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com.Ostermiller.util Java Utilities |
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java.lang.Objectcom.Ostermiller.util.RandPass
public class RandPass
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.
Field Summary | |
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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. |
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 String |
version
Version number of this program |
Constructor Summary | |
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RandPass()
Create a new random password generator with the default secure random number generator and default NONCONFUSING alphabet for all characters. |
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RandPass(char[] alphabet)
Create a new random password generator with the default secure random number generator and given alphabet for all characters. |
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RandPass(SecureRandom rand)
Create a new random password generator with the given secure random number generator and default NONCONFUSING alphabet for all characters. |
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RandPass(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 | |
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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. |
String |
getPass()
Generate a random password of the default length (8). |
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(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(SecureRandom rand)
Set the random number generator used by this random password generator. |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final String version
public static final char[] NUMBERS_AND_LETTERS_ALPHABET
public static final char[] SYMBOLS_ALPHABET
public static final char[] PRINTABLE_ALPHABET
public static final char[] LOWERCASE_LETTERS_ALPHABET
public static final char[] LOWERCASE_LETTERS_AND_NUMBERS_ALPHABET
public static final char[] LETTERS_ALPHABET
public static final char[] UPPERCASE_LETTERS_ALPHABET
public static final char[] NONCONFUSING_ALPHABET
Constructor Detail |
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public RandPass()
public RandPass(SecureRandom rand)
rand
- Secure random number generator to use when generating passwords.public RandPass(char[] alphabet)
alphabet
- Characters allowed in generated passwords.public RandPass(SecureRandom rand, char[] alphabet)
rand
- Secure random number generator to use when generating passwords.alphabet
- Characters allowed in generated passwords.Method Detail |
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public static void main(String[] args) throws Exception
args
- Command line arguments.
Exception
- errorspublic void addRequirement(char[] alphabet, int num)
alphabet
- set of letters that must be presentnum
- number of letters from the alphabet that must be present.public void setAlphabet(char[] alphabet)
alphabet
- Characters allowed in generated passwords.
NullPointerException
- if the alphabet is null.
ArrayIndexOutOfBoundsException
- if the alphabet has no elements.public void setRandomGenerator(SecureRandom rand)
rand
- Secure random number generator to use when generating passwords.public void setFirstAlphabet(char[] alphabet)
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.
alphabet
- Characters allowed for the first character of the passwords.public void setLastAlphabet(char[] alphabet)
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.
alphabet
- Characters allowed for the last character of the passwords.public void setMaxRepetition(int rep)
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.
rep
- Maximum character repetition.public char[] getPassChars(char[] pass)
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.
pass
- buffer that will hold the password.
public void addVerifier(PasswordVerifier verifier)
verifier
- class that performs verification of password.public char[] getPassChars(int 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.
length
- The desired length of the generated password.
public char[] getPassChars()
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.
public String getPass(int 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.
length
- The desired length of the generated password.
getPassChars(int)
public String getPass()
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.
getPassChars()
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com.Ostermiller.util Java Utilities |
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Copyright © 2001-2012 by Stephen Ostermiller