Migrate to new signature generation.

Old biscuits can still be verified using the older format, but new ones
will be generated using the new format.

Author: preuss-adam

src/main/java/org/eclipse/biscuit/token/ThirdPartyBlockRequest.java

@@ -6,6 +6,7 @@
 package org.eclipse.biscuit.token;
 
 import biscuit.format.schema.Schema;
+import com.google.protobuf.ByteString;
 import com.google.protobuf.InvalidProtocolBufferException;
 import io.vavr.control.Either;
 import io.vavr.control.Option;
@@ -14,7 +15,7 @@
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.security.SignatureException;
-import java.util.Objects;
+import java.util.Arrays;
 import org.eclipse.biscuit.crypto.BlockSignatureBuffer;
 import org.eclipse.biscuit.crypto.PublicKey;
 import org.eclipse.biscuit.crypto.Signer;
@@ -23,10 +24,10 @@
 import org.eclipse.biscuit.token.builder.Block;
 
 public final class ThirdPartyBlockRequest {
-  private final PublicKey previousKey;
+  private final byte[] previousSignature;
 
-  ThirdPartyBlockRequest(PublicKey previousKey) {
-    this.previousKey = previousKey;
+  ThirdPartyBlockRequest(byte[] previousSignature) {
+    this.previousSignature = previousSignature;
   }
 
   public Either<Error.FormatError, ThirdPartyBlockContents> createBlock(
@@ -43,8 +44,10 @@ public Either<Error.FormatError, ThirdPartyBlockContents> createBlock(
 
     byte[] serializedBlock = res.get();
     byte[] payload =
-        BlockSignatureBuffer.generateExternalBlockSignaturePayloadV0(
-            serializedBlock, this.previousKey);
+        BlockSignatureBuffer.generateExternalBlockSignaturePayloadV1(
+            serializedBlock,
+            this.previousSignature,
+            BlockSignatureBuffer.THIRD_PARTY_SIGNATURE_VERSION);
     byte[] signature = externalSigner.sign(payload);
 
     PublicKey publicKey = externalSigner.getPublicKey();
@@ -54,15 +57,29 @@ public Either<Error.FormatError, ThirdPartyBlockContents> createBlock(
 
   public Schema.ThirdPartyBlockRequest serialize() throws Error.FormatError.SerializationError {
     Schema.ThirdPartyBlockRequest.Builder b = Schema.ThirdPartyBlockRequest.newBuilder();
-    b.setLegacyPreviousKey(this.previousKey.serialize());
+    b.setPreviousSignature(ByteString.copyFrom(this.previousSignature));
 
     return b.build();
   }
 
   public static ThirdPartyBlockRequest deserialize(Schema.ThirdPartyBlockRequest b)
       throws Error.FormatError.DeserializationError {
-    PublicKey previousKey = PublicKey.deserialize(b.getLegacyPreviousKey());
-    return new ThirdPartyBlockRequest(previousKey);
+
+    if (b.hasLegacyPreviousKey()) {
+      throw new Error.FormatError.DeserializationError(
+          "public keys were provided in third-party block request");
+    }
+    if (b.getLegacyPublicKeysCount() > 0) {
+      throw new Error.FormatError.DeserializationError(
+          "public keys were provided in third-party block request");
+    }
+
+    if (!b.hasPreviousSignature()) {
+      throw new Error.FormatError.DeserializationError(
+          "missing previous signature in third-party block request");
+    }
+
+    return new ThirdPartyBlockRequest(b.getPreviousSignature().toByteArray());
   }
 
   public static ThirdPartyBlockRequest fromBytes(byte[] slice)
@@ -88,16 +105,16 @@ public boolean equals(Object o) {
 
     ThirdPartyBlockRequest that = (ThirdPartyBlockRequest) o;
 
-    return Objects.equals(previousKey, that.previousKey);
+    return Arrays.equals(previousSignature, that.previousSignature);
   }
 
   @Override
   public int hashCode() {
-    return previousKey != null ? previousKey.hashCode() : 0;
+    return previousSignature != null ? Arrays.hashCode(previousSignature) : 0;
   }
 
   @Override
   public String toString() {
-    return "ThirdPartyBlockRequest{previousKey=" + previousKey + '}';
+    return "ThirdPartyBlockRequest{previousKey=" + previousSignature + '}';
   }
 }

src/main/java/org/eclipse/biscuit/token/UnverifiedBiscuit.java

@@ -27,6 +27,7 @@
 import org.eclipse.biscuit.error.Error;
 import org.eclipse.biscuit.token.format.ExternalSignature;
 import org.eclipse.biscuit.token.format.SerializedBiscuit;
+import org.eclipse.biscuit.token.format.SignedBlock;
 
 /**
  * UnverifiedBiscuit auth token. UnverifiedBiscuit means it's deserialized without checking
@@ -262,45 +263,43 @@ public List<PublicKey> blockPublicKeys(int index) {
 
   /** Generates a third party block request from a token */
   public ThirdPartyBlockRequest thirdPartyRequest() {
-    PublicKey previousKey;
+    byte[] previousSignature;
     if (this.serializedBiscuit.getBlocks().isEmpty()) {
-      previousKey = this.serializedBiscuit.getAuthority().getKey();
+      previousSignature = this.serializedBiscuit.getAuthority().getSignature();
     } else {
-      previousKey =
+      previousSignature =
           this.serializedBiscuit
               .getBlocks()
               .get(this.serializedBiscuit.getBlocks().size() - 1)
-              .getKey();
+              .getSignature();
     }
 
-    return new ThirdPartyBlockRequest(previousKey);
+    return new ThirdPartyBlockRequest(previousSignature);
   }
 
   /** Generates a third party block request from a token */
   public UnverifiedBiscuit appendThirdPartyBlock(
       PublicKey externalKey, ThirdPartyBlockContents blockResponse)
       throws NoSuchAlgorithmException, SignatureException, InvalidKeyException, Error {
-    PublicKey previousKey;
+    SignedBlock previousBlock;
     if (this.serializedBiscuit.getBlocks().isEmpty()) {
-      previousKey = this.serializedBiscuit.getAuthority().getKey();
+      previousBlock = this.serializedBiscuit.getAuthority();
     } else {
-      previousKey =
-          this.serializedBiscuit
-              .getBlocks()
-              .get(this.serializedBiscuit.getBlocks().size() - 1)
-              .getKey();
+      previousBlock =
+          this.serializedBiscuit.getBlocks().get(this.serializedBiscuit.getBlocks().size() - 1);
     }
-    KeyPair nextKeyPair = KeyPair.generate(previousKey.getAlgorithm());
+    KeyPair nextKeyPair = KeyPair.generate(previousBlock.getKey().getAlgorithm());
     byte[] payload =
-        BlockSignatureBuffer.generateExternalBlockSignaturePayloadV0(
-            blockResponse.getPayload(), previousKey);
+        BlockSignatureBuffer.generateExternalBlockSignaturePayloadV1(
+            blockResponse.getPayload(),
+            previousBlock.getSignature(),
+            BlockSignatureBuffer.THIRD_PARTY_SIGNATURE_VERSION);
     if (!externalKey.verify(payload, blockResponse.getSignature())) {
       throw new Error.FormatError.Signature.InvalidSignature(
           "signature error: Verification equation was not satisfied");
     }
 
-    Either<Error.FormatError, Block> res =
-        Block.fromBytes(blockResponse.getPayload(), Option.some(externalKey));
+    var res = Block.fromBytes(blockResponse.getPayload(), Option.some(externalKey));
     if (res.isLeft()) {
       throw res.getLeft();
     }
@@ -312,7 +311,7 @@ public UnverifiedBiscuit appendThirdPartyBlock(
 
     UnverifiedBiscuit copiedBiscuit = this.copy();
 
-    Either<Error.FormatError, SerializedBiscuit> containerRes =
+    var containerRes =
         copiedBiscuit.serializedBiscuit.append(nextKeyPair, block, Option.some(externalSignature));
     if (containerRes.isLeft()) {
       throw containerRes.getLeft();