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Computing the public key is a problem of modular exponentiation, which can be done in O(log(e)) steps via exponentiation by squaring. On the other hand, finding the private key is the discrete logarithm problem, for which no equally efficient algorithm exists. You just have to run through all the possible values and try them all. There are some better ...


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Defcon 22 talk by Phil Zimmerman promoting his phone company (SilentCircle) as wiretap-free https://www.youtube.com/watch?v=HuHm1vzzm1g His idea is to get rid of Public Key Infrastructure by verbally comparing session key hashes, he also gives interesting examples of PKI failures, the audience asks many questions that are in my opinion acurate and ...


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I spent a long time trying to reason this one out. I found a real solution, but not one that can be packaged up and made into a product. You see, a passive listener will be absolutely foiled by Diffie-Hellman with big-enough key size. But if the guy is willing to MITM it falls down flat. If we know the topology we can know how long any packet should take ...


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It's possible if and only if, at some point in the past, a trust chain was established that allowed you to authenticate your second party. It should be common sense that if A never had any idea how to identify B (or how to identify anyone else who could indirectly identify B), then, by definition, A simply doesn't have enough information to distinguish ...


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It is not just not proven impossible, and not just practically possible with a sufficient level of security. There also exists a provably secure method ("secure" in a sense of being able to choose the highest possible likelihood arbitrarily). As mentioned in other answers, Diffie-Helmann key exchange with PKI is a reasonably secure way of establishing a ...


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If the attacker is only passively listening to the connection then Diffie Hellman Key Exchange can be done to create a common key known only to the communication peers. But, if the attacker can not only listen to the connection but also actively modify the transferred data, then the attacker might mount a man-in-the-middle attack and claim to be the ...


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There is indeed a solution to this problem! It's called the Diffie-Hellman Key Exchange protocol. You can read a good description at the wikipedia link, but the basic idea is that Alice and Bob each have their private keys and corresponding public keys. From the magic of the Diffie-Hellman math, PublicKey_Alice + PrivateKey_Bob = SharedSecret and ...


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Verifying a remote party's identity with OTR requires a shared secret (and therefore a prior secure means of sharing secrets) or knowledge of their fingerprint (and therefore a verifiable way to communicate fingerprints). I'm not aware of any published account of what Snowden actually did in this particular case. One realistic possibility, though, is that ...


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Secure Storage DEK: Data Encryption Key KEK: Key Encryption Key Master Key: Generally will describe one of the two above keys. Depending on the scheme in which it is implemented. This type of encryption scheme is often used for secure storage. Microsoft Windows is known to use this type of encryption scheme to protect user credentials and other types ...


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This article is intended to be a simplified explanation sans drill-down for people wanting to understand the concept terms. The terms are used in symmetric key cryptography. DEK - Data Encryption Key The key used to encrypt the data e.g. Key: 1234 with AES 128 as encryption algorithem - 1234 is the DEK KEK - Key Encryption Key e.g. Encrypt (from DEK ...


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If B specifically wants the data encrypted end-to-end from the field device to them, then indeed you need devices injected under a BDK known to B -- either you generated and gave to B, or B generated itself and gave to you or your vendor(s)/injection facility(s) -- and preferably not used by or shared with anybody else. You don't say what type(s) of devices ...


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The classical DHE is computationally expensive, at least as these things go. This rarely matters (a normal PC can still do hundreds of DHE per second), but if you are in a situation where computing budget is tight (e.g. small embedded systems) then ECDHE is substantially cheaper. With "normal" implementations, the cost of DHE is proportional to p2r, where p ...


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In order to have high encryption strength, one would use large DH params (16k perhaps) since the classical DHE key exchange is not computationally expensive, I can't give you hard numbers for the speed. The openssl speed command does not seem to offer the benchmark for regular (finite field) Diffie-Hellman. This answer offers guidance on practical ...



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