se.sawano.java.security.otp.TOTP.java Source code

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Here is the source code for se.sawano.java.security.otp.TOTP.java

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/*
 * Copyright 2017 Daniel Sawano
 *
 * 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 se.sawano.java.security.otp;

import org.apache.commons.lang3.StringUtils;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import static org.apache.commons.lang3.Validate.isTrue;
import static org.apache.commons.lang3.Validate.notNull;

/**
 * Representation of a TOTP. This class will throw an {@link UnsupportedOperationException} if serialized in order to
 * prevent accidental serialization of the TOTP code. Encapsulate the TOTP object in another class  if the TOTP code
 * needs to be serialized.
 */
public final class TOTP implements Externalizable {

    public enum Length {
        ONE(1), TWO(2), THREE(3), FOUR(4), FIVE(5), SIX(6), SEVEN(7), EIGHT(8), NINE(9);

        private int value;

        Length(final int value) {
            this.value = value;
        }

        public int value() {
            return value;
        }

    }

    /**
     * Creates a new TOTP using the given code. The TOTP code will be left padded with zeros (0) if it's shorter than
     * the provided length.
     * <p>
     * Example: To create a TOTP of value {@code 046372} you would do:
     * </p>
     * <pre>
     * TOTP totp = TOTP.totp(46372, Length.SIX);
     * </pre>
     *
     * @param code
     *         the integer value of the code
     * @param length
     *         the length of the TOTP code
     *
     * @return the newly created TOTP
     */
    public static TOTP totp(final int code, final Length length) {
        return new TOTP(code, length);
    }

    private final String value;
    private final Length length;

    private TOTP(final int value, final Length length) {
        notNull(length);
        isTrue(value >= 0, "Value cannot be negative");

        final String paddedString = StringUtils.leftPad(Integer.toString(value), length.value(), '0');
        isTrue(paddedString.length() == length.value(), "Value must have length: %d. Was: %d", length.value(),
                paddedString.length());

        this.value = paddedString;
        this.length = length;
    }

    public String value() {
        return value;
    }

    public Length length() {
        return length;
    }

    @Override
    public boolean equals(final Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        final TOTP totp = (TOTP) o;
        return value.equals(totp.value);
    }

    @Override
    public int hashCode() {
        return value.hashCode();
    }

    @Override
    public String toString() {
        return "TOTP{value=*****}";
    }

    @Override
    public void writeExternal(final ObjectOutput out) throws IOException {
        deny();
    }

    @Override
    public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
        deny();
    }

    private static void deny() {
        throw new UnsupportedOperationException("Not allowed");
    }

}