JavaOTP

Lightweight yet powerful library to generate TOTP 2FA codes.

Installation

Please note, that you should first add exploit.org's repository.

Maven:

<repositories>
    <repository>
        <id>exploit</id>
        <name>Exploit Repository</name>
        <url>https://maven.exploit.org</url>
    </repository>
</repositories>

<dependency>
    <groupId>org.exploit</groupId>
    <artifactId>java-otp</artifactId>
    <version>1.0</version>
</dependency>

Gradle:

repositories {
    mavenCentral()

    maven {
        url("https://maven.exploit.org")
    }
}

implementation 'org.exploit:java-otp:1.0'

Usage

First you need to create instance of TOTPGenerator and pass there your TOTPConfig.

public static void main(String[] args) {
    var hashAlgorithm = HashAlgorithm.SHA1;
    var otpLength = 6;
    var secretLength = 20;
    var timeStepSeconds = 30;

    // Please note, parameters above are used in default constructor new TOTPConfig()
    var config = new TOTPConfig(hashAlgorithm, otpLength, secretLength, timeStepSeconds);

    var generator = new TOTPGenerator(config);

    var secretKey = generator.generateSecret();
    var otpCode = generator.generate(secretKey);
}

hashAlgorithm - Hash algorithm used. Most common supported: SHA1, SHA256, SHA512.

otpLength - Length of temporary code produced.

secretLength - Length of secret key used for creating OTP keys.

timeStepSeconds - Time after which temporary code expires.

Backup Codes

You can also generate short secure backup codes for users:

public static void main(String[] args) {
    var count = 10;
    var length = 10;

    // Please note, parameters above are used in default constructor new BackupConfig()
    var config = new BackupConfig(count, length);
    var generator = new BackupCodeGenerator();

    var codes = generator.generateCodes();
    // Or just generate 1 code
    var code = generator.generateCode();
}

License

JavaOTP is licensed under the BSD License. See BSD for more information.