ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_decrypt( string $message = '', string $ad = '', string $nonce = '', string $key = '' ): string

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$messagestringoptional

Default: ''

$adstringoptional

Default: ''

$noncestringoptional

Default: ''

$keystringoptional

Default: ''

Return value

string

Performance profile

How much work a call to ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_decrypt() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reaches the database via ->update().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

72–78

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 84.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

1

1 place in core call this, so the cost is paid more often than your own code shows.

What it touches

• sqldatabase query->update()called directly

What one call costs · 2 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_decrypt() can have, taken from its control-flow graph on PHP 8.5.

Uses · 9

• ParagonIE_Sodium_Core32_Util::strlen()
• ParagonIE_Sodium_Core32_Util::substr()
• ParagonIE_Sodium_Core32_ChaCha20::stream()
• ParagonIE_Sodium_Core32_Poly1305_State::__construct()ParagonIE_Sodium_Core32_Poly1305_State constructor.
• ParagonIE_Sodium_Compat::memzero()It's actually not possible to zero memory buffers in PHP. You need the native library for that.
• ParagonIE_Sodium_Core32_Util::store64_le()
• ParagonIE_Sodium_Core32_Util::verify_16()
• SodiumException::__construct()
• ParagonIE_Sodium_Core32_ChaCha20::streamXorIc()

Used by · 1

• ParagonIE_Sodium_Compat::crypto_aead_chacha20poly1305_decrypt()Authenticated Encryption with Associated Data: Decryption

Source code

View on Trac ↗View on GitHub ↗

71    public static function aead_chacha20poly1305_decrypt(72        $message = '',73        $ad = '',74        $nonce = '',75        $key = ''76    ) {77        /** @var int $len - Length of message (ciphertext + MAC) */78        $len = ParagonIE_Sodium_Core32_Util::strlen($message);79 80        /** @var int  $clen - Length of ciphertext */81        $clen = $len - self::aead_chacha20poly1305_ABYTES;82 83        /** @var int $adlen - Length of associated data */84        $adlen = ParagonIE_Sodium_Core32_Util::strlen($ad);85 86        /** @var string $mac - Message authentication code */87        $mac = ParagonIE_Sodium_Core32_Util::substr(88            $message,89            $clen,90            self::aead_chacha20poly1305_ABYTES91        );92 93        /** @var string $ciphertext - The encrypted message (sans MAC) */94        $ciphertext = ParagonIE_Sodium_Core32_Util::substr($message, 0, $clen);95 96        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */97        $block0 = ParagonIE_Sodium_Core32_ChaCha20::stream(98            32,99            $nonce,100            $key101        );102 103        /* Recalculate the Poly1305 authentication tag (MAC): */104        $state = new ParagonIE_Sodium_Core32_Poly1305_State($block0);105        try {106            ParagonIE_Sodium_Compat::memzero($block0);107        } catch (SodiumException $ex) {108            $block0 = null;109        }110        $state->update($ad);111        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($adlen));112        $state->update($ciphertext);113        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($clen));114        $computed_mac = $state->finish();115 116        /* Compare the given MAC with the recalculated MAC: */117        if (!ParagonIE_Sodium_Core32_Util::verify_16($computed_mac, $mac)) {118            throw new SodiumException('Invalid MAC');119        }120 121        // Here, we know that the MAC is valid, so we decrypt and return the plaintext122        return ParagonIE_Sodium_Core32_ChaCha20::streamXorIc(123            $ciphertext,124            $nonce,125            $key,126            ParagonIE_Sodium_Core32_Util::store64_le(1)127        );128    }

Changelog

Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/sodium_compat/src/Crypto32.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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