Java - Why is my AES program not encrypting/decrypting double quotes?

Question

I'm implementing a simple AES-128 encryption program using Java's Crypto library.

Unfortunately, this doesn't work very well all the time. Sometimes it happens that the double-quotes (") in the plaintext String are when encrypted and then decrypted, show up as � in the decrypted string.

From what I found out, this character is &#xfffd (&#65533), which is a replacement character used by the UTF-8 decoder when it encounters an error.

Thus, my question is why does this error occur, why only sometimes and how do I resolve it?

Here's my code block for encryption and decryption:

public static String encrypt(String value)
    {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);

            byte[] encrypted = cipher.doFinal(value.getBytes());
            return Base64.getEncoder().encodeToString(encrypted);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return null;
    }

    public static String decrypt(String encrypted)
    {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
            byte[] original = cipher.doFinal(Base64.getDecoder().decode(encrypted));

            return new String(original);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

Here are some examples cases:

Case 1: Error caused

Enter Plaintext: had no pictures or conversations in it, “and what is the use of a book,” thought Alice “without pictures or conversations?”
Encrypted String: UgapiW5aYIKkoKkyeHvvFlgf8mCIq1AopmCtYGiJ23eNILNn1OXtM4enEvB5Kt1imNmynyHCCjLbbjB7TV0sq2F3Iz+YUehOw50gje6IMj8fpaEracq1NvZQXSH5T8fyBtAUH3weU5FE5vr3dYmwTSGUxNR2gaRV6MV7vmcEuIz7A5MLnKjsb2+1Sya+l/k2
Enter Ciphertext: UgapiW5aYIKkoKkyeHvvFlgf8mCIq1AopmCtYGiJ23eNILNn1OXtM4enEvB5Kt1imNmynyHCCjLbbjB7TV0sq2F3Iz+YUehOw50gje6IMj8fpaEracq1NvZQXSH5T8fyBtAUH3weU5FE5vr3dYmwTSGUxNR2gaRV6MV7vmcEuIz7A5MLnKjsb2+1Sya+l/k2
After decryption: had no pictures or conversations in it, �and what is the use of a book,� thought Alice �without pictures or conversations?�

Case 2: No issue

Enter Plaintext: Hello there, "Camera-man". He's sitting now. 
Encrypted String: jb2QJ5nLQCjGKw6l2q9GnX6jgTJVGWn6LiVRfE5oRT7WT7vYNejKPHIhgorbfaob
Enter Ciphertext: jb2QJ5nLQCjGKw6l2q9GnX6jgTJVGWn6LiVRfE5oRT7WT7vYNejKPHIhgorbfaob
After decryption: Hello there, "Camera-man". He's sitting now. 

Answer 1

The quote in your paste is not the standard ASCII ", but something else.

You have string-based keys and ivs and use UTF-8 to turn those into actual byte arrays. This is probably a mistake, you're reducing randomness a bit there, but not enough to be too worried about.

However, for the actual payload, you don't do this - and that's where you should have.

It's not value.getBytes(), it's value.getBytes(StandardCharsets.UTF-8), and not new String(original), but new String(original, StandardCharsets.UTF_8).