Remove serde_jcs dependency and make Rekor signature verification mor…

…e robust.
project-oak · Jan 10, 2024 · 99dd502 · 99dd502
1 parent 3a28b30
commit 99dd502
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Showing 2 changed files with 93 additions and 8 deletions.
diff --git a/oak_attestation_verification/src/rekor.rs b/oak_attestation_verification/src/rekor.rs
@@ -21,6 +21,7 @@ use alloc::{collections::BTreeMap, string::String, vec::Vec};
 use anyhow::Context;
 use base64::{prelude::BASE64_STANDARD, Engine as _};
 use serde::{Deserialize, Serialize};
+use serde_json::Value;
 
 use crate::util::{convert_pem_to_raw, hash_sha2_256, verify_signature_raw};
 
@@ -118,10 +119,11 @@ pub struct LogEntryVerification {
 /// be obtained from the `/api/v1/log/publicKey` Rest API. For `sigstore.dev`, it is a PEM-encoded
 /// x509/PKIX public key.
 pub struct RekorSignatureBundle {
+    // TODO: doc here
     /// Canonicalized JSON representation, based on RFC 8785 rules, of a subset of a Rekor LogEntry
     /// fields that are signed to generate `signedEntryTimestamp` (also a field in the Rekor
     /// LogEntry). These fields include body, integratedTime, logID and logIndex.
-    pub canonicalized: Vec<u8>,
+    pub signed_data: Vec<u8>,
 
     /// The signature over the canonicalized JSON document.
     pub signature: Vec<u8>,
@@ -144,7 +146,7 @@ impl TryFrom<&LogEntry> for RekorSignatureBundle {
 
         // Canonicalized JSON document that is signed. Canonicalization should follow the RFC 8785
         // rules.
-        let canonicalized = serde_jcs::to_vec(&entry_subset)
+        let signed_data = serde_jcs::to_vec(&entry_subset)
             .context("couldn't create canonicalized json string")?;
 
         // Extract the signature from the LogEntry.
@@ -159,7 +161,7 @@ impl TryFrom<&LogEntry> for RekorSignatureBundle {
             .context("couldn't decode Base64 signature")?;
 
         Ok(Self {
-            canonicalized,
+            signed_data: signed_data,
             signature,
         })
     }
@@ -202,12 +204,14 @@ pub fn get_rekor_log_entry_body(log_entry: &[u8]) -> anyhow::Result<Body> {
 
 /// Parses a blob into a Rekor log entry and verifies the signature in
 /// `signedEntryTimestamp`` using Rekor's public key.
+///
+/// TODO: specify what log_entry needs to contain.
 pub fn verify_rekor_signature(log_entry: &[u8], rekor_public_key: &[u8]) -> anyhow::Result<()> {
     let signature_bundle = rekor_signature_bundle(log_entry)?;
 
     verify_signature_raw(
         &signature_bundle.signature,
-        &signature_bundle.canonicalized,
+        &signature_bundle.signed_data,
         rekor_public_key,
     )
     .context("couldn't verify signedEntryTimestamp of the Rekor LogEntry")
@@ -255,10 +259,57 @@ pub fn verify_rekor_body(body: &Body, contents_bytes: &[u8]) -> anyhow::Result<(
         .context("couldn't verify signature over the endorsement")
 }
 
-fn rekor_signature_bundle(log_entry: &[u8]) -> anyhow::Result<RekorSignatureBundle> {
-    let parsed: BTreeMap<String, LogEntry> =
-        serde_json::from_slice(log_entry).context("couldn't parse bytes into a LogEntry object")?;
+// TODO remove after tests. Keeping around for now to compare outputs from old and new.
+fn rekor_signature_bundle_old(log_entry_json_bytes: &[u8]) -> anyhow::Result<RekorSignatureBundle> {
+    let parsed: BTreeMap<String, LogEntry> = serde_json::from_slice(log_entry_json_bytes)
+        .context("couldn't parse bytes into a LogEntry object")?;
     let entry = parsed.values().next().context("no entry in the map")?;
 
     RekorSignatureBundle::try_from(entry)
 }
+
+/// For a sample of expected JSON structure, see ../testdata/logentry.json .
+fn rekor_signature_bundle(log_entry_json_bytes: &[u8]) -> anyhow::Result<RekorSignatureBundle> {
+    let mut log_entry_json = serde_json::from_slice::<Value>(log_entry_json_bytes)
+        .context("Couldn't parse bytes as JSON")?;
+
+    let log_entry_root_object = log_entry_json
+        .as_object_mut()
+        .context("JSON root expected to be a JSON object")?;
+
+    anyhow::ensure!(
+        log_entry_root_object.len() == 1,
+        "Expected exactly 1 entry in log entry root JSON object"
+    );
+
+    let log_entry_artifact_object = log_entry_root_object
+        .values_mut()
+        .next()
+        .unwrap() // Already ensured one item must exist.
+        .as_object_mut()
+        .context("Artifact metadata expected to be a JSON object")?;
+
+    let verification: Value = log_entry_artifact_object
+        .remove("verification")
+        .context("'verification' key not found in artifact JSON")?;
+
+    // TODO does this always equal canonicalized?
+    // Note on preserving order: https://users.rust-lang.org/t/how-to-keep-order-after-using-serde-json-from-str-to-deserialize-a-string-to-struct/97727
+    let signed_json_bytes =
+        serde_json::to_vec(log_entry_artifact_object).context("Could not serialize to JSON")?;
+
+    let signed_entry_timestamp_base64_encoded = verification
+        .as_object()
+        .context("Expected 'verification' entry to contain a JSON object")?["signedEntryTimestamp"]
+        .as_str()
+        .context("Expected 'signedEntryTimestamp' entry to contain a JSON string")?;
+
+    let signed_entry_timestamp_bytes = BASE64_STANDARD
+        .decode(signed_entry_timestamp_base64_encoded)
+        .context("Couldn't Base64 decode signedEntryTimestap")?;
+
+    Ok(RekorSignatureBundle {
+        signed_data: signed_json_bytes,
+        signature: signed_entry_timestamp_bytes,
+    })
+}
diff --git a/oak_attestation_verification/testdata/logentry.json b/oak_attestation_verification/testdata/logentry.json
@@ -1 +1,35 @@
-{"24296fb24b8ad77a51d549703a3a1c2dd2639ba49617fc563854031cb93e6d354e7b005065c334a8":{"body":"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","integratedTime":1691754247,"logID":"c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d","logIndex":30891523,"verification":{"inclusionProof":{"checkpoint":"rekor.sigstore.dev - 2605736670972794746\n26728094\nUMgdlhClBSzBbqefL5wyKzDrSb/Wf1yic2lWuqc490o=\nTimestamp: 1691754248454344594\n\n— rekor.sigstore.dev wNI9ajBFAiEAuhZGCMHAXSu1zARzPjKeUQF4i1jY+45EmKodcfQofE4CICxsQ/OxAP0r+9wLT+1PzDuF/kZ5LJ44k6f0oueozZBf\n","hashes":["030b9e9fb6a20219790c620da0677ae9a9d551300d5d53677d2e889b18f93408","665e92da8bb3ecfec55d7084c2e680da9627140ceebd5b90443194974478aaae","d493bd198b0273aaadd90b15daae59f8c437ad7669b1ef0f35ee3bdfcccb0c1c","1c4f5d27f667cf8fdfab11719cb2700c43b6ec0699c0e906582f81cc5bbe627f","6f77ba99b9061179f7cf7d94ad3fafe88137ec4939f7a2855caf7a25b6b4c3eb","f72f831d5e9f5c86157f56bc850d0c505d0baa8af389c91689b5c002b83e47c3","85bbefe750579844c4ef01ba7e50ee147867768adf376df59a7d46d9061a0529","e9f1cc1f52ef6fafa3c87d2c2031f14ef16da2ac47c267601a97c1671307c313","91e4eaeb84796946c5ad1570ea06f4fd07ee9261526b696c251119d888e641e2","e4a5b55c06b38419780a1a1b34b7e1ab1329b55948a105df191ec58325ae6220","1127441051032e9e2b9a7ff43ac6a8d4133438354f8b295c37b23f6292569ff5","fda678e668dd9896f1cdbf160943a690da123917de48afe85edd6c494d08e1b9","5cf299a407ce2c41b16dc87bd3bc7396ba9426d1b5e43ba70bbd979e417c45e6","ba60819f9a3f9ddabeb6ec73d1ba79d04fd2ad69ce8d95c777ab485a9fadb36b","8d152ae03f0ef85238ed66f0f7ab3bc870aee2acd6531a4855fc5011ea6b0e67","ad712c98424de0f1284d4f144b8a95b5d22c181d4c0a246518e7a9a220bdf643"],"logIndex":26728092,"rootHash":"50c81d9610a5052cc16ea79f2f9c322b30eb49bfd67f5ca2736956baa738f74a","treeSize":26728094},"signedEntryTimestamp":"MEYCIQCCN9ip/cW7QfS4EbLyigCs4OKz4wcWUQThuQY00i3PZAIhAKsTz7epe3Gh/9XGLzh4L1yPqcGUCETPPckPvMIZbL/7"}}}
+{
+    "24296fb24b8ad77a51d549703a3a1c2dd2639ba49617fc563854031cb93e6d354e7b005065c334a8": {
+        "body": "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",
+        "integratedTime": 1691754247,
+        "logID": "c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d",
+        "logIndex": 30891523,
+        "verification": {
+            "inclusionProof": {
+                "checkpoint": "rekor.sigstore.dev - 2605736670972794746\n26728094\nUMgdlhClBSzBbqefL5wyKzDrSb/Wf1yic2lWuqc490o=\nTimestamp: 1691754248454344594\n\n— rekor.sigstore.dev wNI9ajBFAiEAuhZGCMHAXSu1zARzPjKeUQF4i1jY+45EmKodcfQofE4CICxsQ/OxAP0r+9wLT+1PzDuF/kZ5LJ44k6f0oueozZBf\n",
+                "hashes": [
+                    "030b9e9fb6a20219790c620da0677ae9a9d551300d5d53677d2e889b18f93408",
+                    "665e92da8bb3ecfec55d7084c2e680da9627140ceebd5b90443194974478aaae",
+                    "d493bd198b0273aaadd90b15daae59f8c437ad7669b1ef0f35ee3bdfcccb0c1c",
+                    "1c4f5d27f667cf8fdfab11719cb2700c43b6ec0699c0e906582f81cc5bbe627f",
+                    "6f77ba99b9061179f7cf7d94ad3fafe88137ec4939f7a2855caf7a25b6b4c3eb",
+                    "f72f831d5e9f5c86157f56bc850d0c505d0baa8af389c91689b5c002b83e47c3",
+                    "85bbefe750579844c4ef01ba7e50ee147867768adf376df59a7d46d9061a0529",
+                    "e9f1cc1f52ef6fafa3c87d2c2031f14ef16da2ac47c267601a97c1671307c313",
+                    "91e4eaeb84796946c5ad1570ea06f4fd07ee9261526b696c251119d888e641e2",
+                    "e4a5b55c06b38419780a1a1b34b7e1ab1329b55948a105df191ec58325ae6220",
+                    "1127441051032e9e2b9a7ff43ac6a8d4133438354f8b295c37b23f6292569ff5",
+                    "fda678e668dd9896f1cdbf160943a690da123917de48afe85edd6c494d08e1b9",
+                    "5cf299a407ce2c41b16dc87bd3bc7396ba9426d1b5e43ba70bbd979e417c45e6",
+                    "ba60819f9a3f9ddabeb6ec73d1ba79d04fd2ad69ce8d95c777ab485a9fadb36b",
+                    "8d152ae03f0ef85238ed66f0f7ab3bc870aee2acd6531a4855fc5011ea6b0e67",
+                    "ad712c98424de0f1284d4f144b8a95b5d22c181d4c0a246518e7a9a220bdf643"
+                ],
+                "logIndex": 26728092,
+                "rootHash": "50c81d9610a5052cc16ea79f2f9c322b30eb49bfd67f5ca2736956baa738f74a",
+                "treeSize": 26728094
+            },
+            "signedEntryTimestamp": "MEYCIQCCN9ip/cW7QfS4EbLyigCs4OKz4wcWUQThuQY00i3PZAIhAKsTz7epe3Gh/9XGLzh4L1yPqcGUCETPPckPvMIZbL/7"
+        }
+    }
+}