simplesamlphp /
simplesamlphp-module-webauthn
| Total Complexity | 46 |
| Total Lines | 390 |
| Duplicated Lines | 0 % |
| Changes | 15 | ||
| Bugs | 0 | Features | 1 |
Complex classes like WebAuthnRegistrationEvent often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use WebAuthnRegistrationEvent, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 18 | class WebAuthnRegistrationEvent extends WebAuthnAbstractEvent |
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| 19 | { |
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| 20 | |||
| 21 | /** |
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| 22 | * Public key algorithm supported. This is -7 - ECDSA with curve P-256 |
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| 23 | */ |
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| 24 | const PK_ALGORITHM = -7; |
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| 25 | const AAGUID_ASSURANCE_LEVEL_NONE = 0; |
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| 26 | const AAGUID_ASSURANCE_LEVEL_SELF = 1; |
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| 27 | const AAGUID_ASSURANCE_LEVEL_BASIC = 2; |
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| 28 | const AAGUID_ASSURANCE_LEVEL_ATTCA = 3; |
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| 29 | |||
| 30 | /** |
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| 31 | * the AAGUID of the newly registered authenticator |
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| 32 | * @var string |
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| 33 | */ |
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| 34 | public $AAGUID; |
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| 35 | |||
| 36 | /** |
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| 37 | * how sure are we about the AAGUID? |
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| 38 | * @var int |
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| 39 | */ |
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| 40 | public $AAGUIDAssurance; |
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| 41 | |||
| 42 | /** |
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| 43 | * An array of known hardware tokens |
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| 44 | * |
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| 45 | * @var array |
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| 46 | */ |
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| 47 | protected $AAGUIDDictionary; |
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| 48 | |||
| 49 | /** |
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| 50 | * Initialize the event object. |
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| 51 | * |
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| 52 | * Validates and parses the configuration. |
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| 53 | * |
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| 54 | * @param string $pubkeyCredType PublicKeyCredential.type |
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| 55 | * @param string $scope the scope of the event |
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| 56 | * @param string $challenge the challenge which was used to trigger this event |
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| 57 | * @param string $idpEntityId the entity ID of our IdP |
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| 58 | * @param string $attestationData the attestation data CBOR blob |
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| 59 | * @param string $responseId the response ID |
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| 60 | * @param string $clientDataJSON the client data JSON string which is present in all types of events |
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| 61 | * @param bool $debugMode print debugging statements? |
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| 62 | */ |
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| 63 | public function __construct( |
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| 64 | string $pubkeyCredType, |
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| 65 | string $scope, |
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| 66 | string $challenge, |
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| 67 | string $idpEntityId, |
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| 68 | string $attestationData, |
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| 69 | string $responseId, |
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| 70 | string $clientDataJSON, |
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| 71 | bool $debugMode = false |
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| 72 | ) |
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| 73 | { |
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| 74 | $this->debugBuffer .= "attestationData raw: " . $attestationData . "<br/>"; |
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| 75 | /** |
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| 76 | * §7.1 STEP 9 : CBOR decode attestationData. |
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| 77 | */ |
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| 78 | $attestationArray = $this->cborDecode($attestationData); |
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| 79 | $authData = $attestationArray['authData']; |
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| 80 | $this->eventType = "REG"; |
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| 81 | parent::__construct($pubkeyCredType, $scope, $challenge, $idpEntityId, $authData, $clientDataJSON, $debugMode); |
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| 82 | |||
| 83 | $this->AAGUIDDictionary = AAGUID::getInstance(); |
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| 84 | |||
| 85 | // this function extracts the public key |
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| 86 | $this->validateAttestedCredentialData(substr($authData, 37), $responseId); |
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| 87 | // this function may need the public key to have been previously extracted |
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| 88 | $this->validateAttestationData($attestationData); |
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| 89 | // the following function sets the credential properties |
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| 90 | $this->debugBuffer .= "Attestation Data (bin2hex): " . bin2hex(substr($authData, 37)) . "<br/>"; |
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| 91 | } |
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| 92 | |||
| 93 | /** |
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| 94 | * validate the incoming attestation data CBOR blob and return the embedded authData |
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| 95 | * @param string $attestationData |
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| 96 | * @return void |
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| 97 | */ |
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| 98 | private function validateAttestationData(string $attestationData): void |
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| 99 | { |
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| 100 | /** |
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| 101 | * STEP 9 of the validation procedure in § 7.1 of the spec: CBOR-decode the attestationObject |
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| 102 | */ |
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| 103 | $attestationArray = $this->cborDecode($attestationData); |
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| 104 | $this->debugBuffer .= "<pre>"; |
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| 105 | $this->debugBuffer .= print_r($attestationArray, true); |
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| 106 | $this->debugBuffer .= "</pre>"; |
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| 107 | |||
| 108 | /** |
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| 109 | * STEP 15 of the validation procedure in § 7.1 of the spec: verify attStmt values |
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| 110 | */ |
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| 111 | switch ($attestationArray['fmt']) { |
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| 112 | case "none": |
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| 113 | $this->validateAttestationFormatNone($attestationArray); |
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| 114 | break; |
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| 115 | case "packed": |
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| 116 | $this->validateAttestationFormatPacked($attestationArray); |
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| 117 | break; |
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| 118 | case "fido-u2f": |
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| 119 | $this->validateAttestationFormatFidoU2F($attestationArray); |
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| 120 | break; |
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| 121 | case "android-safetynet": |
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| 122 | $this->validateAttestationFormatAndroidSafetyNet($attestationArray); |
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| 123 | break; |
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| 124 | case "tpm": |
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| 125 | case "android-key": |
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| 126 | $this->fail("Attestation format " . $attestationArray['fmt'] . " validation not supported right now."); |
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| 127 | break; |
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| 128 | default: |
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| 129 | $this->fail("Unknown attestation format."); |
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| 130 | break; |
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| 131 | } |
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| 132 | } |
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| 133 | |||
| 134 | /** |
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| 135 | * @param array $attestationArray |
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| 136 | * @return void |
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| 137 | */ |
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| 138 | private function validateAttestationFormatNone(array $attestationArray): void |
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| 139 | { |
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| 140 | // § 8.7 of the spec |
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| 141 | /** |
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| 142 | * § 7.1 Step 16 && §8.7 Verification Procedure: stmt must be an empty array |
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| 143 | * § 7.1 Step 17+18 are a NOOP if the format was "none" (which is acceptable as per this RPs policy) |
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| 144 | */ |
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| 145 | if (count($attestationArray['attStmt']) === 0) { |
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| 146 | $this->pass("Attestation format and statement as expected, and no attestation authorities to retrieve."); |
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| 147 | $this->AAGUIDAssurance = self::AAGUID_ASSURANCE_LEVEL_NONE; |
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| 148 | return; |
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| 149 | } else { |
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| 150 | $this->fail("Non-empty attestation authorities are not expected with 'attestationFormat = none'."); |
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| 151 | } |
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| 152 | } |
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| 153 | |||
| 154 | /** |
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| 155 | * @param array $attestationArray |
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| 156 | * @return void |
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| 157 | */ |
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| 158 | private function validateAttestationFormatPacked(array $attestationArray): void |
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| 159 | { |
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| 160 | $stmtDecoded = $attestationArray['attStmt']; |
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| 161 | $this->debugBuffer .= "AttStmt: " . print_r($stmtDecoded, true) . "<br/>"; |
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| 162 | /** |
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| 163 | * §7.1 Step 16: attestation is either done with x5c or ecdaa. |
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| 164 | */ |
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| 165 | if (isset($stmtDecoded['x5c'])) { |
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| 166 | $this->validateAttestationFormatPackedX5C($attestationArray); |
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| 167 | } elseif (isset($stmtDecoded['ecdaa'])) { |
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| 168 | $this->fail("ecdaa attestation not supported right now."); |
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| 169 | } else { |
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| 170 | // if we are still here, we are in the "self" type. |
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| 171 | $this->validateAttestationFormatPackedSelf($attestationArray); |
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| 172 | } |
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| 173 | } |
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| 174 | |||
| 175 | private function validateAttestationFormatPackedX5C($attestationArray) |
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| 176 | { |
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| 177 | $stmtDecoded = $attestationArray['attStmt']; |
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| 178 | /** |
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| 179 | * §8.2 Step 2: check x5c attestation |
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| 180 | */ |
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| 181 | $sigdata = $attestationArray['authData'] . $this->clientDataHash; |
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| 182 | $keyResource = openssl_pkey_get_public($this->der2pem($stmtDecoded['x5c'][0])); |
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| 183 | if ($keyResource === false) { |
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| 184 | $this->fail("Unable to construct public key resource from PEM."); |
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| 185 | } |
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| 186 | /** |
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| 187 | * §8.2 Step 2 Bullet 1: check signature |
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| 188 | */ |
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| 189 | if (openssl_verify($sigdata, $stmtDecoded['sig'], $keyResource, OPENSSL_ALGO_SHA256) !== 1) { |
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| 190 | $this->fail("x5c attestation failed."); |
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| 191 | } |
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| 192 | $this->pass("x5c sig check passed."); |
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| 193 | // still need to perform sanity checks on the attestation certificate |
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| 194 | /** |
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| 195 | * §8.2 Step 2 Bullet 2: check certificate properties listed in §8.2.1 |
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| 196 | */ |
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| 197 | $certProps = openssl_x509_parse($this->der2pem($stmtDecoded['x5c'][0])); |
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| 198 | $this->debugBuffer .= "Attestation Certificate:" . print_r($certProps, true) . "<br/>"; |
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| 199 | if ($certProps['version'] !== 2 || /** §8.2.1 Bullet 1 */ |
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| 200 | $certProps['subject']['OU'] !== "Authenticator Attestation" || /** §8.2.1 Bullet 2 [Subject-OU] */ |
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| 201 | !isset($certProps['subject']['CN']) || /** §8.2.1 Bullet 2 [Subject-CN] */ |
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| 202 | !isset($certProps['extensions']['basicConstraints']) || |
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| 203 | strstr("CA:FALSE", $certProps['extensions']['basicConstraints']) === false /** §8.2.1 Bullet 4 */ |
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| 204 | ) { |
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| 205 | $this->fail("Attestation certificate properties are no good."); |
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| 206 | } |
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| 207 | |||
| 208 | if ($this->AAGUIDDictionary->hasToken($this->AAGUID)) { |
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| 209 | $token = $this->AAGUIDDictionary->get($this->AAGUID); |
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| 210 | if ($certProps['subject']['O'] !== $token['O'] || |
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| 211 | // §8.2.1 Bullet 2 [Subject-O] |
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| 212 | $certProps['subject']['C'] !== $token['C'] |
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| 213 | // §8.2ubject-C] |
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| 214 | ) { |
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| 215 | $this->fail("AAGUID does not match vendor data."); |
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| 216 | } |
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| 217 | if ($token['multi'] === true) { // need to check the OID |
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| 218 | if (!isset($certProps['extensions']['1.3.6.1.4.1.45724.1.1.4'])) { /** §8.2.1 Bullet 3 */ |
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| 219 | $this->fail("This vendor uses one cert for multiple authenticator model attestations, but lacks the AAGUID OID."); |
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| 220 | } |
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| 221 | /** |
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| 222 | * §8.2 Step 2 Bullet 3: compare AAGUID values |
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| 223 | */ |
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| 224 | $AAGUIDFromOid = substr(bin2hex($certProps['extensions']['1.3.6.1.4.1.45724.1.1.4']), 4); |
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| 225 | $this->debugBuffer .= "AAGUID from OID = $AAGUIDFromOid<br/>"; |
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| 226 | if (strtolower($AAGUIDFromOid) !== strtolower($this->AAGUID)) { |
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| 227 | $this->fail("AAGUID mismatch between attestation certificate and attestation statement."); |
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| 228 | } |
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| 229 | } |
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| 230 | // we would need to verify the attestation certificate against a known-good root CA certificate to get more than basic |
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| 231 | /* |
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| 232 | * §7.1 Step 17 is to look at $token['RootPEMs'] |
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| 233 | */ |
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| 234 | /* |
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| 235 | * §7.1 Step 18 is skipped, and we unconditionally return "only" Basic. |
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| 236 | */ |
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| 237 | $this->AAGUIDAssurance = self::AAGUID_ASSURANCE_LEVEL_BASIC; |
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| 238 | } else { |
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| 239 | $this->warn("Unknown authenticator model found: " . $this->AAGUID . "."); |
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| 240 | // unable to verify all cert properties, so this is not enough for BASIC. |
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| 241 | // but it's our own fault, we should add the device to our DB. |
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| 242 | $this->AAGUIDAssurance = self::AAGUID_ASSURANCE_LEVEL_SELF; |
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| 243 | } |
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| 244 | $this->pass("x5c attestation passed."); |
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| 245 | return; |
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| 246 | } |
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| 247 | |||
| 248 | private function validateAttestationFormatPackedSelf($attestationArray) |
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| 274 | } |
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| 275 | } |
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| 276 | |||
| 277 | /** |
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| 278 | * support legacy U2F tokens |
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| 279 | * |
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| 280 | * @param array $attestationData the incoming attestation data |
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| 281 | */ |
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| 282 | private function validateAttestationFormatFidoU2F($attestationData) |
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| 283 | { |
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| 284 | /** |
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| 285 | * §8.6 Verification Step 1 is a NOOP: if we're here, the attStmt was |
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| 286 | * already successfully CBOR decoded |
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| 287 | */ |
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| 288 | $stmtDecoded = $attestationData['attStmt']; |
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| 289 | if (!isset($stmtDecoded['x5c'])) { |
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| 290 | $this->fail("FIDO U2F attestation needs to have the 'x5c' key"); |
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| 291 | } |
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| 292 | /** |
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| 293 | * §8.6 Verification Step 2: extract attCert and sanity check it |
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| 294 | */ |
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| 295 | if (count($stmtDecoded['x5c']) !== 1) { |
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| 296 | $this->fail("FIDO U2F attestation requires 'x5c' to have only exactly one key."); |
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| 297 | } |
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| 298 | $attCert = $this->der2pem($stmtDecoded['x5c'][0]); |
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| 299 | $key = openssl_pkey_get_public($attCert); |
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| 300 | $keyProps = openssl_pkey_get_details($key); |
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| 301 | if (!isset($keyProps['ec']['curve_name']) || $keyProps['ec']['curve_name'] !== "prime256v1") { |
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| 302 | $this->fail("FIDO U2F attestation public key is not P-256!"); |
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| 303 | } |
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| 304 | /** |
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| 305 | * §8.6 Verification Step 3 is a NOOP as these properties are already |
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| 306 | * available as class members: |
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| 307 | * |
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| 308 | * $this->rpIdHash; |
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| 309 | * $this->credentialId; |
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| 310 | * $this->credential; |
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| 311 | */ |
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| 312 | /** |
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| 313 | * §8.6 Verification Step 4: encode the public key in ANSI X9.62 format |
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| 314 | */ |
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| 315 | if (isset($this->credential[-2]) && sizeof($this->credential[-2]) === 32 && |
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| 316 | isset($this->credential[-3]) && sizeof($this->credential[-3]) === 32) { |
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| 317 | $publicKeyU2F = chr(4) . $this->credential[-2] . $this->credential[-3]; |
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| 318 | } else { |
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| 319 | $publicKeyU2F = FALSE; |
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| 320 | $this->fail("FIDO U2F attestation: the public key is not as expected."); |
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| 321 | } |
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| 322 | /** |
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| 323 | * §8.6 Verification Step 5: create verificationData |
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| 324 | */ |
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| 325 | $verificationData = chr(0) . $this->rpIdHash . $this->clientDataHash . $this->credentialId . $publicKeyU2F; |
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| 326 | /** |
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| 327 | * §8.6 Verification Step 6: verify signature |
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| 328 | */ |
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| 329 | if (openssl_verify($verificationData, $stmtDecoded['sig'], $attCert, OPENSSL_ALGO_SHA256) !== 1) { |
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| 330 | $this->fail("FIDO U2F Attestation verification failed."); |
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| 331 | } else { |
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| 332 | $this->pass("Successfully verified FIDO U2F signature."); |
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| 333 | } |
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| 334 | /** |
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| 335 | * §8.6 Verification Step 7: not performed, this is optional as per spec |
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| 336 | */ |
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| 337 | /** |
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| 338 | * §8.6 Verification Step 8: so we always settle for "Basic" |
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| 339 | */ |
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| 340 | $this->AAGUIDAssurance = self::AAGUID_ASSURANCE_LEVEL_BASIC; |
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| 341 | } |
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| 342 | |||
| 343 | /** |
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| 344 | * support Android authenticators (fingerprint etc.) |
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| 345 | * |
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| 346 | * @param array $attestationData the incoming attestation data |
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| 347 | */ |
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| 348 | private function validateAttestationFormatAndroidSafetyNet($attestationData) |
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| 350 | |||
| 351 | } |
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| 352 | |||
| 353 | /** |
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| 354 | * The registration contains the actual credential. This function parses it. |
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| 355 | * @param string $attData the attestation data binary blob |
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| 356 | * @param string $responseId the response ID |
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| 357 | * @return void |
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| 358 | */ |
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| 359 | private function validateAttestedCredentialData(string $attData, string $responseId): void |
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| 360 | { |
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| 361 | $aaguid = substr($attData, 0, 16); |
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| 362 | $credIdLenBytes = substr($attData, 16, 2); |
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| 363 | $credIdLen = intval(bin2hex($credIdLenBytes), 16); |
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| 364 | $credId = substr($attData, 18, $credIdLen); |
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| 365 | $this->debugBuffer .= "AAGUID (hex) = " . bin2hex($aaguid) . "</br/>"; |
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| 366 | $this->AAGUID = bin2hex($aaguid); |
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| 367 | $this->debugBuffer .= "Length Raw = " . bin2hex($credIdLenBytes) . "<br/>"; |
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| 368 | $this->debugBuffer .= "Credential ID Length (decimal) = " . $credIdLen . "<br/>"; |
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| 369 | $this->debugBuffer .= "Credential ID (hex) = " . bin2hex($credId) . "<br/>"; |
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| 370 | if (bin2hex(WebAuthnAbstractEvent::base64url_decode($responseId)) === bin2hex($credId)) { |
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| 371 | $this->pass("Credential IDs in authenticator response and in attestation data match."); |
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| 372 | } else { |
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| 373 | $this->fail("Mismatch of credentialId (" . bin2hex($credId) . ") vs. response ID (" . bin2hex(WebAuthnAbstractEvent::base64url_decode($responseId)) . ")."); |
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| 374 | } |
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| 375 | // so far so good. Now extract the actual public key from its COSE |
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| 376 | // encoding. |
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| 377 | // finding out the number of bytes to CBOR decode appears non-trivial. |
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| 378 | // The simple case is if no ED is present as the CBOR data then goes to |
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| 379 | // the end of the byte sequence. |
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| 380 | // Since we made sure above that no ED is in the sequence, take the rest |
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| 381 | // of the sequence in its entirety. |
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| 382 | $pubKeyCBOR = substr($attData, 18 + $credIdLen); |
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| 383 | $arrayPK = $this->cborDecode($pubKeyCBOR); |
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| 384 | $this->debugBuffer .= "pubKey in canonical form: <pre>" . print_r($arrayPK, true) . "</pre>"; |
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| 385 | /** |
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| 386 | * STEP 13 of the validation procedure in § 7.1 of the spec: is the algorithm the expected one? |
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| 387 | */ |
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| 388 | if ($arrayPK['3'] === self::PK_ALGORITHM) { // we requested -7, so want to see it here |
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| 389 | $this->pass("Public Key Algorithm is the expected one (-7, ECDSA)."); |
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| 390 | } else { |
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| 391 | $this->fail("Public Key Algorithm mismatch!"); |
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| 392 | } |
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| 393 | $this->credentialId = bin2hex($credId); |
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| 394 | $this->credential = bin2hex($pubKeyCBOR); |
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| 395 | } |
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| 396 | |||
| 397 | /** |
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| 398 | * transform DER formatted certificate to PEM format |
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| 399 | * |
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| 400 | * @param string $derData blob of DER data |
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| 401 | * @return string the PEM representation of the certificate |
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| 402 | */ |
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| 403 | private function der2pem(string $derData): string |
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| 408 | } |
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| 409 | |||
| 410 | } |
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| 411 |
Loading history...
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..