Package com.bastiaanjansen.otp

Class HOTPGenerator

java.lang.Object

com.bastiaanjansen.otp.OneTimePasswordGenerator

com.bastiaanjansen.otp.HOTPGenerator

public class HOTPGenerator
extends OneTimePasswordGenerator

Generates counter-based one-time passwords

Author:

Bastiaan Jansen

See Also:

OneTimePasswordGenerator

Field Summary

Fields inherited from class com.bastiaanjansen.otp.OneTimePasswordGenerator

algorithm, DEFAULT_HMAC_ALGORITHM, DEFAULT_PASSWORD_LENGTH, passwordLength, secret

Constructor Summary

Constructors

Constructor	Description
HOTPGenerator(int passwordLength, String secret)	Constructs generator with custom password length
HOTPGenerator(String secret)	Constructs generator with default values
HOTPGenerator(URI uri)	Constructs generator from a OTPAuth URI

Method Summary

Modifier and Type	Method	Description
String	generate(long counter)	Generate a counter-based one-time password
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

Methods inherited from class com.bastiaanjansen.otp.OneTimePasswordGenerator

generate, getAlgorithm, getPasswordLength, getSecret, getURI, verify, verify

Methods inherited from class java.lang.Object

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

Constructor Details

HOTPGenerator

public HOTPGenerator(String secret)

Constructs generator with default values

Parameters:

secret - used to generate hash

HOTPGenerator

public HOTPGenerator(int passwordLength,
String secret)

Constructs generator with custom password length

Parameters:

passwordLength - number of digits for generated code in range 6...8

secret - used to generate hash

HOTPGenerator

public HOTPGenerator(URI uri)
              throws UnsupportedEncodingException

Constructs generator from a OTPAuth URI

Parameters:

uri - OTPAuth URI

Throws:

UnsupportedEncodingException - when URI query can't be encodede

Method Details

generate

public String generate(long counter)
                throws IllegalArgumentException

Generate a counter-based one-time password

Parameters:

counter - how many times time interval has passed since 1970

Returns:

generated HOTP code

Throws:

IllegalArgumentException - when code could not be generated

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