Copybara bot | be50d49 | 2023-11-30 00:16:42 +0100 | [diff] [blame^] | 1 | <?php |
| 2 | |
| 3 | |
| 4 | namespace lbuchs\WebAuthn\Attestation\Format; |
| 5 | use lbuchs\WebAuthn\Attestation\AuthenticatorData; |
| 6 | use lbuchs\WebAuthn\WebAuthnException; |
| 7 | use lbuchs\WebAuthn\Binary\ByteBuffer; |
| 8 | |
| 9 | class Tpm extends FormatBase { |
| 10 | private $_TPM_GENERATED_VALUE = "\xFF\x54\x43\x47"; |
| 11 | private $_TPM_ST_ATTEST_CERTIFY = "\x80\x17"; |
| 12 | private $_alg; |
| 13 | private $_signature; |
| 14 | private $_pubArea; |
| 15 | private $_x5c; |
| 16 | |
| 17 | /** |
| 18 | * @var ByteBuffer |
| 19 | */ |
| 20 | private $_certInfo; |
| 21 | |
| 22 | |
| 23 | public function __construct($AttestionObject, AuthenticatorData $authenticatorData) { |
| 24 | parent::__construct($AttestionObject, $authenticatorData); |
| 25 | |
| 26 | // check packed data |
| 27 | $attStmt = $this->_attestationObject['attStmt']; |
| 28 | |
| 29 | if (!\array_key_exists('ver', $attStmt) || $attStmt['ver'] !== '2.0') { |
| 30 | throw new WebAuthnException('invalid tpm version: ' . $attStmt['ver'], WebAuthnException::INVALID_DATA); |
| 31 | } |
| 32 | |
| 33 | if (!\array_key_exists('alg', $attStmt) || $this->_getCoseAlgorithm($attStmt['alg']) === null) { |
| 34 | throw new WebAuthnException('unsupported alg: ' . $attStmt['alg'], WebAuthnException::INVALID_DATA); |
| 35 | } |
| 36 | |
| 37 | if (!\array_key_exists('sig', $attStmt) || !\is_object($attStmt['sig']) || !($attStmt['sig'] instanceof ByteBuffer)) { |
| 38 | throw new WebAuthnException('signature not found', WebAuthnException::INVALID_DATA); |
| 39 | } |
| 40 | |
| 41 | if (!\array_key_exists('certInfo', $attStmt) || !\is_object($attStmt['certInfo']) || !($attStmt['certInfo'] instanceof ByteBuffer)) { |
| 42 | throw new WebAuthnException('certInfo not found', WebAuthnException::INVALID_DATA); |
| 43 | } |
| 44 | |
| 45 | if (!\array_key_exists('pubArea', $attStmt) || !\is_object($attStmt['pubArea']) || !($attStmt['pubArea'] instanceof ByteBuffer)) { |
| 46 | throw new WebAuthnException('pubArea not found', WebAuthnException::INVALID_DATA); |
| 47 | } |
| 48 | |
| 49 | $this->_alg = $attStmt['alg']; |
| 50 | $this->_signature = $attStmt['sig']->getBinaryString(); |
| 51 | $this->_certInfo = $attStmt['certInfo']; |
| 52 | $this->_pubArea = $attStmt['pubArea']; |
| 53 | |
| 54 | // certificate for validation |
| 55 | if (\array_key_exists('x5c', $attStmt) && \is_array($attStmt['x5c']) && \count($attStmt['x5c']) > 0) { |
| 56 | |
| 57 | // The attestation certificate attestnCert MUST be the first element in the array |
| 58 | $attestnCert = array_shift($attStmt['x5c']); |
| 59 | |
| 60 | if (!($attestnCert instanceof ByteBuffer)) { |
| 61 | throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA); |
| 62 | } |
| 63 | |
| 64 | $this->_x5c = $attestnCert->getBinaryString(); |
| 65 | |
| 66 | // certificate chain |
| 67 | foreach ($attStmt['x5c'] as $chain) { |
| 68 | if ($chain instanceof ByteBuffer) { |
| 69 | $this->_x5c_chain[] = $chain->getBinaryString(); |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | } else { |
| 74 | throw new WebAuthnException('no x5c certificate found', WebAuthnException::INVALID_DATA); |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | |
| 79 | /* |
| 80 | * returns the key certificate in PEM format |
| 81 | * @return string|null |
| 82 | */ |
| 83 | public function getCertificatePem() { |
| 84 | if (!$this->_x5c) { |
| 85 | return null; |
| 86 | } |
| 87 | return $this->_createCertificatePem($this->_x5c); |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * @param string $clientDataHash |
| 92 | */ |
| 93 | public function validateAttestation($clientDataHash) { |
| 94 | return $this->_validateOverX5c($clientDataHash); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * validates the certificate against root certificates |
| 99 | * @param array $rootCas |
| 100 | * @return boolean |
| 101 | * @throws WebAuthnException |
| 102 | */ |
| 103 | public function validateRootCertificate($rootCas) { |
| 104 | if (!$this->_x5c) { |
| 105 | return false; |
| 106 | } |
| 107 | |
| 108 | $chainC = $this->_createX5cChainFile(); |
| 109 | if ($chainC) { |
| 110 | $rootCas[] = $chainC; |
| 111 | } |
| 112 | |
| 113 | $v = \openssl_x509_checkpurpose($this->getCertificatePem(), -1, $rootCas); |
| 114 | if ($v === -1) { |
| 115 | throw new WebAuthnException('error on validating root certificate: ' . \openssl_error_string(), WebAuthnException::CERTIFICATE_NOT_TRUSTED); |
| 116 | } |
| 117 | return $v; |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * validate if x5c is present |
| 122 | * @param string $clientDataHash |
| 123 | * @return bool |
| 124 | * @throws WebAuthnException |
| 125 | */ |
| 126 | protected function _validateOverX5c($clientDataHash) { |
| 127 | $publicKey = \openssl_pkey_get_public($this->getCertificatePem()); |
| 128 | |
| 129 | if ($publicKey === false) { |
| 130 | throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY); |
| 131 | } |
| 132 | |
| 133 | // Concatenate authenticatorData and clientDataHash to form attToBeSigned. |
| 134 | $attToBeSigned = $this->_authenticatorData->getBinary(); |
| 135 | $attToBeSigned .= $clientDataHash; |
| 136 | |
| 137 | // Validate that certInfo is valid: |
| 138 | |
| 139 | // Verify that magic is set to TPM_GENERATED_VALUE. |
| 140 | if ($this->_certInfo->getBytes(0, 4) !== $this->_TPM_GENERATED_VALUE) { |
| 141 | throw new WebAuthnException('tpm magic not TPM_GENERATED_VALUE', WebAuthnException::INVALID_DATA); |
| 142 | } |
| 143 | |
| 144 | // Verify that type is set to TPM_ST_ATTEST_CERTIFY. |
| 145 | if ($this->_certInfo->getBytes(4, 2) !== $this->_TPM_ST_ATTEST_CERTIFY) { |
| 146 | throw new WebAuthnException('tpm type not TPM_ST_ATTEST_CERTIFY', WebAuthnException::INVALID_DATA); |
| 147 | } |
| 148 | |
| 149 | $offset = 6; |
| 150 | $qualifiedSigner = $this->_tpmReadLengthPrefixed($this->_certInfo, $offset); |
| 151 | $extraData = $this->_tpmReadLengthPrefixed($this->_certInfo, $offset); |
| 152 | $coseAlg = $this->_getCoseAlgorithm($this->_alg); |
| 153 | |
| 154 | // Verify that extraData is set to the hash of attToBeSigned using the hash algorithm employed in "alg". |
| 155 | if ($extraData->getBinaryString() !== \hash($coseAlg->hash, $attToBeSigned, true)) { |
| 156 | throw new WebAuthnException('certInfo:extraData not hash of attToBeSigned', WebAuthnException::INVALID_DATA); |
| 157 | } |
| 158 | |
| 159 | // Verify the sig is a valid signature over certInfo using the attestation |
| 160 | // public key in aikCert with the algorithm specified in alg. |
| 161 | return \openssl_verify($this->_certInfo->getBinaryString(), $this->_signature, $publicKey, $coseAlg->openssl) === 1; |
| 162 | } |
| 163 | |
| 164 | |
| 165 | /** |
| 166 | * returns next part of ByteBuffer |
| 167 | * @param ByteBuffer $buffer |
| 168 | * @param int $offset |
| 169 | * @return ByteBuffer |
| 170 | */ |
| 171 | protected function _tpmReadLengthPrefixed(ByteBuffer $buffer, &$offset) { |
| 172 | $len = $buffer->getUint16Val($offset); |
| 173 | $data = $buffer->getBytes($offset + 2, $len); |
| 174 | $offset += (2 + $len); |
| 175 | |
| 176 | return new ByteBuffer($data); |
| 177 | } |
| 178 | |
| 179 | } |
| 180 | |