");
// ...
String confirmLink = "Complete your registration by clicking on following"
    + "\n<a href='" + confirmationURL + encodedEmailString + "'>link</a>";

Answer 2

I encountered this error since my encoded image started with data:image/png;base64,iVBORw0....

This answer led me to the solution:

String partSeparator = ",";
if (data.contains(partSeparator) {
  String encodedImg = data.split(partSeparator)[1];
  byte[] decodedImg = Base64.getDecoder().decode(encodedImg.getBytes(StandardCharsets.UTF_8));
  Path destinationFile = Paths.get("/path/to/imageDir", "myImage.jpg");
  Files.write(destinationFile, decodedImg);
}

Answer 3

Just use the below code to resolve this:

JsonObject obj = Json.createReader(new ByteArrayInputStream(Base64.getDecoder().decode(accessToken.split("\\.")[1].
                        replace('-', '+').replace('_', '/')))).readObject();

In the above code replace('-', '+').replace('_', '/') did the job. For more details see the https://jwt.io/js/jwt.js. I understood the problem from the part of the code got from that link:

function url_base64_decode(str) {
  var output = str.replace(/-/g, '+').replace(/_/g, '/');
  switch (output.length % 4) {
    case 0:
      break;
    case 2:
      output += '==';
      break;
    case 3:
      output += '=';
      break;
    default:
      throw 'Illegal base64url string!';
  }
  var result = window.atob(output); //polifyll https://github.com/davidchambers/Base64.js
  try{
    return decodeURIComponent(escape(result));
  } catch (err) {
    return result;
  }
}

Answer 4

The Base64.Encoder.encodeToString method automatically uses the ISO-8859-1 character set.

For an encryption utility I am writing, I took the input string of cipher text and Base64 encoded it for transmission, then reversed the process. Relevant parts shown below. NOTE: My file.encoding property is set to ISO-8859-1 upon invocation of the JVM so that may also have a bearing.

static String getBase64EncodedCipherText(String cipherText) {
    byte[] cText = cipherText.getBytes();
    // return an ISO-8859-1 encoded String
    return Base64.getEncoder().encodeToString(cText);
}

static String getBase64DecodedCipherText(String encodedCipherText) throws IOException {
    return new String((Base64.getDecoder().decode(encodedCipherText)));
}

public static void main(String[] args) {
    try {
        String cText = getRawCipherText(null, "Hello World of Encryption...");

        System.out.println("Text to encrypt/encode: Hello World of Encryption...");
        // This output is a simple sanity check to display that the text
        // has indeed been converted to a cipher text which 
        // is unreadable by all but the most intelligent of programmers.
        // It is absolutely inhuman of me to do such a thing, but I am a
        // rebel and cannot be trusted in any way.  Please look away.
        System.out.println("RAW CIPHER TEXT: " + cText);
        cText = getBase64EncodedCipherText(cText);
        System.out.println("BASE64 ENCODED: " + cText);
        // There he goes again!!
        System.out.println("BASE64 DECODED:  " + getBase64DecodedCipherText(cText));
        System.out.println("DECODED CIPHER TEXT: " + decodeRawCipherText(null, getBase64DecodedCipherText(cText)));
    } catch (Exception e) {
        e.printStackTrace();
    }

}

The output looks like:

Text to encrypt/encode: Hello World of Encryption...
RAW CIPHER TEXT: q$;�C�l��<8��U���X[7l
BASE64 ENCODED: HnEPJDuhQ+qDbInUCzw4gx0VDqtVwef+WFs3bA==
BASE64 DECODED:  q$;�C�l��<8��U���X[7l``
DECODED CIPHER TEXT: Hello World of Encryption...

Answer 5

I got this error for my Linux Jenkins slave. I fixed it by changing from the node from "Known hosts file Verification Strategy" to "Non verifying Verification Strategy".