| 1 | import XCTest |
| 2 | import CryptoKit |
| 3 | @testable import LChatCore |
| 4 | |
| 5 | // Native half of the inclusion-proof + bind-MAC wire format (#573). The leaf, |
| 6 | // root, and audit-path vectors here are the SAME frozen values checkpoint.go |
| 7 | // (TestGenVectors) and integrity.test.mjs pin: if any of the three platforms |
| 8 | // drifts, they disagree about a valid proof. Fix the code, not the vector. |
| 9 | final class InclusionProofTests: XCTestCase { |
| 10 | |
| 11 | // MARK: Merkle inclusion proofs |
| 12 | |
| 13 | func testLeafHashMatchesVector() { |
| 14 | // journalLeafHash({seq:1, ts:1700000000, kind:"msg", msg_id:42, thread_id:"th", blob_hash:"ab"}) |
| 15 | let got = Checkpoint.leafHashHex(seq: 1, ts: 1_700_000_000, kind: "msg", msgID: 42, blobHash: "ab", threadID: "th") |
| 16 | XCTAssertEqual(got, "e88f7b9ea2a1fdec4ce59c21467efcef2c1b7227b9618d5581c0923328143b15") |
| 17 | } |
| 18 | |
| 19 | // The real 3-leaf tree from checkpoint.go's vector generator; proof for index 1. |
| 20 | private let ROOT = "2d87c04aa784c70ba78cfae713e3434cbd4bea6da2644246b81e5e89240f02dd" |
| 21 | private let AUDIT = [ |
| 22 | "9da3202f6b64da0ed851e92377b58188b5928facc765337938adb1bb32639e3e", |
| 23 | "7a734103ada2f12e8d051e1c894fbf5f3a0a8049c26b4bc598b49c2c4da19189", |
| 24 | ] |
| 25 | private func goodProof() -> InclusionProof { |
| 26 | InclusionProof(seq: 2, ts: 1_700_000_001, kind: "msg", msg_id: 11, thread_id: "t", blob_hash: "h2", |
| 27 | checkpoint_id: 1, root: ROOT, leaf_index: 1, tree_size: 3, audit_path: AUDIT) |
| 28 | } |
| 29 | |
| 30 | func testVerifyInclusionReproducesGoRoot() { |
| 31 | let (ok, root) = Checkpoint.verifyInclusion(goodProof()) |
| 32 | XCTAssertTrue(ok) |
| 33 | XCTAssertEqual(root, ROOT) |
| 34 | } |
| 35 | |
| 36 | func testTamperedProofDoesNotVerify() { |
| 37 | var p = goodProof() |
| 38 | // Wrong content (blob_hash) → different leaf → root won't match. |
| 39 | p = InclusionProof(seq: p.seq, ts: p.ts, kind: p.kind, msg_id: p.msg_id, thread_id: p.thread_id, |
| 40 | blob_hash: "hX", checkpoint_id: p.checkpoint_id, root: p.root, |
| 41 | leaf_index: p.leaf_index, tree_size: p.tree_size, audit_path: p.audit_path) |
| 42 | XCTAssertFalse(Checkpoint.verifyInclusion(p).ok) |
| 43 | // Corrupted sibling. |
| 44 | let corrupt = InclusionProof(seq: 2, ts: 1_700_000_001, kind: "msg", msg_id: 11, thread_id: "t", blob_hash: "h2", |
| 45 | checkpoint_id: 1, root: ROOT, leaf_index: 1, tree_size: 3, |
| 46 | audit_path: [String(repeating: "00", count: 32), AUDIT[1]]) |
| 47 | XCTAssertFalse(Checkpoint.verifyInclusion(corrupt).ok) |
| 48 | // Wrong path length for the tree size → nil root. |
| 49 | XCTAssertNil(Checkpoint.rootFromAuditPath(leafHex: String(repeating: "ab", count: 32), m: 1, n: 3, pathHex: [AUDIT[0]])) |
| 50 | } |
| 51 | |
| 52 | func testAuditPathReproducesRootForEveryShape() { |
| 53 | // A self-contained sweep (like the Go test): build n leaves, prove each. |
| 54 | for n in 1...17 { |
| 55 | var leaves: [String] = [] |
| 56 | for i in 0..<n { |
| 57 | leaves.append(Checkpoint.leafHashHex(seq: Int64(i), ts: Int64(n), kind: "k", msgID: Int64(i), blobHash: "b\(i)", threadID: "t")) |
| 58 | } |
| 59 | let root = merkleRootHex(leaves) |
| 60 | for m in 0..<n { |
| 61 | let path = auditPathHex(leaves, m) |
| 62 | let got = Checkpoint.rootFromAuditPath(leafHex: leaves[m], m: m, n: n, pathHex: path) |
| 63 | XCTAssertEqual(got, root, "n=\(n) m=\(m)") |
| 64 | } |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | // Local reference Merkle (RFC 6962) to cross-check rootFromAuditPath — mirrors |
| 69 | // checkpoint.go merkleRoot/merkleAuditPath, independent of the code under test. |
| 70 | private func nodeHex(_ l: String, _ r: String) -> String { |
| 71 | var d = Data("lchat-ckpt-node\n".utf8) |
| 72 | d.append(Data(hexBytes(l))); d.append(Data(hexBytes(r))) |
| 73 | return SHA256.hash(data: d).map { String(format: "%02x", $0) }.joined() |
| 74 | } |
| 75 | private func merkleRootHex(_ leaves: [String]) -> String { |
| 76 | if leaves.count == 1 { return leaves[0] } |
| 77 | var k = 1; while k * 2 < leaves.count { k *= 2 } |
| 78 | return nodeHex(merkleRootHex(Array(leaves[0..<k])), merkleRootHex(Array(leaves[k...]))) |
| 79 | } |
| 80 | private func auditPathHex(_ leaves: [String], _ m: Int) -> [String] { |
| 81 | let n = leaves.count |
| 82 | if n <= 1 { return [] } |
| 83 | var k = 1; while k * 2 < n { k *= 2 } |
| 84 | if m < k { return auditPathHex(Array(leaves[0..<k]), m) + [merkleRootHex(Array(leaves[k...]))] } |
| 85 | return auditPathHex(Array(leaves[k...]), m - k) + [merkleRootHex(Array(leaves[0..<k]))] |
| 86 | } |
| 87 | private func hexBytes(_ s: String) -> [UInt8] { |
| 88 | var out = [UInt8](); var i = s.startIndex |
| 89 | while i < s.endIndex { let j = s.index(i, offsetBy: 2); out.append(UInt8(s[i..<j], radix: 16)!); i = j } |
| 90 | return out |
| 91 | } |
| 92 | |
| 93 | // MARK: sampleAndVerify (monitor) |
| 94 | |
| 95 | private final class MemStore: IntegrityStore { |
| 96 | var data: Data? |
| 97 | func loadIntegrity() -> Data? { data } |
| 98 | func saveIntegrity(_ d: Data) { data = d } |
| 99 | } |
| 100 | |
| 101 | @MainActor |
| 102 | func testSampleAndVerifyConfirmsAndFlags() async { |
| 103 | let store = MemStore() |
| 104 | // Pre-seed a verified root (as a poll would) via the internal state. |
| 105 | var seed = IntegrityState() |
| 106 | seed.roots = [ROOT] |
| 107 | store.saveIntegrity(try! JSONEncoder().encode(seed)) |
| 108 | let mon = IntegrityMonitor(store: store) |
| 109 | |
| 110 | let r = await mon.sampleAndVerify([(msgID: 11, blobHash: "h2")]) { _ in |
| 111 | CheckpointProofResponse(proofs: [self.goodProof()], committed_to: 5) |
| 112 | } |
| 113 | XCTAssertEqual(r.verified, 1) |
| 114 | XCTAssertEqual(mon.unresolvedAlerts().count, 0) |
| 115 | |
| 116 | // A forged proof against the trusted root → bad-proof alert. |
| 117 | let forged = InclusionProof(seq: 2, ts: 1_700_000_001, kind: "msg", msg_id: 11, thread_id: "t", blob_hash: "h2", |
| 118 | checkpoint_id: 1, root: ROOT, leaf_index: 1, tree_size: 3, |
| 119 | audit_path: [String(repeating: "00", count: 32), AUDIT[1]]) |
| 120 | _ = await mon.sampleAndVerify([(msgID: 11, blobHash: "h2")]) { _ in |
| 121 | CheckpointProofResponse(proofs: [forged], committed_to: 5) |
| 122 | } |
| 123 | XCTAssertTrue(mon.unresolvedAlerts().contains { $0.kind == "bad-proof" }) |
| 124 | } |
| 125 | |
| 126 | @MainActor |
| 127 | func testSampleWithNoTrustedRootsIsSilent() async { |
| 128 | let mon = IntegrityMonitor(store: MemStore()) // no roots verified yet |
| 129 | let r = await mon.sampleAndVerify([(msgID: 11, blobHash: "h2")]) { _ in |
| 130 | CheckpointProofResponse(proofs: [self.goodProof()], committed_to: 5) |
| 131 | } |
| 132 | XCTAssertEqual(r.checked, 0) |
| 133 | XCTAssertEqual(mon.unresolvedAlerts().count, 0) |
| 134 | } |
| 135 | |
| 136 | // MARK: bind-MAC (key transparency) |
| 137 | |
| 138 | func testBindKeyDeterministicAndDomainSeparated() throws { |
| 139 | let t = InviteCrypto.randomSecret() |
| 140 | let a = try InviteCrypto.derive(t) |
| 141 | let b = try InviteCrypto.derive(t) |
| 142 | XCTAssertEqual(a.bindKey, b.bindKey) |
| 143 | XCTAssertNotEqual(a.bindKey, a.claimSecret) // domain separation |
| 144 | let c = try InviteCrypto.derive(InviteCrypto.randomSecret()) |
| 145 | XCTAssertNotEqual(a.bindKey, c.bindKey) |
| 146 | } |
| 147 | |
| 148 | func testBindMacVerifiesAndRejectsSubstitution() throws { |
| 149 | let d = try InviteCrypto.derive(InviteCrypto.randomSecret()) |
| 150 | let kp = ECIES.generateUserKeypair() |
| 151 | let mac = InviteCrypto.bindMac(bindKeyB64: d.bindKey, pubB64: kp.pub) |
| 152 | XCTAssertNotNil(mac) |
| 153 | XCTAssertTrue(InviteCrypto.verifyBindMac(bindKeyB64: d.bindKey, pubB64: kp.pub, macB64: mac!)) |
| 154 | // A substituted key must not verify — the whole point. |
| 155 | let evil = ECIES.generateUserKeypair() |
| 156 | XCTAssertFalse(InviteCrypto.verifyBindMac(bindKeyB64: d.bindKey, pubB64: evil.pub, macB64: mac!)) |
| 157 | // Wrong bind key rejected. |
| 158 | let other = try InviteCrypto.derive(InviteCrypto.randomSecret()) |
| 159 | XCTAssertFalse(InviteCrypto.verifyBindMac(bindKeyB64: other.bindKey, pubB64: kp.pub, macB64: mac!)) |
| 160 | // Malformed never throws → false. |
| 161 | XCTAssertFalse(InviteCrypto.verifyBindMac(bindKeyB64: d.bindKey, pubB64: kp.pub, macB64: "not base64!!")) |
| 162 | XCTAssertFalse(InviteCrypto.verifyBindMac(bindKeyB64: "", pubB64: kp.pub, macB64: mac!)) |
| 163 | } |
| 164 | |
| 165 | // The web/Swift bind-MAC must interoperate: a MAC one produces the other |
| 166 | // verifies. Cross-check against a value the JS test could reproduce (MAC |
| 167 | // over decoded key bytes) via a fixed key + pub. |
| 168 | func testBindMacIsOverDecodedBytesNotString() throws { |
| 169 | let d = try InviteCrypto.derive(InviteCrypto.randomSecret()) |
| 170 | let kp = ECIES.generateUserKeypair() |
| 171 | let mac = InviteCrypto.bindMac(bindKeyB64: d.bindKey, pubB64: kp.pub)! |
| 172 | // Re-encode the SAME key bytes with '=' padding — a server re-encoding |
| 173 | // trick that must NOT break verification (bind is over bytes, not string). |
| 174 | let padded = kp.pub + "=" |
| 175 | XCTAssertTrue(InviteCrypto.verifyBindMac(bindKeyB64: d.bindKey, pubB64: padded, macB64: mac)) |
| 176 | } |
| 177 | } |
| 178 | |
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