Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
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2answers
243 views
What is the best way to send two floating point numbers to a server on the internet from a small device such as an arduino?
I was thinking about sending some sensitive data (temperature) from an arduino (AVR 8-bit processor) to a server on the internet.
But I would like to make sure that it would not be possible for Eve ...
2
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1answer
148 views
Does an attacker gain an advantage if they have the initialisation vector?
Does an attacker gain any advantage by knowing which initialisation vector was used for encryption?
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4answers
294 views
Can I determine if a user has the wrong symmetric encryption key?
We're using the Objectivity/DB object database with a custom encryption plugin that encrypts serialized objects on disk. Encryption uses AES with a shared secret key held by all users. I would like to ...
10
votes
1answer
2k views
How to choose a padding mode with AES
Depending on the framework you are using, there are various padding modes that can be used with AES encryption. For example, with .NET we can choose PKCS7, ISO10126, ANSIX923, Zeros or None.
I ...
3
votes
3answers
616 views
What is the importance of Modular arithmetic in cryptography?
Why do we use modular arithmetic so often in Cryptography?
4
votes
1answer
310 views
Are there two-way encryption algorithms that include a work factor?
I recently learned about the hashing algorithm bcrypt, which allows you to specify a "work factor" for the hash which can be incremented to stay ahead of Moore's Law. I understand there are some other ...
3
votes
3answers
179 views
Derived Shared Key vs Distinct Keys?
I've seen a lot of 2-party applications that derive a shared key from distinct keys created by each party.
Why is this technique employed? Would it not be better to use those two distinct keys for ...
13
votes
2answers
963 views
How can we reason about the cryptographic capabilities of code-breaking agencies like the NSA or GCHQ?
I have read in Applied Cryptography that the NSA is the largest hardware buyer and the largest mathematician employer in the world.
How can we reason about the symmetric ciphers cryptanalysis ...
3
votes
1answer
85 views
uniquely identify a symmetric key
Is there a safe way to uniquely identify a symmetric key? I know with asymmetric keys you typically use a hash of the public key, but I assume that using a hash of a symmetric key would reveal too ...
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3answers
472 views
How does one scale encryption strength upwards from 256-bit?
I have seen many examples of encryption up to about 256-bit. But how does one programmatically scale the logic upwards in a language such as PHP or Java to say 1024-bit or even 4096-bit and higher?
...
3
votes
1answer
142 views
Is a changing public truecrypt container secure?
I have a Truecrypt container which I want to synchronise between computers (i.e. different people, that I want to share the data with).
If I used Dropbox for synchronisation and someone downloaded ...
10
votes
3answers
2k views
Why is public-key encryption so much less efficient than secret-key encryption?
I'm currently reading Cryptography Engineering. After giving a high level explanation of the difference between secret-key encryption and public-key encryption, the book says:
So why do we bother ...
