RandPass

java.lang.Object
- com.Ostermiller.util.RandPass

```
public class RandPass
extends java.lang.Object
```
Generates a random String using a cryptographically secure random number generator.
The alphabet (characters used in the passwords generated) may be specified, and the random number generator can be externally supplied.
Care should be taken when using methods that limit the types of passwords may be generated. Using an alphabet that is too small, using passwords that are too short, requiring too many of a certain type of character, or not allowing repetition, may decrease security.
More information about this class is available from ostermiller.org.

Since:

ostermillerutils 1.00.00

Field Summary

Fields
Modifier and Type	Field and Description
`protected char[]`	`alphabet` Set of characters which may be used in the generated passwords.
`protected char[]`	`firstAlphabet` Set of characters which may be used for the first character in the generated passwords.
`protected static java.util.ResourceBundle`	`labels` Locale specific strings displayed to the user.
`protected char[]`	`lastAlphabet` Set of characters which may be used for the last character in the generated passwords.
`static char[]`	`LETTERS_ALPHABET` Alphabet consisting of upper and lower case letters A-Z.
`static char[]`	`LOWERCASE_LETTERS_ALPHABET` Alphabet consisting of the lower case letters A-Z.
`static char[]`	`LOWERCASE_LETTERS_AND_NUMBERS_ALPHABET` Alphabet consisting of the lower case letters A-Z and the digits 0-9.
`static char[]`	`NONCONFUSING_ALPHABET` Alphabet consisting of upper and lower case letters A-Z and the digits 0-9 but with characters that are often mistaken for each other when typed removed.
`static char[]`	`NUMBERS_AND_LETTERS_ALPHABET` Alphabet consisting of upper and lower case letters A-Z and the digits 0-9.
`static char[]`	`PRINTABLE_ALPHABET` Alphabet consisting of all the printable ASCII characters.
`protected java.security.SecureRandom`	`rand` Random number generator used.
`protected int`	`repetition` One less than the maximum number of repeated characters that are allowed in a password.
`static char[]`	`SYMBOLS_ALPHABET` Alphabet consisting of all the printable ASCII symbols.
`static char[]`	`UPPERCASE_LETTERS_ALPHABET` Alphabet consisting of the upper letters A-Z.
`static java.lang.String`	`version` Version number of this program

Constructor Summary

Constructors
Constructor and Description
`RandPass()` Create a new random password generator with the default secure random number generator and default NONCONFUSING alphabet for all characters.
`RandPass(char[] alphabet)` Create a new random password generator with the default secure random number generator and given alphabet for all characters.
`RandPass(java.security.SecureRandom rand)` Create a new random password generator with the given secure random number generator and default NONCONFUSING alphabet for all characters.
`RandPass(java.security.SecureRandom rand, char[] alphabet)` Create a new random password generator with the given secure random number generator and given alphabet for all characters.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addRequirement(char[] alphabet, int num)` Require that a certain number of characters from an alphabet be present in generated passwords.
`void`	`addVerifier(PasswordVerifier verifier)` Add a class that will verify passwords.
`java.lang.String`	`getPass()` Generate a random password of the default length (8).
`java.lang.String`	`getPass(int length)` Generate a random password of the given length.
`char[]`	`getPassChars()` Generate a random password of the default length (8).
`char[]`	`getPassChars(char[] pass)` Fill the given buffer with random characters.
`char[]`	`getPassChars(int length)` Generate a random password of the given length.
`static void`	`main(java.lang.String[] args)` Generate a random passwords.
`void`	`setAlphabet(char[] alphabet)` Set the alphabet used by this random password generator.
`void`	`setFirstAlphabet(char[] alphabet)` Set the alphabet used by this random password generator for the first character of passwords.
`void`	`setLastAlphabet(char[] alphabet)` Set the alphabet used by this random password generator for the last character of passwords.
`void`	`setMaxRepetition(int rep)` Set the maximum number of characters that may appear in sequence more than once in a password.
`void`	`setRandomGenerator(java.security.SecureRandom rand)` Set the random number generator used by this random password generator.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - version
```
public static final java.lang.String version
```
    Version number of this program
    
    Since:
    
    ostermillerutils 1.00.00
    
    See Also:
    
    Constant Field Values
  - labels
```
protected static java.util.ResourceBundle labels
```
    Locale specific strings displayed to the user.
    
    Since:
    
    ostermillerutils 1.00.00
  - NUMBERS_AND_LETTERS_ALPHABET
```
public static final char[] NUMBERS_AND_LETTERS_ALPHABET
```
    Alphabet consisting of upper and lower case letters A-Z and the digits 0-9.
    
    Since:
    
    ostermillerutils 1.00.00
  - SYMBOLS_ALPHABET
```
public static final char[] SYMBOLS_ALPHABET
```
    Alphabet consisting of all the printable ASCII symbols.
    
    Since:
    
    ostermillerutils 1.00.00
  - PRINTABLE_ALPHABET
```
public static final char[] PRINTABLE_ALPHABET
```
    Alphabet consisting of all the printable ASCII characters.
    
    Since:
    
    ostermillerutils 1.00.00
  - LOWERCASE_LETTERS_ALPHABET
```
public static final char[] LOWERCASE_LETTERS_ALPHABET
```
    Alphabet consisting of the lower case letters A-Z.
    
    Since:
    
    ostermillerutils 1.00.00
  - LOWERCASE_LETTERS_AND_NUMBERS_ALPHABET
```
public static final char[] LOWERCASE_LETTERS_AND_NUMBERS_ALPHABET
```
    Alphabet consisting of the lower case letters A-Z and the digits 0-9.
    
    Since:
    
    ostermillerutils 1.00.00
  - LETTERS_ALPHABET
```
public static final char[] LETTERS_ALPHABET
```
    Alphabet consisting of upper and lower case letters A-Z.
    
    Since:
    
    ostermillerutils 1.00.00
  - UPPERCASE_LETTERS_ALPHABET
```
public static final char[] UPPERCASE_LETTERS_ALPHABET
```
    Alphabet consisting of the upper letters A-Z.
    
    Since:
    
    ostermillerutils 1.00.00
  - NONCONFUSING_ALPHABET
```
public static final char[] NONCONFUSING_ALPHABET
```
    Alphabet consisting of upper and lower case letters A-Z and the digits 0-9 but with characters that are often mistaken for each other when typed removed. (I,L,O,U,V,i,l,o,u,v,0,1)
    
    Since:
    
    ostermillerutils 1.00.00
  - rand
```
protected java.security.SecureRandom rand
```
    Random number generator used.
    
    Since:
    
    ostermillerutils 1.00.00
  - repetition
```
protected int repetition
```
    One less than the maximum number of repeated characters that are allowed in a password. Set to -1 to disable this feature.
    
    Since:
    
    ostermillerutils 1.00.00
  - alphabet
```
protected char[] alphabet
```
    Set of characters which may be used in the generated passwords.
    This value may not be null or have no elements.
    
    Since:
    
    ostermillerutils 1.00.00
  - firstAlphabet
```
protected char[] firstAlphabet
```
    Set of characters which may be used for the first character in the generated passwords.
    This value may be null but it must have at least one element otherwise.
    
    Since:
    
    ostermillerutils 1.00.00
  - lastAlphabet
```
protected char[] lastAlphabet
```
    Set of characters which may be used for the last character in the generated passwords.
    This value may be null but it must have at least one element otherwise.
    
    Since:
    
    ostermillerutils 1.00.00
- Constructor Detail
  - RandPass
```
public RandPass()
```
    Create a new random password generator with the default secure random number generator and default NONCONFUSING alphabet for all characters.
    
    Since:
    
    ostermillerutils 1.00.00
  - RandPass
```
public RandPass(java.security.SecureRandom rand)
```
    Create a new random password generator with the given secure random number generator and default NONCONFUSING alphabet for all characters.
    
    Parameters:
    
    rand - Secure random number generator to use when generating passwords.
    
    Since:
    
    ostermillerutils 1.00.00
  - RandPass
```
public RandPass(char[] alphabet)
```
    Create a new random password generator with the default secure random number generator and given alphabet for all characters.
    
    Parameters:
    
    alphabet - Characters allowed in generated passwords.
    
    Since:
    
    ostermillerutils 1.00.00
  - RandPass
```
public RandPass(java.security.SecureRandom rand,
                char[] alphabet)
```
    Create a new random password generator with the given secure random number generator and given alphabet for all characters.
    
    Parameters:
    
    rand - Secure random number generator to use when generating passwords.
    
    alphabet - Characters allowed in generated passwords.
    
    Since:
    
    ostermillerutils 1.00.00
- Method Detail
  - main
```
public static void main(java.lang.String[] args)
                 throws java.lang.Exception
```
    Generate a random passwords. Run with --help argument for more information.
    
    Parameters:
    
    args - Command line arguments.
    
    Throws:
    
    java.lang.Exception - errors
    
    Since:
    
    ostermillerutils 1.00.00
  - addRequirement
```
public void addRequirement(char[] alphabet,
                           int num)
```
    Require that a certain number of characters from an alphabet be present in generated passwords.
    
    Parameters:
    
    alphabet - set of letters that must be present
    
    num - number of letters from the alphabet that must be present.
    
    Since:
    
    ostermillerutils 1.00.00
  - setAlphabet
```
public void setAlphabet(char[] alphabet)
```
    Set the alphabet used by this random password generator.
    
    Parameters:
    
    alphabet - Characters allowed in generated passwords.
    
    Throws:
    
    java.lang.NullPointerException - if the alphabet is null.
    
    java.lang.ArrayIndexOutOfBoundsException - if the alphabet has no elements.
    
    Since:
    
    ostermillerutils 1.00.00
  - setRandomGenerator
```
public void setRandomGenerator(java.security.SecureRandom rand)
```
    Set the random number generator used by this random password generator.
    
    Parameters:
    
    rand - Secure random number generator to use when generating passwords.
    
    Since:
    
    ostermillerutils 1.00.00
  - setFirstAlphabet
```
public void setFirstAlphabet(char[] alphabet)
```
    Set the alphabet used by this random password generator for the first character of passwords.
    If the alphabet for the first character is set to null or has no elements, the main alphabet will be used for the first character.
    
    Parameters:
    
    alphabet - Characters allowed for the first character of the passwords.
    
    Since:
    
    ostermillerutils 1.00.00
  - setLastAlphabet
```
public void setLastAlphabet(char[] alphabet)
```
    Set the alphabet used by this random password generator for the last character of passwords.
    If the alphabet for the last character is set to null or has no elements, the main alphabet will be used for the last character.
    
    Parameters:
    
    alphabet - Characters allowed for the last character of the passwords.
    
    Since:
    
    ostermillerutils 1.00.00
  - setMaxRepetition
```
public void setMaxRepetition(int rep)
```
    Set the maximum number of characters that may appear in sequence more than once in a password. Your alphabet must be large enough to handle this option. If your alphabet is {'a', 'b'} and you want 8 character passwords in which no character appears twice (repetition 1) you are out of luck. In such instances your request for no repetition will be ignored.
    For example setRepetition(3) will allow a password ababab but not allow abcabc.
    Using this method can greatly reduce the pool of passwords that are generated. For example if only one repetition is allowed then the pool of passwords is the permutation of the alphabet rather than the combination.
    
    Parameters:
    
    rep - Maximum character repetition.
    
    Since:
    
    ostermillerutils 1.00.00
  - getPassChars
```
public char[] getPassChars(char[] pass)
```
    Fill the given buffer with random characters.
    Using this method, the password character array can easily be reused for efficiency, or overwritten with new random characters for security.
    NOTE: If it is possible for a hacker to examine memory to find passwords, the password should be overwritten in memory as soon as possible after i is no longer in use.
    
    Parameters:
    
    pass - buffer that will hold the password.
    
    Returns:
    
    the buffer, filled with random characters.
    
    Since:
    
    ostermillerutils 1.00.00
  - addVerifier
```
public void addVerifier(PasswordVerifier verifier)
```
    Add a class that will verify passwords. No password will be returned unless all verifiers approve of it.
    
    Parameters:
    
    verifier - class that performs verification of password.
    
    Since:
    
    ostermillerutils 1.00.00
  - getPassChars
```
public char[] getPassChars(int length)
```
    Generate a random password of the given length.
    NOTE: If it is possible for a hacker to examine memory to find passwords, the password should be overwritten in memory as soon as possible after i is no longer in use.
    
    Parameters:
    
    length - The desired length of the generated password.
    
    Returns:
    
    a random password
    
    Since:
    
    ostermillerutils 1.00.00
  - getPassChars
```
public char[] getPassChars()
```
    Generate a random password of the default length (8).
    NOTE: If it is possible for a hacker to examine memory to find passwords, the password should be overwritten in memory as soon as possible after i is no longer in use.
    
    Returns:
    
    a random password
    
    Since:
    
    ostermillerutils 1.00.00
  - getPass
```
public java.lang.String getPass(int length)
```
    Generate a random password of the given length.
    NOTE: Strings can not be modified. If it is possible for a hacker to examine memory to find passwords, getPassChars() should be used so that the password can be zeroed out of memory when no longer in use.
    
    Parameters:
    
    length - The desired length of the generated password.
    
    Returns:
    
    a random password
    
    Since:
    
    ostermillerutils 1.00.00
    
    See Also:
    
    getPassChars(int)
  - getPass
```
public java.lang.String getPass()
```
    Generate a random password of the default length (8).
    NOTE: Strings can not be modified. If it is possible for a hacker to examine memory to find passwords, getPassChars() should be used so that the password can be zeroed out of memory when no longer in use.
    
    Returns:
    
    a random password
    
    Since:
    
    ostermillerutils 1.00.00
    
    See Also:
    
    getPassChars()

com.Ostermiller.util Java Utilities

Class RandPass

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

version

labels

NUMBERS_AND_LETTERS_ALPHABET

SYMBOLS_ALPHABET

PRINTABLE_ALPHABET

LOWERCASE_LETTERS_ALPHABET

LOWERCASE_LETTERS_AND_NUMBERS_ALPHABET

LETTERS_ALPHABET

UPPERCASE_LETTERS_ALPHABET

NONCONFUSING_ALPHABET

rand

repetition

alphabet

firstAlphabet

lastAlphabet

Constructor Detail

RandPass

RandPass

RandPass

RandPass

Method Detail

main

addRequirement

setAlphabet

setRandomGenerator

setFirstAlphabet

setLastAlphabet

setMaxRepetition

getPassChars

addVerifier

getPassChars

getPassChars

getPass

getPass

com.Ostermiller.util Java Utilities