# Tag Info

## New answers tagged stream-cipher

1

Maybe you have a more specific class of applications in mind, but in my experience there is fairly limited use of cryptography in web applications. The cases I can think of: SSL, in which case the encryption is done by the web server and not by the application (though maybe you don't consider that distinction relevant). The type of encryption is then ...

-1

I don't think stream ciphers are implemented in Web applications ( Actually they are not approved because of weak security) However the protocols like IPsec, SSL and PGP etc do make use of various block ciphers( e.g AES ). Web application security is totally dependent upon the security at individual OSI layers.

2

Whenever you're trying to attack a scheme that is [algebraically] relatively simple like this one, a sensible first step is to write out everything you know. Now, considering the information you've been given, try and substitute things into oneanother, and see where this leads you. Let $(m,c)$ be the first 1024 bits of the plaintext-ciphertext pair. Now, ...

0

In principle, there is no way to solve this problem. Snapchat is a lie. If Alice is motivated and knowledgeable, she can arrange to make persistent copies of any snapchats that she can view. There are probably dozens of ways to do this: making screenshots, reverse-engineering the app to steal the decryption key, rummaging through memory to find the data ...

0

Is my suggested approach cryptographically secure? Indeed, an attacker will look at your implementation and exploit the fact that you're relying on a PRF that the attacker can access. You would at least need to separate the PRF from the rest to be secure. Especially, since you state that you would be feeding a unique user-id to the PRF during your ...

0

Kerckhoffs's principle (also called Kerckhoffs's desiderata, Kerckhoffs's assumption, axiom, or law) was stated by Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge. Kerckhoffs's principle was reformulated (or perhaps independently formulated) by Claude Shannon as ...

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