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 }
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 }
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 }