375 lines
16 KiB
Markdown
375 lines
16 KiB
Markdown
# Sodium Compat
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[](https://github.com/paragonie/sodium_compat/actions)
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[](https://github.com/paragonie/sodium_compat/actions)
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[](https://ci.appveyor.com/project/paragonie-scott/sodium-compat)
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[](https://packagist.org/packages/paragonie/sodium_compat)
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[](https://packagist.org/packages/paragonie/sodium_compat)
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[](https://packagist.org/packages/paragonie/sodium_compat)
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[](https://packagist.org/packages/paragonie/sodium_compat)
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Sodium Compat is a pure PHP polyfill for the Sodium cryptography library
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(libsodium), a core extension in PHP 7.2.0+ and otherwise [available in PECL](https://pecl.php.net/package/libsodium).
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This library tentatively supports PHP 5.2.4 - 8.x (latest), but officially
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only supports [non-EOL'd versions of PHP](https://secure.php.net/supported-versions.php).
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If you have the PHP extension installed, Sodium Compat will opportunistically
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and transparently use the PHP extension instead of our implementation.
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## IMPORTANT!
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This cryptography library has not been formally audited by an independent third
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party that specializes in cryptography or cryptanalysis.
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If you require such an audit before you can use sodium_compat in your projects
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and have the funds for such an audit, please open an issue or contact
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`security at paragonie dot com` so we can help get the ball rolling.
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However, sodium_compat has been adopted by high profile open source projects,
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such as [Joomla!](https://github.com/joomla/joomla-cms/blob/459d74686d2a638ec51149d7c44ddab8075852be/composer.json#L40)
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and [Magento](https://github.com/magento/magento2/blob/8fd89cfdf52c561ac0ca7bc20fd38ef688e201b0/composer.json#L44).
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Furthermore, sodium_compat was developed by Paragon Initiative Enterprises, a
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company that *specializes* in secure PHP development and PHP cryptography, and
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has been informally reviewed by many other security experts who also specialize
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in PHP.
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If you'd like to learn more about the defensive security measures we've taken
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to prevent sodium_compat from being a source of vulnerability in your systems,
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please read [*Cryptographically Secure PHP Development*](https://paragonie.com/blog/2017/02/cryptographically-secure-php-development).
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# Installing Sodium Compat
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If you're using Composer:
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```bash
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composer require paragonie/sodium_compat
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```
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### Install From Source
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If you're not using Composer, download a [release tarball](https://github.com/paragonie/sodium_compat/releases)
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(which should be signed with [our GnuPG public key](https://paragonie.com/static/gpg-public-key.txt)), extract
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its contents, then include our `autoload.php` script in your project.
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```php
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<?php
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require_once "/path/to/sodium_compat/autoload.php";
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```
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### PHP Archives (Phar) Releases
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Since version 1.3.0, [sodium_compat releases](https://github.com/paragonie/sodium_compat/releases) include a
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PHP Archive (.phar file) and associated GPG signature. First, download both files and verify them with our
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GPG public key, like so:
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```bash
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# Getting our public key from the keyserver:
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gpg --fingerprint 7F52D5C61D1255C731362E826B97A1C2826404DA
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if [ $? -ne 0 ]; then
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echo -e "\033[33mDownloading PGP Public Key...\033[0m"
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gpg --keyserver pgp.mit.edu --recv-keys 7F52D5C61D1255C731362E826B97A1C2826404DA
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# Security <security@paragonie.com>
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gpg --fingerprint 7F52D5C61D1255C731362E826B97A1C2826404DA
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if [ $? -ne 0 ]; then
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echo -e "\033[31mCould not download PGP public key for verification\033[0m"
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exit 1
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fi
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fi
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# Verifying the PHP Archive
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gpg --verify sodium-compat.phar.sig sodium-compat.phar
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```
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Now, simply include this .phar file in your application.
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```php
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<?php
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require_once "/path/to/sodium-compat.phar";
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```
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# Support
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[Commercial support for libsodium](https://download.libsodium.org/doc/commercial_support/) is available
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from multiple vendors. If you need help using sodium_compat in one of your projects, [contact Paragon Initiative Enterprises](https://paragonie.com/contact).
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Non-commercial report will be facilitated through [Github issues](https://github.com/paragonie/sodium_compat/issues).
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We offer no guarantees of our availability to resolve questions about integrating sodium_compat into third-party
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software for free, but will strive to fix any bugs (security-related or otherwise) in our library.
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## Support Contracts
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If your company uses this library in their products or services, you may be
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interested in [purchasing a support contract from Paragon Initiative Enterprises](https://paragonie.com/enterprise).
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# Using Sodium Compat
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## True Polyfill
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As per the [second vote on the libsodium RFC](https://wiki.php.net/rfc/libsodium#proposed_voting_choices),
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PHP 7.2 uses `sodium_*` instead of `\Sodium\*`.
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```php
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<?php
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require_once "/path/to/sodium_compat/autoload.php";
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$alice_kp = sodium_crypto_sign_keypair();
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$alice_sk = sodium_crypto_sign_secretkey($alice_kp);
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$alice_pk = sodium_crypto_sign_publickey($alice_kp);
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$message = 'This is a test message.';
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$signature = sodium_crypto_sign_detached($message, $alice_sk);
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if (sodium_crypto_sign_verify_detached($signature, $message, $alice_pk)) {
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echo 'OK', PHP_EOL;
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} else {
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throw new Exception('Invalid signature');
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}
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```
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## Polyfill For the Old PECL Extension API
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If you're using PHP 5.3.0 or newer and do not have the PECL extension installed,
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you can just use the [standard ext/sodium API features as-is](https://paragonie.com/book/pecl-libsodium)
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and the polyfill will work its magic.
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```php
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<?php
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require_once "/path/to/sodium_compat/autoload.php";
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$alice_kp = \Sodium\crypto_sign_keypair();
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$alice_sk = \Sodium\crypto_sign_secretkey($alice_kp);
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$alice_pk = \Sodium\crypto_sign_publickey($alice_kp);
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$message = 'This is a test message.';
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$signature = \Sodium\crypto_sign_detached($message, $alice_sk);
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if (\Sodium\crypto_sign_verify_detached($signature, $message, $alice_pk)) {
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echo 'OK', PHP_EOL;
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} else {
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throw new Exception('Invalid signature');
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}
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```
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The polyfill does not expose this API on PHP < 5.3, or if you have the PHP
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extension installed already.
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## General-Use Polyfill
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If your users are on PHP < 5.3, or you want to write code that will work
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whether or not the PECL extension is available, you'll want to use the
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**`ParagonIE_Sodium_Compat`** class for most of your libsodium needs.
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The above example, written for general use:
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```php
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<?php
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require_once "/path/to/sodium_compat/autoload.php";
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$alice_kp = ParagonIE_Sodium_Compat::crypto_sign_keypair();
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$alice_sk = ParagonIE_Sodium_Compat::crypto_sign_secretkey($alice_kp);
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$alice_pk = ParagonIE_Sodium_Compat::crypto_sign_publickey($alice_kp);
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$message = 'This is a test message.';
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$signature = ParagonIE_Sodium_Compat::crypto_sign_detached($message, $alice_sk);
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if (ParagonIE_Sodium_Compat::crypto_sign_verify_detached($signature, $message, $alice_pk)) {
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echo 'OK', PHP_EOL;
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} else {
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throw new Exception('Invalid signature');
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}
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```
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Generally: If you replace `\Sodium\ ` with `ParagonIE_Sodium_Compat::`, any
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code already written for the libsodium PHP extension should work with our
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polyfill without additional code changes.
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Since this doesn't require a namespace, this API *is* exposed on PHP 5.2.
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Since version 0.7.0, we have our own namespaced API (`ParagonIE\Sodium\*`) to allow brevity
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in software that uses PHP 5.3+. This is useful if you want to use our file cryptography
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features without writing `ParagonIE_Sodium_File` every time. This is not exposed on PHP < 5.3,
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so if your project supports PHP < 5.3, use the underscore method instead.
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To learn how to use Libsodium, read [*Using Libsodium in PHP Projects*](https://paragonie.com/book/pecl-libsodium).
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## Help, Sodium_Compat is Slow! How can I make it fast?
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There are three ways to make it fast:
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1. Use a newer version of PHP (at least 7.2).
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2. [Install the libsodium PHP extension from PECL](https://paragonie.com/book/pecl-libsodium/read/00-intro.md#installing-libsodium).
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3. Only if the previous two options are not available for you:
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1. Verify that [the processor you're using actually implements constant-time multiplication](https://bearssl.org/ctmul.html).
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Sodium_compat does, but it must trade some speed in order to attain cross-platform security.
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2. Only if you are 100% certain that your processor is safe, you can set `ParagonIE_Sodium_Compat::$fastMult = true;`
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without harming the security of your cryptography keys. If your processor *isn't* safe, then decide whether you
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want speed or security because you can't have both.
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### How can I tell if sodium_compat will be slow, at runtime?
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Since version 1.8, you can use the `polyfill_is_fast()` static method to
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determine if sodium_compat will be slow at runtime.
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```php
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<?php
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if (ParagonIE_Sodium_Compat::polyfill_is_fast()) {
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// Use libsodium now
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$process->execute();
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} else {
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// Defer to a cron job or other sort of asynchronous process
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$process->enqueue();
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}
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```
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### Help, my PHP only has 32-Bit Integers! It's super slow!
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If the `PHP_INT_SIZE` constant equals `4` instead of `8` (PHP 5 on Windows,
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Linux on i386, etc.), you will run into **significant performance issues**.
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In particular: public-key cryptography (encryption and signatures)
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is affected. There is nothing we can do about that.
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The root cause of these performance issues has to do with implementing cryptography
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algorithms in constant-time using 16-bit limbs (to avoid overflow) in pure PHP.
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To mitigate these performance issues, simply install PHP 7.2 or newer and enable
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the `sodium` extension.
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Affected users are encouraged to install the sodium extension (or libsodium from
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older version of PHP).
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Windows users on PHP 5 may be able to simply upgrade to PHP 7 and the slowdown
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will be greatly reduced.
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## Documentation
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First, you'll want to read the [Libsodium Quick Reference](https://paragonie.com/blog/2017/06/libsodium-quick-reference-quick-comparison-similar-functions-and-which-one-use).
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It aims to answer, "Which function should I use for [common problem]?".
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If you don't find the answers in the Quick Reference page, check out
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[*Using Libsodium in PHP Projects*](https://paragonie.com/book/pecl-libsodium).
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Finally, the [official libsodium documentation](https://download.libsodium.org/doc/)
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(which was written for the C library, not the PHP library) also contains a lot of
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insightful technical information you may find helpful.
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## API Coverage
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**Recommended reading:** [Libsodium Quick Reference](https://paragonie.com/blog/2017/06/libsodium-quick-reference-quick-comparison-similar-functions-and-which-one-use)
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* Mainline NaCl Features
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* `crypto_auth()`
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* `crypto_auth_verify()`
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* `crypto_box()`
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* `crypto_box_open()`
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* `crypto_scalarmult()`
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* `crypto_secretbox()`
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* `crypto_secretbox_open()`
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* `crypto_sign()`
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* `crypto_sign_open()`
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* PECL Libsodium Features
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* `crypto_aead_aes256gcm_encrypt()`
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* `crypto_aead_aes256gcm_decrypt()`
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* `crypto_aead_chacha20poly1305_encrypt()`
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* `crypto_aead_chacha20poly1305_decrypt()`
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* `crypto_aead_chacha20poly1305_ietf_encrypt()`
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* `crypto_aead_chacha20poly1305_ietf_decrypt()`
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* `crypto_aead_xchacha20poly1305_ietf_encrypt()`
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* `crypto_aead_xchacha20poly1305_ietf_decrypt()`
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* `crypto_box_xchacha20poly1305()`
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* `crypto_box_xchacha20poly1305_open()`
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* `crypto_box_seal()`
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* `crypto_box_seal_open()`
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* `crypto_generichash()`
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* `crypto_generichash_init()`
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* `crypto_generichash_update()`
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* `crypto_generichash_final()`
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* `crypto_kx()`
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* `crypto_secretbox_xchacha20poly1305()`
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* `crypto_secretbox_xchacha20poly1305_open()`
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* `crypto_shorthash()`
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* `crypto_sign_detached()`
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* `crypto_sign_ed25519_pk_to_curve25519()`
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* `crypto_sign_ed25519_sk_to_curve25519()`
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* `crypto_sign_verify_detached()`
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* For advanced users only:
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* `crypto_core_ristretto255_add()`
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* `crypto_core_ristretto255_from_hash()`
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* `crypto_core_ristretto255_is_valid_point()`
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* `crypto_core_ristretto255_random()`
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* `crypto_core_ristretto255_scalar_add()`
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* `crypto_core_ristretto255_scalar_complement()`
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* `crypto_core_ristretto255_scalar_invert()`
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* `crypto_core_ristretto255_scalar_mul()`
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* `crypto_core_ristretto255_scalar_negate()`
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* `crypto_core_ristretto255_scalar_random()`
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* `crypto_core_ristretto255_scalar_reduce()`
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* `crypto_core_ristretto255_scalar_sub()`
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* `crypto_core_ristretto255_sub()`
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* `crypto_scalarmult_ristretto255_base()`
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* `crypto_scalarmult_ristretto255()`
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* `crypto_stream()`
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* `crypto_stream_keygen()`
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* `crypto_stream_xor()`
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* `crypto_stream_xchacha20()`
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* `crypto_stream_xchacha20_keygen()`
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* `crypto_stream_xchacha20_xor()`
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* `crypto_stream_xchacha20_xor_ic()`
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* Other utilities (e.g. `crypto_*_keypair()`)
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* `add()`
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* `base642bin()`
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* `bin2base64()`
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* `bin2hex()`
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* `hex2bin()`
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* `crypto_kdf_derive_from_key()`
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* `crypto_kx_client_session_keys()`
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* `crypto_kx_server_session_keys()`
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* `crypto_secretstream_xchacha20poly1305_init_push()`
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* `crypto_secretstream_xchacha20poly1305_push()`
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* `crypto_secretstream_xchacha20poly1305_init_pull()`
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* `crypto_secretstream_xchacha20poly1305_pull()`
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* `crypto_secretstream_xchacha20poly1305_rekey()`
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* `pad()`
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* `unpad()`
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### Cryptography Primitives Provided
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* **X25519** - Elliptic Curve Diffie Hellman over Curve25519
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* **Ed25519** - Edwards curve Digital Signature Algorithm over Curve25519
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* **Xsalsa20** - Extended-nonce Salsa20 stream cipher
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* **ChaCha20** - Stream cipher
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* **Xchacha20** - Extended-nonce ChaCha20 stream cipher
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* **Poly1305** - Polynomial Evaluation Message Authentication Code modulo 2^130 - 5
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* **BLAKE2b** - Cryptographic Hash Function
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* **SipHash-2-4** - Fast hash, but not collision-resistant; ideal for hash tables.
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### Features Excluded from this Polyfill
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* `\Sodium\memzero()` - Although we expose this API endpoint, we can't reliably
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zero buffers from PHP.
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If you have the PHP extension installed, sodium_compat
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will use the native implementation to zero out the string provided. Otherwise
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it will throw a `SodiumException`.
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* `\Sodium\crypto_pwhash()` - It's not feasible to polyfill scrypt or Argon2
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into PHP and get reasonable performance. Users would feel motivated to select
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parameters that downgrade security to avoid denial of service (DoS) attacks.
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The only winning move is not to play.
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If ext/sodium or ext/libsodium is installed, these API methods will fallthrough
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to the extension. Otherwise, our polyfill library will throw a `SodiumException`.
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To detect support for Argon2i at runtime, use
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`ParagonIE_Sodium_Compat::crypto_pwhash_is_available()`, which returns a
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boolean value (`TRUE` or `FALSE`).
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### PHPCompatibility Ruleset
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For sodium_compat users and that utilize [`PHPCompatibility`](https://github.com/PHPCompatibility/PHPCompatibility)
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in their CI process, there is now a custom ruleset available which can be used
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to prevent false positives being thrown by `PHPCompatibility` for the native
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PHP functionality being polyfilled by this repo.
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You can find the repo for the `PHPCompatibilityParagonieSodiumCompat` ruleset
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here [on Github](https://github.com/PHPCompatibility/PHPCompatibilityParagonie)
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and [on Packagist](https://packagist.org/packages/phpcompatibility/phpcompatibility-paragonie).
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