Questions tagged [symmetric]
Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
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Can I secure my key by XORing it with a hashed password?
I'd like to build a simple password-protected symmetric key system. The key-creation process in my system operates as follows:
The system creates a 256-bit key purely at random.
The user chooses a ...
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Realize a MAC using a Pseudo-random function?
Given a pseudo-random function and assuming that we do not have any other tools,
How can we construct a MAC?
I believe this can be done. Would like to know if there is more than one way of doing ...
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Why do we need asymmetric algorithms for key exchange?
In SSL protocols, both symmetric and asymmetric algorithms are used. Why is it so? The symmetric algorithms are more secure and easier to implement. Why are asymmetric algorithms usually preferred in ...
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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 ...
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Information leakage from the ecryptfs filesystem
I'm wondering what information might be leaked from the ecryptfs filesystem. This is what Ubuntu uses if you check the box for "encrypted home directory" when using the desktop installer, so is ...
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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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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 ...
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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 ...
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What is the importance of Modular arithmetic in cryptography?
Why do we use modular arithmetic so often in Cryptography?
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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 ...
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How to distribute session keys in public key cryptography?
In public key cryptography we can also use session keys which are symmetric. How do the sender (say a server) provides this session key information to its clients?
If the sender (here server) ...
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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 ...
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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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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?
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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 ...
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