Package com.amdelamar.jotp

Class OTP

java.lang.Object

com.amdelamar.jotp.OTP

public final class OTP
extends java.lang.Object

OTP (One Time Password) utility in Java. To enable two-factor authentication (2FA) using HMAC-based) or Time-based algorithms.

Since:

1.0.0

See Also:

https://github.com/amdelamar/jotp

Field Summary

Fields

Modifier and Type	Field	Description
static int	BYTES

Method Summary

Modifier and Type	Method	Description
static java.lang.String	create(java.lang.String secret, java.lang.String base, int digits, Type type)	Create a one-time-password with the given key, base, digits, and OTP.Type.
static java.lang.String	getURL(java.lang.String secret, int digits, Type type, java.lang.String issuer, java.lang.String email)	Gets the "otpauth://" URL for adding to 2FA compatible devices/apps.
static java.lang.String	random(java.lang.String characters, int length)	Deprecated.
static java.lang.String	randomBase32(int length)	Generate a random string in Base32, with the specified length.
static java.lang.String	timeInHex()	Deprecated.
static java.lang.String	timeInHex(long timeInMillis)	A quick method to get a Time rounded down to the nearest 30 seconds.
static java.lang.String	timeInHex(long timeInMillis, int periodInSec)	A method to get a Unix Time converted to Hexadecimal using a token period.
protected static boolean	validateParameters(java.lang.String secret, java.lang.String base, int digits, Type type)	Validate the parameters used for generating one-time passwords.
static boolean	verify(java.lang.String secret, java.lang.String base, java.lang.String code, int digits, Type type)	Returns true if the code is valid for the Hmac-based or Time-based OTP of the secret.

Methods inherited from class java.lang.Object

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

Field Detail

BYTES

public static final int BYTES

See Also:

Constant Field Values

Method Detail

random

@Deprecated
public static java.lang.String random(java.lang.String characters,
                                      int length)

Deprecated.

Generate a random string using the characters provided, with the specified length.

Parameters:

characters - A set of possible characters to be chosen.

length - default 20

Returns:

secure random string

randomBase32

public static java.lang.String randomBase32(int length)

Generate a random string in Base32, with the specified length.

Parameters:

length - default 20

Returns:

secure random string

timeInHex

@Deprecated
public static java.lang.String timeInHex()
                                  throws java.io.IOException

Deprecated.

A quick method to get Unix Time rounded down to the nearest 30 seconds.

Returns:

String Hex time

Throws:

java.io.IOException - when generating Unix time

timeInHex

public static java.lang.String timeInHex(long timeInMillis)
                                  throws java.io.IOException

A quick method to get a Time rounded down to the nearest 30 seconds.

Parameters:

timeInMillis - long (like System.currentTimeMillis())

Returns:

String Hex time

Throws:

java.io.IOException - when generating Unix time

timeInHex

public static java.lang.String timeInHex(long timeInMillis,
                                         int periodInSec)
                                  throws java.io.IOException

A method to get a Unix Time converted to Hexadecimal using a token period.

Parameters:

timeInMillis - long (like System.currentTimeMillis())

periodInSec - int seconds period for the time to be rounded down to

Returns:

String Hex time

Throws:

java.io.IOException

create

public static java.lang.String create(java.lang.String secret,
                                      java.lang.String base,
                                      int digits,
                                      Type type)
                               throws java.lang.IllegalArgumentException,
                                      java.security.InvalidKeyException,
                                      java.security.NoSuchAlgorithmException

Create a one-time-password with the given key, base, digits, and OTP.Type.

Parameters:

secret - The secret.

base - The offset. (e.g. TOTP base is time from UTC rounded to the half-second while HOTP is a counter)

digits - The length of the code (Commonly '6')

type - Type.TOTP or Type.HOTP

Returns:

code

Throws:

java.lang.IllegalArgumentException - when parameters are invalid

java.security.NoSuchAlgorithmException - when HMAC is not available on this jvm

java.security.InvalidKeyException - when secret is invalid

See Also:

https://tools.ietf.org/html/rfc4226, https://tools.ietf.org/html/rfc6238

verify

public static boolean verify(java.lang.String secret,
                             java.lang.String base,
                             java.lang.String code,
                             int digits,
                             Type type)
                      throws java.lang.IllegalArgumentException,
                             java.security.InvalidKeyException,
                             java.security.NoSuchAlgorithmException

Returns true if the code is valid for the Hmac-based or Time-based OTP of the secret. For Hmac-based the 'base' is a counter, like 1,2,3. For Time-based the 'base' is Unix-time rounded down to the nearest 30 seconds.

Parameters:

secret - Shhhhh. (Base32)

base - The base or counter.

code - An OTP code to check.

digits - Length of code (Commonly '6')

type - Type.TOTP or Type.HOTP

Returns:

true if valid

Throws:

java.lang.IllegalArgumentException - when parameters are invalid

java.security.NoSuchAlgorithmException - when HMAC is not available on this jvm

java.security.InvalidKeyException - when secret is invalid

See Also:

https://tools.ietf.org/html/rfc4226, https://tools.ietf.org/html/rfc6238

validateParameters

protected static boolean validateParameters(java.lang.String secret,
                                            java.lang.String base,
                                            int digits,
                                            Type type)
                                     throws java.lang.IllegalArgumentException

Validate the parameters used for generating one-time passwords.

Parameters:

secret - Shhhhh. (Base32)

base - The base or counter.

digits - Length of code (Commonly '6')

type - Type.TOTP or Type.HOTP

Returns:

true if parameters are valid

Throws:

java.lang.IllegalArgumentException - when parameters are invalid

getURL

public static java.lang.String getURL(java.lang.String secret,
                                      int digits,
                                      Type type,
                                      java.lang.String issuer,
                                      java.lang.String email)
                               throws java.lang.IllegalArgumentException

Gets the "otpauth://" URL for adding to 2FA compatible devices/apps.

Parameters:

secret - Shhhhh. (Base32)

digits - Length of code (Commonly '6')

type - Type.TOTP or Type.HOTP

issuer - Company or Domain name

email - Username or Email address

Returns:

otpauth://...

Throws:

java.lang.IllegalArgumentException - when parameters are invalid