<?php

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * Contains a class representing GPG sub-keys and constants for GPG algorithms
 *
 * LICENSE:
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of the
 * License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see
 * <http://www.gnu.org/licenses/>
 *
 * @category  Encryption
 * @package   Crypt_GPG
 * @author    Michael Gauthier <mike@silverorange.com>
 * @author    Nathan Fredrickson <nathan@silverorange.com>
 * @copyright 2005-2010 silverorange
 * @license   http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
 * @link      http://pear.php.net/package/Crypt_GPG
 */

/**
 * A class for GPG sub-key information
 *
 * This class is used to store the results of the {@link Crypt_GPG::getKeys()}
 * method. Sub-key objects are members of a {@link Crypt_GPG_Key} object.
 *
 * @category  Encryption
 * @package   Crypt_GPG
 * @author    Michael Gauthier <mike@silverorange.com>
 * @author    Nathan Fredrickson <nathan@silverorange.com>
 * @copyright 2005-2010 silverorange
 * @license   http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
 * @link      http://pear.php.net/package/Crypt_GPG
 * @see       Crypt_GPG::getKeys()
 * @see       Crypt_GPG_Key::getSubKeys()
 */
class Crypt_GPG_SubKey
{
    /**
     * RSA encryption algorithm.
     */
    const ALGORITHM_RSA = 1;

    /**
     * Elgamal encryption algorithm (encryption only).
     */
    const ALGORITHM_ELGAMAL_ENC = 16;

    /**
     * DSA encryption algorithm (sometimes called DH, sign only).
     */
    const ALGORITHM_DSA = 17;

    /**
     * Elgamal encryption algorithm (signage and encryption - should not be
     * used).
     */
    const ALGORITHM_ELGAMAL_ENC_SGN = 20;

    /**
     * Key can be used to encrypt
     */
    const USAGE_ENCRYPT = 1;

    /**
     * Key can be used to sign
     */
    const USAGE_SIGN = 2;

    /**
     * Key can be used to certify other keys
     */
    const USAGE_CERTIFY = 4;

    /**
     * Key can be used for authentication
     */
    const USAGE_AUTHENTICATION = 8;

    /**
     * The id of this sub-key
     *
     * @var string
     */
    private $_id = '';

    /**
     * The algorithm used to create this sub-key
     *
     * The value is one of the Crypt_GPG_SubKey::ALGORITHM_* constants.
     *
     * @var int
     */
    private $_algorithm = 0;

    /**
     * The fingerprint of this sub-key
     *
     * @var string
     */
    private $_fingerprint = '';

    /**
     * Length of this sub-key in bits
     *
     * @var int
     */
    private $_length = 0;

    /**
     * Date this sub-key was created
     *
     * This is a Unix timestamp.
     *
     * @var DateTime|null
     */
    private $_creationDate = null;

    /**
     * Date this sub-key expires
     *
     * This is a Unix timestamp. If this sub-key does not expire, this will be
     * null.
     *
     * @var DateTime|null
     */
    private $_expirationDate = null;

    /**
     * Contains usage flags of this sub-key
     *
     * @var int
     */
    private $_usage = 0;

    /**
     * Whether or not the private key for this sub-key exists in the keyring
     *
     * @var bool
     */
    private $_hasPrivate = false;

    /**
     * Whether or not this sub-key is revoked
     *
     * @var bool
     */
    private $_isRevoked = false;

    /**
     * Creates a new sub-key object
     *
     * Sub-keys can be initialized from an array of named values. Available
     * names are:
     *
     * - <kbd>string id</kbd>          - the key id of the sub-key.
     * - <kbd>int    algorithm</kbd>   - the encryption algorithm of the
     *                                   sub-key.
     * - <kbd>string fingerprint</kbd> - the fingerprint of the sub-key. The
     *                                   fingerprint should not contain
     *                                   formatting characters.
     * - <kbd>int    length</kbd>      - the length of the sub-key in bits.
     * - <kbd>int    creation</kbd>    - the date the sub-key was created.
     *                                   This is a UNIX timestamp.
     * - <kbd>int    expiration</kbd>  - the date the sub-key expires. This
     *                                   is a UNIX timestamp. If the sub-key
     *                                   does not expire, use 0.
     * - <kbd>bool   canSign</kbd>     - whether or not the sub-key can be
     *                                   used to sign data.
     * - <kbd>bool   canEncrypt</kbd>  - whether or not the sub-key can be
     *                                   used to encrypt data.
     * - <kbd>int    usage</kbd>       - the sub-key usage flags
     * - <kbd>bool   hasPrivate</kbd>  - whether or not the private key for
     *                                   the sub-key exists in the keyring.
     * - <kbd>bool   isRevoked</kbd>   - whether or not this sub-key is
     *                                   revoked.
     *
     * @param Crypt_GPG_SubKey|string|array|null $key Either an existing sub-key object,
     *                                                which is copied; a sub-key string,
     *                                                which is parsed; or an array
     *                                                of initial values.
     */
    public function __construct($key = null)
    {
        // parse from string
        if (is_string($key)) {
            $key = self::parse($key);
        }

        // copy from object
        if ($key instanceof Crypt_GPG_SubKey) {
            $this->_id             = $key->_id;
            $this->_algorithm      = $key->_algorithm;
            $this->_fingerprint    = $key->_fingerprint;
            $this->_length         = $key->_length;
            $this->_creationDate   = $key->_creationDate;
            $this->_expirationDate = $key->_expirationDate;
            $this->_usage          = $key->_usage;
            $this->_hasPrivate     = $key->_hasPrivate;
            $this->_isRevoked      = $key->_isRevoked;
        }

        // initialize from array
        if (is_array($key)) {
            if (array_key_exists('id', $key)) {
                $this->setId($key['id']);
            }

            if (array_key_exists('algorithm', $key)) {
                $this->setAlgorithm($key['algorithm']);
            }

            if (array_key_exists('fingerprint', $key)) {
                $this->setFingerprint($key['fingerprint']);
            }

            if (array_key_exists('length', $key)) {
                $this->setLength($key['length']);
            }

            if (array_key_exists('creation', $key)) {
                $this->setCreationDate($key['creation']);
            }

            if (array_key_exists('expiration', $key)) {
                $this->setExpirationDate($key['expiration']);
            }

            if (array_key_exists('usage', $key)) {
                $this->setUsage($key['usage']);
            }

            if (array_key_exists('canSign', $key)) {
                $this->setCanSign($key['canSign']);
            }

            if (array_key_exists('canEncrypt', $key)) {
                $this->setCanEncrypt($key['canEncrypt']);
            }

            if (array_key_exists('hasPrivate', $key)) {
                $this->setHasPrivate($key['hasPrivate']);
            }

            if (array_key_exists('isRevoked', $key)) {
                $this->setRevoked($key['isRevoked']);
            }
        }
    }

    /**
     * Gets the id of this sub-key
     *
     * @return string The id of this sub-key.
     */
    public function getId()
    {
        return $this->_id;
    }

    /**
     * Gets the algorithm used by this sub-key
     *
     * The algorithm should be one of the Crypt_GPG_SubKey::ALGORITHM_*
     * constants.
     *
     * @return int The algorithm used by this sub-key.
     */
    public function getAlgorithm()
    {
        return $this->_algorithm;
    }

    /**
     * Gets the creation date of this sub-key
     *
     * This is a Unix timestamp. Warning: On 32-bit systems it returns
     * invalid value for dates after 2038-01-19. Use getCreationDateTime().
     *
     * @return int The creation date of this sub-key.
     */
    public function getCreationDate()
    {
        return $this->_creationDate ? (int) $this->_creationDate->format('U') : 0;
    }

    /**
     * Gets the creation date-time (UTC) of this sub-key
     *
     * @return DateTime|null The creation date of this sub-key.
     */
    public function getCreationDateTime()
    {
        return $this->_creationDate ? $this->_creationDate : null;
    }

    /**
     * Gets the date this sub-key expires
     *
     * This is a Unix timestamp. If this sub-key does not expire, this will be
     * zero. Warning: On 32-bit systems it returns invalid value for dates
     * after 2038-01-19. Use getExpirationDateTime().
     *
     * @return int The date this sub-key expires.
     */
    public function getExpirationDate()
    {
        return $this->_expirationDate ? (int) $this->_expirationDate->format('U') : 0;
    }

    /**
     * Gets the date-time (UTC) this sub-key expires
     *
     * @return DateTime|null The date this sub-key expires.
     */
    public function getExpirationDateTime()
    {
        return $this->_expirationDate ? $this->_expirationDate : null;
    }

    /**
     * Gets the fingerprint of this sub-key
     *
     * @return string The fingerprint of this sub-key.
     */
    public function getFingerprint()
    {
        return $this->_fingerprint;
    }

    /**
     * Gets the length of this sub-key in bits
     *
     * @return int The length of this sub-key in bits.
     */
    public function getLength()
    {
        return $this->_length;
    }

    /**
     * Gets whether or not this sub-key can sign data
     *
     * @return bool True if this sub-key can sign data and false if this
     *              sub-key can not sign data.
     */
    public function canSign()
    {
        return ($this->_usage & self::USAGE_SIGN) != 0;
    }

    /**
     * Gets whether or not this sub-key can encrypt data
     *
     * @return bool True if this sub-key can encrypt data and false if this
     *              sub-key can not encrypt data.
     */
    public function canEncrypt()
    {
        return ($this->_usage & self::USAGE_ENCRYPT) != 0;
    }

    /**
     * Gets usage flags of this sub-key
     *
     * @return int Sum of usage flags
     */
    public function usage()
    {
        return $this->_usage;
    }

    /**
     * Gets whether or not the private key for this sub-key exists in the
     * keyring
     *
     * @return bool True the private key for this sub-key exists in the
     *              keyring and false if it does not.
     */
    public function hasPrivate()
    {
        return $this->_hasPrivate;
    }

    /**
     * Gets whether or not this sub-key is revoked
     *
     * @return bool True if this sub-key is revoked and false if it is not.
     */
    public function isRevoked()
    {
        return $this->_isRevoked;
    }

    /**
     * Sets the creation date of this sub-key
     *
     * The creation date is a Unix timestamp or DateTime object.
     *
     * @param int|DateTime $creationDate The creation date of this sub-key.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setCreationDate($creationDate)
    {
        if (empty($creationDate)) {
            $this->_creationDate = null;
            return $this;
        }

        if ($creationDate instanceof DateTime) {
            $this->_creationDate = $creationDate;
        } else {
            $tz = new DateTimeZone('UTC');
            $this->_creationDate = new DateTime("@$creationDate", $tz);
        }

        return $this;
    }

    /**
     * Sets the expiration date of this sub-key
     *
     * The expiration date is a Unix timestamp. Specify zero if this sub-key
     * does not expire.
     *
     * @param int|DateTime $expirationDate The expiration date of this sub-key.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setExpirationDate($expirationDate)
    {
        if (empty($expirationDate)) {
            $this->_expirationDate = null;
            return $this;
        }

        if ($expirationDate instanceof DateTime) {
            $this->_expirationDate = $expirationDate;
        } else {
            $tz = new DateTimeZone('UTC');
            $this->_expirationDate = new DateTime("@$expirationDate", $tz);
        }

        return $this;
    }

    /**
     * Sets the id of this sub-key
     *
     * @param string $id The id of this sub-key.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setId($id)
    {
        $this->_id = strval($id);
        return $this;
    }

    /**
     * Sets the algorithm used by this sub-key
     *
     * @param int $algorithm The algorithm used by this sub-key.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setAlgorithm($algorithm)
    {
        $this->_algorithm = intval($algorithm);
        return $this;
    }

    /**
     * Sets the fingerprint of this sub-key
     *
     * @param string $fingerprint The fingerprint of this sub-key.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setFingerprint($fingerprint)
    {
        $this->_fingerprint = strval($fingerprint);
        return $this;
    }

    /**
     * Sets the length of this sub-key in bits
     *
     * @param int $length The length of this sub-key in bits.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setLength($length)
    {
        $this->_length = intval($length);
        return $this;
    }

    /**
     * Sets whether or not this sub-key can sign data
     *
     * @param bool $canSign True if this sub-key can sign data and false if
     *                      it can not.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setCanSign($canSign)
    {
        if ($canSign) {
            $this->_usage |= self::USAGE_SIGN;
        } else {
            $this->_usage &= ~self::USAGE_SIGN;
        }

        return $this;
    }

    /**
     * Sets whether or not this sub-key can encrypt data
     *
     * @param bool $canEncrypt True if this sub-key can encrypt data and
     *                         false if it can not.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setCanEncrypt($canEncrypt)
    {
        if ($canEncrypt) {
            $this->_usage |= self::USAGE_ENCRYPT;
        } else {
            $this->_usage &= ~self::USAGE_ENCRYPT;
        }

        return $this;
    }

    /**
     * Sets usage flags of the sub-key
     *
     * @param int $usage Usage flags
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setUsage($usage)
    {
        $this->_usage = (int) $usage;
        return $this;
    }

    /**
     * Sets whether of not the private key for this sub-key exists in the
     * keyring
     *
     * @param bool $hasPrivate True if the private key for this sub-key
     *                         exists in the keyring and false if it does
     *                         not.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setHasPrivate($hasPrivate)
    {
        $this->_hasPrivate = ($hasPrivate) ? true : false;
        return $this;
    }

    /**
     * Sets whether or not this sub-key is revoked
     *
     * @param bool $isRevoked Whether or not this sub-key is revoked.
     *
     * @return Crypt_GPG_SubKey The current object, for fluent interface.
     */
    public function setRevoked($isRevoked)
    {
        $this->_isRevoked = ($isRevoked) ? true : false;
        return $this;
    }

    /**
     * Parses a sub-key object from a sub-key string
     *
     * See <b>doc/DETAILS</b> in the
     * {@link http://www.gnupg.org/download/ GPG distribution} for information
     * on how the sub-key string is parsed.
     *
     * @param string $string The string containing the sub-key.
     *
     * @return Crypt_GPG_SubKey The sub-key object parsed from the string.
     */
    public static function parse($string)
    {
        $tokens = explode(':', $string);

        $subKey = new Crypt_GPG_SubKey();

        $subKey->setId($tokens[4]);
        $subKey->setLength($tokens[2]);
        $subKey->setAlgorithm($tokens[3]);
        $subKey->setCreationDate(self::_parseDate($tokens[5]));
        $subKey->setExpirationDate(self::_parseDate($tokens[6]));

        if ($tokens[1] == 'r') {
            $subKey->setRevoked(true);
        }

        $usage = 0;
        $usage_map = array(
            'a' => self::USAGE_AUTHENTICATION,
            'c' => self::USAGE_CERTIFY,
            'e' => self::USAGE_ENCRYPT,
            's' => self::USAGE_SIGN,
        );

        foreach ($usage_map as $key => $flag) {
            if (strpos($tokens[11], $key) !== false) {
                $usage |= $flag;
            }
        }

        $subKey->setUsage($usage);

        return $subKey;
    }

    /**
     * Parses a date string as provided by GPG into a UNIX timestamp
     *
     * @param string $string The date string.
     *
     * @return DateTime|null The date corresponding to the provided date string.
     */
    private static function _parseDate($string)
    {
        if (empty($string)) {
            return null;
        }

        // all times are in UTC according to GPG documentation
        $timeZone = new DateTimeZone('UTC');

        if (strpos($string, 'T') === false) {
            // interpret as UNIX timestamp
            $string = '@' . $string;
        }

        return new DateTime($string, $timeZone);
    }
}
