Improve this question. Community Bot 1. Wow this a new one. In a networking class we constructed a reliable protocol on top of UDP that had better packet recovery semantics than TCP. You could certainly stack TLS on it.
I'm pretty sure you could also stack TLS directly over serial line, but why would you want to? The actual premisses of your question are not even stated here. Add a comment. Active Oldest Votes. Improve this answer. Tobi Nary Tobi Nary Thank you especially for your second paragraph. I think I can use that as an answer, should the professor ask. Someone said this in a past exam: "A reliable connection is required because if a ChangeCipherSpec gets lost, the connection can continue without the cipher suite being applied.
Can you please tell me whether you agree with me or him? The connection would rather end to work for both parties, as they do not use the same cipher from that loss onwards and would not be able to convey actual, useful information - the layer 7 protocol would not like that, probably. So the connection might not fail instantly, but eventually. That's what I thought. Sounds more convincing. Does the client wait for the server's "finished" message when establishing a connection or may the client send the first payload data immediately after sending its own "finished" message?
I'm pretty sure it waits because otherwise the protocol seems like it could be attacked, but I want to be sure that's actually how it works. Show 6 more comments. Steffen Ullrich Steffen Ullrich k 27 27 gold badges silver badges bronze badges. There are several reasons for this: If a packet were dropped or corrupted, TLS would have no way of recovering the data from that packet to present to the application layer and, thus, the assumption of reliability presented to the application layer would be lost.
I don't think there are any protocols which do not have this feature anything running on top of Ethernet, PPP SCTP extension. Of course it does not protect against malicious changes - for that you need TLS or something similar.
I was only describing in general why TLS needs reliability in the underlying transport protocol. This was an important need at that time, just prior to the dot-com bubble. The SSL 1.
Most of its design was done by Kipp Hickman, with much less participation from the public community. Even though it had its own vulnerabilities, it earned the trust and respect of the public as a strong protocol.
The very first deployment of SSL 2. Mostly due to U. A export regulations, Netscape had to weaken its encryption scheme to use bit long keys.
This limited all possible key combinations to a million million, which were tried by a set of researchers in 30 hours with many spare CPU cycles; they were able to recover the encrypted data. SSL 2. This encouraged many other vendors including Microsoft to come up with their own security implementations. Among the differences between SSL 2. With non-encrypted operational mode, PCT only provides authentication — no data encryption.
As discussed before, due to the U. A export regulation laws, SSL 2. Even though the regulations did not mandate to use weak cryptographic keys for authentication, SSL 2. Netscape released SSL 3. This was after an attempt to introduce SSL 2. But it never went pass the draft stage and Netscape decided it was the time to design everything from ground up.
SSL 3. It fixed issues in its predecessor, introduced due to MD5 hashing. In , Microsoft came up with a new proposal to merge SSL 3. Due to the interest shown by many vendors in solving the same problem in different ways, in the IETF initiated the Transport Layer Security working group to standardize all vendor-specific implementations. TLS 1. The differences between TLS 1. The first draft of the TLS 1. TCP is a layer of abstraction of a reliable network running over an unreliable channel.
IP Internet Protocol provides host-to-host routing and addressing. Each layer has its own responsibilities and communicates with each other using a well-defined interface. HTTP does not care how the packets are transported from one host to another.
This is mostly due to the inherent characteristics of TCP. During the data transmission, TCP takes care of retransmission of lost data, ordered delivery of packets, congestion control and avoidance, data integrity and many more. The Internet Protocol IP functions at the internet layer.
Its responsibility is to provide a hardware-independent addressing scheme to the messages pass-through. Finally it becomes the responsibility of the network access layer to transport the messages via the physical network.
The network access layer interacts directly with the physical network and provides an addressing scheme to identify each device the messages pass-through. The Ethernet protocol operates at the network access layer. Our discussion from here onward focuses only on TCP, which operates at the transport layer. Any TCP connection bootstraps with a 3-way handshake. In other words TCP is a connection-oriented protocol and the client has to establish a connection with the server prior to the data transmission.
Before the data transmission begins between the client and the server, each party has to exchange with each other, a set of parameters. These parameters include, the starting packet sequence numbers and many other connection specific parameters. This packet is known as the SYN packet. The SYN packet includes a randomly picked sequence number by the client, the source client port number, destination server port number and many other fields as shown in the Figure 2.
If you look closely at the Figure 2 you will notice that the source client IP address and the destination server IP address are outside the TCP packet and are included as part of the IP packet. As discussed before, IP operates at the network layer and the IP addresses are defined to be hardware-independent. This field indicates the length of the application data this packet carries.
Once the server receives the initial message from the client, it too picks its own random sequence number and passes it back in the response to the client. The two main characteristics of TCP: error control recover from lost packets and ordered delivery require each TCP packet to be identified uniquely.
The exchange of sequence numbers between the client and the server helps to keep that promise. Once the packets are numbered, both the sides of the communication channel know, which packets get lost during the transmission, duplicate packets and how to order a set of packets, which are delivered in a random order.
This includes the source server port, destination client port, server sequence number and the acknowledgement number. Adding one to the client sequence number found in the SYN packet derives the acknowledgement number.
This is known as the ACK packet. Once the handshake is complete, the application data transmission between the client and the server can begin. The client sends the application data packets to the server immediately after it sends the ACK packet. The transport layer gets the application data from the application layer.
If you look closely at the value of the TCP Segment Len field in Figure 5, you will notice that it is now set to a non-zero value. Once the application data transmission between the client and the server begins, the other should acknowledge each data packet sent by either party. Whenever either of the two parties at either end of the communication channel wants to send a message to the other, it sends a packet with the ACK flag as an acknowledgement to the last received sequence number from that party.
Figure assumes the same optimistic 28 millisecond one-way "light in fiber" delay between New York and London as used in previous TCP connection establishment examples; see Table One of the design goals for TLS 1. For the curious, the Wikipedia article on Diffie-Hellman key exchange is a great place to learn about the algorithm and its properties. The abbreviated handshake eliminates a full roundtrip of latency and significantly reduces computational costs for both sides.
In fact, if the browser requires multiple connections to the same host e. In practice, deploying session tickets across a set of load-balanced servers also requires some careful thinking and systems architecture: all servers must be initialized with the same session key, and an additional mechanism is required to periodically and securely rotate the shared key across all servers.
Speaking of optimizing CPU cycles, make sure to keep your servers up to date with the latest version of the TLS libraries! In addition to the security improvements, you will also often see performance benefits.
Security and performance go hand-in-hand.
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