Pfthb

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.

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>";

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);

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;
 

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...