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Questions tagged [protocols]

A description and set of rules for the ordered exchange of structured information designed with the goal of protecting the security of the system.

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549
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3answers
496k views

What's the difference between SSL, TLS, and HTTPS?

I get confused with the terms in this area. What is SSL, TLS, and HTTPS? What are the differences between them?
110
votes
6answers
27k views

What would one need to do in order to hijack a satellite?

I realise this borders on sci-fi, but there's been some interesting demonstrations regarding security of various satellites. What would be required to hack a satellite (in general terms, any hack ...
90
votes
10answers
20k views

Does it improve security to use obscure port numbers?

I recently started a job at a small company where the CTO prefers to host SSH services at obscure, high numbered ports on our servers rather than the well known port 22. His rationale is that "it ...
88
votes
4answers
113k views

What is ECDHE-RSA?

What is the difference between ECDHE-RSA and DHE-RSA? I know that DHE-RSA is (in one sentence) Diffie Hellman signed using RSA keys. Where DH is used for forward secrecy and RSA guards against MITM, ...
73
votes
16answers
14k views

Ensure that a file can only be decrypted after a specific date

Are there any cryptographic schemes/protocols that would allow me to encrypt a file, make it publicly available, but ensure that it can only be decrypted after specific date? I assume it would be ...
64
votes
8answers
118k views

What is the difference in security between a VPN- and a SSL-connection?

I would like to design a client-server application where the server is placed on Internet. I assume that I could set up the client-server connection using VPN (is it using IPSec?) or using a SSL ...
48
votes
3answers
4k views

Is Git crowdsourcing cryptographic attacks?

A strong cryptographic hash makes collisions unlikely. Many cryptographic protocols build on that fact. But Git is using SHA-1 hashes as object identifiers. So there are a lot of already computed ...
35
votes
6answers
20k views

Preventing artificial latency or “Lag Hacking” in multiplayer games

There is an attack that some people have dubbed "lag hacking", and its gaining popularity in multiplayer games. There are at-least two ways of creating artificial latency. One method of introducing ...
34
votes
2answers
37k views

What changed between TLS and DTLS

What did the DTLS (TLS over UDP) authors have to change so that it could run without TCP? Bonus points: Do any of the protocol difference affect the way it should be used, both in terms of interface ...
29
votes
3answers
66k views

IKEv2 vs OpenVPN

I want to ask you for information about the IKEv2 protocol for a VPN connection. I haven't found so much information on the web. I am interested especially regarding the usage on a mobile phone. Is it ...
29
votes
2answers
13k views

Is there a standard for printing a public key as a barcode?

Is there a standard for storing a public key printed on paper? Say, I want to hand out business cards with my public key pre-printed on them at a key signing party to help build the web of trust. My ...
28
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10answers
4k views

Why can protocols on higher layers be left unchanged?

In his answer to "How does SSL/TLS work?", Luc gives an explanation of how SSL works: SSL (and its successor, TLS) is a protocol that operates directly on top of TCP (although there are also ...
27
votes
4answers
26k views

How do the processes for digital certificates, signatures and ssl work?

I have been trying to understand how ssl works. Instead of Alice and Bob, lets consider client and server communication. Server has a digital certificate acquired from a CA. It also has public and ...
26
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2answers
12k views

Which protocols exist for end-to-end encrypted group chat?

I am looking for existing protocols for a group chat with two things: End to end encrypted. Just what you would expect: messages are only decipherable by the chat members and message tampering is ...
25
votes
2answers
1k views

Aviation security - Lessons to learn from PlaneSploit

A somewhat related question has already been asked (What would one need to do in order to hijack a satellite?), only at a more abstract level. Now we have a presentation by Hugo Teso from n.runs AG ...
24
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3answers
3k views

How does Convergence (CA replacement) prevent its notaries from being MITM'd as well?

I have been looking into Convergence and how it works, but I cant figure out how it is effective against a MITM attack that happens near the target system. My understanding is that Convergence works ...
22
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5answers
4k views

Why did TLS 1.3 drop AES-CBC?

I was watching this video about TLS 1.3: "Deploying TLS 1.3: the great, the good and the bad (33c3)" and was somewhat surprised to see that in their effort to provide "fewer, better choices" they ...
22
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3answers
5k views

Convergence - an SSL replacement?

Today, Moxie Marlinspike, a security researcher famous for his research on Android and SSL and related protocols (author of sslstrip/sslsniff), released "Convergence" which says is "an agile ...
20
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3answers
82k views

Four-way Handshake in WPA-Personal (WPA-PSK)

Can someone explain to me in what consists the Four-way Handshake in WPA-Personal (WPA with Pre-Shared Key), which informations are being sent between AP and client, how is it possible to find the AP ...
20
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2answers
15k views

The inner workings of iMessage security?

This is a very interesting article about the iMessage technology used in Apple's very popular communication devices. So far, there has not been much technical details released by Apple. Hopefully ...
16
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6answers
13k views

How to implement multi factor authentication using a token generator?

I'd like to implement multi factor authentication on a few projects. Now the first factor would be username and password, for the second factor I would like to use a token generator. These tokens ...
15
votes
1answer
329 views

Why is caller ID spoofing so simple, and catching offenders so hard?

There is plenty of software which allows a user to input a recipient's information, and a fake-originator's information, and the software will complete the caller ID spoof. I'm trying to understand ...
13
votes
1answer
27k views

What is the significance of the version field in a TLS 1.1+ ClientHello message?

I am trying to add TLS 1.1 and 1.2 support to a packet capture product which already has TLS 1.0 support. I have used Wireshark to capture traffic between my browser and an openssl server to generate ...
13
votes
1answer
2k views

Native rsync protocol security

Is the native rsync protocol (port 873) secure? Does it encrypt data or credentials? I'm planning on using rsync to store encrypted files in the cloud, I'm wondering whatever the password is ...
13
votes
3answers
2k views

Is off-the-record style encryption possible with email?

The instant messaging world has off-the-record encryption - which means you get authentication, encryption, and forward deniability. Key material is published after a session ends such that an ...
13
votes
3answers
3k views

How does Diaspora work?

I hear all this hype about Diaspora being decentralized, but the only information I can find on their official website and the Wikipedia article is that several people can run Diaspora servers. The ...
13
votes
1answer
1k views

Secure backup encryption with OpenSSL

I know, the general advice is "keep your hands off crypto stuff". And the standard way to encrypt backup data securely would be using GnuPG. However, for a rather academic exercise, I would like to ...
12
votes
3answers
2k views

What are locked domain names technically?

I just learned about domain name locking at registrar level. I’m having problem to understand what it is, all I found is it’s a protection against domain name takeover through transfer. Now, I also ...
12
votes
1answer
13k views

What does chacha20-poly1305@openssh.com mean for me?

OpenSSH just introduced a new protocol, chacha20-poly1305@openssh.com, which combines the two algorithms from DJB: ChaCha20 and Poly1305-AES. It was inspired by a similar proposal for TLS, which ...
12
votes
1answer
3k views

SSL TLS renegotiation vulnerability - current situation in clients

Reading about the SSL renegotiation problem CVE-2009-3555 one knows that servers supporting old type of renegotiation are vulnerable to data injection. We also have tools to test them (openssl ...
12
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2answers
3k views

How are mobile telephony networks like LTE and HSPA encrypted?

How are mobile telephony networks like LTE (4G) and HSPA (3G) encrypted? between what parts is the communication encrypted? who has access to the keys? is symmetric or asymmetric encryption used? is ...
11
votes
5answers
11k views

How secure is using CRAM-MD5 for email authentication, when not using an SSL connection?

Background: My current server-provider tells me it's no problem to store the passwords in plain-text in the database, saying he has to do so because they use CRAM-MD5 for email authentication. My ...
11
votes
2answers
9k views

Difference between Bluetooth LE Secure Connections security mode 1 and level 3 and 4?

In BLUETOOTH SPECIFICATION Version 4.2 [Vol 3, Part C], page 372, there is a section called LE Security Modes, which states: There are two LE security modes, LE security mode 1 and LE security mode ...
10
votes
1answer
702 views

Why does TLS 1.3 deprecate custom DHE groups?

According to the second draft of the TLS 1.3 specification, custom DH groups have been deprecated. As we all know, hardcoded DH groups are vulnerable to a precomputation attack that allows retroactive ...
10
votes
2answers
703 views

How do new security and cryptography techniques/protocols avoid the chicken-and-egg problem?

. . .better solutions have been proposed and will be worth considering once they have withstood the test of time (i.e. “5 to 10 years in the field, and not broken yet”). -From Thomas Pornin's ...
10
votes
2answers
4k views

Is there any protection against malicious devices on a CAN bus?

CAN (controller area network) is a bus used in all modern cars. You can read a lot of the cars information over this bus and I think (but I'm not too sure about this) that some critical control ...
10
votes
2answers
467 views

Are there any meta-formats for crypto?

Are there are any (properly specified) meta-formats / schema formats for describing cryptographic message structures? I'm looking for a way to describe the format (where some channels might want ...
10
votes
1answer
129 views

SSL 3.0 for clients without room for chosen plaintext attacks

I've collected the issues that affect SSL 3.0 and found that they are either configuration issues (disabling RC4, RC2, DES, anon, export, null suites, compression, proper key lengths, etc.) or ...
9
votes
2answers
4k views

Is it already the right time to say goodbye to TLS1.1 support on web servers? [closed]

Reading different articles, mentioning this one, for the sake of this question on old TLS topic. Quoting part of the article: 30 June 2018 is the deadline for disabling SSL/early TLS and ...
9
votes
4answers
6k views

extract from pcap all protocols found

I have some pcap files, and i would like just to get a list of protocols that are present on that pcap file. I would like it in a batch mode, not using wireshark I think tshark is able to do it, but ...
9
votes
1answer
5k views

Why would HTTP client only send authentication headers once an unauthenticated request was rejected?

The default usage of HttpClient and HttpWebRequest .NET classes is setting Credentials property and then asking the class instance to perform an HTTP request. If the target requres Basic authorization ...
9
votes
3answers
20k views

Safe to expose Active Directory via LDAPS externally?

We currently access Active Directory via LDAPS internally for authentication and user data retrieval. Is it common, or safe, to expose this publicly over LDAPs? Addendum 1: Our business case, ...
8
votes
3answers
9k views

What common products use Public-key cryptography?

I want know what common use products are there that use public key/private key cryptography?
8
votes
4answers
3k views

Is this type of ARP poisoning attack possible?

I am wondering if it is possible to paralyze a network by sending out a bunch of fake ARP response packets. Some basis: I recently read a moderately detailed description of how ARP and ARP poisoning ...
8
votes
3answers
6k views

What makes the Blackberry device and network more secure?

One of Blackberry's strongest assets is the "network" that it uses. Can someone explain, or link to technical information that covers what this secure network is, and what it does better than the ...
8
votes
3answers
7k views

Secure communication between two applications on the same system

I'm writing a software which is divided into two separate stand-alone pieces. One is a service like application that handles all the logics, the other one is a GUI application that just works as a ...
8
votes
1answer
1k views

What were the specific security flaws with OAuth 1.0? How are they being addressed in 2.0?

I read an article documenting Twitter abruptly pulling its OAuth support back in April 2009. The article said it wouldn't specify the hole for security reasons, but mentioned "social engineering" is ...
8
votes
1answer
5k views

What block ciphers and algorithms are now safe? [closed]

I work for a large non-US based international organisation. Regarding the recent leaks about the NSA breaking most encryption on the internet, we now know the US and UK governments are actively ...
8
votes
1answer
286 views

Main difference between Yahalom and Needham-Schroeder key exchange protocols

I am just wondering what is the main difference between the Yahalom and Needham-Schroeder key exchange protocols? Which protocol uses less computational power?
7
votes
1answer
5k views

What are non-standard ports and protocols [closed]

I am new to the security field and reading about how to check if an application is secure. One of the checks involves finding out if the app uses non-standard security ports and protocols. However, ...