Package tech.mgl.utils.security.gen

Class PasscodeGenerator

java.lang.Object

tech.mgl.utils.security.gen.PasscodeGenerator

public class PasscodeGenerator
extends Object

An implementation of the HOTP generator specified by RFC 4226. Generates short passcodes that may be used in challenge-response protocols or as timeout passcodes that are only valid for a short period. The default passcode is a 6-digit decimal code. The maximum passcode length is 9 digits.

Author:

sweis@google.com (Steve Weis)

Field Summary

Fields

Modifier and Type	Field	Description
static final int	INTERVAL	Default time interval

Constructor Summary

Constructors

Constructor	Description
PasscodeGenerator(Mac mac)
PasscodeGenerator(Mac mac, int passCodeLength)
PasscodeGenerator(tech.mgl.utils.security.gen.PasscodeGenerator.Signer signer)
PasscodeGenerator(tech.mgl.utils.security.gen.PasscodeGenerator.Signer signer, int passCodeLength)

Method Summary

Modifier and Type	Method	Description
String	generateResponseCode(byte[] challenge)
String	generateResponseCode(long state)
String	generateResponseCode(long state, byte[] challenge)
boolean	verifyResponseCode(long challenge, String response)
boolean	verifyTimeoutCode(long currentInterval, String timeoutCode)	Verify a timeout code.
boolean	verifyTimeoutCode(String timeoutCode, long currentInterval, int pastIntervals, int futureIntervals)	Verify a timeout code.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

INTERVAL

public static final int INTERVAL

Default time interval

See Also:

• Constant Field Values

Constructor Details

PasscodeGenerator

public PasscodeGenerator(Mac mac)

Parameters:

mac - A Mac used to generate passcodes

PasscodeGenerator

public PasscodeGenerator(tech.mgl.utils.security.gen.PasscodeGenerator.Signer signer)

PasscodeGenerator

public PasscodeGenerator(Mac mac,
 int passCodeLength)

Parameters:

mac - A Mac used to generate passcodes

passCodeLength - The length of the decimal passcode

PasscodeGenerator

public PasscodeGenerator(tech.mgl.utils.security.gen.PasscodeGenerator.Signer signer,
 int passCodeLength)

Method Details

generateResponseCode

public String generateResponseCode(long state)
                            throws GeneralSecurityException

Parameters:

state - 8-byte integer value representing internal OTP state.

Returns:

A decimal response code

Throws:

GeneralSecurityException - If a JCE exception occur

generateResponseCode

public String generateResponseCode(long state,
 byte[] challenge)
                            throws GeneralSecurityException

Parameters:

state - 8-byte integer value representing internal OTP state.

challenge - Optional challenge as array of bytes.

Returns:

A decimal response code

Throws:

GeneralSecurityException - If a JCE exception occur

generateResponseCode

public String generateResponseCode(byte[] challenge)
                            throws GeneralSecurityException

Parameters:

challenge - An arbitrary byte array used as a challenge

Returns:

A decimal response code

Throws:

GeneralSecurityException - If a JCE exception occur

verifyResponseCode

public boolean verifyResponseCode(long challenge,
 String response)
                           throws GeneralSecurityException

Parameters:

challenge - A challenge to check a response against

response - A response to verify

Returns:

True if the response is valid

Throws:

GeneralSecurityException

verifyTimeoutCode

public boolean verifyTimeoutCode(long currentInterval,
 String timeoutCode)
                          throws GeneralSecurityException

Verify a timeout code. The timeout code will be valid for a time determined by the interval period and the number of adjacent intervals checked.

Parameters:

timeoutCode - The timeout code

Returns:

True if the timeout code is valid

Throws:

GeneralSecurityException

verifyTimeoutCode

public boolean verifyTimeoutCode(String timeoutCode,
 long currentInterval,
 int pastIntervals,
 int futureIntervals)
                          throws GeneralSecurityException

Verify a timeout code. The timeout code will be valid for a time determined by the interval period and the number of adjacent intervals checked.

Parameters:

timeoutCode - The timeout code

pastIntervals - The number of past intervals to check

futureIntervals - The number of future intervals to check

Returns:

True if the timeout code is valid

Throws:

GeneralSecurityException