OQS Wrapper Extension

A minimal PHP extension wrapping liboqs KEM and signature APIs into a namespaced API suitable for the SecuDoc stack. The runtime namespace, configure flag, and module name are OQS (extension: oqs.so).

Note on naming: NIST standardized Kyber as ML-KEM (FIPS 203). liboqs exposes both names (Kyber{512,768,1024} and ML-KEM-{512,768,1024}) depending on build options. This extension accepts whatever your liboqs provides.

Once PHP natively supports PQC, this wrapper will likely be deprecated.

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API

KEM

OQS\KEM exposes post-quantum key encapsulation:

• OQS\KEM::algorithms(): string[] — list enabled KEM identifiers.
• OQS\KEM::keypair(string $algorithm): array{0: string $publicKey, 1: string $secretKey}
• OQS\KEM::encapsulate(string $algorithm, string $publicKey): array{0: string $ciphertext, 1: string $sharedSecret}
• OQS\KEM::decapsulate(string $algorithm, string $ciphertext, string $secretKey): string

All algorithm identifiers surfaced by liboqs are also available as class constants, e.g. OQS\KEM::ALG_KYBER768 and/or OQS\KEM::ALG_ML_KEM_768 (depending on your liboqs build).

Binary outputs: All keys, ciphertexts, and shared secrets are raw binary strings. Base64-encode if you need printable or JSON-safe values.

Signatures

OQS\Signature wraps stateless PQ signatures:

• OQS\Signature::algorithms(): string[]
• OQS\Signature::keypair(string $algorithm): array{0: string $publicKey, 1: string $secretKey}
• OQS\Signature::sign(string $algorithm, string $message, string $secretKey): string
• OQS\Signature::verify(string $algorithm, string $message, string $signature, string $publicKey): bool

Signature identifiers are also class constants, e.g. OQS\Signature::ALG_DILITHIUM_3.

Global namespace constants (e.g. OQS\VERSION_TEXT) mirror liboqs build info.

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Quick start (usage)

<?php
use OQS\KEM;

// Pick an algorithm supported by your liboqs build:
$alg = defined('OQS\\KEM::ALG_ML_KEM_768') ? OQS\KEM::ALG_ML_KEM_768 : OQS\KEM::ALG_KYBER768;

[$pk, $sk] = KEM::keypair($alg);
[$ct, $ss1] = KEM::encapsulate($alg, $pk);
$ss2 = KEM::decapsulate($alg, $ct, $sk);

assert(hash_equals($ss1, $ss2));

// If you need text-safe values:
echo base64_encode($ct), "\n", base64_encode($ss1), "\n";

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Installing liboqs

Before building this PHP extension, you need the liboqs C library and headers installed on your system.
You can either build it from source or install it via a package manager if available.

Build from source (recommended)

git clone https://github.com/open-quantum-safe/liboqs.git
cd liboqs
mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX=/usr/local -DOQS_BUILD_ONLY_LIB=ON ..
make -j$(nproc)
sudo make install

This installs liboqs.so to /usr/local/lib and headers to /usr/local/include/oqs.

Verify installation

pkg-config --modversion liboqs
# should report 0.14.0 or newer

Then proceed with the build steps below.

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Requirements

• PHP dev tools (phpize, php-config, headers)
• liboqs 0.14.0 or newer (headers under include/oqs, libs under lib)
• A compiler toolchain (gcc/clang, make, autoconf)

Check your liboqs version:

pkg-config --modversion liboqs
# or:
grep -E 'OQS_VERSION_(TEXT|MAJOR|MINOR|PATCH)' /usr/local/include/oqs/oqsconfig.h

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Build & install

Using pkg-config (recommended)

/php/bin/phpize
./configure --with-php-config=/php/bin/php-config
make -j$(nproc)
sudo make install
echo "extension=oqs.so" | sudo tee /etc/php/<ver>/mods-available/oqs.ini
sudo phpenmod oqs
php -m | grep oqs

Using an explicit liboqs prefix

If liboqs isn’t in pkg-config, pass the prefix that contains include/oqs and lib/:

/php/php-8.4/bin/phpize
./configure --with-php-config=/php/php-8.4/bin/php-config --with-oqs=/usr/local
make -j$(nproc) && sudo make install

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Troubleshooting

• liboqs 0.14.0 or newer is required
  Ensure pkg-config finds liboqs ≥ 0.14.0 (pkg-config --modversion liboqs) or your --with-oqs prefix points to headers with oqs/oqsconfig.h reporting ≥ 0.14.0.

• oqs.h not found
  Your --with-oqs=/prefix must contain /prefix/include/oqs/oqs.h and /prefix/lib/liboqs.*.

• Runtime loader can’t find liboqs.so
  Either install liboqs to a standard location (e.g. /usr/local) or set:

  export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH    # Linux
  export DYLD_LIBRARY_PATH=/usr/local/lib:$DYLD_LIBRARY_PATH # macOS (disable SIP for non-system paths)

• Which algorithms are enabled?

  print_r(OQS\KEM::algorithms());
  print_r(OQS\Signature::algorithms());

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Notes

• Algorithms and sizes are defined by liboqs at build time. If an identifier isn’t present in OQS\KEM::algorithms(), your liboqs was built without it.
• Thread safety: the extension itself is stateless; use a thread-safe PHP build (ZTS) if your SAPI requires it.

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Disclaimer

This extension is provided as-is without any warranty. It is intended for experimentation, prototyping, and research purposes only. Do not use this software in production environments that require certified or audited cryptographic implementations. The liboqs library itself is not a FIPS-validated module, and the PHP wrapper has not been security reviewed. Use entirely at your own risk.