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feat(core): Handle split keys on tdf3 encrypt and decrypt (#109)
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equivalent to opentdf/platform#1038
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@elizabethhealy
elizabethhealy committed Aug 19, 2024
1 parent bfbef70 commit 943751f
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Showing 5 changed files with 196 additions and 39 deletions.
54 changes: 54 additions & 0 deletions .github/workflows/checks.yaml
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Expand Up @@ -190,6 +190,60 @@ jobs:
fi
working-directory: cmdline

- uses: JarvusInnovations/background-action@2428e7b970a846423095c79d43f759abf979a635
name: start another KAS server in background
with:
run: >
<opentdf.yaml >opentdf-beta.yaml yq e '
(.server.port = 8282)
| (.mode = ["kas"])
| (.sdk_config = {"endpoint":"http://localhost:8080","plaintext":true,"client_id":"opentdf","client_secret":"secret"})
'
&& go run ./service --config-file ./opentdf-beta.yaml start
wait-on: |
tcp:localhost:8282
log-output-if: true
wait-for: 90s
working-directory: platform
- name: Make sure that the second platform is up
run: |
grpcurl -plaintext localhost:8282 kas.AccessService/PublicKey
- name: Validate multikas through the command line interface
run: |
printf 'here is some data to encrypt' > data
java -jar target/cmdline.jar \
--client-id=opentdf-sdk \
--client-secret=secret \
--platform-endpoint=localhost:8080 \
-i \
encrypt --kas-url=localhost:8080,localhost:8282 -f data -m 'here is some metadata' > test.tdf
java -jar target/cmdline.jar \
--client-id=opentdf-sdk \
--client-secret=secret \
--platform-endpoint=localhost:8080 \
-i \
decrypt -f test.tdf > decrypted
java -jar target/cmdline.jar \
--client-id=opentdf-sdk \
--client-secret=secret \
--platform-endpoint=localhost:8080 \
-i \
metadata -f test.tdf > metadata
if ! diff -q data decrypted; then
printf 'decrypted data is incorrect [%s]' "$(< decrypted)"
exit 1
fi
if [ "$(< metadata)" != 'here is some metadata' ]; then
printf 'metadata is incorrect [%s]\n' "$(< metadata)"
exit 1
fi
working-directory: cmdline

platform-xtest:
permissions:
contents: read
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3 changes: 2 additions & 1 deletion cmdline/src/main/java/io/opentdf/platform/Command.java
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Expand Up @@ -3,6 +3,7 @@
import com.nimbusds.jose.JOSEException;
import io.opentdf.platform.sdk.*;
import io.opentdf.platform.sdk.TDF;

import org.apache.commons.codec.DecoderException;
import picocli.CommandLine;
import picocli.CommandLine.Option;
Expand Down Expand Up @@ -49,7 +50,7 @@ class Command {
@CommandLine.Command(name = "encrypt")
void encrypt(
@Option(names = {"-f", "--file"}, defaultValue = Option.NULL_VALUE) Optional<File> file,
@Option(names = {"-k", "--kas-url"}, required = true) List<String> kas,
@Option(names = {"-k", "--kas-url"}, required = true, split = ",") List<String> kas,
@Option(names = {"-m", "--metadata"}, defaultValue = Option.NULL_VALUE) Optional<String> metadata,
@Option(names = {"--mime-type"}, defaultValue = Option.NULL_VALUE) Optional<String> mimeType) throws
IOException, JOSEException {
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12 changes: 12 additions & 0 deletions sdk/src/main/java/io/opentdf/platform/sdk/Config.java
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,16 @@ public AssertionConfig() {
}
}

public static class SplitStep {
public String kas;
public String splitID;

public SplitStep(String kas, String sid) {
this.kas = kas;
this.splitID = sid;
}
}

public static class TDFConfig {
public int defaultSegmentSize;
public boolean enableEncryption;
Expand All @@ -67,6 +77,7 @@ public static class TDFConfig {
public List<Assertion> assertionList;
public AssertionConfig assertionConfig;
public String mimeType;
public List<SplitStep> splitPlan;

public TDFConfig() {
this.defaultSegmentSize = DEFAULT_SEGMENT_SIZE;
Expand All @@ -78,6 +89,7 @@ public TDFConfig() {
this.kasInfoList = new ArrayList<>();
this.assertionList = new ArrayList<>();
this.mimeType = DEFAULT_MIME_TYPE;
this.splitPlan = new ArrayList<>();
}
}

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1 change: 1 addition & 0 deletions sdk/src/main/java/io/opentdf/platform/sdk/Manifest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,7 @@ static public class KeyAccess {

public String encryptedMetadata;
public String kid;
public String sid;

@Override
public boolean equals(Object o) {
Expand Down
165 changes: 127 additions & 38 deletions sdk/src/main/java/io/opentdf/platform/sdk/TDF.java
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Expand Up @@ -13,6 +13,7 @@
import com.nimbusds.jose.crypto.RSASSAVerifier;
import com.nimbusds.jwt.JWTClaimsSet;
import com.nimbusds.jwt.SignedJWT;

import com.nimbusds.jose.crypto.RSASSASigner;
import com.nimbusds.jose.crypto.MACSigner;
import org.apache.commons.codec.DecoderException;
Expand Down Expand Up @@ -68,6 +69,12 @@ public TDF() {

private static final Gson gson = new Gson();

public class SplitKeyException extends IOException {
public SplitKeyException(String errorMessage) {
super(errorMessage);
}
}

public static class DataSizeNotSupported extends RuntimeException {
public DataSizeNotSupported(String errorMessage) {
super(errorMessage);
Expand Down Expand Up @@ -164,57 +171,112 @@ PolicyObject createPolicyObject(List<String> attributes) {
}

private static final Base64.Encoder encoder = Base64.getEncoder();
private void prepareManifest(Config.TDFConfig tdfConfig) {
private void prepareManifest(Config.TDFConfig tdfConfig, SDK.KAS kas) {
manifest.encryptionInformation.keyAccessType = kSplitKeyType;
manifest.encryptionInformation.keyAccessObj = new ArrayList<>();

PolicyObject policyObject = createPolicyObject(tdfConfig.attributes);
String base64PolicyObject = encoder.encodeToString(gson.toJson(policyObject).getBytes(StandardCharsets.UTF_8));
List<byte[]> symKeys = new ArrayList<>();
Map<String, Config.KASInfo> latestKASInfo = new HashMap<>();
if (tdfConfig.splitPlan.isEmpty()) {
// Default split plan: Split keys across all KASes
List<Config.SplitStep> splitPlan = new ArrayList<>(tdfConfig.kasInfoList.size());
int i = 0;
for (Config.KASInfo kasInfo : tdfConfig.kasInfoList) {
Config.SplitStep step = new Config.SplitStep(kasInfo.URL, "");
if (tdfConfig.kasInfoList.size() > 1) {
step.splitID = String.format("s-%d", i++);
}
splitPlan.add(step);
if (kasInfo.PublicKey != null && !kasInfo.PublicKey.isEmpty()) {
latestKASInfo.put(kasInfo.URL, kasInfo);
}
}
tdfConfig.splitPlan = splitPlan;
}

// Seed anything passed in manually
for (Config.KASInfo kasInfo: tdfConfig.kasInfoList) {
if (kasInfo.PublicKey == null || kasInfo.PublicKey.isEmpty()) {
throw new KasPublicKeyMissing("Kas public key is missing in kas information list");
if (kasInfo.PublicKey != null && !kasInfo.PublicKey.isEmpty()) {
latestKASInfo.put(kasInfo.URL, kasInfo);
}
}

// split plan: restructure by conjunctions
Map<String, List<Config.KASInfo>> conjunction = new HashMap<>();
List<String> splitIDs = new ArrayList<>();

for (Config.SplitStep splitInfo : tdfConfig.splitPlan) {
// Public key was passed in with kasInfoList
// TODO First look up in attribute information / add to split plan?
Config.KASInfo ki = latestKASInfo.get(splitInfo.kas);
if (ki == null || ki.PublicKey == null || ki.PublicKey.isBlank()) {
logger.info("no public key provided for KAS at {}, retrieving", splitInfo.kas);
var getKI = new Config.KASInfo();
getKI.URL = splitInfo.kas;
getKI.PublicKey = kas.getPublicKey(getKI);
getKI.KID = kas.getKid(getKI);
latestKASInfo.put(splitInfo.kas, getKI);
ki = getKI;
}
if (conjunction.containsKey(splitInfo.splitID)) {
conjunction.get(splitInfo.splitID).add(ki);
} else {
List<Config.KASInfo> newList = new ArrayList<>();
newList.add(ki);
conjunction.put(splitInfo.splitID, newList);
splitIDs.add(splitInfo.splitID);
}
}

for (String splitID: splitIDs) {
// Symmetric key
byte[] symKey = new byte[GCM_KEY_SIZE];
sRandom.nextBytes(symKey);

Manifest.KeyAccess keyAccess = new Manifest.KeyAccess();
keyAccess.keyType = kWrapped;
keyAccess.url = kasInfo.URL;
keyAccess.kid = kasInfo.KID;
keyAccess.protocol = kKasProtocol;
symKeys.add(symKey);

// Add policyBinding
var hexBinding = Hex.encodeHexString(CryptoUtils.CalculateSHA256Hmac(symKey, base64PolicyObject.getBytes(StandardCharsets.UTF_8)));
var policyBinding = new Manifest.PolicyBinding();
policyBinding.alg = kHmacIntegrityAlgorithm;
policyBinding.hash = encoder.encodeToString(hexBinding.getBytes(StandardCharsets.UTF_8));
keyAccess.policyBinding = policyBinding;

// Wrap the key with kas public key
AsymEncryption asymmetricEncrypt = new AsymEncryption(kasInfo.PublicKey);
byte[] wrappedKey = asymmetricEncrypt.encrypt(symKey);

keyAccess.wrappedKey = encoder.encodeToString(wrappedKey);


// Add meta data
var encryptedMetadata = new String();
if(tdfConfig.metaData != null && !tdfConfig.metaData.trim().isEmpty()) {
AesGcm aesGcm = new AesGcm(symKey);
var encrypted = aesGcm.encrypt(tdfConfig.metaData.getBytes(StandardCharsets.UTF_8));

EncryptedMetadata encryptedMetadata = new EncryptedMetadata();
encryptedMetadata.iv = encoder.encodeToString(encrypted.getIv());
encryptedMetadata.ciphertext = encoder.encodeToString(encrypted.asBytes());
EncryptedMetadata em = new EncryptedMetadata();
em.iv = encoder.encodeToString(encrypted.getIv());
em.ciphertext = encoder.encodeToString(encrypted.asBytes());

var metadata = gson.toJson(encryptedMetadata);
keyAccess.encryptedMetadata = encoder.encodeToString(metadata.getBytes(StandardCharsets.UTF_8));
var metadata = gson.toJson(em);
encryptedMetadata = encoder.encodeToString(metadata.getBytes(StandardCharsets.UTF_8));
}

symKeys.add(symKey);
manifest.encryptionInformation.keyAccessObj.add(keyAccess);
for (Config.KASInfo kasInfo: conjunction.get(splitID)){
if (kasInfo.PublicKey == null || kasInfo.PublicKey.isEmpty()) {
throw new KasPublicKeyMissing("Kas public key is missing in kas information list");
}

// Wrap the key with kas public key
AsymEncryption asymmetricEncrypt = new AsymEncryption(kasInfo.PublicKey);
byte[] wrappedKey = asymmetricEncrypt.encrypt(symKey);

Manifest.KeyAccess keyAccess = new Manifest.KeyAccess();
keyAccess.keyType = kWrapped;
keyAccess.url = kasInfo.URL;
keyAccess.kid = kasInfo.KID;
keyAccess.protocol = kKasProtocol;
keyAccess.policyBinding = policyBinding;
keyAccess.wrappedKey = encoder.encodeToString(wrappedKey);
keyAccess.encryptedMetadata = encryptedMetadata;

manifest.encryptionInformation.keyAccessObj.add(keyAccess);
}
}

manifest.encryptionInformation.policy = base64PolicyObject;
Expand Down Expand Up @@ -319,10 +381,8 @@ public TDFObject createTDF(InputStream payload,
throw new KasInfoMissing("kas information is missing");
}

fillInPublicKeyInfo(tdfConfig.kasInfoList, kas);

TDFObject tdfObject = new TDFObject();
tdfObject.prepareManifest(tdfConfig);
tdfObject.prepareManifest(tdfConfig, kas);

long encryptedSegmentSize = tdfConfig.defaultSegmentSize + kGcmIvSize + kAesBlockSize;
TDFWriter tdfWriter = new TDFWriter(outputStream);
Expand Down Expand Up @@ -483,17 +543,6 @@ public TDFObject createTDF(InputStream payload,
return tdfObject;
}

private void fillInPublicKeyInfo(List<Config.KASInfo> kasInfoList, SDK.KAS kas) {
for (var kasInfo: kasInfoList) {
if (kasInfo.PublicKey != null && !kasInfo.PublicKey.isBlank()) {
continue;
}
logger.info("no public key provided for KAS at {}, retrieving", kasInfo.URL);
kasInfo.PublicKey = kas.getPublicKey(kasInfo);
kasInfo.KID = kas.getKid(kasInfo);
}
}

public Reader loadTDF(SeekableByteChannel tdf, Config.AssertionConfig assertionConfig, SDK.KAS kas) throws NotValidateRootSignature, SegmentSizeMismatch,
IOException, FailedToCreateGMAC, JOSEException, ParseException, NoSuchAlgorithmException, DecoderException {

Expand All @@ -502,15 +551,39 @@ public Reader loadTDF(SeekableByteChannel tdf, Config.AssertionConfig assertionC
Manifest manifest = gson.fromJson(manifestJson, Manifest.class);
byte[] payloadKey = new byte[GCM_KEY_SIZE];
String unencryptedMetadata = null;

Set<String> knownSplits = new HashSet<String>();
Set<String> foundSplits = new HashSet<String>();;
Map<Config.SplitStep, Exception> skippedSplits = new HashMap<>();
boolean mixedSplits = manifest.encryptionInformation.keyAccessObj.size() > 1 &&
(manifest.encryptionInformation.keyAccessObj.get(0).sid != null) &&
!manifest.encryptionInformation.keyAccessObj.get(0).sid.isEmpty();

MessageDigest digest = MessageDigest.getInstance("SHA-256");

if (manifest.payload.isEncrypted) {
for (Manifest.KeyAccess keyAccess: manifest.encryptionInformation.keyAccessObj) {
var unwrappedKey = kas.unwrap(keyAccess, manifest.encryptionInformation.policy);
Config.SplitStep ss = new Config.SplitStep(keyAccess.url, keyAccess.sid);
byte[] unwrappedKey;
if (!mixedSplits) {
unwrappedKey = kas.unwrap(keyAccess, manifest.encryptionInformation.policy);
} else {
knownSplits.add(unencryptedMetadata);
if (foundSplits.contains(ss.splitID)){
continue;
}
try {
unwrappedKey = kas.unwrap(keyAccess, manifest.encryptionInformation.policy);
} catch (Exception e) {
skippedSplits.put(ss, e);
continue;
}
}

for (int index = 0; index < unwrappedKey.length; index++) {
payloadKey[index] ^= unwrappedKey[index];
}
foundSplits.add(ss.splitID);

if (keyAccess.encryptedMetadata != null && !keyAccess.encryptedMetadata.isEmpty()) {
AesGcm aesGcm = new AesGcm(unwrappedKey);
Expand All @@ -528,6 +601,22 @@ public Reader loadTDF(SeekableByteChannel tdf, Config.AssertionConfig assertionC
unencryptedMetadata = new String(decrypted, StandardCharsets.UTF_8);
}
}

if (mixedSplits && knownSplits.size() > foundSplits.size()) {
List<Exception> exceptionList = new ArrayList<>(skippedSplits.size() + 1);
exceptionList.add(new Exception("splitKey.unable to reconstruct split key: " + skippedSplits));

for (Map.Entry<Config.SplitStep, Exception> entry : skippedSplits.entrySet()) {
exceptionList.add(entry.getValue());
}

StringBuilder combinedMessage = new StringBuilder();
for (Exception e : exceptionList) {
combinedMessage.append(e.getMessage()).append("\n");
}

throw new SplitKeyException(combinedMessage.toString());
}
}

// Validate root signature
Expand Down

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