Rekor Verifier should match artifact hash

Signed-off-by: Appu Goundan <[email protected]>

fuzzing/src/main/java/fuzzing/RekorVerifierFuzzer.java

@@ -32,14 +32,15 @@ public class RekorVerifierFuzzer {
   public static void fuzzerTestOneInput(FuzzedDataProvider data) {
     try {
       var tLogs = Tuf.transparencyLogsFrom(data);
+      byte[] digest = data.consumeBytes(32);
       byte[] byteArray = data.consumeRemainingAsBytes();
       String string = new String(byteArray, StandardCharsets.UTF_8);
 
       URI uri = new URI(URL);
       RekorEntry entry = RekorResponse.newRekorResponse(uri, string).getEntry();
       RekorVerifier verifier = RekorVerifier.newRekorVerifier(tLogs);
 
-      verifier.verifyEntry(entry);
+      verifier.verifyHashedRekord(entry, digest);
     } catch (URISyntaxException | RekorParseException | RekorVerificationException e) {
       // Known exception
     }

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

@@ -336,7 +336,7 @@ public List<Bundle> sign(List<byte[]> artifactDigests) throws KeylessSignerExcep
       }
 
       try {
-        rekorVerifier.verifyEntry(rekorResponse.getEntry());
+        rekorVerifier.verifyHashedRekord(rekorResponse.getEntry(), artifactDigest);
       } catch (RekorVerificationException ex) {
         throw new KeylessSignerException("Failed to validate rekor response after signing", ex);
       }

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

@@ -175,9 +175,9 @@ public void verify(byte[] artifactDigest, Bundle bundle, VerificationOptions opt
 
     RekorEntry rekorEntry = bundle.getEntries().get(0);
 
-    // verify the rekor entry is signed by the log keys
+    // verify the rekor entry is signed by the log keys and is relevant to this artifact
     try {
-      rekorVerifier.verifyEntry(rekorEntry);
+      rekorVerifier.verifyHashedRekord(rekorEntry, artifactDigest);
     } catch (RekorVerificationException ex) {
       throw new KeylessVerificationException("Rekor entry signature was not valid", ex);
     }

sigstore-java/src/main/java/dev/sigstore/rekor/client/HashedRekordRequest.java

@@ -19,7 +19,7 @@
 
 import com.google.common.hash.Hashing;
 import com.google.common.primitives.Bytes;
-import dev.sigstore.rekor.*;
+import dev.sigstore.rekor.hashedRekord.v0_0_1.*;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Base64;

sigstore-java/src/main/java/dev/sigstore/rekor/client/RekorTypes.java

@@ -17,7 +17,7 @@
 
 import static dev.sigstore.json.GsonSupplier.GSON;
 
-import dev.sigstore.rekor.HashedRekord;
+import dev.sigstore.rekor.hashedRekord.v0_0_1.HashedRekord;
 
 /** Parser for the body.spec element of {@link RekorEntry}. */
 public class RekorTypes {

sigstore-java/src/main/java/dev/sigstore/rekor/client/RekorVerifier.java

@@ -16,8 +16,12 @@
 package dev.sigstore.rekor.client;
 
 import com.google.common.hash.Hashing;
+import com.google.gson.JsonSyntaxException;
 import dev.sigstore.encryption.signers.Verifiers;
+import dev.sigstore.json.GsonSupplier;
 import dev.sigstore.rekor.client.RekorEntry.Checkpoint;
+import dev.sigstore.rekor.hashedRekord.v0_0_1.Hash.Algorithm;
+import dev.sigstore.rekor.hashedRekord.v0_0_1.HashedRekord;
 import dev.sigstore.trustroot.SigstoreTrustedRoot;
 import dev.sigstore.trustroot.TransparencyLog;
 import java.security.InvalidKeyException;
@@ -27,6 +31,8 @@
 import java.util.Arrays;
 import java.util.Base64;
 import java.util.List;
+import java.util.Objects;
+import org.bouncycastle.util.encoders.DecoderException;
 import org.bouncycastle.util.encoders.Hex;
 
 /** Verifier for rekor entries. */
@@ -46,12 +52,54 @@ private RekorVerifier(List<TransparencyLog> tlogs) {
   }
 
   /**
-   * Verify that a Rekor Entry is signed with the rekor public key loaded into this verifier
+   * Verify that a Rekor Entry is signed with any public key loaded into this verifier. Also checks
+   * if the embedded hashrekord has a matching artifactDigest.
    *
    * @param entry the entry to verify
    * @throws RekorVerificationException if the entry cannot be verified
    */
-  public void verifyEntry(RekorEntry entry) throws RekorVerificationException {
+  public void verifyHashedRekord(RekorEntry entry, byte[] artifactDigest)
+      throws RekorVerificationException {
+    verifyEntry(entry);
+
+    try {
+      RekorEntryBody entryBody = entry.getBodyDecoded();
+      if (!Objects.equals(entryBody.getKind(), "hashedrekord")
+          || !Objects.equals(entryBody.getApiVersion(), "0.0.1")) {
+        throw new RekorVerificationException(
+            "Rekor entry was not expected type hashedrekord:0.0.1");
+      }
+      HashedRekord hashedRekord =
+          GsonSupplier.GSON.get().fromJson(entryBody.getSpec(), HashedRekord.class);
+      var algorithm = hashedRekord.getData().getHash().getAlgorithm();
+      if (hashedRekord.getData().getHash().getAlgorithm() != Algorithm.SHA_256) {
+        throw new RekorVerificationException(
+            "Cannot process hashedRekord with hashing algorithm " + algorithm.toString());
+      }
+      var entryDigest = Hex.decode(hashedRekord.getData().getHash().getValue());
+      if (!Arrays.equals(artifactDigest, entryDigest)) {
+        throw new RekorVerificationException(
+            "Provided artifact digest does not match digest in log entry"
+                + "\nprovided(hex) : "
+                + Hex.toHexString(artifactDigest)
+                + "\nlog(hex) : "
+                + Hex.toHexString(entryDigest));
+      }
+    } catch (JsonSyntaxException jse) {
+      throw new RekorVerificationException("Could not parse hashrekord during verification", jse);
+    } catch (DecoderException de) {
+      throw new RekorVerificationException(
+          "Could not decode hex sha256 artifact hash in hashrekord", de);
+    }
+  }
+
+  /**
+   * Verify that a Rekor Entry is signed with the rekor public key loaded into this verifier.
+   *
+   * @param entry the entry to verify
+   * @throws RekorVerificationException if the entry cannot be verified
+   */
+  private void verifyEntry(RekorEntry entry) throws RekorVerificationException {
     if (entry.getVerification() == null) {
       throw new RekorVerificationException("No verification information in entry.");
     }

sigstore-java/src/main/resources/rekor/model/hashedRekord.json → sigstore-java/src/main/resources/rekor/model/hashedRekord/v0.0.1/hashedRekord.json

@@ -1,6 +1,6 @@
 {
     "$schema": "http://json-schema.org/draft-07/schema#",
-    "$id": "http://rekor.sigstore.dev/types/rekord/rekord_v0_0_1_schema.json",
+    "$id": "http://rekor.sigstore.dev/types/rekord/hashedrekord_v0_0_1_schema.json",
     "title": "Hashed Rekor v0.0.1 Schema",
     "description": "Schema for Hashed Rekord object",
     "type": "object",
@@ -15,11 +15,11 @@
                     "format": "byte"
                 },
                 "publicKey" : {
-                    "description": "The public key that can verify the signature",
+                    "description": "The public key that can verify the signature; this can also be an X509 code signing certificate that contains the raw public key information",
                     "type": "object",
                     "properties": {
                         "content": {
-                            "description": "Specifies the content of the public key inline within the document",
+                            "description": "Specifies the content of the public key or code signing certificate inline within the document",
                             "type": "string",
                             "format": "byte"
                         }
@@ -38,10 +38,10 @@
                         "algorithm": {
                             "description": "The hashing function used to compute the hash value",
                             "type": "string",
-                            "enum": [ "sha256" ]
+                            "enum": [ "sha256", "sha384", "sha512" ]
                         },
                         "value": {
-                            "description": "The hash value for the content",
+                            "description": "The hash value for the content, as represented by a lower case hexadecimal string",
                             "type": "string"
                         }
                     },

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/java/dev/sigstore/rekor/client/RekorVerifierTest.java

@@ -42,6 +42,7 @@
 public class RekorVerifierTest {
   public String rekorResponse;
   public byte[] rekorPub;
+  public byte[] artifactHash;
 
   public static SigstoreTrustedRoot trustRoot;
 
@@ -54,6 +55,7 @@ public void loadResources() throws IOException {
     rekorPub =
         Resources.toByteArray(
             Resources.getResource("dev/sigstore/samples/rekor-response/valid/rekor.pub"));
+    artifactHash = Hex.decode("47c1db9fb5fe7ff66e3d7c15b2ca5d3a046ee8f4aa043dedd317e46b321c4390");
   }
 
   @BeforeAll
@@ -77,17 +79,34 @@ public void verifyEntry_invalid() throws Exception {
 
     var thrown =
         Assertions.assertThrows(
-            RekorVerificationException.class, () -> verifier.verifyEntry(response.getEntry()));
+            RekorVerificationException.class,
+            () -> verifier.verifyHashedRekord(response.getEntry(), artifactHash));
     Assertions.assertEquals("Entry SET was not valid", thrown.getMessage());
   }
 
+  @Test
+  public void verifyEntry_withMismatchedArtifactHash() throws Exception {
+    var response = RekorResponse.newRekorResponse(new URI("https://somewhere"), rekorResponse);
+    var verifier = RekorVerifier.newRekorVerifier(trustRoot);
+    // change the provided artifact hash
+    artifactHash[0] = 10;
+
+    var thrown =
+        Assertions.assertThrows(
+            RekorVerificationException.class,
+            () -> verifier.verifyHashedRekord(response.getEntry(), artifactHash));
+    MatcherAssert.assertThat(
+        thrown.getMessage(),
+        CoreMatchers.startsWith("Provided artifact digest does not match digest in log entry"));
+  }
+
   @Test
   public void verifyEntry() throws Exception {
     var response = RekorResponse.newRekorResponse(new URI("https://somewhere"), rekorResponse);
     var verifier = RekorVerifier.newRekorVerifier(trustRoot);
 
     var entry = response.getEntry();
-    verifier.verifyEntry(entry);
+    verifier.verifyHashedRekord(entry, artifactHash);
   }
 
   @Test
@@ -101,7 +120,8 @@ public void verifyEntry_withInvalidInclusionProof() throws Exception {
     var entry = response.getEntry();
     var thrown =
         Assertions.assertThrows(
-            RekorVerificationException.class, () -> verifier.verifyEntry(entry));
+            RekorVerificationException.class,
+            () -> verifier.verifyHashedRekord(entry, artifactHash));
 
     MatcherAssert.assertThat(
         thrown.getMessage(),
@@ -139,7 +159,8 @@ public void verifyEntry_logIdMismatch() throws Exception {
 
     var thrown =
         Assertions.assertThrows(
-            RekorVerificationException.class, () -> verifier.verifyEntry(response.getEntry()));
+            RekorVerificationException.class,
+            () -> verifier.verifyHashedRekord(response.getEntry(), artifactHash));
     Assertions.assertEquals(
         "Log entry (logid, timestamp) does not match any provided transparency logs.",
         thrown.getMessage());
@@ -180,7 +201,8 @@ public void verifyEntry_logIdTimeMismatch() throws Exception {
 
     var thrown =
         Assertions.assertThrows(
-            RekorVerificationException.class, () -> verifier.verifyEntry(response.getEntry()));
+            RekorVerificationException.class,
+            () -> verifier.verifyHashedRekord(response.getEntry(), artifactHash));
     Assertions.assertEquals(
         "Log entry (logid, timestamp) does not match any provided transparency logs.",
         thrown.getMessage());

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": "eyJhcGlWZXJzaW9uIjoiMC4wLjEiLCJraW5kIjoiaGFzaGVkcmVrb3JkIiwic3BlYyI6eyJkYXRhIjp7Imhhc2giOnsiYWxnb3JpdGhtIjoic2hhMjU2IiwidmFsdWUiOiJkNDBlYzNlZWJjYjI5OTE0OTRmMjI3MzZhM2Y1ZmE3YjJlNGI2OTcyZDdjMDQ2ZDVjNWQ3ZTUwNmFiZTlmNzUyIn19LCJzaWduYXR1cmUiOnsiY29udGVudCI6Ik1FUUNJRWhQanlEZXFCdDJyNnBkNTVTczVYdi9rTG54NXozb0hDOE42TCtWOW1MSUFpQktpQ2xLcTNPV2ttcHZUcXpyRDZ1a2RmdTQvRXhGVVVmdHoxcnMvL04ySnc9PSIsInB1YmxpY0tleSI6eyJjb250ZW50IjoiTFMwdExTMUNSVWRKVGlCRFJWSlVTVVpKUTBGVVJTMHRMUzB0Q2sxSlNVTjRla05EUVdzeVowRjNTVUpCWjBsVlJteERWeTlHUWtabFVrRmtkVU12Y1c0eGVrNTBOVWt2YlN0SmQwTm5XVWxMYjFwSmVtb3dSVUYzVFhjS1RucEZWazFDVFVkQk1WVkZRMmhOVFdNeWJHNWpNMUoyWTIxVmRWcEhWakpOVWpSM1NFRlpSRlpSVVVSRmVGWjZZVmRrZW1SSE9YbGFVekZ3WW01U2JBcGpiVEZzV2tkc2FHUkhWWGRJYUdOT1RXcFJlRTFVU1hoTmFrRjZUVlJGTlZkb1kwNU5hbEY0VFZSSmVFMXFRVEJOVkVVMVYycEJRVTFHYTNkRmQxbElDa3R2V2tsNmFqQkRRVkZaU1V0dldrbDZhakJFUVZGalJGRm5RVVZzWlhwUWFXeEtWVlZqTkV0cGJtWkVURTl0UTNobVRVNXpLMlJ4Ums5c2JYWkNZMnNLUW1aaWRHeHRXRWRpWTNKRGVtTkxNWGRuTm5SdVYzVklObmhHZUhKclJFUmxaMU5ITDBoYU1HcGpVekJMVUU0M1EyRlBRMEZYZDNkblowWnZUVUUwUndwQk1WVmtSSGRGUWk5M1VVVkJkMGxJWjBSQlZFSm5UbFpJVTFWRlJFUkJTMEpuWjNKQ1owVkdRbEZqUkVGNlFXUkNaMDVXU0ZFMFJVWm5VVlZ4TVZsQ0NteHZUbXg1VDFkU2FuUkZOREZtTVdkeU5GbEZiR2haZDBoM1dVUldVakJxUWtKbmQwWnZRVlV6T1ZCd2VqRlphMFZhWWpWeFRtcHdTMFpYYVhocE5Ga0tXa1E0ZDBoUldVUldVakJTUVZGSUwwSkNUWGRGV1VWUVdWaENkMlJWUW01aU1qbHVZa2RWZFZreU9YUk5RMnRIUTJselIwRlJVVUpuTnpoM1FWRkZSUXBITW1nd1pFaENlazlwT0haWlYwNXFZak5XZFdSSVRYVmFNamwyV2pKNGJFeHRUblppVkVGeVFtZHZja0puUlVWQldVOHZUVUZGU1VKQ01FMUhNbWd3Q21SSVFucFBhVGgyV1ZkT2FtSXpWblZrU0UxMVdqSTVkbG95ZUd4TWJVNTJZbFJEUW1sUldVdExkMWxDUWtGSVYyVlJTVVZCWjFJM1FraHJRV1IzUWpFS1FVNHdPVTFIY2tkNGVFVjVXWGhyWlVoS2JHNU9kMHRwVTJ3Mk5ETnFlWFF2TkdWTFkyOUJka3RsTms5QlFVRkNhekZDYzBWTU5FRkJRVkZFUVVWWmR3cFNRVWxuUkdkNE5tUkNNMHR2YlhoUGVVSXdaakY1SzNZMGJUYzNNWE4yY1dWMUszZHVjazFUVG14WWNHNVNXVU5KUkRkTlZVUjVRa1ZhVlhobmVUSmFDbFJWZDNnd1NUWnllR2hOTm5weU5qRXJNamc0YXpkQmVYQktMMlZOUVc5SFEwTnhSMU5OTkRsQ1FVMUVRVEpuUVUxSFZVTk5VVU16VGpaR05sUlZWVk1LYTA5bVNrSnRZMWhPV2psSFRGaEhWbFYzV2xaQ1IwWmtSSEF2VkZkT1ZrNVZTeTlyT1ZZNE1VcFFXbFF6TkRWcVVUVm5SMUEzVFVOTlJXWjNPVEZUV2dwV00zSllZVWd6VkdGRFZYZGFSM0pQY205RE5XSmFNMGRzYW1oQ05raEdSMk5OUjFSM1JXUlFObE0ySzNsNVNHOTBkbkpYVW5kSFEwOVJQVDBLTFMwdExTMUZUa1FnUTBWU1ZFbEdTVU5CVkVVdExTMHRMUW89In19fX0="
+    }],
+    "certificate": {
+      "rawBytes": "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"
+    }
+  },
+  "messageSignature": {
+    "messageDigest": {
+      "algorithm": "SHA2_256",
+      "digest": "oM/HEnHW4njlfNMy/5V8P3BD/do1TEy7GQow1W76Ab8="
+    },
+    "signature": "MEYCIQCGZcJ+4mTIMPAyIKV7XZjZ5KyvX1tz/glbin9vVF+9fwIhANUb5z/2Rb88vtvtABHAmQyBl4Yp8ipMLCnv36Ln8/Eb"
+  }
+}