diff --git a/src/lib/WebAuthn/Attestation/AttestationObject.php b/src/lib/WebAuthn/Attestation/AttestationObject.php
new file mode 100644
index 0000000..65151ea
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/AttestationObject.php
@@ -0,0 +1,179 @@
+<?php
+
+namespace lbuchs\WebAuthn\Attestation;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\CBOR\CborDecoder;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+/**
+ * @author Lukas Buchs
+ * @license https://github.com/lbuchs/WebAuthn/blob/master/LICENSE MIT
+ */
+class AttestationObject {
+    private $_authenticatorData;
+    private $_attestationFormat;
+    private $_attestationFormatName;
+
+    public function __construct($binary , $allowedFormats) {
+        $enc = CborDecoder::decode($binary);
+        // validation
+        if (!\is_array($enc) || !\array_key_exists('fmt', $enc) || !is_string($enc['fmt'])) {
+            throw new WebAuthnException('invalid attestation format', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('attStmt', $enc) || !\is_array($enc['attStmt'])) {
+            throw new WebAuthnException('invalid attestation format (attStmt not available)', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('authData', $enc) || !\is_object($enc['authData']) || !($enc['authData'] instanceof ByteBuffer)) {
+            throw new WebAuthnException('invalid attestation format (authData not available)', WebAuthnException::INVALID_DATA);
+        }
+
+        $this->_authenticatorData = new AuthenticatorData($enc['authData']->getBinaryString());
+        $this->_attestationFormatName = $enc['fmt'];
+
+        // Format ok?
+        if (!in_array($this->_attestationFormatName, $allowedFormats)) {
+            throw new WebAuthnException('invalid atttestation format: ' . $this->_attestationFormatName, WebAuthnException::INVALID_DATA);
+        }
+
+
+        switch ($this->_attestationFormatName) {
+            case 'android-key': $this->_attestationFormat = new Format\AndroidKey($enc, $this->_authenticatorData); break;
+            case 'android-safetynet': $this->_attestationFormat = new Format\AndroidSafetyNet($enc, $this->_authenticatorData); break;
+            case 'apple': $this->_attestationFormat = new Format\Apple($enc, $this->_authenticatorData); break;
+            case 'fido-u2f': $this->_attestationFormat = new Format\U2f($enc, $this->_authenticatorData); break;
+            case 'none': $this->_attestationFormat = new Format\None($enc, $this->_authenticatorData); break;
+            case 'packed': $this->_attestationFormat = new Format\Packed($enc, $this->_authenticatorData); break;
+            case 'tpm': $this->_attestationFormat = new Format\Tpm($enc, $this->_authenticatorData); break;
+            default: throw new WebAuthnException('invalid attestation format: ' . $enc['fmt'], WebAuthnException::INVALID_DATA);
+        }
+    }
+
+    /**
+     * returns the attestation format name
+     * @return string
+     */
+    public function getAttestationFormatName() {
+        return $this->_attestationFormatName;
+    }
+
+    /**
+     * returns the attestation format class
+     * @return Format\FormatBase
+     */
+    public function getAttestationFormat() {
+        return $this->_attestationFormat;
+    }
+
+    /**
+     * returns the attestation public key in PEM format
+     * @return AuthenticatorData
+     */
+    public function getAuthenticatorData() {
+        return $this->_authenticatorData;
+    }
+
+    /**
+     * returns the certificate chain as PEM
+     * @return string|null
+     */
+    public function getCertificateChain() {
+        return $this->_attestationFormat->getCertificateChain();
+    }
+
+    /**
+     * return the certificate issuer as string
+     * @return string
+     */
+    public function getCertificateIssuer() {
+        $pem = $this->getCertificatePem();
+        $issuer = '';
+        if ($pem) {
+            $certInfo = \openssl_x509_parse($pem);
+            if (\is_array($certInfo) && \array_key_exists('issuer', $certInfo) && \is_array($certInfo['issuer'])) {
+
+                $cn = $certInfo['issuer']['CN'] ?? '';
+                $o = $certInfo['issuer']['O'] ?? '';
+                $ou = $certInfo['issuer']['OU'] ?? '';
+
+                if ($cn) {
+                    $issuer .= $cn;
+                }
+                if ($issuer && ($o || $ou)) {
+                    $issuer .= ' (' . trim($o . ' ' . $ou) . ')';
+                } else {
+                    $issuer .= trim($o . ' ' . $ou);
+                }
+            }
+        }
+
+        return $issuer;
+    }
+
+    /**
+     * return the certificate subject as string
+     * @return string
+     */
+    public function getCertificateSubject() {
+        $pem = $this->getCertificatePem();
+        $subject = '';
+        if ($pem) {
+            $certInfo = \openssl_x509_parse($pem);
+            if (\is_array($certInfo) && \array_key_exists('subject', $certInfo) && \is_array($certInfo['subject'])) {
+
+                $cn = $certInfo['subject']['CN'] ?? '';
+                $o = $certInfo['subject']['O'] ?? '';
+                $ou = $certInfo['subject']['OU'] ?? '';
+
+                if ($cn) {
+                    $subject .= $cn;
+                }
+                if ($subject && ($o || $ou)) {
+                    $subject .= ' (' . trim($o . ' ' . $ou) . ')';
+                } else {
+                    $subject .= trim($o . ' ' . $ou);
+                }
+            }
+        }
+
+        return $subject;
+    }
+
+    /**
+     * returns the key certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        return $this->_attestationFormat->getCertificatePem();
+    }
+
+    /**
+     * checks validity of the signature
+     * @param string $clientDataHash
+     * @return bool
+     * @throws WebAuthnException
+     */
+    public function validateAttestation($clientDataHash) {
+        return $this->_attestationFormat->validateAttestation($clientDataHash);
+    }
+
+    /**
+     * validates the certificate against root certificates
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        return $this->_attestationFormat->validateRootCertificate($rootCas);
+    }
+
+    /**
+     * checks if the RpId-Hash is valid
+     * @param string$rpIdHash
+     * @return bool
+     */
+    public function validateRpIdHash($rpIdHash) {
+        return $rpIdHash === $this->_authenticatorData->getRpIdHash();
+    }
+}
diff --git a/src/lib/WebAuthn/Attestation/AuthenticatorData.php b/src/lib/WebAuthn/Attestation/AuthenticatorData.php
new file mode 100644
index 0000000..0a9eec8
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/AuthenticatorData.php
@@ -0,0 +1,481 @@
+<?php
+
+namespace lbuchs\WebAuthn\Attestation;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\CBOR\CborDecoder;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+/**
+ * @author Lukas Buchs
+ * @license https://github.com/lbuchs/WebAuthn/blob/master/LICENSE MIT
+ */
+class AuthenticatorData {
+    protected $_binary;
+    protected $_rpIdHash;
+    protected $_flags;
+    protected $_signCount;
+    protected $_attestedCredentialData;
+    protected $_extensionData;
+
+
+
+    // Cose encoded keys
+    private static $_COSE_KTY = 1;
+    private static $_COSE_ALG = 3;
+
+    // Cose curve
+    private static $_COSE_CRV = -1;
+    private static $_COSE_X = -2;
+    private static $_COSE_Y = -3;
+
+    // Cose RSA PS256
+    private static $_COSE_N = -1;
+    private static $_COSE_E = -2;
+
+    // EC2 key type
+    private static $_EC2_TYPE = 2;
+    private static $_EC2_ES256 = -7;
+    private static $_EC2_P256 = 1;
+
+    // RSA key type
+    private static $_RSA_TYPE = 3;
+    private static $_RSA_RS256 = -257;
+
+    // OKP key type
+    private static $_OKP_TYPE = 1;
+    private static $_OKP_ED25519 = 6;
+    private static $_OKP_EDDSA = -8;
+
+    /**
+     * Parsing the authenticatorData binary.
+     * @param string $binary
+     * @throws WebAuthnException
+     */
+    public function __construct($binary) {
+        if (!\is_string($binary) || \strlen($binary) < 37) {
+            throw new WebAuthnException('Invalid authenticatorData input', WebAuthnException::INVALID_DATA);
+        }
+        $this->_binary = $binary;
+
+        // Read infos from binary
+        // https://www.w3.org/TR/webauthn/#sec-authenticator-data
+
+        // RP ID
+        $this->_rpIdHash = \substr($binary, 0, 32);
+
+        // flags (1 byte)
+        $flags = \unpack('Cflags', \substr($binary, 32, 1))['flags'];
+        $this->_flags = $this->_readFlags($flags);
+
+        // signature counter: 32-bit unsigned big-endian integer.
+        $this->_signCount = \unpack('Nsigncount', \substr($binary, 33, 4))['signcount'];
+
+        $offset = 37;
+        // https://www.w3.org/TR/webauthn/#sec-attested-credential-data
+        if ($this->_flags->attestedDataIncluded) {
+            $this->_attestedCredentialData = $this->_readAttestData($binary, $offset);
+        }
+
+        if ($this->_flags->extensionDataIncluded) {
+            $this->_readExtensionData(\substr($binary, $offset));
+        }
+    }
+
+    /**
+     * Authenticator Attestation Globally Unique Identifier, a unique number
+     * that identifies the model of the authenticator (not the specific instance
+     * of the authenticator)
+     * The aaguid may be 0 if the user is using a old u2f device and/or if
+     * the browser is using the fido-u2f format.
+     * @return string
+     * @throws WebAuthnException
+     */
+    public function getAAGUID() {
+        if (!($this->_attestedCredentialData instanceof \stdClass)) {
+            throw  new WebAuthnException('credential data not included in authenticator data', WebAuthnException::INVALID_DATA);
+        }
+        return $this->_attestedCredentialData->aaguid;
+    }
+
+    /**
+     * returns the authenticatorData as binary
+     * @return string
+     */
+    public function getBinary() {
+        return $this->_binary;
+    }
+
+    /**
+     * returns the credentialId
+     * @return string
+     * @throws WebAuthnException
+     */
+    public function getCredentialId() {
+        if (!($this->_attestedCredentialData instanceof \stdClass)) {
+            throw  new WebAuthnException('credential id not included in authenticator data', WebAuthnException::INVALID_DATA);
+        }
+        return $this->_attestedCredentialData->credentialId;
+    }
+
+    /**
+     * returns the public key in PEM format
+     * @return string
+     */
+    public function getPublicKeyPem() {
+        if (!($this->_attestedCredentialData instanceof \stdClass) || !isset($this->_attestedCredentialData->credentialPublicKey)) {
+            throw  new WebAuthnException('credential data not included in authenticator data', WebAuthnException::INVALID_DATA);
+        }
+        
+        $der = null;
+        switch ($this->_attestedCredentialData->credentialPublicKey->kty ?? null) {
+            case self::$_EC2_TYPE: $der = $this->_getEc2Der(); break;
+            case self::$_RSA_TYPE: $der = $this->_getRsaDer(); break;
+            case self::$_OKP_TYPE: $der = $this->_getOkpDer(); break;
+            default: throw new WebAuthnException('invalid key type', WebAuthnException::INVALID_DATA);
+        }
+
+        $pem = '-----BEGIN PUBLIC KEY-----' . "\n";
+        $pem .= \chunk_split(\base64_encode($der), 64, "\n");
+        $pem .= '-----END PUBLIC KEY-----' . "\n";
+        return $pem;
+    }
+
+    /**
+     * returns the public key in U2F format
+     * @return string
+     * @throws WebAuthnException
+     */
+    public function getPublicKeyU2F() {
+        if (!($this->_attestedCredentialData instanceof \stdClass) || !isset($this->_attestedCredentialData->credentialPublicKey)) {
+            throw  new WebAuthnException('credential data not included in authenticator data', WebAuthnException::INVALID_DATA);
+        }
+        if (($this->_attestedCredentialData->credentialPublicKey->kty ?? null) !== self::$_EC2_TYPE) {
+            throw new WebAuthnException('signature algorithm not ES256', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+        return "\x04" . // ECC uncompressed
+                $this->_attestedCredentialData->credentialPublicKey->x .
+                $this->_attestedCredentialData->credentialPublicKey->y;
+    }
+
+    /**
+     * returns the SHA256 hash of the relying party id (=hostname)
+     * @return string
+     */
+    public function getRpIdHash() {
+        return $this->_rpIdHash;
+    }
+
+    /**
+     * returns the sign counter
+     * @return int
+     */
+    public function getSignCount() {
+        return $this->_signCount;
+    }
+
+    /**
+     * returns true if the user is present
+     * @return boolean
+     */
+    public function getUserPresent() {
+        return $this->_flags->userPresent;
+    }
+
+    /**
+     * returns true if the user is verified
+     * @return boolean
+     */
+    public function getUserVerified() {
+        return $this->_flags->userVerified;
+    }
+
+    // -----------------------------------------------
+    // PRIVATE
+    // -----------------------------------------------
+
+    /**
+     * Returns DER encoded EC2 key
+     * @return string
+     */
+    private function _getEc2Der() {
+        return $this->_der_sequence(
+            $this->_der_sequence(
+                $this->_der_oid("\x2A\x86\x48\xCE\x3D\x02\x01") . // OID 1.2.840.10045.2.1 ecPublicKey
+                $this->_der_oid("\x2A\x86\x48\xCE\x3D\x03\x01\x07")  // 1.2.840.10045.3.1.7 prime256v1
+            ) .
+            $this->_der_bitString($this->getPublicKeyU2F())
+        );
+    }
+
+    /**
+     * Returns DER encoded EdDSA key
+     * @return string
+     */
+    private function _getOkpDer() {
+        return $this->_der_sequence(
+            $this->_der_sequence(
+                $this->_der_oid("\x2B\x65\x70") // OID 1.3.101.112 curveEd25519 (EdDSA 25519 signature algorithm)
+            ) .
+            $this->_der_bitString($this->_attestedCredentialData->credentialPublicKey->x)
+        );
+    }
+
+    /**
+     * Returns DER encoded RSA key
+     * @return string
+     */
+    private function _getRsaDer() {
+        return $this->_der_sequence(
+            $this->_der_sequence(
+                $this->_der_oid("\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01") . // OID 1.2.840.113549.1.1.1 rsaEncryption
+                $this->_der_nullValue()
+            ) .
+            $this->_der_bitString(
+                $this->_der_sequence(
+                    $this->_der_unsignedInteger($this->_attestedCredentialData->credentialPublicKey->n) .
+                    $this->_der_unsignedInteger($this->_attestedCredentialData->credentialPublicKey->e)
+                )
+            )
+        );
+    }
+
+    /**
+     * reads the flags from flag byte
+     * @param string $binFlag
+     * @return \stdClass
+     */
+    private function _readFlags($binFlag) {
+        $flags = new \stdClass();
+
+        $flags->bit_0 = !!($binFlag & 1);
+        $flags->bit_1 = !!($binFlag & 2);
+        $flags->bit_2 = !!($binFlag & 4);
+        $flags->bit_3 = !!($binFlag & 8);
+        $flags->bit_4 = !!($binFlag & 16);
+        $flags->bit_5 = !!($binFlag & 32);
+        $flags->bit_6 = !!($binFlag & 64);
+        $flags->bit_7 = !!($binFlag & 128);
+
+        // named flags
+        $flags->userPresent = $flags->bit_0;
+        $flags->userVerified = $flags->bit_2;
+        $flags->attestedDataIncluded = $flags->bit_6;
+        $flags->extensionDataIncluded = $flags->bit_7;
+        return $flags;
+    }
+
+    /**
+     * read attested data
+     * @param string $binary
+     * @param int $endOffset
+     * @return \stdClass
+     * @throws WebAuthnException
+     */
+    private function _readAttestData($binary, &$endOffset) {
+        $attestedCData = new \stdClass();
+        if (\strlen($binary) <= 55) {
+            throw new WebAuthnException('Attested data should be present but is missing', WebAuthnException::INVALID_DATA);
+        }
+
+        // The AAGUID of the authenticator
+        $attestedCData->aaguid = \substr($binary, 37, 16);
+
+        //Byte length L of Credential ID, 16-bit unsigned big-endian integer.
+        $length = \unpack('nlength', \substr($binary, 53, 2))['length'];
+        $attestedCData->credentialId = \substr($binary, 55, $length);
+
+        // set end offset
+        $endOffset = 55 + $length;
+
+        // extract public key
+        $attestedCData->credentialPublicKey = $this->_readCredentialPublicKey($binary, 55 + $length, $endOffset);
+
+        return $attestedCData;
+    }
+
+    /**
+     * reads COSE key-encoded elliptic curve public key in EC2 format
+     * @param string $binary
+     * @param int $endOffset
+     * @return \stdClass
+     * @throws WebAuthnException
+     */
+    private function _readCredentialPublicKey($binary, $offset, &$endOffset) {
+        $enc = CborDecoder::decodeInPlace($binary, $offset, $endOffset);
+
+        // COSE key-encoded elliptic curve public key in EC2 format
+        $credPKey = new \stdClass();
+        $credPKey->kty = $enc[self::$_COSE_KTY];
+        $credPKey->alg = $enc[self::$_COSE_ALG];
+
+        switch ($credPKey->alg) {
+            case self::$_EC2_ES256: $this->_readCredentialPublicKeyES256($credPKey, $enc); break;
+            case self::$_RSA_RS256: $this->_readCredentialPublicKeyRS256($credPKey, $enc); break;
+            case self::$_OKP_EDDSA: $this->_readCredentialPublicKeyEDDSA($credPKey, $enc); break;
+        }
+
+        return $credPKey;
+    }
+
+    /**
+     * extract EDDSA informations from cose
+     * @param \stdClass $credPKey
+     * @param \stdClass $enc
+     * @throws WebAuthnException
+     */
+    private function _readCredentialPublicKeyEDDSA(&$credPKey, $enc) {
+        $credPKey->crv = $enc[self::$_COSE_CRV];
+        $credPKey->x   = $enc[self::$_COSE_X] instanceof ByteBuffer ? $enc[self::$_COSE_X]->getBinaryString() : null;
+        unset ($enc);
+
+        // Validation
+        if ($credPKey->kty !== self::$_OKP_TYPE) {
+            throw new WebAuthnException('public key not in OKP format', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if ($credPKey->alg !== self::$_OKP_EDDSA) {
+            throw new WebAuthnException('signature algorithm not EdDSA', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if ($credPKey->crv !== self::$_OKP_ED25519) {
+            throw new WebAuthnException('curve not Ed25519', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if (\strlen($credPKey->x) !== 32) {
+            throw new WebAuthnException('Invalid X-coordinate', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+    }
+
+    /**
+     * extract ES256 informations from cose
+     * @param \stdClass $credPKey
+     * @param \stdClass $enc
+     * @throws WebAuthnException
+     */
+    private function _readCredentialPublicKeyES256(&$credPKey, $enc) {
+        $credPKey->crv = $enc[self::$_COSE_CRV];
+        $credPKey->x   = $enc[self::$_COSE_X] instanceof ByteBuffer ? $enc[self::$_COSE_X]->getBinaryString() : null;
+        $credPKey->y   = $enc[self::$_COSE_Y] instanceof ByteBuffer ? $enc[self::$_COSE_Y]->getBinaryString() : null;
+        unset ($enc);
+
+        // Validation
+        if ($credPKey->kty !== self::$_EC2_TYPE) {
+            throw new WebAuthnException('public key not in EC2 format', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if ($credPKey->alg !== self::$_EC2_ES256) {
+            throw new WebAuthnException('signature algorithm not ES256', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if ($credPKey->crv !== self::$_EC2_P256) {
+            throw new WebAuthnException('curve not P-256', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if (\strlen($credPKey->x) !== 32) {
+            throw new WebAuthnException('Invalid X-coordinate', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if (\strlen($credPKey->y) !== 32) {
+            throw new WebAuthnException('Invalid Y-coordinate', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+    }
+
+    /**
+     * extract RS256 informations from COSE
+     * @param \stdClass $credPKey
+     * @param \stdClass $enc
+     * @throws WebAuthnException
+     */
+    private function _readCredentialPublicKeyRS256(&$credPKey, $enc) {
+        $credPKey->n = $enc[self::$_COSE_N] instanceof ByteBuffer ? $enc[self::$_COSE_N]->getBinaryString() : null;
+        $credPKey->e = $enc[self::$_COSE_E] instanceof ByteBuffer ? $enc[self::$_COSE_E]->getBinaryString() : null;
+        unset ($enc);
+
+        // Validation
+        if ($credPKey->kty !== self::$_RSA_TYPE) {
+            throw new WebAuthnException('public key not in RSA format', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if ($credPKey->alg !== self::$_RSA_RS256) {
+            throw new WebAuthnException('signature algorithm not ES256', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if (\strlen($credPKey->n) !== 256) {
+            throw new WebAuthnException('Invalid RSA modulus', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        if (\strlen($credPKey->e) !== 3) {
+            throw new WebAuthnException('Invalid RSA public exponent', WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+    }
+
+    /**
+     * reads cbor encoded extension data.
+     * @param string $binary
+     * @return array
+     * @throws WebAuthnException
+     */
+    private function _readExtensionData($binary) {
+        $ext = CborDecoder::decode($binary);
+        if (!\is_array($ext)) {
+            throw new WebAuthnException('invalid extension data', WebAuthnException::INVALID_DATA);
+        }
+
+        return $ext;
+    }
+
+
+    // ---------------
+    // DER functions
+    // ---------------
+
+    private function _der_length($len) {
+        if ($len < 128) {
+            return \chr($len);
+        }
+        $lenBytes = '';
+        while ($len > 0) {
+            $lenBytes = \chr($len % 256) . $lenBytes;
+            $len = \intdiv($len, 256);
+        }
+        return \chr(0x80 | \strlen($lenBytes)) . $lenBytes;
+    }
+
+    private function _der_sequence($contents) {
+        return "\x30" . $this->_der_length(\strlen($contents)) . $contents;
+    }
+
+    private function _der_oid($encoded) {
+        return "\x06" . $this->_der_length(\strlen($encoded)) . $encoded;
+    }
+
+    private function _der_bitString($bytes) {
+        return "\x03" . $this->_der_length(\strlen($bytes) + 1) . "\x00" . $bytes;
+    }
+
+    private function _der_nullValue() {
+        return "\x05\x00";
+    }
+
+    private function _der_unsignedInteger($bytes) {
+        $len = \strlen($bytes);
+
+        // Remove leading zero bytes
+        for ($i = 0; $i < ($len - 1); $i++) {
+            if (\ord($bytes[$i]) !== 0) {
+                break;
+            }
+        }
+        if ($i !== 0) {
+            $bytes = \substr($bytes, $i);
+        }
+
+        // If most significant bit is set, prefix with another zero to prevent it being seen as negative number
+        if ((\ord($bytes[0]) & 0x80) !== 0) {
+            $bytes = "\x00" . $bytes;
+        }
+
+        return "\x02" . $this->_der_length(\strlen($bytes)) . $bytes;
+    }
+}
diff --git a/src/lib/WebAuthn/Attestation/Format/AndroidKey.php b/src/lib/WebAuthn/Attestation/Format/AndroidKey.php
new file mode 100644
index 0000000..4581272
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/AndroidKey.php
@@ -0,0 +1,96 @@
+<?php
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class AndroidKey extends FormatBase {
+    private $_alg;
+    private $_signature;
+    private $_x5c;
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+
+        // check u2f data
+        $attStmt = $this->_attestationObject['attStmt'];
+
+        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('no signature found', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('x5c', $attStmt) || !\is_array($attStmt['x5c']) || \count($attStmt['x5c']) < 1) {
+            throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\is_object($attStmt['x5c'][0]) || !($attStmt['x5c'][0] instanceof ByteBuffer)) {
+            throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
+        }
+
+        $this->_alg = $attStmt['alg'];
+        $this->_signature = $attStmt['sig']->getBinaryString();
+        $this->_x5c = $attStmt['x5c'][0]->getBinaryString();
+
+        if (count($attStmt['x5c']) > 1) {
+            for ($i=1; $i<count($attStmt['x5c']); $i++) {
+                $this->_x5c_chain[] = $attStmt['x5c'][$i]->getBinaryString();
+            }
+            unset ($i);
+        }
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        return $this->_createCertificatePem($this->_x5c);
+    }
+
+    /**
+     * @param string $clientDataHash
+     */
+    public function validateAttestation($clientDataHash) {
+        $publicKey = \openssl_pkey_get_public($this->getCertificatePem());
+
+        if ($publicKey === false) {
+            throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        // Verify that sig is a valid signature over the concatenation of authenticatorData and clientDataHash
+        // using the attestation public key in attestnCert with the algorithm specified in alg.
+        $dataToVerify = $this->_authenticatorData->getBinary();
+        $dataToVerify .= $clientDataHash;
+
+        $coseAlgorithm = $this->_getCoseAlgorithm($this->_alg);
+
+        // check certificate
+        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, $coseAlgorithm->openssl) === 1;
+    }
+
+    /**
+     * validates the certificate against root certificates
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        $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;
+    }
+}
+
diff --git a/src/lib/WebAuthn/Attestation/Format/AndroidSafetyNet.php b/src/lib/WebAuthn/Attestation/Format/AndroidSafetyNet.php
new file mode 100644
index 0000000..ba0db52
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/AndroidSafetyNet.php
@@ -0,0 +1,152 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class AndroidSafetyNet extends FormatBase {
+    private $_signature;
+    private $_signedValue;
+    private $_x5c;
+    private $_payload;
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+
+        // check data
+        $attStmt = $this->_attestationObject['attStmt'];
+
+        if (!\array_key_exists('ver', $attStmt) || !$attStmt['ver']) {
+            throw new WebAuthnException('invalid Android Safety Net Format', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('response', $attStmt) || !($attStmt['response'] instanceof ByteBuffer)) {
+            throw new WebAuthnException('invalid Android Safety Net Format', WebAuthnException::INVALID_DATA);
+        }
+
+        $response = $attStmt['response']->getBinaryString();
+
+        // Response is a JWS [RFC7515] object in Compact Serialization.
+        // JWSs have three segments separated by two period ('.') characters
+        $parts = \explode('.', $response);
+        unset ($response);
+        if (\count($parts) !== 3) {
+            throw new WebAuthnException('invalid JWS data', WebAuthnException::INVALID_DATA);
+        }
+
+        $header = $this->_base64url_decode($parts[0]);
+        $payload = $this->_base64url_decode($parts[1]);
+        $this->_signature = $this->_base64url_decode($parts[2]);
+        $this->_signedValue = $parts[0] . '.' . $parts[1];
+        unset ($parts);
+
+        $header = \json_decode($header);
+        $payload = \json_decode($payload);
+
+        if (!($header instanceof \stdClass)) {
+            throw new WebAuthnException('invalid JWS header', WebAuthnException::INVALID_DATA);
+        }
+        if (!($payload instanceof \stdClass)) {
+            throw new WebAuthnException('invalid JWS payload', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!isset($header->x5c) || !is_array($header->x5c) || count($header->x5c) === 0) {
+            throw new WebAuthnException('No X.509 signature in JWS Header', WebAuthnException::INVALID_DATA);
+        }
+
+        // algorithm
+        if (!\in_array($header->alg, array('RS256', 'ES256'))) {
+            throw new WebAuthnException('invalid JWS algorithm ' . $header->alg, WebAuthnException::INVALID_DATA);
+        }
+
+        $this->_x5c = \base64_decode($header->x5c[0]);
+        $this->_payload = $payload;
+
+        if (count($header->x5c) > 1) {
+            for ($i=1; $i<count($header->x5c); $i++) {
+                $this->_x5c_chain[] = \base64_decode($header->x5c[$i]);
+            }
+            unset ($i);
+        }
+    }
+
+    /**
+     * ctsProfileMatch: A stricter verdict of device integrity.
+     * If the value of ctsProfileMatch is true, then the profile of the device running your app matches
+     * the profile of a device that has passed Android compatibility testing and
+     * has been approved as a Google-certified Android device.
+     * @return bool
+     */
+    public function ctsProfileMatch() {
+        return isset($this->_payload->ctsProfileMatch) ? !!$this->_payload->ctsProfileMatch : false;
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        return $this->_createCertificatePem($this->_x5c);
+    }
+
+    /**
+     * @param string $clientDataHash
+     */
+    public function validateAttestation($clientDataHash) {
+        $publicKey = \openssl_pkey_get_public($this->getCertificatePem());
+
+        // Verify that the nonce in the response is identical to the Base64 encoding
+        // of the SHA-256 hash of the concatenation of authenticatorData and clientDataHash.
+        if (empty($this->_payload->nonce) || $this->_payload->nonce !== \base64_encode(\hash('SHA256', $this->_authenticatorData->getBinary() . $clientDataHash, true))) {
+            throw new WebAuthnException('invalid nonce in JWS payload', WebAuthnException::INVALID_DATA);
+        }
+
+        // Verify that attestationCert is issued to the hostname "attest.android.com"
+        $certInfo = \openssl_x509_parse($this->getCertificatePem());
+        if (!\is_array($certInfo) || ($certInfo['subject']['CN'] ?? '') !== 'attest.android.com') {
+            throw new WebAuthnException('invalid certificate CN in JWS (' . ($certInfo['subject']['CN'] ?? '-'). ')', WebAuthnException::INVALID_DATA);
+        }
+
+        // Verify that the basicIntegrity attribute in the payload of response is true.
+        if (empty($this->_payload->basicIntegrity)) {
+            throw new WebAuthnException('invalid basicIntegrity in payload', WebAuthnException::INVALID_DATA);
+        }
+
+        // check certificate
+        return \openssl_verify($this->_signedValue, $this->_signature, $publicKey, OPENSSL_ALGO_SHA256) === 1;
+    }
+
+
+    /**
+     * validates the certificate against root certificates
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        $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;
+    }
+
+
+    /**
+     * decode base64 url
+     * @param string $data
+     * @return string
+     */
+    private function _base64url_decode($data) {
+        return \base64_decode(\strtr($data, '-_', '+/') . \str_repeat('=', 3 - (3 + \strlen($data)) % 4));
+    }
+}
+
diff --git a/src/lib/WebAuthn/Attestation/Format/Apple.php b/src/lib/WebAuthn/Attestation/Format/Apple.php
new file mode 100644
index 0000000..e4f38e0
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/Apple.php
@@ -0,0 +1,139 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class Apple extends FormatBase {
+    private $_x5c;
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+
+        // check packed data
+        $attStmt = $this->_attestationObject['attStmt'];
+
+
+        // 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('invalid Apple attestation statement: missing x5c', WebAuthnException::INVALID_DATA);
+        }
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string|null
+     */
+    public function getCertificatePem() {
+        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) {
+        $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 nonceToHash.
+        $nonceToHash = $this->_authenticatorData->getBinary();
+        $nonceToHash .= $clientDataHash;
+
+        // Perform SHA-256 hash of nonceToHash to produce nonce
+        $nonce = hash('SHA256', $nonceToHash, true);
+
+        $credCert = openssl_x509_read($this->getCertificatePem());
+        if ($credCert === false) {
+            throw new WebAuthnException('invalid x5c certificate: ' . \openssl_error_string(), WebAuthnException::INVALID_DATA);
+        }
+
+        $keyData = openssl_pkey_get_details(openssl_pkey_get_public($credCert));
+        $key = is_array($keyData) && array_key_exists('key', $keyData) ? $keyData['key'] : null;
+
+
+        // Verify that nonce equals the value of the extension with OID ( 1.2.840.113635.100.8.2 ) in credCert.
+        $parsedCredCert = openssl_x509_parse($credCert);
+        $nonceExtension = $parsedCredCert['extensions']['1.2.840.113635.100.8.2'] ?? '';
+
+        // nonce padded by ASN.1 string: 30 24 A1 22 04 20
+        // 30     — type tag indicating sequence
+        // 24     — 36 byte following
+        //   A1   — Enumerated [1]
+        //   22   — 34 byte following
+        //     04 — type tag indicating octet string
+        //     20 — 32 byte following
+
+        $asn1Padding = "\x30\x24\xA1\x22\x04\x20";
+        if (substr($nonceExtension, 0, strlen($asn1Padding)) === $asn1Padding) {
+            $nonceExtension = substr($nonceExtension, strlen($asn1Padding));
+        }
+
+        if ($nonceExtension !== $nonce) {
+            throw new WebAuthnException('nonce doesn\'t equal the value of the extension with OID 1.2.840.113635.100.8.2', WebAuthnException::INVALID_DATA);
+        }
+
+        // Verify that the credential public key equals the Subject Public Key of credCert.
+        $authKeyData = openssl_pkey_get_details(openssl_pkey_get_public($this->_authenticatorData->getPublicKeyPem()));
+        $authKey = is_array($authKeyData) && array_key_exists('key', $authKeyData) ? $authKeyData['key'] : null;
+
+        if ($key === null || $key !== $authKey) {
+            throw new WebAuthnException('credential public key doesn\'t equal the Subject Public Key of credCert', WebAuthnException::INVALID_DATA);
+        }
+
+        return true;
+    }
+
+}
+
diff --git a/src/lib/WebAuthn/Attestation/Format/FormatBase.php b/src/lib/WebAuthn/Attestation/Format/FormatBase.php
new file mode 100644
index 0000000..eed916b
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/FormatBase.php
@@ -0,0 +1,193 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+
+
+abstract class FormatBase {
+    protected $_attestationObject = null;
+    protected $_authenticatorData = null;
+    protected $_x5c_chain = array();
+    protected $_x5c_tempFile = null;
+
+    /**
+     *
+     * @param Array $AttestionObject
+     * @param AuthenticatorData $authenticatorData
+     */
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        $this->_attestationObject = $AttestionObject;
+        $this->_authenticatorData = $authenticatorData;
+    }
+
+    /**
+     *
+     */
+    public function __destruct() {
+        // delete X.509 chain certificate file after use
+        if ($this->_x5c_tempFile && \is_file($this->_x5c_tempFile)) {
+            \unlink($this->_x5c_tempFile);
+        }
+    }
+
+    /**
+     * returns the certificate chain in PEM format
+     * @return string|null
+     */
+    public function getCertificateChain() {
+        if ($this->_x5c_tempFile && \is_file($this->_x5c_tempFile)) {
+            return \file_get_contents($this->_x5c_tempFile);
+        }
+        return null;
+    }
+
+    /**
+     * returns the key X.509 certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        // need to be overwritten
+        return null;
+    }
+
+    /**
+     * checks validity of the signature
+     * @param string $clientDataHash
+     * @return bool
+     * @throws WebAuthnException
+     */
+    public function validateAttestation($clientDataHash) {
+        // need to be overwritten
+        return false;
+    }
+
+    /**
+     * validates the certificate against root certificates
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        // need to be overwritten
+        return false;
+    }
+
+
+    /**
+     * create a PEM encoded certificate with X.509 binary data
+     * @param string $x5c
+     * @return string
+     */
+    protected function _createCertificatePem($x5c) {
+        $pem = '-----BEGIN CERTIFICATE-----' . "\n";
+        $pem .= \chunk_split(\base64_encode($x5c), 64, "\n");
+        $pem .= '-----END CERTIFICATE-----' . "\n";
+        return $pem;
+    }
+
+    /**
+     * creates a PEM encoded chain file
+     * @return type
+     */
+    protected function _createX5cChainFile() {
+        $content = '';
+        if (\is_array($this->_x5c_chain) && \count($this->_x5c_chain) > 0) {
+            foreach ($this->_x5c_chain as $x5c) {
+                $certInfo = \openssl_x509_parse($this->_createCertificatePem($x5c));
+
+                // check if certificate is self signed
+                if (\is_array($certInfo) && \is_array($certInfo['issuer']) && \is_array($certInfo['subject'])) {
+                    $selfSigned = false;
+
+                    $subjectKeyIdentifier = $certInfo['extensions']['subjectKeyIdentifier'] ?? null;
+                    $authorityKeyIdentifier = $certInfo['extensions']['authorityKeyIdentifier'] ?? null;
+
+                    if ($authorityKeyIdentifier && substr($authorityKeyIdentifier, 0, 6) === 'keyid:') {
+                        $authorityKeyIdentifier = substr($authorityKeyIdentifier, 6);
+                    }
+                    if ($subjectKeyIdentifier && substr($subjectKeyIdentifier, 0, 6) === 'keyid:') {
+                        $subjectKeyIdentifier = substr($subjectKeyIdentifier, 6);
+                    }
+
+                    if (($subjectKeyIdentifier && !$authorityKeyIdentifier) || ($authorityKeyIdentifier && $authorityKeyIdentifier === $subjectKeyIdentifier)) {
+                        $selfSigned = true;
+                    }
+
+                    if (!$selfSigned) {
+                        $content .= "\n" . $this->_createCertificatePem($x5c) . "\n";
+                    }
+                }
+            }
+        }
+
+        if ($content) {
+            $this->_x5c_tempFile = \sys_get_temp_dir() . '/x5c_chain_' . \base_convert(\rand(), 10, 36) . '.pem';
+            if (\file_put_contents($this->_x5c_tempFile, $content) !== false) {
+                return $this->_x5c_tempFile;
+            }
+        }
+
+        return null;
+    }
+
+
+    /**
+     * returns the name and openssl key for provided cose number.
+     * @param int $coseNumber
+     * @return \stdClass|null
+     */
+    protected function _getCoseAlgorithm($coseNumber) {
+        // https://www.iana.org/assignments/cose/cose.xhtml#algorithms
+        $coseAlgorithms = array(
+            array(
+                'hash' => 'SHA1',
+                'openssl' => OPENSSL_ALGO_SHA1,
+                'cose' => array(
+                    -65535  // RS1
+                )),
+
+            array(
+                'hash' => 'SHA256',
+                'openssl' => OPENSSL_ALGO_SHA256,
+                'cose' => array(
+                    -257, // RS256
+                    -37,  // PS256
+                    -7,   // ES256
+                    5     // HMAC256
+                )),
+
+            array(
+                'hash' => 'SHA384',
+                'openssl' => OPENSSL_ALGO_SHA384,
+                'cose' => array(
+                    -258, // RS384
+                    -38,  // PS384
+                    -35,  // ES384
+                    6     // HMAC384
+                )),
+
+            array(
+                'hash' => 'SHA512',
+                'openssl' => OPENSSL_ALGO_SHA512,
+                'cose' => array(
+                    -259, // RS512
+                    -39,  // PS512
+                    -36,  // ES512
+                    7     // HMAC512
+                ))
+        );
+
+        foreach ($coseAlgorithms as $coseAlgorithm) {
+            if (\in_array($coseNumber, $coseAlgorithm['cose'], true)) {
+                $return = new \stdClass();
+                $return->hash = $coseAlgorithm['hash'];
+                $return->openssl = $coseAlgorithm['openssl'];
+                return $return;
+            }
+        }
+
+        return null;
+    }
+}
diff --git a/src/lib/WebAuthn/Attestation/Format/None.php b/src/lib/WebAuthn/Attestation/Format/None.php
new file mode 100644
index 0000000..ba95e40
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/None.php
@@ -0,0 +1,41 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+
+class None extends FormatBase {
+
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        return null;
+    }
+
+    /**
+     * @param string $clientDataHash
+     */
+    public function validateAttestation($clientDataHash) {
+        return true;
+    }
+
+    /**
+     * validates the certificate against root certificates.
+     * Format 'none' does not contain any ca, so always false.
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        return false;
+    }
+}
diff --git a/src/lib/WebAuthn/Attestation/Format/Packed.php b/src/lib/WebAuthn/Attestation/Format/Packed.php
new file mode 100644
index 0000000..c2ced07
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/Packed.php
@@ -0,0 +1,139 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class Packed extends FormatBase {
+    private $_alg;
+    private $_signature;
+    private $_x5c;
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+
+        // check packed data
+        $attStmt = $this->_attestationObject['attStmt'];
+
+        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('no signature found', WebAuthnException::INVALID_DATA);
+        }
+
+        $this->_alg = $attStmt['alg'];
+        $this->_signature = $attStmt['sig']->getBinaryString();
+
+        // 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[] = $chain->getBinaryString();
+                }
+            }
+        }
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string|null
+     */
+    public function getCertificatePem() {
+        if (!$this->_x5c) {
+            return null;
+        }
+        return $this->_createCertificatePem($this->_x5c);
+    }
+
+    /**
+     * @param string $clientDataHash
+     */
+    public function validateAttestation($clientDataHash) {
+        if ($this->_x5c) {
+            return $this->_validateOverX5c($clientDataHash);
+        } else {
+            return $this->_validateSelfAttestation($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);
+        }
+
+        // Verify that sig is a valid signature over the concatenation of authenticatorData and clientDataHash
+        // using the attestation public key in attestnCert with the algorithm specified in alg.
+        $dataToVerify = $this->_authenticatorData->getBinary();
+        $dataToVerify .= $clientDataHash;
+
+        $coseAlgorithm = $this->_getCoseAlgorithm($this->_alg);
+
+        // check certificate
+        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, $coseAlgorithm->openssl) === 1;
+    }
+
+    /**
+     * validate if self attestation is in use
+     * @param string $clientDataHash
+     * @return bool
+     */
+    protected function _validateSelfAttestation($clientDataHash) {
+        // Verify that sig is a valid signature over the concatenation of authenticatorData and clientDataHash
+        // using the credential public key with alg.
+        $dataToVerify = $this->_authenticatorData->getBinary();
+        $dataToVerify .= $clientDataHash;
+
+        $publicKey = $this->_authenticatorData->getPublicKeyPem();
+
+        // check certificate
+        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, OPENSSL_ALGO_SHA256) === 1;
+    }
+}
+
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);
+    }
+
+}
+
diff --git a/src/lib/WebAuthn/Attestation/Format/U2f.php b/src/lib/WebAuthn/Attestation/Format/U2f.php
new file mode 100644
index 0000000..2b51ba8
--- /dev/null
+++ b/src/lib/WebAuthn/Attestation/Format/U2f.php
@@ -0,0 +1,93 @@
+<?php
+
+
+namespace lbuchs\WebAuthn\Attestation\Format;
+use lbuchs\WebAuthn\Attestation\AuthenticatorData;
+use lbuchs\WebAuthn\WebAuthnException;
+use lbuchs\WebAuthn\Binary\ByteBuffer;
+
+class U2f extends FormatBase {
+    private $_alg = -7;
+    private $_signature;
+    private $_x5c;
+
+    public function __construct($AttestionObject, AuthenticatorData $authenticatorData) {
+        parent::__construct($AttestionObject, $authenticatorData);
+
+        // check u2f data
+        $attStmt = $this->_attestationObject['attStmt'];
+
+        if (\array_key_exists('alg', $attStmt) && $attStmt['alg'] !== $this->_alg) {
+            throw new WebAuthnException('u2f only accepts algorithm -7 ("ES256"), but got ' . $attStmt['alg'], WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('sig', $attStmt) || !\is_object($attStmt['sig']) || !($attStmt['sig'] instanceof ByteBuffer)) {
+            throw new WebAuthnException('no signature found', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\array_key_exists('x5c', $attStmt) || !\is_array($attStmt['x5c']) || \count($attStmt['x5c']) !== 1) {
+            throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
+        }
+
+        if (!\is_object($attStmt['x5c'][0]) || !($attStmt['x5c'][0] instanceof ByteBuffer)) {
+            throw new WebAuthnException('invalid x5c certificate', WebAuthnException::INVALID_DATA);
+        }
+
+        $this->_signature = $attStmt['sig']->getBinaryString();
+        $this->_x5c = $attStmt['x5c'][0]->getBinaryString();
+    }
+
+
+    /*
+     * returns the key certificate in PEM format
+     * @return string
+     */
+    public function getCertificatePem() {
+        $pem = '-----BEGIN CERTIFICATE-----' . "\n";
+        $pem .= \chunk_split(\base64_encode($this->_x5c), 64, "\n");
+        $pem .= '-----END CERTIFICATE-----' . "\n";
+        return $pem;
+    }
+
+    /**
+     * @param string $clientDataHash
+     */
+    public function validateAttestation($clientDataHash) {
+        $publicKey = \openssl_pkey_get_public($this->getCertificatePem());
+
+        if ($publicKey === false) {
+            throw new WebAuthnException('invalid public key: ' . \openssl_error_string(), WebAuthnException::INVALID_PUBLIC_KEY);
+        }
+
+        // Let verificationData be the concatenation of (0x00 || rpIdHash || clientDataHash || credentialId || publicKeyU2F)
+        $dataToVerify = "\x00";
+        $dataToVerify .= $this->_authenticatorData->getRpIdHash();
+        $dataToVerify .= $clientDataHash;
+        $dataToVerify .= $this->_authenticatorData->getCredentialId();
+        $dataToVerify .= $this->_authenticatorData->getPublicKeyU2F();
+
+        $coseAlgorithm = $this->_getCoseAlgorithm($this->_alg);
+
+        // check certificate
+        return \openssl_verify($dataToVerify, $this->_signature, $publicKey, $coseAlgorithm->openssl) === 1;
+    }
+
+    /**
+     * validates the certificate against root certificates
+     * @param array $rootCas
+     * @return boolean
+     * @throws WebAuthnException
+     */
+    public function validateRootCertificate($rootCas) {
+        $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;
+    }
+}