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Transitive verification: vouch for verified peers over Noise
When a Noise session establishes with a peer I verified and that peer advertises the .vouch capability, send signed attestations (up to 16, most recently verified first, at most once per peer per 24h) for the OTHER fingerprints I verified. Receivers accept vouches only from senders they verified themselves, verify the Ed25519 signature against the sender's announce-bound signing key, and surface the result as a new derived trust tier: vouched (unfilled seal) between casual and trusted. Protocol: - NoisePayloadType.vouch = 0x12 carries a batch of TLV attestations: voucheeFingerprint (32B), voucheeSigningKey (32B), timestamp (uint64 ms BE), Ed25519 signature over "bitchat-vouch-v1" | fingerprint | signingKey | timestamp. The voucher is implicit in the authenticated session. - PeerCapabilities.localSupported now advertises .vouch. Storage (SecureIdentityStateManager / IdentityCache): - vouches keyed by vouchee, capped at 8 vouchers each; validity is recomputed on read (voucher still verified-by-me, < 30 days old), so unverifying a voucher retires their vouches without cascade deletes. - New IdentityCache fields are Optional so pre-existing encrypted caches decode cleanly; TrustLevel.vouched is inserted mid-ladder but raw values are strings, so persisted values are unaffected (and vouched itself is never persisted). - Panic wipe clears vouch state with the rest of the identity cache. UI: unfilled checkmark.seal badge in the mesh peer list (filled seal stays exclusive to verified) and a "vouched for by N people you verified" section with voucher names in FingerprintView; VoiceOver labels and xcstrings entries included. Tests: attestation encode/decode + signature (forged/tampered/expired), accept-policy gates, batch cap, trust-level derivation incl. voucher invalidation, persistence compat, and coordinator exchange/accept policies. Full macOS suite: 1088 tests passing. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
jack
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import CryptoKit
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import Foundation
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import Testing
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@testable import bitchat
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struct VouchAttestationTests {
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private let voucherKey = Curve25519.Signing.PrivateKey()
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private func makeAttestation(
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fingerprint: Data = Data(repeating: 0xAA, count: 32),
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signingKey: Data = Data(repeating: 0xBB, count: 32),
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timestampMs: UInt64 = UInt64(Date().timeIntervalSince1970 * 1000),
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signedBy key: Curve25519.Signing.PrivateKey? = nil
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) throws -> VouchAttestation {
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let signer = key ?? voucherKey
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return try #require(
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VouchAttestation.build(
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voucheeFingerprint: fingerprint,
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voucheeSigningKey: signingKey,
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timestampMs: timestampMs,
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sign: { try? signer.signature(for: $0) }
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)
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)
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}
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@Test
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func roundTripsAndVerifiesSignature() throws {
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let attestation = try makeAttestation()
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let encoded = try #require(attestation.encode())
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let decoded = try #require(VouchAttestation.decode(from: encoded))
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#expect(decoded == attestation)
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#expect(decoded.voucheeFingerprintHex == String(repeating: "aa", count: 32))
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#expect(decoded.verifySignature(voucherSigningKey: voucherKey.publicKey.rawRepresentation))
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}
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@Test
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func decodeSkipsUnknownTLVsAndRejectsMalformedInput() throws {
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let attestation = try makeAttestation()
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var encoded = try #require(attestation.encode())
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// Unknown TLV appended: skipped for forward compatibility.
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encoded.append(contentsOf: [0x7F, 0x02, 0x01, 0x02])
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#expect(VouchAttestation.decode(from: encoded) == attestation)
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// Truncation and missing fields are rejected.
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#expect(VouchAttestation.decode(from: encoded.dropLast()) == nil)
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#expect(VouchAttestation.decode(from: Data([0x01, 0x20])) == nil)
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#expect(VouchAttestation.decode(from: Data()) == nil)
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// Wrong field sizes are rejected.
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var wrongSize = Data([0x01, 0x10])
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wrongSize.append(Data(repeating: 0xAA, count: 16))
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#expect(VouchAttestation.decode(from: wrongSize) == nil)
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}
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@Test
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func buildRejectsWrongKeyAndFingerprintSizes() {
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let sign: (Data) -> Data? = { try? self.voucherKey.signature(for: $0) }
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#expect(VouchAttestation.build(
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voucheeFingerprint: Data(repeating: 0xAA, count: 16),
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voucheeSigningKey: Data(repeating: 0xBB, count: 32),
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sign: sign
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) == nil)
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#expect(VouchAttestation.build(
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voucheeFingerprint: Data(repeating: 0xAA, count: 32),
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voucheeSigningKey: Data(repeating: 0xBB, count: 16),
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sign: sign
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) == nil)
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}
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@Test
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func forgedSignatureFailsVerification() throws {
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let attestation = try makeAttestation()
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let otherKey = Curve25519.Signing.PrivateKey()
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// Verifying against a key that didn't sign fails.
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#expect(!attestation.verifySignature(voucherSigningKey: otherKey.publicKey.rawRepresentation))
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// An attestation signed by an imposter fails against the real key.
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let forged = try makeAttestation(signedBy: otherKey)
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#expect(!forged.verifySignature(voucherSigningKey: voucherKey.publicKey.rawRepresentation))
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#expect(!attestation.verifySignature(voucherSigningKey: Data(repeating: 0x01, count: 3)))
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}
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@Test
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func tamperedFieldsFailVerification() throws {
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let attestation = try makeAttestation()
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let publicKey = voucherKey.publicKey.rawRepresentation
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var tamperedFingerprint = attestation.voucheeFingerprint
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tamperedFingerprint[0] ^= 0xFF
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let tampered = VouchAttestation(
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voucheeFingerprint: tamperedFingerprint,
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voucheeSigningKey: attestation.voucheeSigningKey,
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timestampMs: attestation.timestampMs,
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signature: attestation.signature
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)
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#expect(!tampered.verifySignature(voucherSigningKey: publicKey))
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let backdated = VouchAttestation(
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voucheeFingerprint: attestation.voucheeFingerprint,
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voucheeSigningKey: attestation.voucheeSigningKey,
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timestampMs: attestation.timestampMs - 1,
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signature: attestation.signature
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)
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#expect(!backdated.verifySignature(voucherSigningKey: publicKey))
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}
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@Test
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func expiryWindowIsEnforced() throws {
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let now = Date()
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let fresh = try makeAttestation(timestampMs: UInt64(now.timeIntervalSince1970 * 1000))
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#expect(!fresh.isExpired(now: now))
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let thirtyOneDaysAgo = now.addingTimeInterval(-31 * 24 * 60 * 60)
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let expired = try makeAttestation(timestampMs: UInt64(thirtyOneDaysAgo.timeIntervalSince1970 * 1000))
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#expect(expired.isExpired(now: now))
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let farFuture = now.addingTimeInterval(2 * 60 * 60)
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let fromTheFuture = try makeAttestation(timestampMs: UInt64(farFuture.timeIntervalSince1970 * 1000))
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#expect(fromTheFuture.isExpired(now: now))
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// A verified-but-expired attestation still has a valid signature; the
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// two checks are independent gates.
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#expect(expired.verifySignature(voucherSigningKey: voucherKey.publicKey.rawRepresentation))
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}
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@Test
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func batchRoundTripsAndEnforcesCap() throws {
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let attestations = try (0..<3).map { index in
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try makeAttestation(fingerprint: Data(repeating: UInt8(index + 1), count: 32))
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}
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let payload = try #require(VouchAttestation.encodeList(attestations))
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#expect(VouchAttestation.decodeList(from: payload) == attestations)
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#expect(VouchAttestation.encodeList([]) == nil)
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let tooMany = try (0..<17).map { index in
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try makeAttestation(fingerprint: Data(repeating: UInt8(index + 1), count: 32))
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}
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#expect(VouchAttestation.encodeList(tooMany) == nil)
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}
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@Test
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func decodeListIgnoresEntriesBeyondCapAndMalformedEntries() throws {
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let attestations = try (0..<17).map { index in
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try makeAttestation(fingerprint: Data(repeating: UInt8(index + 1), count: 32))
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}
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// Hand-build an oversized batch that lies about its count.
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var payload = Data([UInt8(attestations.count)])
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for attestation in attestations {
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let encoded = try #require(attestation.encode())
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payload.append(UInt8(encoded.count >> 8))
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payload.append(UInt8(encoded.count & 0xFF))
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payload.append(encoded)
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}
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let decoded = VouchAttestation.decodeList(from: payload)
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#expect(decoded.count == VouchAttestation.maxBatchCount)
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#expect(decoded == Array(attestations.prefix(VouchAttestation.maxBatchCount)))
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// A malformed middle entry is dropped without killing the batch.
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let good = try makeAttestation()
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let goodEncoded = try #require(good.encode())
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var mixed = Data([2])
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mixed.append(contentsOf: [0x00, 0x03, 0xDE, 0xAD, 0xBE])
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mixed.append(UInt8(goodEncoded.count >> 8))
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mixed.append(UInt8(goodEncoded.count & 0xFF))
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mixed.append(goodEncoded)
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#expect(VouchAttestation.decodeList(from: mixed) == [good])
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#expect(VouchAttestation.decodeList(from: Data()) == [])
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#expect(VouchAttestation.decodeList(from: Data([5])) == [])
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}
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}
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