Android file storage storing memory location

Question

I'm trying to store a hash of a password into a .txt file in my apps file directory, however all that seems to be getting stored or read is the memory location rather than the actual hash.

This is the function that takes care of hashing the password:

private void hashPassword(String pass)throws UnsupportedEncodingException, NoSuchAlgorithmException {
    //Hashed password is a global String
    hashedPassword = hasher.hash(pass);
}

This is the Hasher class method called above to create a SHA-256 hash of the password:

public String hash(String text) throws UnsupportedEncodingException, NoSuchAlgorithmException {
    byte[] b = text.getBytes(StandardCharsets.UTF_8);
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    return new String(digest.digest(b));
}

This is the function I use to set up the files for writing to:

//Set up a file in the directory path of the app and give it the name pass.txt and pubKey.txt
private void setUpFiles(String typeSetup) {
    //Check to see if it's setting up the pass file or key file
    if(typeSetup.equals("pass")){
        //passFile is a global file object object
        passFile = new File(makeId.this.getApplicationContext().getFilesDir(),"pass.txt");
    } else if (typeSetup.equals("key")){
        encryptionKeyFile = new File(makeId.this.getApplicationContext().getFilesDir(),"pubKey.txt");
    }
}

And finally, this is the function that handles storing the pass:

//Store the login info provided by the user
private boolean storeLogin() throws IOException {
    //Store the hashed password in a text file
    setUpFiles("pass");
    //Create objects to handle file writing
    FileWriter pw = new FileWriter(passFile);
    BufferedWriter bw = new BufferedWriter(pw);
    //Write the hashed password to the file
    bw.write(new String(hashedPassword));
    //Close resources
    bw.close();
    pw.close();
    //Return if the file was created or not
    return passFile.exists();
}

Those were the functions to store a hashed password into a text file, below are the functions used by another activity to read from the file, store and display the hash.

    public void loadPassHash() throws FileNotFoundException {
    //File that should contain the hash of the password
    File passFile = new File(c.getFilesDir(),"pass.txt");
    //Create a textview object
    tv = (TextView) findViewById(R.id.viewer);
    //Create a scanner object to read the file
    Scanner myScan = new Scanner(passFile);
    //Initialize the text variable to store the contents of the file
    String text = null;
    //Loop the file and set the text to it
    while (myScan.hasNext()) {
        text=myScan.next();
    }
    //If there is something in the file
    if (text!=null) {
        //Set the global passHash string to the value of text
        passHash=text;
        //Display the hashed password for development 
        tv.setText(passHash);
        //Close the scanner
        myScan.close();
    } else {
        finish();
    }

}

The results of this is that only a memory location is displayed and I am unable to compare the password hashes and validate the login. Any help would be appreciated.

Please can you show us what you see, both in the textbox and the contents of the file. — RichColours, Dec 08 '16 at 20:16
I've stuck your hash() function into a unit test and it appears to do something meaningful. — RichColours, Dec 08 '16 at 20:17
`text=myScan.next();`. You are throwing away the former. Add them up. `text+=myScan.next();`. Initialize text with "" instead of null. — greenapps, Dec 08 '16 at 20:27

score 0 · Accepted Answer · answered Dec 08 '16 at 20:14

0

You want to read line by line from the password file, currently you are reading until whitespace.

while (myScan.hasNextLine()) {
    text=myScan.nextLine();
}

answered Dec 08 '16 at 20:14

Victory

5,811
2
26
45

There should only be one thing in the file as I'm storing the files ilndividually until I get a database set up so I'm trying to read the entire contents of the file (should be one word/line. I am about to try to read the whole line in case the hash is creating a new line character. That worked correctly, thanks for helping me see that. – CS2016 Dec 08 '16 at 20:27
Might be more straight forward to store the values hex encoded, see http://stackoverflow.com/questions/332079/in-java-how-do-i-convert-a-byte-array-to-a-string-of-hex-digits-while-keeping-l – Victory Dec 08 '16 at 20:33

Android file storage storing memory location

1 Answers1