Package com.bastiaanjansen.otp

Class HOTPGenerator

java.lang.Object

com.bastiaanjansen.otp.HOTPGenerator

public final class HOTPGenerator
extends Object

Generates counter-based one-time passwords

Author:

Bastiaan Jansen

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	HOTPGenerator.Builder

Method Summary

Modifier and Type	Method	Description
static HOTPGenerator	fromURI(URI uri)	Build a TOTPGenerator from an OTPAuth URI
String	generate(long counter)	Generate a code
HMACAlgorithm	getAlgorithm()
int	getPasswordLength()
URI	getURI(int counter, String issuer)	Create an OTPAuth URI for easy user on-boarding with only an issuer
URI	getURI(int counter, String issuer, String account)	Create an OTPAuth URI for easy user on-boarding with an issuer and account name
boolean	verify(String code, long counter)	Checks whether a code is valid for a specific counter with a delay window of 0
boolean	verify(String code, long counter, int delayWindow)	Checks whether a code is valid for a specific counter taking a delay window into account
static HOTPGenerator	withDefaultValues(byte[] secret)	Create a com.bastiaanjansen.otp.HOTPGenerator with default values

Methods inherited from class java.lang.Object

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

Method Detail

fromURI

public static HOTPGenerator fromURI(URI uri)
                             throws URISyntaxException

Build a TOTPGenerator from an OTPAuth URI

Parameters:

uri - OTPAuth URI

Returns:

HOTP

Throws:

URISyntaxException - when URI cannot be parsed

withDefaultValues

public static HOTPGenerator withDefaultValues(byte[] secret)

Create a com.bastiaanjansen.otp.HOTPGenerator with default values

Parameters:

secret - used to generate hash

Returns:

a com.bastiaanjansen.otp.HOTPGenerator with default values

getURI

public URI getURI(int counter,
                  String issuer)
           throws URISyntaxException

Create an OTPAuth URI for easy user on-boarding with only an issuer

Parameters:

counter - of URI

issuer - name for URI

Returns:

OTPAuth URI

Throws:

URISyntaxException - when URI cannot be created

getURI

public URI getURI(int counter,
                  String issuer,
                  String account)
           throws URISyntaxException

Create an OTPAuth URI for easy user on-boarding with an issuer and account name

Parameters:

counter - of URI

issuer - name for URI

account - name for URI

Returns:

OTPAuth URI

Throws:

URISyntaxException - when URI cannot be created

getPasswordLength

public int getPasswordLength()

getAlgorithm

public HMACAlgorithm getAlgorithm()

verify

public boolean verify(String code,
                      long counter)

Checks whether a code is valid for a specific counter with a delay window of 0

Parameters:

code - an OTP code

counter - how many times time interval has passed since 1970

Returns:

a boolean, true if code is valid, otherwise false

verify

public boolean verify(String code,
                      long counter,
                      int delayWindow)

Checks whether a code is valid for a specific counter taking a delay window into account

Parameters:

code - an OTP codee

counter - how many times time interval has passed since 1970

delayWindow - window in which a code can still be deemed valid

Returns:

a boolean, true if code is valid, otherwise false

generate

public String generate(long counter)
                throws IllegalStateException

Generate a code

Parameters:

counter - how many times time interval has passed since 1970

Returns:

generated OTP code

Throws:

IllegalStateException - when hashing algorithm throws an error