Class Password

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, PasswordCallback

    public class Password
    extends java.lang.Object
    implements PasswordCallback, java.lang.Cloneable, java.io.Serializable
    Stores a password. clear should be called when the password is no longer needed so that the sensitive information is not left in memory.

    A Password can be used as a hard-coded PasswordCallback.

    See Also:
    PasswordCallback, Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static org.slf4j.Logger logger  
    • Constructor Summary

      Constructors 
      Constructor Description
      Password​(char[] pw)
      Creates a Password from a char array, then wipes the char array.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static byte[] charToByte​(char[] charArray)
      Converts a char array to a null-terminated byte array using a standard encoding, which is currently UTF8.
      void clear()
      Clears the password so that sensitive data is no longer present in memory.
      java.lang.Object clone()
      Clones the password.
      boolean equals​(java.lang.Object obj)
      Compares this password to another and returns true if they are the same.
      protected void finalize()
      The finalizer clears the sensitive information before releasing it to the garbage collector, but it should have been cleared manually before this point anyway.
      char[] getCharCopy()
      Returns a char array that is a copy of the password.
      char[] getChars()
      Returns the char array underlying this password.
      Password getPasswordAgain​(PasswordCallbackInfo info)
      An implementation of PasswordCallback.getPasswordAgain.
      Password getPasswordFirstAttempt​(PasswordCallbackInfo info)
      An implementation of PasswordCallback.getPasswordFirstAttempt.
      static Password readPasswordFromConsole()
      Reads a password from the console with echo disabled.
      static void wipeBytes​(byte[] byteArray)
      Wipes a byte array by setting all its elements to zero.
      static void wipeChars​(char[] charArray)
      Wipes a char array by setting all its elements to zero.
      • Methods inherited from class java.lang.Object

        getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • logger

        public static org.slf4j.Logger logger
    • Constructor Detail

      • Password

        public Password​(char[] pw)
        Creates a Password from a char array, then wipes the char array.
        Parameters:
        pw - A char[] containing the password. This array will be cleared (set to zeroes) by the constructor.
    • Method Detail

      • equals

        public boolean equals​(java.lang.Object obj)
        Compares this password to another and returns true if they are the same.
        Overrides:
        equals in class java.lang.Object
      • getPasswordAgain

        public Password getPasswordAgain​(PasswordCallbackInfo info)
                                  throws PasswordCallback.GiveUpException
        An implementation of PasswordCallback.getPasswordAgain. This allows a Password object to be used as a PasswordCallback. This method is only called after a call to getPasswordFirstAttempt returned the wrong password. This means the password is incorrect and there's no sense returning it again, so a GiveUpException is thrown.
        Specified by:
        getPasswordAgain in interface PasswordCallback
        Parameters:
        info - Information about the token that is being logged into.
        Returns:
        The password. This password object is owned by and will be cleared by the caller.
        Throws:
        PasswordCallback.GiveUpException - If the callback does not want to supply a password. This may often be the case if the first attempt failed.
      • getChars

        public char[] getChars()
        Returns the char array underlying this password. It must not be modified in any way.
      • getCharCopy

        public char[] getCharCopy()
        Returns a char array that is a copy of the password. The caller is responsible for wiping the returned array, for example using wipeChars.
      • clear

        public void clear()
        Clears the password so that sensitive data is no longer present in memory. This should be called as soon as the password is no longer needed.
      • clone

        public java.lang.Object clone()
        Clones the password. The resulting clone will be completely independent of the parent, which means it will have to be separately cleared.
        Overrides:
        clone in class java.lang.Object
      • finalize

        protected void finalize()
                         throws java.lang.Throwable
        The finalizer clears the sensitive information before releasing it to the garbage collector, but it should have been cleared manually before this point anyway.
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable
      • charToByte

        public static byte[] charToByte​(char[] charArray)
        Converts a char array to a null-terminated byte array using a standard encoding, which is currently UTF8. The caller is responsible for clearing the copy (with wipeBytes, for example).
        Parameters:
        charArray - A character array, which should not be null. It will be wiped with zeroes.
        Returns:
        A copy of the charArray, converted from Unicode to UTF8. It is the responsibility of the caller to clear the output byte array; wipeBytes is ideal for this purpose.
        See Also:
        wipeBytes(byte[])
      • wipeBytes

        public static void wipeBytes​(byte[] byteArray)
        Wipes a byte array by setting all its elements to zero. null must not be passed in.
      • wipeChars

        public static void wipeChars​(char[] charArray)
        Wipes a char array by setting all its elements to zero. null must not be passed in.
      • readPasswordFromConsole

        public static Password readPasswordFromConsole()
                                                throws PasswordCallback.GiveUpException
        Reads a password from the console with echo disabled. This is a blocking call which will return after the user types a newline. It only works with ASCII password characters. The call is synchronized because it alters terminal settings in a way that is not thread-safe.
        Returns:
        The password the user entered at the command line.
        Throws:
        PasswordCallback.GiveUpException - If the user enters no password (just hits <enter>).