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Support for Factory attestation and removed RKP
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@subrahmanyaman
subrahmanyaman committed Dec 2, 2022
1 parent f79a011 commit deba5a4
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Showing 58 changed files with 993 additions and 6,432 deletions.
209 changes: 123 additions & 86 deletions Applet/AndroidSEProvider/src/com/android/javacard/keymaster/KMAndroidSEApplet.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,6 @@
import org.globalplatform.upgrade.UpgradeManager;

import com.android.javacard.seprovider.KMAndroidSEProvider;
import com.android.javacard.seprovider.KMDeviceUniqueKeyPair;
import com.android.javacard.seprovider.KMError;
import com.android.javacard.seprovider.KMException;
import com.android.javacard.seprovider.KMType;
Expand All @@ -38,12 +37,12 @@ public class KMAndroidSEApplet extends KMKeymasterApplet implements OnUpgradeLis
// MSB byte is for Major version and LSB byte is for Minor version.
public static final short KM_APPLET_PACKAGE_VERSION = 0x0300;

private static final byte KM_BEGIN_STATE = 0x00;
private static final byte ILLEGAL_STATE = KM_BEGIN_STATE + 1;
private static final short POWER_RESET_MASK_FLAG = (short) 0x4000;

// Provider specific Commands
private static final byte INS_KEYMINT_PROVIDER_APDU_START = 0x00;
private static final byte INS_PROVISION_ATTESTATION_KEY_CMD = INS_KEYMINT_PROVIDER_APDU_START + 1; //0x01
private static final byte INS_PROVISION_ATTESTATION_CERT_DATA_CMD = INS_KEYMINT_PROVIDER_APDU_START + 2; //0x02
private static final byte INS_PROVISION_ATTEST_IDS_CMD = INS_KEYMINT_PROVIDER_APDU_START + 3;
// Commands 4, 5 and 6 are reserved for vendor usage.
private static final byte INS_GET_PROVISION_STATUS_CMD = INS_KEYMINT_PROVIDER_APDU_START + 7;
Expand All @@ -52,10 +51,7 @@ public class KMAndroidSEApplet extends KMKeymasterApplet implements OnUpgradeLis
private static final byte INS_SE_FACTORY_PROVISIONING_LOCK_CMD = INS_KEYMINT_PROVIDER_APDU_START + 10;
private static final byte INS_PROVISION_OEM_ROOT_PUBLIC_KEY_CMD = INS_KEYMINT_PROVIDER_APDU_START + 11;
private static final byte INS_OEM_UNLOCK_PROVISIONING_CMD = INS_KEYMINT_PROVIDER_APDU_START + 12;
private static final byte INS_PROVISION_RKP_DEVICE_UNIQUE_KEYPAIR_CMD =
INS_KEYMINT_PROVIDER_APDU_START + 13;
private static final byte INS_PROVISION_RKP_ADDITIONAL_CERT_CHAIN_CMD =
INS_KEYMINT_PROVIDER_APDU_START + 14;
// 13 and 14 are reserved for RKP Device UniqueKeyPair and Cert chain.
private static final byte INS_PROVISION_PRESHARED_SECRET_CMD =
INS_KEYMINT_PROVIDER_APDU_START + 15;
private static final byte INS_SET_BOOT_PARAMS_CMD = INS_KEYMINT_PROVIDER_APDU_START + 16; // Unused
Expand Down Expand Up @@ -131,12 +127,12 @@ public void process(APDU apdu) {
processGetProvisionStatusCmd(apdu);
break;

case INS_PROVISION_RKP_DEVICE_UNIQUE_KEYPAIR_CMD:
processProvisionRkpDeviceUniqueKeyPair(apdu);
case INS_PROVISION_ATTESTATION_KEY_CMD:
processProvisionAttestationKey(apdu);
break;

case INS_PROVISION_RKP_ADDITIONAL_CERT_CHAIN_CMD:
processProvisionRkpAdditionalCertChain(apdu);
case INS_PROVISION_ATTESTATION_CERT_DATA_CMD:
processProvisionAttestationCertDataCmd(apdu);
break;

case INS_SE_FACTORY_PROVISIONING_LOCK_CMD:
Expand Down Expand Up @@ -217,8 +213,8 @@ && isSeFactoryProvisioningLocked())) {
}
break;

case INS_PROVISION_RKP_DEVICE_UNIQUE_KEYPAIR_CMD:
case INS_PROVISION_RKP_ADDITIONAL_CERT_CHAIN_CMD:
case INS_PROVISION_ATTESTATION_KEY_CMD:
case INS_PROVISION_ATTESTATION_CERT_DATA_CMD:
if(isSeFactoryProvisioningLocked()) {
result = false;
}
Expand Down Expand Up @@ -247,8 +243,10 @@ private boolean isSeFactoryProvisioningLocked() {

private boolean isSeFactoryProvisioningComplete() {
short pStatus = kmDataStore.getProvisionStatus();
if (PROVISION_STATUS_DEVICE_UNIQUE_KEYPAIR ==
(pStatus & PROVISION_STATUS_DEVICE_UNIQUE_KEYPAIR)) {
short completeStatus = PROVISION_STATUS_ATTESTATION_CERT_CHAIN |
PROVISION_STATUS_ATTESTATION_KEY |
PROVISION_STATUS_ATTESTATION_CERT_PARAMS;
if (completeStatus == (pStatus & completeStatus)) {
return true;
}
return false;
Expand Down Expand Up @@ -304,7 +302,6 @@ private void authenticateOEM(byte[] plainMsg, APDU apdu) {

private void processProvisionOEMRootPublicKeyCmd(APDU apdu) {
// Re-purpose the apdu buffer as scratch pad.
byte[] scratchPad = apdu.getBuffer();
// Arguments
short keyparams = KMKeyParameters.exp();
short keyFormatPtr = KMEnum.instance(KMType.KEY_FORMAT);
Expand Down Expand Up @@ -366,72 +363,6 @@ private void processProvisionOEMRootPublicKeyCmd(APDU apdu) {
KMByteBlob.cast(tmpVariables[0]).length());
}

private static void processProvisionRkpDeviceUniqueKeyPair(APDU apdu) {
// Re-purpose the apdu buffer as scratch pad.
byte[] scratchPad = apdu.getBuffer();
short arr = KMArray.instance((short) 1);
short coseKeyExp = KMCoseKey.exp();
KMArray.cast(arr).add((short) 0, coseKeyExp); //[ CoseKey ]
arr = receiveIncoming(apdu, arr);
// Get cose key.
short coseKey = KMArray.cast(arr).get((short) 0);
short pubKeyLen = KMCoseKey.cast(coseKey).getEcdsa256PublicKey(scratchPad, (short) 0);
short privKeyLen = KMCoseKey.cast(coseKey).getPrivateKey(scratchPad, pubKeyLen);
//Store the Device unique Key.
kmDataStore.createRkpDeviceUniqueKeyPair(scratchPad, (short) 0, pubKeyLen, scratchPad,
pubKeyLen, privKeyLen);
short bcc = generateBcc(false, scratchPad);
short len = KMKeymasterApplet.encodeToApduBuffer(bcc, scratchPad, (short) 0,
MAX_COSE_BUF_SIZE);
kmDataStore.persistBootCertificateChain(scratchPad, (short) 0, len);
kmDataStore.setProvisionStatus(PROVISION_STATUS_DEVICE_UNIQUE_KEYPAIR);
sendResponse(apdu, KMError.OK);
}

private void processProvisionRkpAdditionalCertChain(APDU apdu) {
// X509 certificate chain is received as shown below:
/**
* x509CertChain = bstr .cbor UdsCerts
*
* AdditionalDKSignatures = {
* * SignerName => DKCertChain
* }
* ; SignerName is a string identifier that indicates both the signing authority as
* ; well as the format of the DKCertChain
* SignerName = tstr
*
* DKCertChain = [
* 2* X509Certificate ; Root -> ... -> Leaf. "Root" is the vendor self-signed
* ; cert, "Leaf" contains DK_pub. There may also be
* ; intermediate certificates between Root and Leaf.
* ]
* ; A bstr containing a DER-encoded X.509 certificate (RSA, NIST P-curve, or edDSA)
* X509Certificate = bstr
*/
// Store the cbor encoded UdsCerts as it is in the persistent memory so cbor decoding is
// required here.
byte[] srcBuffer = apdu.getBuffer();
short recvLen = apdu.setIncomingAndReceive();
short srcOffset = apdu.getOffsetCdata();
short bufferLength = apdu.getIncomingLength();
short bufferStartOffset = repository.allocReclaimableMemory(bufferLength);
short index = bufferStartOffset;
byte[] buffer = repository.getHeap();
while (recvLen > 0 && ((short) (index - bufferStartOffset) < bufferLength)) {
Util.arrayCopyNonAtomic(srcBuffer, srcOffset, buffer, index, recvLen);
index += recvLen;
recvLen = apdu.receiveBytes(srcOffset);
}
short byteHeaderLen = decoder.readCertificateChainHeaderLen(buffer, bufferStartOffset,
bufferLength);
kmDataStore.persistAdditionalCertChain(buffer, (short) (bufferStartOffset + byteHeaderLen),
(short) (bufferLength - byteHeaderLen));
kmDataStore.setProvisionStatus(PROVISION_STATUS_ADDITIONAL_CERT_CHAIN);
// reclaim memory
repository.reclaimMemory(bufferLength);
sendResponse(apdu, KMError.OK);
}

private void processProvisionAttestIdsCmd(APDU apdu) {
short keyparams = KMKeyParameters.exp();
short cmd = KMArray.instance((short) 1);
Expand Down Expand Up @@ -488,6 +419,113 @@ private void processProvisionPreSharedSecretCmd(APDU apdu) {
KMByteBlob.cast(val).length());

}

private void processProvisionAttestationKey(APDU apdu) {
// Re-purpose the apdu buffer as scratch pad.
byte[] scratchPad = apdu.getBuffer();
// Arguments
short keyparams = KMKeyParameters.exp();
short keyFormatPtr = KMEnum.instance(KMType.KEY_FORMAT);
short blob = KMByteBlob.exp();
short argsProto = KMArray.instance((short) 3);
KMArray.cast(argsProto).add((short) 0, keyparams);
KMArray.cast(argsProto).add((short) 1, keyFormatPtr);
KMArray.cast(argsProto).add((short) 2, blob);
short args = receiveIncoming(apdu, argsProto);

// key params should have os patch, os version and verified root of trust
data[KEY_PARAMETERS] = KMArray.cast(args).get((short) 0);
tmpVariables[0] = KMArray.cast(args).get((short) 1);
data[IMPORTED_KEY_BLOB] = KMArray.cast(args).get((short) 2);
// Key format must be RAW format
byte keyFormat = KMEnum.cast(tmpVariables[0]).getVal();
if (keyFormat != KMType.RAW) {
KMException.throwIt(KMError.UNIMPLEMENTED);
}
data[ORIGIN] = KMType.IMPORTED;

// get algorithm - only EC keys expected
tmpVariables[0] = KMEnumTag.getValue(KMType.ALGORITHM, data[KEY_PARAMETERS]);
if (tmpVariables[0] != KMType.EC) {
KMException.throwIt(KMError.INVALID_ARGUMENT);
}
// get digest - only SHA256 supported
tmpVariables[0] =
KMKeyParameters.findTag(KMType.ENUM_ARRAY_TAG, KMType.DIGEST, data[KEY_PARAMETERS]);
if (tmpVariables[0] != KMType.INVALID_VALUE) {
if (KMEnumArrayTag.cast(tmpVariables[0]).length() != 1) {
KMException.throwIt(KMError.INVALID_ARGUMENT);
}
tmpVariables[0] = KMEnumArrayTag.cast(tmpVariables[0]).get((short) 0);
if (tmpVariables[0] != KMType.SHA2_256) {
KMException.throwIt(KMError.INCOMPATIBLE_DIGEST);
}
} else {
KMException.throwIt(KMError.INVALID_ARGUMENT);
}
// Purpose should be ATTEST_KEY
tmpVariables[0] =
KMKeyParameters.findTag(KMType.ENUM_ARRAY_TAG, KMType.PURPOSE, data[KEY_PARAMETERS]);
if (tmpVariables[0] != KMType.INVALID_VALUE) {
if (KMEnumArrayTag.cast(tmpVariables[0]).length() != 1) {
KMException.throwIt(KMError.INVALID_ARGUMENT);
}
tmpVariables[0] = KMEnumArrayTag.cast(tmpVariables[0]).get((short) 0);
if (tmpVariables[0] != KMType.ATTEST_KEY) {
KMException.throwIt(KMError.INCOMPATIBLE_PURPOSE);
}
} else {
KMException.throwIt(KMError.INVALID_ARGUMENT);
}
// Import EC Key - initializes data[SECRET] data[PUB_KEY]
importECKeys(scratchPad, keyFormat);
// persist key
kmDataStore.createAttestationKeyPair(
KMByteBlob.cast(data[SECRET]).getBuffer(),
KMByteBlob.cast(data[SECRET]).getStartOff(),
KMByteBlob.cast(data[SECRET]).length());
kmDataStore.setProvisionStatus(PROVISION_STATUS_ATTESTATION_KEY);
sendResponse(apdu, KMError.OK);
}

private void processProvisionAttestationCertDataCmd(APDU apdu) {
byte[] srcBuffer = apdu.getBuffer();
short recvLen = apdu.setIncomingAndReceive();
short srcOffset = apdu.getOffsetCdata();
short bufferLength = apdu.getIncomingLength();
short bufferStartOffset = repository.allocReclaimableMemory(bufferLength);
short index = bufferStartOffset;
byte[] buffer = repository.getHeap();
while (recvLen > 0 && ((short) (index - bufferStartOffset) < bufferLength)) {
Util.arrayCopyNonAtomic(srcBuffer, srcOffset, buffer, index, recvLen);
index += recvLen;
recvLen = apdu.receiveBytes(srcOffset);
}
// CertificateData = [
// X509CertifcateChain: bstr, ; DER encoded X.509 certificate chain ordered from Leaf to Root.
// Issuer: bstr, ; DER encoded subject field
// ]

// srcBuffer holds the corresponding offsets and lengths of the certChain, certIssuer and certExpiry
// respectively in the input buffer.
decoder.decodeCertificateData((short) 2, /* Length of the input array */
buffer, bufferStartOffset, bufferLength, srcBuffer, (short) 0);
// Persist data.
// The offset and length of the CertChain in the input buffer are stored in the srcBuffer
// at 0th and 2nd positions respectively.
kmDataStore.persistAttestationCertChain(buffer,
Util.getShort(srcBuffer, (short) 0), Util.getShort(srcBuffer, (short) 2));
// The offset and length of the CertIssuer in the input buffer are stored in the srcBuffer
// at 4th and 6th positions respectively.
kmDataStore.persistAttestationCertIssuer(buffer,
Util.getShort(srcBuffer, (short) 4), Util.getShort(srcBuffer, (short) 6));

// reclaim memory
repository.reclaimMemory(bufferLength);
kmDataStore.setProvisionStatus(
(short) (PROVISION_STATUS_ATTESTATION_CERT_CHAIN | PROVISION_STATUS_ATTESTATION_CERT_PARAMS));
sendResponse(apdu, KMError.OK);
}

//This function masks the error code with POWER_RESET_MASK_FLAG
// in case if card reset event occurred. The clients of the Applet
Expand Down Expand Up @@ -524,10 +562,9 @@ private void processGetProvisionStatusCmd(APDU apdu) {

private boolean isProvisioningComplete() {
short pStatus = kmDataStore.getProvisionStatus();
short pCompleteStatus =
PROVISION_STATUS_DEVICE_UNIQUE_KEYPAIR | PROVISION_STATUS_PRESHARED_SECRET
| PROVISION_STATUS_ATTEST_IDS | PROVISION_STATUS_OEM_PUBLIC_KEY |
PROVISION_STATUS_SECURE_BOOT_MODE;
short pCompleteStatus = PROVISION_STATUS_ATTESTATION_CERT_CHAIN | PROVISION_STATUS_ATTESTATION_CERT_PARAMS
| PROVISION_STATUS_ATTESTATION_KEY | PROVISION_STATUS_PRESHARED_SECRET | PROVISION_STATUS_ATTEST_IDS
| PROVISION_STATUS_OEM_PUBLIC_KEY | PROVISION_STATUS_SECURE_BOOT_MODE;
if (kmDataStore.isProvisionLocked() || (pCompleteStatus == (pStatus & pCompleteStatus))) {
return true;
}
Expand Down
19 changes: 13 additions & 6 deletions Applet/AndroidSEProvider/src/com/android/javacard/keymaster/KMAttestationCertImpl.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -382,7 +382,8 @@ private static void pushExtensions() {
if (states[KEY_USAGE] != 0) {
pushKeyUsage(states[KEY_USAGE], states[UNUSED_BITS]);
}
if (states[CERT_MODE] == KMType.ATTESTATION_CERT) {
if (states[CERT_MODE] == KMType.ATTESTATION_CERT ||
states[CERT_MODE] == KMType.FACTORY_ATTESTATION_CERT) {
pushKeyDescription();
}
pushSequenceHeader((short) (last - indexes[STACK_PTR]));
Expand Down Expand Up @@ -907,12 +908,16 @@ else if (rsaSign) {
if (sigLen > ECDSA_MAX_SIG_LEN)
KMException.throwIt(KMError.UNKNOWN_ERROR);
}
// Adjust signature length
indexes[STACK_PTR] = signatureOffset;
pushBitStringHeader((byte) 0, sigLen);
} else if (!fakeCert) { // No attestation key provisioned in the factory
KMException.throwIt(KMError.ATTESTATION_KEYS_NOT_PROVISIONED);
} else if (!fakeCert) {
// Sign with Factory provisioned attestation key.
sigLen = seProvider.ecSign256(KMKeymintDataStore.instance().getAttestationKeyPair(),
stack, indexes[TBS_START], indexes[TBS_LENGTH], stack, signatureOffset);
if (sigLen > ECDSA_MAX_SIG_LEN)
KMException.throwIt(KMError.UNKNOWN_ERROR);
}
// Adjust signature length
indexes[STACK_PTR] = signatureOffset;
pushBitStringHeader((byte) 0, sigLen);
last = (short) (signatureOffset + sigLen);
// Add certificate sequence header
indexes[STACK_PTR] = indexes[TBS_START];
Expand All @@ -925,6 +930,8 @@ else if (rsaSign) {
public void build() {
if(states[CERT_MODE] == KMType.FAKE_CERT) {
build(KMType.INVALID_VALUE, KMType.INVALID_VALUE, true, true);
} else if(states[CERT_MODE] == KMType.FACTORY_ATTESTATION_CERT) {
build(KMType.INVALID_VALUE, KMType.INVALID_VALUE, false, false);
} else {
build(indexes[CERT_ATT_KEY_SECRET], indexes[CERT_ATT_KEY_RSA_PUB_MOD], (states[CERT_RSA_SIGN] == 0 ? false: true), false);
}
Expand Down
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