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185

TLS is the new name for SSL. Namely, SSL protocol got to version 3.0; TLS 1.0 is "SSL 3.1". TLS versions currently defined include TLS 1.1 and 1.2. Each new version adds a few features and modifies some internal details. We sometimes say "SSL/TLS". HTTPS is HTTP-within-SSL/TLS. SSL (TLS) establishes a secured, bidirectional tunnel for arbitrary binary data ...


69

Overview First, I learned a lot of my information from a combination of my amateur radio experience and an awesome talk I sat in at DEFCON 18. The majority of satellite systems are simple repeaters. The signal that comes in on a transponder is cleaned, amplified, and retransmitted. If you know the location and input frequency, and you pump more effective ...


69

You should think of OSI layers as packaging. Let's say I want to ship a glass to you. I chose an original package for advertisement purposes, showing how nice is my product and what you can buy to add to your "glass" experience. That's the high layer of my protocol. Then I put this package in a box filled with soft thingies because I don't want it to be ...


66

Time is relative. Cryptography lives in the ethereal world of abstract computing machines: there are machines that can do operations. Bigger machines can do operations faster. There is no clock that you can enforce; physical time has no meaning. In other words, if an attacker wants to get your file earlier, he just has to buy a faster computer. Now one can ...


55

If you do not want to involve a third party, you (the party encrypting the file) could simply release the key to decrypt the file on the target date. I have seen this done for video game releases. Customers are allowed to download an encrypted copy of the game in advance. Then, when the release time comes, the game company simply releases the key. That way, ...


48

Is Git crowdsourcing the production of SHA-1 preimages? Not to any meaningful degree. Github doesn't say how many commits it's tracking, but it's probably not more than a few billion. For comparison, there are 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible SHA-1 hashes, so the odds of finding a plaintext matching an arbitrary ...


43

Carefully place a spaceship broadcasting the decryption key in orbit around a black hole. The pull of gravity will delay the message until the appropriate time. Or you could just do like normal people and place the key broadcasting spaceship an appropriate number of light years away from the intended audience.


39

ECDHE suites use elliptic curve diffie-hellman key exchange, where DHE suites use normal diffie-hellman. This exchange is signed with RSA, in the same way in both cases. The main advantage of ECDHE is that it is significantly faster than DHE. This blog article talks a bit about the performance of ECDHE vs. DHE in the context of SSL.


35

VPN means "Virtual Private Network". It is a generic concept which designates a part of a bigger network (e.g. the Internet at large) which is logically isolated from the bigger network through non-hardware means (that's what "virtual" means): it is not that we are using distinct cables and switches; rather, isolation is performed through use of ...


31

SSL and TLS are protocols that aim to provide privacy and data integrity between two parties (see RFC 2246), designed to run over a reliable communication protocol (typically TCP). Although the TLS specification doesn't talk about sockets, the design of SSL/TLS was done so that applications could use them almost like traditional TCP sockets, for example ...


30

To add a bit of information on what @CodesInChaos says: When you use ECDHE instead of DHE, you may obtain the following advantages: Better performance. ECDHE is faster, for a given security level; @CodesInChaos points to an article which gives figures; see also this answer for why elliptic curve offer better performance. Smaller messages. An ECDH public ...


21

What would be required to hack a satellite (in general terms, any hack really)? When it comes to satellites, the word general does not apply. Almost every satellite, with very few exceptions is custom. Even the currently orbiting GPS satellites are not all the same: there are GPS IIA, GPS IIR, GPS IIR-M, and GPS IIF. I would venture that even satellites ...


20

This behaviour is specified by RFC2617. The reason for the extra round trip is that the server can request different kinds of authentication: basic, digest, etc. If you know in advance that the server takes basic authentication, then as you say, you can save a round trip. But that isn't the default, and I think the .NET libraries are right to expose this as ...


19

There are a few confusions in your post. First of all, HMAC is not a hash function. More about HMAC later on. Hash Functions A hash function is a completely public algorithm (no key in that) which mashes bit together in a way which is truly infeasible to untangle: anybody can run the hash function on any data, but finding the data back from the hash output ...


17

DTLS is currently (version 1.2) defined in RFC 6347 by explaining the differences with TLS 1.2 (RFC 5246). Most of the TLS elements are reused with only the smallest differences. The context is that the client and the server want to send each other a lot of data as "datagrams"; they really both want to send a long sequence of bytes, with a defined order, ...


16

The native rsync protocol does not encrypt anything. It is meant only for trusted networks. To use rsync in a secure way, use it with SSH (see the "-e" command-line option) or over a VPN.


16

Details on Convergence are to be found in the Perspectives Project, notably the corresponding Usenix article. An attacker able to "hide" the server from all notaries (i.e. an attacker working over the local network of the server, mostly) is what the authors call the Lserver model. Ultimately, that attack "works" with default notaries, which use "network ...


16

Just to be clear, it's explicitly not an SSL replacement. It's a replacement for CAs, with the explicit design goal of not forcing some giant IPv6-like "change the world" rollout. It's based in large part on earlier work on solving the SSH Host Key validation problem - see http://www.usenix.org/event/usenix08/tech/full_papers/wendlandt/wendlandt_html/ In ...


16

Use secret sharing to split a private encryption key into N parts, parameterized to allow reconstruction of the key with K or more parts, where K <= N. Best done using CRM, as described on the following page: http://en.wikipedia.org/wiki/Secret_sharing Then send each part to independent services that agree to publish at a given date in the future. Up ...


14

This is incomplete. But hopefully of some use. http://imfreedom.org/wiki/IMessage and https://github.com/meeee/pushproxy (especially the docs section) have done some reverse engineering of apple's proprietary protocol. Seems that every apple device has a SSL/TLS client-side cert for authentication that setup to be known to apple's push server. This is ...


14

Public/Private key crypto is used in a wide variety of protocols and data formats, which are implemented by a huge range of application and system software: SSL (https) protocol SSH (secure remote login, tunneling, etc) (public/private authn/authz is optional) Digitally signed PDF files (including attachments within the PDF) Signed Applets and jar archive ...


13

@ewanm89 is entirely correct. Securing the connection between ground control and a plane should be no different from securing any regular connection. The main issue is that the protocol designers are relying on security by obscurity. Obscurity through the relatively unknown protocol being used. Obscurity through what used to be relatively difficult to ...


13

To complement the answer from @raz, one must be aware of Protocol Downgrade Attacks. Browsers like IE send their maximum supported version, and then the server chooses (in your case, IE says "I know up to TLS 1.2" and the server responds with "we will do TLS 1.0"). However, browsers know that there exist buggy servers out there, that will simply have an ...


12

This book is a very good resource on wireless security. This section explains the details of the four-way handshake, but you really need to read the whole chapter to understand it. Both WPA2-PSK and WPA2-EAP result in a Pairwise Master Key (PMK) known to both the supplicant (client) and the authenticator (AP). (In PSK the PMK is derived directly from the ...


12

In lieu of waxing elequent in a topic that I am only briefly versed, I will defer my response to a DEFCON talk I saw last year that will do at least three things: Blow your mind Expose vulnerabilities in Sats Enlighten your knowledge on the subject in painstaking detail (see item one) Here is the archived talk with video. This is a very nice guy (Matt ...


12

There have been some discussions about mitigating issues with some record splitting. Namely, what makes Poodle efficient is that padding may use up to a full block (8 bytes with 3DES or RC2, 16 bytes with AES). When this happens, only the last byte of the block is checked by the recipient, which is why the alteration from the attacker gets through with ...


12

You could probably compute your own SHA1 hashes quicker from small arbitrary texts than that you harvest the hashes that someone else computed. But there's a lot of possible SHA1 digests, about as many as atoms in the world. That illustrates the challenge if you want to keep a list of all known digests and search that list.


11

Both have security issues if not configured correctly. But first lets start with some definitions: Cisco have a good definition of a VPN: VPN can take several forms. A VPN can be between two end systems, or it can be between two or more networks. A VPN can be built using tunnels or encryption (at essentially any layer of the protocol stack), or both, or ...


11

I see two conceptual paths for dealing with lag attacks: Punish lags. When an "artificial" lag is detected, evict the offender and enforce a ban period. This is hard to do in practice because there is a delicate balance to be found between people who cheat through lagging, and people who simply suffer from an occasional hiccup in their Internet connection. ...



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