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
}