Fix typo

SignalServiceKit/src/Loki/API/LokiAPI+Message.swift

@@ -40,8 +40,7 @@ public extension LokiAPI {
                         if isPoWRequired {
                             // The storage server takes a time interval in milliseconds
                             let now = NSDate.ows_millisecondTimeStamp()
-                            let ttlInSeconds = ttl / 1000
-                            if let nonce = ProofOfWork.calculate(data: data, pubKey: destination, timestamp: now, ttl: ttlInSeconds) {
+                            if let nonce = ProofOfWork.calculate(data: data, pubKey: destination, timestamp: now, ttl: ttl) {
                                 let result = Message(destination: destination, data: data, ttl: ttl, timestamp: now, nonce: nonce)
                                 seal.fulfill(result)
                             } else {

SignalServiceKit/src/Loki/Crypto/ProofOfWork.swift

@@ -63,7 +63,7 @@ public enum ProofOfWork {
     ///   - data: The message data
     ///   - pubKey: The message recipient
     ///   - timestamp: The timestamp
-    ///   - ttl: The message time to live, in **seconds**
+    ///   - ttl: The message time to live
     /// - Returns: A nonce string or `nil` if it failed
     public static func calculate(data: String, pubKey: String, timestamp: UInt64, ttl: UInt64) -> String? {
         let payload = createPayload(pubKey: pubKey, data: data, timestamp: timestamp, ttl: ttl)
@@ -103,7 +103,8 @@ public enum ProofOfWork {
 
         // Do all the calculations
         let totalLength = UInt64(payloadLength + nonceLength)
-        let ttlMult = ttl * totalLength
+        let ttlInSeconds = ttl / 1000
+        let ttlMult = ttlInSeconds * totalLength
         
         // UInt64 values
         let innerFrac = ttlMult / two16