Rekor Entries should be reconstructed and compared

sigstore-java/src/main/java/dev/sigstore/KeylessSigner.java

@@ -63,8 +63,10 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import javax.annotation.Nullable;
+import org.bouncycastle.util.encoders.Base64;
 
 /**
  * A full sigstore keyless signing flow.
@@ -335,6 +337,12 @@ public List<Bundle> sign(List<byte[]> artifactDigests) throws KeylessSignerExcep
         throw new KeylessSignerException("Failed to put entry in rekor", ex);
       }
 
+      var calculatedHashedRekord =
+          Base64.toBase64String(rekorRequest.toJsonPayload().getBytes(StandardCharsets.UTF_8));
+      if (!Objects.equals(calculatedHashedRekord, rekorResponse.getEntry().getBody())) {
+        throw new KeylessSignerException("Returned log entry was inconsistent with request");
+      }
+
       try {
         rekorVerifier.verifyEntry(rekorResponse.getEntry());
       } catch (RekorVerificationException ex) {

sigstore-java/src/main/java/dev/sigstore/KeylessVerifier.java

@@ -26,11 +26,13 @@
 import dev.sigstore.encryption.signers.Verifiers;
 import dev.sigstore.fulcio.client.FulcioVerificationException;
 import dev.sigstore.fulcio.client.FulcioVerifier;
+import dev.sigstore.rekor.client.HashedRekordRequest;
 import dev.sigstore.rekor.client.RekorEntry;
 import dev.sigstore.rekor.client.RekorVerificationException;
 import dev.sigstore.rekor.client.RekorVerifier;
 import dev.sigstore.tuf.SigstoreTufClient;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
@@ -44,7 +46,9 @@
 import java.sql.Date;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
+import org.bouncycastle.util.encoders.Base64;
 import org.bouncycastle.util.encoders.Hex;
 
 /** Verify hashrekords from rekor signed using the keyless signing flow with fulcio certificates. */
@@ -182,6 +186,23 @@ public void verify(byte[] artifactDigest, Bundle bundle, VerificationOptions opt
       throw new KeylessVerificationException("Rekor entry signature was not valid", ex);
     }
 
+    // verify the log entry is relevant to the provided verification materials
+    try {
+      var calculatedHashedRekord =
+          Base64.toBase64String(
+              HashedRekordRequest.newHashedRekordRequest(
+                      artifactDigest, Certificates.toPemBytes(leafCert), signature)
+                  .toJsonPayload()
+                  .getBytes(StandardCharsets.UTF_8));
+      if (!Objects.equals(calculatedHashedRekord, rekorEntry.getBody())) {
+        throw new KeylessVerificationException(
+            "Provided verification materials are inconsistent with log entry");
+      }
+    } catch (IOException e) {
+      // this should be unreachable, we know leafCert is a valid certificate at this point
+      throw new RuntimeException("Unexpected IOException on valid leafCert", e);
+    }
+
     // check if the time of entry inclusion in the log (a stand-in for signing time) is within the
     // validity period for the certificate
     var entryTime = Date.from(rekorEntry.getIntegratedTimeInstant());

sigstore-java/src/test/java/dev/sigstore/KeylessVerifierTest.java

@@ -65,6 +65,27 @@ public void testVerify_mismatchedSet() throws Exception {
                 VerificationOptions.empty()));
   }
 
+  @Test
+  public void testVerify_mismatchedArtifactHash() throws Exception {
+    // a bundle file that uses the tlog entry from another artifact signed with the same
+    // certificate. The Bundle is fully valid except that the artifact hash doesn't match
+    var bundleFile =
+        Resources.toString(
+            Resources.getResource(
+                "dev/sigstore/samples/bundles/bundle-with-wrong-tlog-entry.sigstore"),
+            StandardCharsets.UTF_8);
+    var artifact = Resources.getResource("dev/sigstore/samples/bundles/artifact.txt").getPath();
+
+    var verifier = KeylessVerifier.builder().sigstorePublicDefaults().build();
+    Assertions.assertThrows(
+        KeylessVerificationException.class,
+        () ->
+            verifier.verify(
+                Path.of(artifact),
+                Bundle.from(new StringReader(bundleFile)),
+                VerificationOptions.empty()));
+  }
+
   @Test
   public void testVerify_errorsOnDSSEBundle() throws Exception {
     var bundleFile =

sigstore-java/src/test/resources/dev/sigstore/samples/bundles/bundle-with-wrong-tlog-entry.sigstore

@@ -0,0 +1,39 @@
+{
+  "mediaType": "application/vnd.dev.sigstore.bundle.v0.3+json",
+  "verificationMaterial": {
+    "tlogEntries": [{
+      "logIndex": "150603746",
+      "logId": {
+        "keyId": "wNI9atQGlz+VWfO6LRygH4QUfY/8W4RFwiT5i5WRgB0="
+      },
+      "kindVersion": {
+        "kind": "hashedrekord",
+        "version": "0.0.1"
+      },
+      "integratedTime": "1732221080",
+      "inclusionPromise": {
+        "signedEntryTimestamp": "MEUCIQDY5kN3WEDvMndKO5JImUGrtV5jW1cVGnEDylEKRk7ZsAIgZN1MIv+eILssoHtsqqk+b9Tda+2ZN3Lkz1Mw8GwTD9k="
+      },
+      "inclusionProof": {
+        "logIndex": "28699484",
+        "rootHash": "p+AbctDd928yM1oCzeJPou8nHME2Qyka0DMB1tOlqsI=",
+        "treeSize": "28699488",
+        "hashes": ["fcyRKy95RMsZh/HeRQaZK8jFhhrdqqA5iFs+wInZsaI=", "zl59JwaJVeTvAF5pCTPbaXXdXgsYidumj8TgjRvcZIA=", "4mck2Czn6tiBqOQYPlh3ATO9DaTvouT7biFAkCz4bWM=", "BipkUG/DzduS/XjrbEd3uC5odEYaC9OTJTYElA10POo=", "9yDO9YZftL6yDveO6bWY32s8D4y3+uWUKVLEPmRwbHk=", "GMMIMtm+cQ0ajPC1YWzZCJIZ517pDeYJ5+FnZinynQg=", "9henJICU+Lo3pa+Rrtnt8+5esX8hhksuDcqmaYvxLHA=", "aL2yyr/c5w5R72E6L+AagxQB/oMUftqB7fHIs625QR0=", "Fvp+S31pMTO9ts92nEBj6sYay8OFauXxYrevM73sg3U=", "tk7EpIXIblK0ktOJNY9T+WCMpW0loWy+GouFKk7me8k=", "Ky28cDNBQqCVLHhOLegW99yo/fkUTkjmWsr56fXTt+E=", "PTN8SB4uaeclDiwUlPK/FSmiK7voPpkD8GBfNeRCFnw=", "0C1qnoT2c+8KErA01/VosqRATcsPFXeswb8bk/eb/3g=", "5EVC7yaMdjhwDR6OLXLyveRuRrF8xvXTzlm+8+vzfxE=", "bulsENariUUsC4xiR1yFtqKzD8evI9p/s+YCpl8t9tE=", "E2rLOYPJFKiizYiyu07QLqkMVTVL7i2ZgXiQywdI9KQ=", "4lUF0YOu9XkIDXKXA0wMSzd6VeDY3TZAgmoOeWmS2+Y=", "gf+9m552B3PnkWnO0o4KdVvjcT3WVHLrCbf1DoVYKFw="],
+        "checkpoint": {
+          "envelope": "rekor.sigstore.dev - 1193050959916656506\n28699488\np+AbctDd928yM1oCzeJPou8nHME2Qyka0DMB1tOlqsI\u003d\n\n— rekor.sigstore.dev wNI9ajBFAiEA+50Xtrawp0K2slioi3f8lpCrZGu8k919PDoZ+Z80/WUCIDaUTds/GljSB8/Mu7DLj879oi/odHrPZ0OUeubKlBGd\n"
+        }
+      },
+      "canonicalizedBody": "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"
+    }],
+    "certificate": {
+      "rawBytes": "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"
+    }
+  },
+  "messageSignature": {
+    "messageDigest": {
+      "algorithm": "SHA2_256",
+      "digest": "oM/HEnHW4njlfNMy/5V8P3BD/do1TEy7GQow1W76Ab8="
+    },
+    "signature": "MEYCIQCGZcJ+4mTIMPAyIKV7XZjZ5KyvX1tz/glbin9vVF+9fwIhANUb5z/2Rb88vtvtABHAmQyBl4Yp8ipMLCnv36Ln8/Eb"
+  }
+}