OTP

Simple but Secure AIO OTP solution. Supports,

• Generic OTP (storage-less otp solution)
• TOTP (RFC6238)
• HOTP (RFC4226)
• OCRA (RFC6287)

Table of Contents

• Prerequisites
• Installation
• Why this library?
• Usage
  • HOTP (RFC4226)
  • TOTP (RFC6238)
  • Generic OTP
  • OCRA (RFC6287)
• Support
• References

Prerequisites

Language: PHP 8.2/+

Library Version	PHP Version
3.x.x/+	8.2.x or Higher
2.x.x	8.x.x
1.x.x	7.x.x

Installation

composer require infocyph/otp

Why this library?

TOTP & HOTP

• Uses offline QR code generator (no more exposing your secret online)
• Time-safe Base32 encoding (30 seconds validity means 30 seconds)

Generic OTP

• No need to dedicate extra storage/db for User information (just build a unique signature)

OCRA

• One of a few implementation in PHP, easy to use

Usage

HOTP (RFC4226)

• Generate secret

$secret = \Infocyph\OTP\HOTP::generateSecret();

• Get QR Code Image for secret $secret (in SVG format)

// supports digit count in 2nd parameter, recommended to be either 6 or 8 (default 6)
(new \Infocyph\OTP\HOTP($secret))
// only required if the counter is being imported from another system or if it is old, & for QR only
->setCounter(3)
// default is sha1; Caution: many app (in fact, most of them) have algorithm limitation
->setAlgorithm('sha256') 
// or `getProvisioningUri` just to get the URI
->getProvisioningUriQR('TestName', 'abc@def.ghi'); 

The getProvisioningUriQR & getProvisioningUri accepts 3rd parameter, where it takes array of parameters ['algorithm', 'digits', 'period', 'counter']. Problem you might encounter, with the URI/Image is that most of the OTP generator might not support all of those options. In that case, passing in a blank array will remove all the optional keys, or you can pass in selective parameters as you need. Additionally, you can also pass in additional parameter to reflect in URI string or QR image in 4th parameter. But be cautious that, it might not be supported by the Client Apps.

• Get current OTP for a given counter

$counter = 346;
$otp = (new \Infocyph\OTP\HOTP($secret))->getOTP($counter);

• Verify

(new \Infocyph\OTP\HOTP($secret))->verify($otp,$counter);

TOTP (RFC6238)

• Generate secret

$secret = \Infocyph\OTP\TOTP::generateSecret();

• Get QR Code Image for secret $secret (in SVG format)

// supports digit count in 2nd parameter, recommended to be either 6 or 8 (default 6)
(new \Infocyph\OTP\TOTP($secret))
// default is sha1; Caution: many app (in fact, most of them) have algorithm limitation
->setAlgorithm('sha256') 
// or `getProvisioningUri` just to get the URI
->getProvisioningUriQR('TestName', 'abc@def.ghi'); 

The getProvisioningUriQR & getProvisioningUri accepts 3rd parameter, where it takes array of parameters ['algorithm', 'digits', 'period', 'counter']. Problem you might encounter, with the URI/Image is that most of the OTP generator might not support all of those options. In that case, passing in a blank array will remove all the optional keys, or you can pass in selective parameters as you need. Additionally, you can also pass in additional parameter to reflect in URI string or QR image in 4th parameter. But be cautious that, it might not be supported by the Client Apps.

• Get current OTP for a given counter

$counter = 346;
$otp = (new \Infocyph\OTP\TOTP($secret))->getOTP($counter);
// or get OTP for another specified epoch time
$otp = (new \Infocyph\OTP\TOTP($secret))->getOTP(1604820275);

• Verify

(new \Infocyph\OTP\TOTP($secret))->verify($otp);
// or verify for a specified time
(new \Infocyph\OTP\TOTP($secret))->verify($otp, 1604820275);

On 3rd parameter (bool) it supports, enabling leeway. If enabled, it will also check with last segment's generated otp.

Generic OTP

• Initiate

/**
* Param 1 is OTP length (default 6)
* Param 2 is validity in seconds (default 30)
* Param 3 is retry count on failure (default 3)
*/
$otpInstance = new \Infocyph\OTP\OTP(4, 60, 2);

• Generate & get the OTP

$otp = $otpInstance->generate('an unique signature for a cause');

• Verify the OTP

$otpInstance->verify('an unique signature for a cause', $otp);

On 3rd parameter setting false will keep the record till the otp is verified or expired. By default, will keep the record till the key name match or the otp is verified or expired

• Delete a record

$otpInstance->delete('an unique signature for a cause');

• Flush all the existing OTPs (if any)

$otpInstance->flush()

Generic OTP uses temporary location for storage, make sure you have proper access permission

OCRA (RFC6287)

// Example usage:
$sharedKey = 'mySecretKey'; // Replace with your actual shared key (binary format)
$challenge = '123456'; // Replace with your challenge value
$counter = 0; // Replace with the appropriate counter value

// Create an OCRA instance
$suite = new \Infocyph\OTP\OCRA('OCRA-1:HOTP-SHA1-6:C-QN08', $sharedKey);

// If the OCRA suite supports session, set the session
$suite->setSession('...');

// If the OCRA suite supports time format, set the time
$suite->setTime(new \DateTime());

// If the OCRA suite supports pin, set the pin
$suite->setPin('...');

// Generate the OCRA value
$suite->generate($challenge, $counter);

Forming an OCRA Suite

According to current RFC6287, an example string should be in the following format:

OCRA-1:HOTP-SHA1-6:C-QN08-PSHA1

Here OCRA-1:HOTP- is fixed as of current documentation.

• SHA1 is cryptographic hash function. (supported: SHA1, SHA256, SHA512)
• 6 is the number of digits in the generated OTP. (supported: 0, 4-10)
• C denotes counter support (optional)
• QN08 denotes the mode (it can be either of QNxx, QAxx, QHxx)

Format (F)	Up to Length (xx)
A (alphanumeric)	04-64
N (numeric)	04-64
H (hexadecimal)	04-64

• Next part is optional & little tricky
  • PSHA1 denotes the hash function used for pin support (it can be either of PSHA1, PSHA256, PSHA512)
  • S (not in example) denotes session length (3 digits)
  • T (not in example) denotes time format as of below table,

Time-Step Size (G)	Examples
[1-59]S	number of seconds, e.g., 20S
[1-59]M	number of minutes, e.g., 5M
[0-48]H	number of hours, e.g., 24H

Support

Having trouble? Create an issue!

References

• HOTP (RFC4226): https://tools.ietf.org/html/rfc4226
• TOTP (RFC6238): https://tools.ietf.org/html/rfc6238
• OCRA (RFC6287): https://tools.ietf.org/html/rfc6287