php_tomcrypt

PHP bindings for libtomcrypt.

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Why?

I made this extension for two reasons:

• First, I wanted to learn how to write a PHP extension.

• The mcrypt extension was deprecated in PHP 7.0-7.1 and it has been completely removed from PHP 7.2.

  While I agree with the rationale behind that decision (libmcrypt has not been maintained since 2007), I also needed a replacement for some of my own projects. Therefore, I decided to look for a crypto library with:

  • a permissive license (see below)
  • a simple API so that I could easily write bindings for it (I didn't want to have to learn OpenSSL's API for example)
  • relatively good support (eg. widely packaged, receiving updates, etc.)

Installation

POSIX systems (Linux, etc.)

You can install this extension using pear:

wget https://github.com/fpoirotte/tomcrypt/archive/master.tar.gz
tar zxvf master.tar.gz
pear install tomcrypt-master/package.xml

It will also try to add the extension to your php.ini automatically. If it fails to do so, you can enable the extension manually by adding the following line to your php.ini:

extension=tomcrypt.so

Microsoft Windows

Download a pre-built php_tomcrypt.dll from the release page or compile the DLL yourself.

After that, just drop the DLL into you're PHP installation's extension_dir and add the following line of configuration to your php.ini:

extension=php_tomcrypt.dll

Usage

Encryption

Use code such as the following to encrypt some plaintext data:

<?php
    $algo       = TOMCRYPT_CIPHER_RIJNDAEL;
    $mode       = TOMCRYPT_MODE_ECB;
    $plaintext  = "Confidential msg";
    $key        = "some secret key!";
    $ciphertext = tomcrypt_cipher_encrypt($algo, $key, $plaintext, $mode);
?>

The list of supported ciphers for your platform can be obtained through tomcrypt_list_ciphers(). This extension also provides constants which can be used to refer to the various ciphers:

• TOMCRYPT_CIPHER_3DES
• TOMCRYPT_CIPHER_AES
• TOMCRYPT_CIPHER_ANUBIS
• TOMCRYPT_CIPHER_BLOWFISH
• TOMCRYPT_CIPHER_CAMELLIA
• TOMCRYPT_CIPHER_CAST5
• TOMCRYPT_CIPHER_CHACHA
• TOMCRYPT_CIPHER_DES
• TOMCRYPT_CIPHER_KASUMI
• TOMCRYPT_CIPHER_KHAZAD
• TOMCRYPT_CIPHER_MULTI2
• TOMCRYPT_CIPHER_NOEKEON
• TOMCRYPT_CIPHER_RC2
• TOMCRYPT_CIPHER_RC4
• TOMCRYPT_CIPHER_RC5
• TOMCRYPT_CIPHER_RC6
• TOMCRYPT_CIPHER_RIJNDAEL (alias for TOMCRYPT_CIPHER_AES)
• TOMCRYPT_CIPHER_SAFER128 (alias for TOMCRYPT_CIPHER_SAFERSK128)
• TOMCRYPT_CIPHER_SAFER64 (alias for TOMCRYPT_CIPHER_SAFERSK64)
• TOMCRYPT_CIPHER_SAFERK128
• TOMCRYPT_CIPHER_SAFERK64
• TOMCRYPT_CIPHER_SAFERPLUS
• TOMCRYPT_CIPHER_SAFERSK128
• TOMCRYPT_CIPHER_SAFERSK64
• TOMCRYPT_CIPHER_SOBER128
• TOMCRYPT_CIPHER_SEED
• TOMCRYPT_CIPHER_SKIPJACK
• TOMCRYPT_CIPHER_TRIPLEDES (alias for TOMCRYPT_CIPHER_3DES)
• TOMCRYPT_CIPHER_TWOFISH
• TOMCRYPT_CIPHER_XTEA

The list of supported encryption/decryption modes can be retrieved through tomcrypt_list_modes(). The following constants are also provided:

• TOMCRYPT_MODE_CBC
• TOMCRYPT_MODE_CCM
• TOMCRYPT_MODE_CFB
• TOMCRYPT_MODE_CHACHA20POLY1305
• TOMCRYPT_MODE_CTR
• TOMCRYPT_MODE_EAX
• TOMCRYPT_MODE_ECB
• TOMCRYPT_MODE_F8
• TOMCRYPT_MODE_GCM
• TOMCRYPT_MODE_LRW
• TOMCRYPT_MODE_OCB
• TOMCRYPT_MODE_OCB3
• TOMCRYPT_MODE_OFB
• TOMCRYPT_MODE_STREAM
• TOMCRYPT_MODE_XTS

Note

TOMCRYPT_MODE_STREAM only works for stream ciphers (ie. TOMCRYPT_CIPHER_RC4, TOMCRYPT_CIPHER_CHACHA and TOMCRYPT_CIPHER_SOBER128). Likewise, these stream ciphers will not work with other modes.

Decryption

Decryption works pretty much the same way encryption does:

<?php
    $algo       = TOMCRYPT_CIPHER_RIJNDAEL;
    $mode       = TOMCRYPT_MODE_ECB;
    $key        = "some secret key!";
    $plaintext  = tomcrypt_cipher_decrypt($algo, $key, $ciphertext, $mode);
?>

Of course, for decryption to work properly, the same algorithm (cipher), mode and secret key should be used during encryption and decryption.

Hashing

Hashing data can easily be done using the following code:

<?php
    $algo = TOMCRYPT_HASH_SHA256;

    // Returns the hash value for the given data in hexadecimal form
    $hash = tomcrypt_hash_string($algo, $data, false);

    // Returns the hash value for the given data in raw (binary) form
    $hash = tomcrypt_hash_string($algo, $data, true);

    // Returns the hash value for the given file in raw (binary) form
    $hash = tomcrypt_hash_file($algo, "/tmp/file", true);
?>

Use tomcrypt_list_hashes() to get a list of supported hashing algorithms. Like with ciphers, several constants are provided to refer to the various known hashing algorithms:

• TOMCRYPT_HASH_BLAKE2B_160
• TOMCRYPT_HASH_BLAKE2B_256
• TOMCRYPT_HASH_BLAKE2B_384
• TOMCRYPT_HASH_BLAKE2B_512
• TOMCRYPT_HASH_BLAKE2S_128
• TOMCRYPT_HASH_BLAKE2S_160
• TOMCRYPT_HASH_BLAKE2S_224
• TOMCRYPT_HASH_BLAKE2S_256
• TOMCRYPT_HASH_MD2
• TOMCRYPT_HASH_MD4
• TOMCRYPT_HASH_MD5
• TOMCRYPT_HASH_RIPEMD128
• TOMCRYPT_HASH_RIPEMD160
• TOMCRYPT_HASH_RIPEMD256
• TOMCRYPT_HASH_RIPEMD320
• TOMCRYPT_HASH_SHA1
• TOMCRYPT_HASH_SHA224 (alias for TOMCRYPT_HASH_SHA2_224)
• TOMCRYPT_HASH_SHA256 (alias for TOMCRYPT_HASH_SHA2_256)
• TOMCRYPT_HASH_SHA384 (alias for TOMCRYPT_HASH_SHA2_384)
• TOMCRYPT_HASH_SHA512 (alias for TOMCRYPT_HASH_SHA2_512)
• TOMCRYPT_HASH_SHA512_224 (alias for TOMCRYPT_HASH_SHA2_512_224)
• TOMCRYPT_HASH_SHA512_256 (alias for TOMCRYPT_HASH_SHA2_512_256)
• TOMCRYPT_HASH_SHA2_224
• TOMCRYPT_HASH_SHA2_256
• TOMCRYPT_HASH_SHA2_384
• TOMCRYPT_HASH_SHA2_512
• TOMCRYPT_HASH_SHA2_512_224
• TOMCRYPT_HASH_SHA2_512_256
• TOMCRYPT_HASH_SHA3_224
• TOMCRYPT_HASH_SHA3_256
• TOMCRYPT_HASH_SHA3_384
• TOMCRYPT_HASH_SHA3_512
• TOMCRYPT_HASH_TIGER
• TOMCRYPT_HASH_WHIRLPOOL

Message Authentication Codes

Generating a Message Authentication Code (MAC) can be done using the following code:

<?php
    $algo1  = TOMCRYPT_MAC_HMAC;
    $hash   = TOMCRYPT_HASH_SHA1;
    $key    = "my secret key...";
    $data   = "some data here";

    // Returns the HMAC for the given data in hexadecimal form,
    // using the SHA-1 hashing algorithm.
    $hmac   = tomcrypt_mac_string($algo1, $hash, $key, $data, false);

    // Returns the PMAC for the given data in raw (binary) form,
    // using the Rijndael cipher algorithm.
    $algo2  = TOMCRYPT_MAC_PMAC;
    $cipher = TOMCRYPT_CIPHER_RIJNDAEL;
    $pmac   = tomcrypt_mac_string($algo2, $cipher, $key, $data, true);

    // Returns the HMAC for the given file in raw (binary) form,
    // using the SHA-1 hashing algorithm.
    $hmac   = tomcrypt_mac_file($algo1, $hash, $key, "/tmp/file", true);
?>

Use tomcrypt_list_macs() for a list of MAC algorithms supported by your platform. The following constants are also provided:

• TOMCRYPT_MAC_BLAKE2B
• TOMCRYPT_MAC_BLAKE2S
• TOMCRYPT_MAC_CMAC
• TOMCRYPT_MAC_F9
• TOMCRYPT_MAC_HMAC
• TOMCRYPT_MAC_PELICAN
• TOMCRYPT_MAC_PMAC
• TOMCRYPT_MAC_POLY1305
• TOMCRYPT_MAC_XCBC

Most of these MAC algorithms require an additional algorithm to be given:

• TOMCRYPT_MAC_BLAKE2B, TOMCRYPT_MAC_BLAKE2S and TOMCRYPT_MAC_POLY1305: no additional algorithm is necessary (i.e. you may pass null instead of an algorithm)
• TOMCRYPT_MAC_HMAC: some hashing algorithm must be passed
• other MAC algorithms: a cipher must be passed

Please refer to the documentation on Encryption and Hashing for more information about supported algorithms.

(Pseudo-)Random Number Generators

This extension can provide you with data generated at random, as an alternative to openssl_random_pseudo_bytes().

The following code can be used to generate (pseudo-)random number generators:

<?php
    // Attempt to get 42 bytes of purely random data.
    // Returns FALSE if random data cannot be obtained in a secure way.
    $random = tomcrypt_rng_get_bytes(42, TOMCRYPT_RNG_SECURE);
?>

Various algorithms of (pseudo-)random number generators are available:

• TOMCRYPT_RNG_CHACHA20
• TOMCRYPT_RNG_FORTUNA
• TOMCRYPT_RNG_RC4
• TOMCRYPT_RNG_SECURE
• TOMCRYPT_RNG_SOBER128
• TOMCRYPT_RNG_YARROW

Warning

Apart from TOMCRYPT_RNG_SECURE --- which is the default RNG used by tomcrypt_rng_get_bytes(), all the other generators are only PRNGs and should not be used when truly random data is required.

It is also possible to export/import the state of a random number generator (eg. to reseed a PRNG between restarts of the PHP interpreter or to get predictable outputs from the PRNG):

<?php
    $rand0 = tomcrypt_rng_get_bytes(8, TOMCRYPT_RNG_RC4);
    $state = tomcrypt_rng_export(TOMCRYPT_RNG_RC4);

    tomcrypt_rng_import(TOMCRYPT_RNG_RC4, $state);
    $rand1 = tomcrypt_rng_get_bytes(8, TOMCRYPT_RNG_RC4);
    tomcrypt_rng_import(TOMCRYPT_RNG_RC4, $state);
    $rand2 = tomcrypt_rng_get_bytes(8, TOMCRYPT_RNG_RC4);

    var_dump($rand0 == $rand1); // bool(false)
    var_dump($rand1 == $rand2); // bool(true)
?>

Note

Because TOMCRYPT_RNG_SECURE refers to the system's actual random number generator, it is not possible to export/import the state for that generator. Trying to do so will only result in an empty state being exported/imported.

Caveats

The following is a list of currently known problems:

• For the time being, the API for Authenticated Encryption (using the options array to pass the expected tag during decryption) is a bit awkward to work with.
• The context used during encryption/decryption with stream ciphers is reinitialized between each operation, therefore making it unusable in any real streaming scenario.

License

libtomcrypt is released under a dual public domain / WTFPL license.

php_tomcrypt is released under version 3.01 of the PHP license.