Project import generated by Copybara.
GitOrigin-RevId: 63746295f1a5ab5a619056791995793d65529e62
diff --git a/src/lib/WebAuthn/Attestation/Format/Tpm.php b/src/lib/WebAuthn/Attestation/Format/Tpm.php
new file mode 100644
index 0000000..338cd45
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/Tpm.php
@@ -0,0 +1,180 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class Tpm extends FormatBase {
+ private $_TPM_GENERATED_VALUE = "\xFF\x54\x43\x47";
+ private $_TPM_ST_ATTEST_CERTIFY = "\x80\x17";
+ private $_alg;
+ private $_signature;
+ private $_pubArea;
+ private $_x5c;
+
+ /**
+ * @var ByteBuffer
+ */
+ private $_certInfo;
+
+
+ public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+ parent::__construct($AttestionObject, $authenticatorData);
+
+ // check packed data
+ $attStmt = $this->_attestationObject['attStmt'];
+
+ if (!\array_key_exists('ver', $attStmt) || $attStmt['ver'] !== '2.0') {
+ throw new WebAuthnException('invalid tpm version: ' . $attStmt['ver'], WebAuthnException::INVALID_DATA);
+ }
+
+ if (!\array_key_exists('alg', $attStmt) || $this->_getCoseAlgorithm($attStmt['alg']) === null) {
+ throw new WebAuthnException('unsupported alg: ' . $attStmt['alg'], WebAuthnException::INVALID_DATA);
+ }
+
+ if (!\array_key_exists('sig', $attStmt) || !\is_object($attStmt['sig']) || !($attStmt['sig'] instanceof ByteBuffer)) {
+ throw new WebAuthnException('signature not found', WebAuthnException::INVALID_DATA);
+ }
+
+ if (!\array_key_exists('certInfo', $attStmt) || !\is_object($attStmt['certInfo']) || !($attStmt['certInfo'] instanceof ByteBuffer)) {
+ throw new WebAuthnException('certInfo not found', WebAuthnException::INVALID_DATA);
+ }
+
+ if (!\array_key_exists('pubArea', $attStmt) || !\is_object($attStmt['pubArea']) || !($attStmt['pubArea'] instanceof ByteBuffer)) {
+ throw new WebAuthnException('pubArea not found', WebAuthnException::INVALID_DATA);
+ }
+
+ $this->_alg = $attStmt['alg'];
+ $this->_signature = $attStmt['sig']->getBinaryString();
+ $this->_certInfo = $attStmt['certInfo'];
+ $this->_pubArea = $attStmt['pubArea'];
+
+ // certificate for validation
+ if (\array_key_exists('x5c', $attStmt) && \is_array($attStmt['x5c']) && \count($attStmt['x5c']) > 0) {
+
+ // The attestation certificate attestnCert MUST be the first element in the array
+ $attestnCert = array_shift($attStmt['x5c']);
+
+ if (!($attestnCert instanceof ByteBuffer)) {
+ throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
+ }
+
+ $this->_x5c = $attestnCert->getBinaryString();
+
+ // certificate chain
+ foreach ($attStmt['x5c'] as $chain) {
+ if ($chain instanceof ByteBuffer) {
+ $this->_x5c_chain[] = $chain->getBinaryString();
+ }
+ }
+
+ } else {
+ throw new WebAuthnException('no x5c certificate found', WebAuthnException::INVALID_DATA);
+ }
+ }
+
+
+ /*
+ * returns the key certificate in PEM format
+ * @return string|null
+ */
+ public function getCertificatePem() {
+ if (!$this->_x5c) {
+ return null;
+ }
+ return $this->_createCertificatePem($this->_x5c);
+ }
+
+ /**
+ * @param string $clientDataHash
+ */
+ public function validateAttestation($clientDataHash) {
+ return $this->_validateOverX5c($clientDataHash);
+ }
+
+ /**
+ * validates the certificate against root certificates
+ * @param array $rootCas
+ * @return boolean
+ * @throws WebAuthnException
+ */
+ public function validateRootCertificate($rootCas) {
+ if (!$this->_x5c) {
+ return false;
+ }
+
+ $chainC = $this->_createX5cChainFile();
+ if ($chainC) {
+ $rootCas[] = $chainC;
+ }
+
+ $v = \openssl_x509_checkpurpose($this->getCertificatePem(), -1, $rootCas);
+ if ($v === -1) {
+ throw new WebAuthnException('error on validating root certificate: ' . \openssl_error_string(), WebAuthnException::CERTIFICATE_NOT_TRUSTED);
+ }
+ return $v;
+ }
+
+ /**
+ * validate if x5c is present
+ * @param string $clientDataHash
+ * @return bool
+ * @throws WebAuthnException
+ */
+ protected function _validateOverX5c($clientDataHash) {
+ $publicKey = \openssl_pkey_get_public($this->getCertificatePem());
+
+ if ($publicKey === false) {
+ throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY);
+ }
+
+ // Concatenate authenticatorData and clientDataHash to form attToBeSigned.
+ $attToBeSigned = $this->_authenticatorData->getBinary();
+ $attToBeSigned .= $clientDataHash;
+
+ // Validate that certInfo is valid:
+
+ // Verify that magic is set to TPM_GENERATED_VALUE.
+ if ($this->_certInfo->getBytes(0, 4) !== $this->_TPM_GENERATED_VALUE) {
+ throw new WebAuthnException('tpm magic not TPM_GENERATED_VALUE', WebAuthnException::INVALID_DATA);
+ }
+
+ // Verify that type is set to TPM_ST_ATTEST_CERTIFY.
+ if ($this->_certInfo->getBytes(4, 2) !== $this->_TPM_ST_ATTEST_CERTIFY) {
+ throw new WebAuthnException('tpm type not TPM_ST_ATTEST_CERTIFY', WebAuthnException::INVALID_DATA);
+ }
+
+ $offset = 6;
+ $qualifiedSigner = $this->_tpmReadLengthPrefixed($this->_certInfo, $offset);
+ $extraData = $this->_tpmReadLengthPrefixed($this->_certInfo, $offset);
+ $coseAlg = $this->_getCoseAlgorithm($this->_alg);
+
+ // Verify that extraData is set to the hash of attToBeSigned using the hash algorithm employed in "alg".
+ if ($extraData->getBinaryString() !== \hash($coseAlg->hash, $attToBeSigned, true)) {
+ throw new WebAuthnException('certInfo:extraData not hash of attToBeSigned', WebAuthnException::INVALID_DATA);
+ }
+
+ // Verify the sig is a valid signature over certInfo using the attestation
+ // public key in aikCert with the algorithm specified in alg.
+ return \openssl_verify($this->_certInfo->getBinaryString(), $this->_signature, $publicKey, $coseAlg->openssl) === 1;
+ }
+
+
+ /**
+ * returns next part of ByteBuffer
+ * @param ByteBuffer $buffer
+ * @param int $offset
+ * @return ByteBuffer
+ */
+ protected function _tpmReadLengthPrefixed(ByteBuffer $buffer, &$offset) {
+ $len = $buffer->getUint16Val($offset);
+ $data = $buffer->getBytes($offset + 2, $len);
+ $offset += (2 + $len);
+
+ return new ByteBuffer($data);
+ }
+
+}
+