# All Questions

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### How is the key shared in symmetric key cryptography?

Symmetric key cryptography is an encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Is the key public or it is ...
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### Initialization vector in symmetric-key encryption

Can we use symmetric-key algorithms without an initialization vector? I am making an app where both the sender and receiver share a key and there is no way to create an initialization vector for each ...
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### Can you really insert the text you want in one-time pad?

The Wikipedia article "One-time pad ~ Authentication" says : For example, an attacker who knows that the message contains "meet jane and me tomorrow at three thirty pm" at a particular point can ...
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### Finite fields and ECC

I understand modular arithmetic(or at least I think I do!) and I've tried to read and learn about how the Math in RSA works(and I think it went pretty well). I've been reading up on ECC and it looks ...
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### CBC-MAC , fixed length, all blocks returned

CBC-MAC, with fixed length message. Is it safe to return all ciphered blocks instead of the last? My intuition says it is less secure, since is gives an attacker more information. But how could one ...
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### A proof-of-work random number generation system for Pokémon [closed]

(The original question that was here was considered too confusing, unclear, and rambling. You can still view it in the edit history, but the content is no longer useful by itself, and cannot be ...
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### AES Key Length vs Block Length

This answer points out that certain key and block lengths were a requirement for the AES submissions: The candidate algorithm shall be capable of supporting key-block combinations with sizes of ...
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### The meaning of “scheme”

This question is a bit different from other questions here, but I think it is suitable to correctly understand the terminology of cryptography. Consider the following two sets of terms: Encryption ...
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### How many keys does the Playfair Cipher have?

I was just studying the Playfair cipher and from what I've understood, it is just a slightly better version of a Caesar cipher, in that it isn't actually mono-alphabetic but rather the 'digrams' are ...
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### Why pairing based crypto is suitable for some particular cryptographic primitives?

Why pairing based crypto is being widely used in some special crypto primitives as ID based crypto and variations of standard signatures? I mean taking as deep as possible what makes it suitable for ...
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### What is the difference between these AES encryption methods

I am using AES encryption (Rijindael) with Base-64 encoding in Obj-C and VB. I am currently using the following two projects to achieve this: Obj-C: ...
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### How much bigger does a precomputed lookup table get when salt is added?

I am trying to wrap my head around the benefits of salt in cryptography. http://en.wikipedia.org/wiki/Salt_(cryptography) I understand that adding salt makes it harder to precompute a table. But ...