net.cortexx.otp.google.GoogleAuthenticator.java Source code

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Here is the source code for net.cortexx.otp.google.GoogleAuthenticator.java

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/*
 * Copyright 2013 Patrick Kelchner
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.cortexx.otp.google;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import net.cortexx.otp.HmacBasedOneTimePassword.Algorithm;

import org.apache.commons.codec.binary.Base32;

/**
 * Utility functions for use with <a href="http://code.google.com/p/google-authenticator/">Google
 * Authenticator</a>.
 * 
 * <p>
 * <b>Note:</b> This class requires the optional <a
 * href="http://commons.apache.org/proper/commons-codec/"><code>commons-codec</code></a> dependency.
 * 
 * <p>
 * Example to generate a QR Code from a generated Authenticator URI with the <a
 * href="http://code.google.com/p/zxing/"><code>zxing</code></a> library:
 * 
 * <pre>import com.google.zxing.BarcodeFormat;
 *import com.google.zxing.client.j2se.MatrixToImageWriter;
 *import com.google.zxing.common.BitMatrix;
 *import com.google.zxing.qrcode.QRCodeWriter;
 *
 *BitMatrix matrix = new QRCodeWriter().encode(
 *    GoogleAuthenticator.createDefaultTimeBasedURI("account", secret), 
 *    BarcodeFormat.QR_CODE, 
 *    250, 250);
 *    
 *MatrixToImageWriter.writeToFile(matrix, "PNG", new File("totp.png"));</pre>
 */
public class GoogleAuthenticator {
    /**
     * Creates a URI for a time-based one-time password consumable by the
     * <a href="http://code.google.com/p/google-authenticator/">Google Authenticator</a>.
     * 
     * <p>
     * <b>Note:</b> This class requires the optional <a
     * href="http://commons.apache.org/proper/commons-codec/"><code>commons-codec</code></a>
     * dependency.
     * 
     * @param description
     *        the display name for the token inside the Authenticator
     * @param algorithm
     *        the algorithm to be used
     * @param digits
     *        the number of digits for this password
     * @param periodSeconds
     *        the length of the period for which one password value stays valid
     * @param secret
     *        the secret for the password
     * 
     * @return
     *         the <code>otpauth</code> URI corresponding to the given parameters
     * 
     * @see <a href="http://code.google.com/p/google-authenticator/wiki/KeyUriFormat">restrictions
     *      applying to the Google Authenticator</a>
     */
    public static String createTimeBasedURI(final String description, final Algorithm algorithm, final int digits,
            final int periodSeconds, final byte... secret) {

        if (description == null || algorithm == null || secret == null) {
            throw new NullPointerException();
        }
        if (description.length() == 0) {
            throw new IllegalArgumentException("'description' must not be empty");
        }
        if (secret.length == 0) {
            throw new IllegalArgumentException("'secret' must contain at least one byte");
        }
        if (digits < 6 || digits > 8) {
            throw new IllegalArgumentException("'digits' must be in the range [6..8]");
        }
        if (periodSeconds <= 0) {
            throw new IllegalArgumentException("'periodSeconds' must be positive");
        }

        try {
            final StringBuilder uri = new StringBuilder().append("otpauth://totp/")
                    .append(URLEncoder.encode(description, "UTF-8")).append("?secret=")
                    .append(new Base32().encodeToString(secret));

            if (algorithm != Algorithm.SHA1) {
                uri.append("&algorithm=").append(algorithm);
            }
            if (digits != 6) {
                uri.append("&digits=").append(digits);
            }
            if (periodSeconds != 30) {
                uri.append("&period=").append(periodSeconds);
            }

            return uri.toString();
        } catch (UnsupportedEncodingException e) {
            throw new IllegalStateException(e);
        }
    }

    /**
     * Equivalent to the call {@link #createCounterBasedURI(String, Algorithm, int, long, byte...)
     * createCounterBasedURI(description, SHA1, 6, 30, secret)}.
     */
    public static String createDefaultTimeBasedURI(final String description, final byte... secret) {
        return createTimeBasedURI(description, Algorithm.SHA1, 6, 30, secret);
    }

    /**
     * Creates a URI for a counter-based one-time password consumable by the
     * <a href="http://code.google.com/p/google-authenticator/">Google Authenticator</a>.
     * 
     * <p>
     * <b>Note:</b> This class requires the optional <a
     * href="http://commons.apache.org/proper/commons-codec/"><code>commons-codec</code></a>
     * dependency.
     * 
     * @param description
     *        the display name for the token inside the Authenticator
     * @param algorithm
     *        the algorithm to be used.
     * @param digits
     *        the number of digits for this password
     * @param counter
     *        the counter this counter-based password is initialized with
     * @param secret
     *        the secret for the token.
     * 
     * @return
     *         the <code>otpauth</code> URI corresponding to the given parameters
     * 
     * @see <a href="http://code.google.com/p/google-authenticator/wiki/KeyUriFormat">restrictions
     *      applying to the Google Authenticator</a>
     */
    public static String createCounterBasedURI(final String description, final Algorithm algorithm,
            final int digits, final long counter, final byte... secret) {

        if (description == null || algorithm == null || secret == null) {
            throw new NullPointerException();
        }
        if (description.length() == 0) {
            throw new IllegalArgumentException("'description' must not be empty");
        }
        if (secret.length == 0) {
            throw new IllegalArgumentException("'secret' must contain at least one byte");
        }
        if (digits < 6 || digits > 8) {
            throw new IllegalArgumentException("'digits' must be in the range [6..8]");
        }
        if (counter < 0) {
            throw new IllegalArgumentException("'counter' must be non-negative");
        }

        try {
            final StringBuilder uri = new StringBuilder().append("otpauth://hotp/")
                    .append(URLEncoder.encode(description, "UTF-8")).append("?secret=")
                    .append(new Base32().encodeToString(secret)).append("&counter=").append(counter);

            if (algorithm != Algorithm.SHA1) {
                uri.append("&algorithm=").append(algorithm);
            }
            if (digits != 6) {
                uri.append("&digits=").append(digits);
            }

            return uri.toString();
        } catch (UnsupportedEncodingException e) {
            throw new IllegalStateException(e);
        }
    }

    /**
     * Equivalent to the call {@link #createCounterBasedURI(String, Algorithm, int, long, byte...)
     * createCounterBasedURI(description, SHA1, 6, 0, secret)}.
     */
    public static String createDefaultCounterBasedURI(final String description, final byte... secret) {
        return createCounterBasedURI(description, Algorithm.SHA1, 6, 0, secret);
    }
}