ios_client

ios_client 0.8.5/Kecalek/Crypto/ContactVerification.swift

@@ -0,0 +1,162 @@
+import Foundation
+import CryptoKit
+
+/// Contact key verification: fingerprints, safety numbers, QR codes.
+/// Matches Python: crypto_utils.py compute_fingerprint, compute_safety_number, etc.
+enum ContactVerification {
+
+    /// Version byte for fingerprint computation (Signal's NumericFingerprint).
+    private static let fingerprintVersion: UInt16 = 0
+
+    /// Number of SHA-512 iterations for fingerprint computation.
+    private static let fingerprintIterations = 5200
+
+    // MARK: - Fingerprint
+
+    /// Compute a 32-byte fingerprint for a user's identity key.
+    ///
+    /// Uses iterated SHA-512 (Signal's NumericFingerprint algorithm).
+    /// Seed: version(2B big-endian) + identity_key(32B) + user_id(UTF-8).
+    /// Each iteration: SHA-512(previous_hash + identity_key).
+    /// Output: first 32 bytes of final hash.
+    static func computeFingerprint(userId: String, identityKey: Data, iterations: Int = fingerprintIterations) -> Data {
+        let versionBytes = fingerprintVersion.bigEndianData
+        var data = versionBytes + identityKey + Data(userId.utf8)
+        for _ in 0..<iterations {
+            var hasher = SHA512()
+            hasher.update(data: data)
+            hasher.update(data: identityKey)
+            let digest = hasher.finalize()
+            data = Data(digest)
+        }
+        return Data(data.prefix(32))
+    }
+
+    /// Format 32-byte fingerprint as 6 groups of 5 zero-padded digits (30 digits).
+    ///
+    /// Each group: int(bytes[i*5:(i+1)*5], big-endian) % 100000.
+    /// Output: two lines of 3 groups each, space-separated.
+    static func formatFingerprint(_ fpBytes: Data) -> String {
+        var groups: [String] = []
+        for i in 0..<6 {
+            let start = i * 5
+            let end = min(start + 5, fpBytes.count)
+            let slice = fpBytes[fpBytes.startIndex + start ..< fpBytes.startIndex + end]
+            let num = bigEndianUInt64(slice) % 100000
+            groups.append(String(format: "%05d", num))
+        }
+        return groups[0..<3].joined(separator: " ") + "\n" + groups[3..<6].joined(separator: " ")
+    }
+
+    // MARK: - Safety Number
+
+    /// Compute a 60-digit safety number for a pair of users.
+    ///
+    /// Both users see the same number regardless of who computes it.
+    /// Lower user_id's fingerprint comes first (deterministic ordering).
+    /// Output: 12 groups of 5 digits, formatted as 3 lines of 4 groups.
+    static func computeSafetyNumber(
+        myUserId: String, myIdentityKey: Data,
+        theirUserId: String, theirIdentityKey: Data
+    ) -> String {
+        let fpMine = computeFingerprint(userId: myUserId, identityKey: myIdentityKey)
+        let fpTheirs = computeFingerprint(userId: theirUserId, identityKey: theirIdentityKey)
+
+        let combined: Data
+        if myUserId < theirUserId {
+            combined = fpMine + fpTheirs
+        } else {
+            combined = fpTheirs + fpMine
+        }
+
+        // 64 bytes -> 12 groups of 5 digits
+        var groups: [String] = []
+        for i in 0..<12 {
+            let start = i * 5
+            let end = min(start + 5, combined.count)
+            let slice = combined[combined.startIndex + start ..< combined.startIndex + end]
+            let num = bigEndianUInt64(slice) % 100000
+            groups.append(String(format: "%05d", num))
+        }
+
+        return [
+            groups[0..<4].joined(separator: " "),
+            groups[4..<8].joined(separator: " "),
+            groups[8..<12].joined(separator: " "),
+        ].joined(separator: "\n")
+    }
+
+    // MARK: - QR Code
+
+    /// Encode user identity for QR code verification.
+    ///
+    /// Format: version(1B=0x01) + uid_len(1B) + uid(UTF-8) + identity_key(32B).
+    static func encodeVerificationQR(userId: String, identityKey: Data) -> Data {
+        let uidBytes = Data(userId.utf8)
+        var data = Data([0x01, UInt8(uidBytes.count)])
+        data.append(uidBytes)
+        data.append(identityKey)
+        return data
+    }
+
+    /// Decode QR code verification payload.
+    ///
+    /// Returns (userId, identityKey).
+    /// Throws on invalid format.
+    static func decodeVerificationQR(_ data: Data) throws -> (userId: String, identityKey: Data) {
+        guard data.count >= 3 else {
+            throw VerificationError.qrDataTooShort
+        }
+        guard data[data.startIndex] == 0x01 else {
+            throw VerificationError.unknownQRVersion(data[data.startIndex])
+        }
+        let uidLen = Int(data[data.startIndex + 1])
+        guard data.count >= 2 + uidLen + 32 else {
+            throw VerificationError.qrDataTruncated
+        }
+        let uidData = data[data.startIndex + 2 ..< data.startIndex + 2 + uidLen]
+        guard let userId = String(data: uidData, encoding: .utf8) else {
+            throw VerificationError.invalidUTF8
+        }
+        let identityKey = Data(data[data.startIndex + 2 + uidLen ..< data.startIndex + 2 + uidLen + 32])
+        return (userId, identityKey)
+    }
+
+    // MARK: - Helpers
+
+    /// Convert up to 8 bytes to UInt64, big-endian.
+    private static func bigEndianUInt64(_ data: Data) -> UInt64 {
+        var result: UInt64 = 0
+        for byte in data {
+            result = result << 8 | UInt64(byte)
+        }
+        return result
+    }
+}
+
+// MARK: - UInt16 Big-Endian
+
+private extension UInt16 {
+    var bigEndianData: Data {
+        var value = self.bigEndian
+        return Data(bytes: &value, count: 2)
+    }
+}
+
+// MARK: - Verification Errors
+
+enum VerificationError: Error, LocalizedError {
+    case qrDataTooShort
+    case unknownQRVersion(UInt8)
+    case qrDataTruncated
+    case invalidUTF8
+
+    var errorDescription: String? {
+        switch self {
+        case .qrDataTooShort: return "QR data too short"
+        case .unknownQRVersion(let v): return "Unknown QR version: \(v)"
+        case .qrDataTruncated: return "QR data truncated"
+        case .invalidUTF8: return "Invalid UTF-8 in QR data"
+        }
+    }
+}