Exemple #1
0
func (client *clientImpl) getTCertsFromTCA(attrhash string, attributes []string, num int) error {
	client.Debugf("Get [%d] certificates from the TCA...", num)

	// Contact the TCA
	TCertOwnerKDFKey, certDERs, err := client.callTCACreateCertificateSet(num, attributes)
	if err != nil {
		client.Debugf("Failed contacting TCA [%s].", err.Error())

		return err
	}

	//	client.debug("TCertOwnerKDFKey [%s].", utils.EncodeBase64(TCertOwnerKDFKey))

	// Store TCertOwnerKDFKey and checks that every time it is always the same key
	if client.tCertOwnerKDFKey != nil {
		// Check that the keys are the same
		equal := bytes.Equal(client.tCertOwnerKDFKey, TCertOwnerKDFKey)
		if !equal {
			return errors.New("Failed reciving kdf key from TCA. The keys are different.")
		}
	} else {
		client.tCertOwnerKDFKey = TCertOwnerKDFKey

		// TODO: handle this situation more carefully
		if err := client.storeTCertOwnerKDFKey(); err != nil {
			client.Errorf("Failed storing TCertOwnerKDFKey [%s].", err.Error())

			return err
		}
	}

	// Validate the Certificates obtained

	TCertOwnerEncryptKey := primitives.HMACAESTruncated(client.tCertOwnerKDFKey, []byte{1})
	ExpansionKey := primitives.HMAC(client.tCertOwnerKDFKey, []byte{2})

	j := 0
	for i := 0; i < num; i++ {
		// DER to x509
		x509Cert, err := primitives.DERToX509Certificate(certDERs[i].Cert)
		prek0 := certDERs[i].Prek0
		if err != nil {
			client.Debugf("Failed parsing certificate [% x]: [%s].", certDERs[i].Cert, err)

			continue
		}

		// Handle Critical Extenstion TCertEncTCertIndex
		tCertIndexCT, err := primitives.GetCriticalExtension(x509Cert, primitives.TCertEncTCertIndex)
		if err != nil {
			client.Errorf("Failed getting extension TCERT_ENC_TCERTINDEX [% x]: [%s].", primitives.TCertEncTCertIndex, err)

			continue
		}

		// Verify certificate against root
		if _, err := primitives.CheckCertAgainRoot(x509Cert, client.tcaCertPool); err != nil {
			client.Warningf("Warning verifing certificate [%s].", err.Error())

			continue
		}

		// Verify public key

		// 384-bit ExpansionValue = HMAC(Expansion_Key, TCertIndex)
		// Let TCertIndex = Timestamp, RandValue, 1,2,…
		// Timestamp assigned, RandValue assigned and counter reinitialized to 1 per batch

		// Decrypt ct to TCertIndex (TODO: || EnrollPub_Key || EnrollID ?)
		pt, err := primitives.CBCPKCS7Decrypt(TCertOwnerEncryptKey, tCertIndexCT)
		if err != nil {
			client.Errorf("Failed decrypting extension TCERT_ENC_TCERTINDEX [%s].", err.Error())

			continue
		}

		// Compute ExpansionValue based on TCertIndex
		TCertIndex := pt
		//		TCertIndex := []byte(strconv.Itoa(i))

		client.Debugf("TCertIndex: [% x].", TCertIndex)
		mac := hmac.New(primitives.NewHash, ExpansionKey)
		mac.Write(TCertIndex)
		ExpansionValue := mac.Sum(nil)

		// Derive tpk and tsk accordingly to ExpansionValue from enrollment pk,sk
		// Computable by TCA / Auditor: TCertPub_Key = EnrollPub_Key + ExpansionValue G
		// using elliptic curve point addition per NIST FIPS PUB 186-4- specified P-384

		// Compute temporary secret key
		tempSK := &ecdsa.PrivateKey{
			PublicKey: ecdsa.PublicKey{
				Curve: client.enrollPrivKey.Curve,
				X:     new(big.Int),
				Y:     new(big.Int),
			},
			D: new(big.Int),
		}

		var k = new(big.Int).SetBytes(ExpansionValue)
		var one = new(big.Int).SetInt64(1)
		n := new(big.Int).Sub(client.enrollPrivKey.Params().N, one)
		k.Mod(k, n)
		k.Add(k, one)

		tempSK.D.Add(client.enrollPrivKey.D, k)
		tempSK.D.Mod(tempSK.D, client.enrollPrivKey.PublicKey.Params().N)

		// Compute temporary public key
		tempX, tempY := client.enrollPrivKey.PublicKey.ScalarBaseMult(k.Bytes())
		tempSK.PublicKey.X, tempSK.PublicKey.Y =
			tempSK.PublicKey.Add(
				client.enrollPrivKey.PublicKey.X, client.enrollPrivKey.PublicKey.Y,
				tempX, tempY,
			)

		// Verify temporary public key is a valid point on the reference curve
		isOn := tempSK.Curve.IsOnCurve(tempSK.PublicKey.X, tempSK.PublicKey.Y)
		if !isOn {
			client.Error("Failed temporary public key IsOnCurve check.")

			continue
		}

		// Check that the derived public key is the same as the one in the certificate
		certPK := x509Cert.PublicKey.(*ecdsa.PublicKey)

		if certPK.X.Cmp(tempSK.PublicKey.X) != 0 {
			client.Error("Derived public key is different on X")

			continue
		}

		if certPK.Y.Cmp(tempSK.PublicKey.Y) != 0 {
			client.Error("Derived public key is different on Y")

			continue
		}

		// Verify the signing capability of tempSK
		err = primitives.VerifySignCapability(tempSK, x509Cert.PublicKey)
		if err != nil {
			client.Errorf("Failed verifing signing capability [%s].", err.Error())

			continue
		}

		// Marshall certificate and secret key to be stored in the database
		if err != nil {
			client.Errorf("Failed marshalling private key [%s].", err.Error())

			continue
		}

		if err := primitives.CheckCertPKAgainstSK(x509Cert, interface{}(tempSK)); err != nil {
			client.Errorf("Failed checking TCA cert PK against private key [%s].", err.Error())

			continue
		}

		client.Debugf("Sub index [%d]", j)
		j++
		client.Debugf("Certificate [%d] validated.", i)

		prek0Cp := make([]byte, len(prek0))
		copy(prek0Cp, prek0)

		tcertBlk := new(TCertBlock)

		tcertBlk.tCert = &tCertImpl{client, x509Cert, tempSK, prek0Cp}
		tcertBlk.attributesHash = attrhash

		client.tCertPool.AddTCert(tcertBlk)
	}

	if j == 0 {
		client.Error("No valid TCert was sent")

		return errors.New("No valid TCert was sent.")
	}

	return nil
}
Exemple #2
0
func (client *clientImpl) getTCertFromExternalDER(der []byte) (tCert, error) {
	// DER to x509
	x509Cert, err := primitives.DERToX509Certificate(der)
	if err != nil {
		client.Debugf("Failed parsing certificate [% x]: [%s].", der, err)

		return nil, err
	}

	// Handle Critical Extension TCertEncTCertIndex
	tCertIndexCT, err := primitives.GetCriticalExtension(x509Cert, primitives.TCertEncTCertIndex)
	if err != nil {
		client.Errorf("Failed getting extension TCERT_ENC_TCERTINDEX [% x]: [%s].", der, err)

		return nil, err
	}

	// Handle Critical Extension TCertEncEnrollmentID TODO validate encEnrollmentID
	_, err = primitives.GetCriticalExtension(x509Cert, primitives.TCertEncEnrollmentID)
	if err != nil {
		client.Errorf("Failed getting extension TCERT_ENC_ENROLLMENT_ID [%s].", err.Error())

		return nil, err
	}

	// Handle Critical Extension TCertAttributes
	//	for i := 0; i < len(x509Cert.Extensions) - 2; i++ {
	//		attributeExtensionIdentifier := append(utils.TCertEncAttributesBase, i + 9)
	//		_ , err = utils.GetCriticalExtension(x509Cert, attributeExtensionIdentifier)
	//		if err != nil {
	//			client.Errorf("Failed getting extension TCERT_ATTRIBUTE_%s [%s].", i, err.Error())
	//
	//			return nil, err
	//		}
	//	}

	// Verify certificate against root
	if _, err := primitives.CheckCertAgainRoot(x509Cert, client.tcaCertPool); err != nil {
		client.Warningf("Warning verifing certificate [% x]: [%s].", der, err)

		return nil, err
	}

	// Try to extract the signing key from the TCert by decrypting the TCertIndex

	// 384-bit ExpansionValue = HMAC(Expansion_Key, TCertIndex)
	// Let TCertIndex = Timestamp, RandValue, 1,2,…
	// Timestamp assigned, RandValue assigned and counter reinitialized to 1 per batch
	// Decrypt ct to TCertIndex (TODO: || EnrollPub_Key || EnrollID ?)
	TCertOwnerEncryptKey := primitives.HMACAESTruncated(client.tCertOwnerKDFKey, []byte{1})
	ExpansionKey := primitives.HMAC(client.tCertOwnerKDFKey, []byte{2})
	pt, err := primitives.CBCPKCS7Decrypt(TCertOwnerEncryptKey, tCertIndexCT)

	if err == nil {
		// Compute ExpansionValue based on TCertIndex
		TCertIndex := pt
		//		TCertIndex := []byte(strconv.Itoa(i))

		// TODO: verify that TCertIndex has right format.

		client.Debugf("TCertIndex: [% x].", TCertIndex)
		mac := hmac.New(primitives.NewHash, ExpansionKey)
		mac.Write(TCertIndex)
		ExpansionValue := mac.Sum(nil)

		// Derive tpk and tsk accordingly to ExpansionValue from enrollment pk,sk
		// Computable by TCA / Auditor: TCertPub_Key = EnrollPub_Key + ExpansionValue G
		// using elliptic curve point addition per NIST FIPS PUB 186-4- specified P-384

		// Compute temporary secret key
		tempSK := &ecdsa.PrivateKey{
			PublicKey: ecdsa.PublicKey{
				Curve: client.enrollPrivKey.Curve,
				X:     new(big.Int),
				Y:     new(big.Int),
			},
			D: new(big.Int),
		}

		var k = new(big.Int).SetBytes(ExpansionValue)
		var one = new(big.Int).SetInt64(1)
		n := new(big.Int).Sub(client.enrollPrivKey.Params().N, one)
		k.Mod(k, n)
		k.Add(k, one)

		tempSK.D.Add(client.enrollPrivKey.D, k)
		tempSK.D.Mod(tempSK.D, client.enrollPrivKey.PublicKey.Params().N)

		// Compute temporary public key
		tempX, tempY := client.enrollPrivKey.PublicKey.ScalarBaseMult(k.Bytes())
		tempSK.PublicKey.X, tempSK.PublicKey.Y =
			tempSK.PublicKey.Add(
				client.enrollPrivKey.PublicKey.X, client.enrollPrivKey.PublicKey.Y,
				tempX, tempY,
			)

		// Verify temporary public key is a valid point on the reference curve
		isOn := tempSK.Curve.IsOnCurve(tempSK.PublicKey.X, tempSK.PublicKey.Y)
		if !isOn {
			client.Warning("Failed temporary public key IsOnCurve check. This is an foreign certificate.")

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		// Check that the derived public key is the same as the one in the certificate
		certPK := x509Cert.PublicKey.(*ecdsa.PublicKey)

		if certPK.X.Cmp(tempSK.PublicKey.X) != 0 {
			client.Warning("Derived public key is different on X. This is an foreign certificate.")

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		if certPK.Y.Cmp(tempSK.PublicKey.Y) != 0 {
			client.Warning("Derived public key is different on Y. This is an foreign certificate.")

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		// Verify the signing capability of tempSK
		err = primitives.VerifySignCapability(tempSK, x509Cert.PublicKey)
		if err != nil {
			client.Warning("Failed verifing signing capability [%s]. This is an foreign certificate.", err.Error())

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		// Marshall certificate and secret key to be stored in the database
		if err != nil {
			client.Warningf("Failed marshalling private key [%s]. This is an foreign certificate.", err.Error())

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		if err = primitives.CheckCertPKAgainstSK(x509Cert, interface{}(tempSK)); err != nil {
			client.Warningf("Failed checking TCA cert PK against private key [%s]. This is an foreign certificate.", err.Error())

			return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
		}

		return &tCertImpl{client, x509Cert, tempSK, []byte{}}, nil
	}
	client.Warningf("Failed decrypting extension TCERT_ENC_TCERTINDEX [%s]. This is an foreign certificate.", err.Error())
	return &tCertImpl{client, x509Cert, nil, []byte{}}, nil
}
Exemple #3
0
func (client *clientImpl) getTCertFromDER(certBlk *TCertDBBlock) (certBlock *TCertBlock, err error) {
	if client.tCertOwnerKDFKey == nil {
		return nil, fmt.Errorf("KDF key not initialized yet")
	}

	TCertOwnerEncryptKey := primitives.HMACAESTruncated(client.tCertOwnerKDFKey, []byte{1})
	ExpansionKey := primitives.HMAC(client.tCertOwnerKDFKey, []byte{2})

	// DER to x509
	x509Cert, err := primitives.DERToX509Certificate(certBlk.tCertDER)
	if err != nil {
		client.Debugf("Failed parsing certificate [% x]: [%s].", certBlk.tCertDER, err)

		return
	}

	// Handle Critical Extenstion TCertEncTCertIndex
	tCertIndexCT, err := primitives.GetCriticalExtension(x509Cert, primitives.TCertEncTCertIndex)
	if err != nil {
		client.Errorf("Failed getting extension TCERT_ENC_TCERTINDEX [%v].", err.Error())

		return
	}

	// Verify certificate against root
	if _, err = primitives.CheckCertAgainRoot(x509Cert, client.tcaCertPool); err != nil {
		client.Warningf("Warning verifing certificate [%s].", err.Error())

		return
	}

	// Verify public key

	// 384-bit ExpansionValue = HMAC(Expansion_Key, TCertIndex)
	// Let TCertIndex = Timestamp, RandValue, 1,2,…
	// Timestamp assigned, RandValue assigned and counter reinitialized to 1 per batch

	// Decrypt ct to TCertIndex (TODO: || EnrollPub_Key || EnrollID ?)
	pt, err := primitives.CBCPKCS7Decrypt(TCertOwnerEncryptKey, tCertIndexCT)
	if err != nil {
		client.Errorf("Failed decrypting extension TCERT_ENC_TCERTINDEX [%s].", err.Error())

		return
	}

	// Compute ExpansionValue based on TCertIndex
	TCertIndex := pt
	//		TCertIndex := []byte(strconv.Itoa(i))

	client.Debugf("TCertIndex: [% x].", TCertIndex)
	mac := hmac.New(primitives.NewHash, ExpansionKey)
	mac.Write(TCertIndex)
	ExpansionValue := mac.Sum(nil)

	// Derive tpk and tsk accordingly to ExpansionValue from enrollment pk,sk
	// Computable by TCA / Auditor: TCertPub_Key = EnrollPub_Key + ExpansionValue G
	// using elliptic curve point addition per NIST FIPS PUB 186-4- specified P-384

	// Compute temporary secret key
	tempSK := &ecdsa.PrivateKey{
		PublicKey: ecdsa.PublicKey{
			Curve: client.enrollPrivKey.Curve,
			X:     new(big.Int),
			Y:     new(big.Int),
		},
		D: new(big.Int),
	}

	var k = new(big.Int).SetBytes(ExpansionValue)
	var one = new(big.Int).SetInt64(1)
	n := new(big.Int).Sub(client.enrollPrivKey.Params().N, one)
	k.Mod(k, n)
	k.Add(k, one)

	tempSK.D.Add(client.enrollPrivKey.D, k)
	tempSK.D.Mod(tempSK.D, client.enrollPrivKey.PublicKey.Params().N)

	// Compute temporary public key
	tempX, tempY := client.enrollPrivKey.PublicKey.ScalarBaseMult(k.Bytes())
	tempSK.PublicKey.X, tempSK.PublicKey.Y =
		tempSK.PublicKey.Add(
			client.enrollPrivKey.PublicKey.X, client.enrollPrivKey.PublicKey.Y,
			tempX, tempY,
		)

	// Verify temporary public key is a valid point on the reference curve
	isOn := tempSK.Curve.IsOnCurve(tempSK.PublicKey.X, tempSK.PublicKey.Y)
	if !isOn {
		client.Error("Failed temporary public key IsOnCurve check.")

		return nil, fmt.Errorf("Failed temporary public key IsOnCurve check.")
	}

	// Check that the derived public key is the same as the one in the certificate
	certPK := x509Cert.PublicKey.(*ecdsa.PublicKey)

	if certPK.X.Cmp(tempSK.PublicKey.X) != 0 {
		client.Error("Derived public key is different on X")

		return nil, fmt.Errorf("Derived public key is different on X")
	}

	if certPK.Y.Cmp(tempSK.PublicKey.Y) != 0 {
		client.Error("Derived public key is different on Y")

		return nil, fmt.Errorf("Derived public key is different on Y")
	}

	// Verify the signing capability of tempSK
	err = primitives.VerifySignCapability(tempSK, x509Cert.PublicKey)
	if err != nil {
		client.Errorf("Failed verifing signing capability [%s].", err.Error())

		return
	}

	// Marshall certificate and secret key to be stored in the database
	if err != nil {
		client.Errorf("Failed marshalling private key [%s].", err.Error())

		return
	}

	if err = primitives.CheckCertPKAgainstSK(x509Cert, interface{}(tempSK)); err != nil {
		client.Errorf("Failed checking TCA cert PK against private key [%s].", err.Error())

		return
	}

	certBlock = &TCertBlock{&tCertImpl{client, x509Cert, tempSK, certBlk.preK0}, certBlk.attributesHash}

	return
}