Encryption is the process of transforming plaintext using a cipher to make it unreadable to anyone except those possessing the key.
8
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2answers
530 views
Salting when encrypting?
I was attending a database encryption session at a developers conference. The presenter (who was a published author on the subject) said that MS SQL Server did not support salted hashes in the ...
7
votes
4answers
1k views
What is the effect of the different AES key lengths?
How does a changing key length affects the ciphertext, not only in case of AES, but in general? I know that the key spaces become much larger and the number of rounds in case of AES changes, but is ...
6
votes
1answer
589 views
AES and perfect ciphers
I'm taking a crypto class this semester and after learning the definition of a perfect cipher. I started wondering how this definition applies to AES.
Obviously AES isn't a perfect cipher, since the ...
6
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4answers
967 views
What is the difference between a stream cipher and a one-time-pad?
A (synchronous) stream cipher is an algorithm which maps some fixed-length key to an arbitrary-length key-stream (i.e. a sequence of bits): $C : \{0,1\}^k \to \{0,1\}^{\infty}$.
This key-stream is ...
4
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1answer
98 views
Why should I use an Initialization Vector (IV) when I have unique keys?
I took a look at this question. My question is not the same.
I've unique keys encrypting (in CBC mode, AES-256) each plaintext, i.e. I do not use a key to encrypt more than one plaintext. Is it ...
4
votes
2answers
206 views
Provable Encryption
Is it possible to encrypt data in a way that it can be proven that the data is encrypted, without revealing the key?
Alice chooses some plaintext, then she encrypts it with a certain scheme. She ...
4
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3answers
925 views
Why programming languages don't provide simple encryption methods?
In c#, there is a namespace called System.Security.Cryptography and there are many classes in this namespace, which help developers encrypt and decrypt data. ...
4
votes
1answer
516 views
How does a key wrapping like RFC 3394 secure my cryptographic keys?
So I'm messing around in the BouncyCastle library with the RFC 3394 AES Key Wrap engine and I'm trying to understand the benefit of it.
The problem I'm running into is how to store keys securely on a ...
4
votes
1answer
1k views
What are the details of the DES weakness of reusing the same IV in CBC mode with the same key?
I think I once faced the recommendation, that the initialization vector should always be random and never be used twice with the same key.
How serious is this weakness?
Also, is AES less effected ...
3
votes
2answers
181 views
Two step encryption
Is there any asymmetric cryptography algorithm which will allow recursive encryption.
...
3
votes
1answer
431 views
Why, or when, to use an Initialization Vector?
i'm trying to figure out when an Intialization Vector (IV) should be used.
There are anecdotal reports that WEP was broken because of weak IV's. It's also claimed that if two pieces of plaintext are ...
3
votes
3answers
528 views
How will Cryptography be changed by Quantum Computing?
I realise this isn't a 'yes or no' question, and I apologise for asking something that could be seen as a discussion thread, but I had to ask.
I'm currently doing an EPQ in CS (specifically how QC ...
3
votes
4answers
289 views
Which block cipher modes of operation allow a predictable IV?
Recently I found out that in the modes CBC and PCBC the IV may be passed in cleartext but never must be predictable. However for this part of my app I rather have the IV be predictable and unique ...
3
votes
1answer
117 views
How to communicate authentication tag for GCM?
I have written some code to do AES in GCM. I currently manually append the tag property to the ciphertext, is this the proper way to communicate the authentication tag?
3
votes
1answer
346 views
Advanced Encryption Standard Algorithm Secret Key
just a follow up question with this question..
How does the key schedule of Rijndael looks for keysizes other than 128 bit?
A 256-bit key can still encrypt a block of plaintext in 128 bit?
but in ...
3
votes
1answer
183 views
How can one share information using the 'host-proof' paradigm?
I am attempting to make a web-based secure password management and sharing utility, both as an academic exercise and to fully understand and feel safe about using it.
I really like the idea of a ...
2
votes
2answers
284 views
Why is a non fixed-length encryption scheme worse than a fixed-length one?
I have the following definition (highlights by me):
An (efficient secret-key) encryption scheme $(Gen,Enc,Dec)$, where $Gen$ and $Enc$ are PPT algorithms and $Dec$ is a Deterministic Polytime ...
2
votes
2answers
239 views
Avalanche noise RNG for one-time pad use
I came across this little HRNG widget and was really intrigued as I have been looking for a decent but afordable source for truly random bits to use in a one-time pad.
The question is, would a HRNG ...
2
votes
3answers
289 views
Can I pre-define the points in Shamir's Secret Sharing algorithm
With Shamir's secret sharing is it possible to pre-define the points returned by the algorithm?
For simplicity if I have (k, n) where k=2, and n=4, and I have the points X,Y,Z, and Q. Can I create ...
1
vote
1answer
127 views
Indistinguishability attack example
I want solve the next exercise. The author defined the experiment for the cryptosystem $\Pi$, the adversary $A$ and the security parameter $n$ as follows
$\mathsf{PRIV_{EAV}}(\Pi,A,n)$
The ...
1
vote
1answer
346 views
How can I implement the “Multiplication Modulo” and “Addition Modulo” operations in IDEA?
I am currently working on IDEA (International Data Encryption Algorithm), and I don't know how to perform Multiplication Modulo and Addition Modulo.
This is how IDEA operates:
IDEA operates on ...
1
vote
2answers
124 views
RSA keys finding when messages are known
I have this situation, where, in a game, people send messages to each other (game moves etc...) These messages need to be encrypted, and should only be readable by the destination person. I am using ...
1
vote
1answer
283 views
How to implement order preserving encryption or order preserving hashing
Does anybody know any free implementation of either order preserving encryption or order preserving hashing? I've found some codes like CMPH but I need to dynamically add new DATA and that's why most ...
1
vote
4answers
423 views
Is my pseudo-random initialization vector secure?
How can I know if I am generating a secure pseudorandom initialization vector?
Currently I am planning to generate a pseudo-random initialization Vector using current date and time - is this secure ...
1
vote
3answers
449 views
Which attacks can be avoided by the use of OFB instead of ECB?
For a file encryption program, I was told to use Output Feedback mode (OFB) instead of ECB (Electronic code book) mode.
Which attacks can I avoid by this choice?
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0answers
76 views
Two untrusted party want to exchange data: how to ensure each one gets the data it needs? [duplicate]
Possible Duplicate:
Two untrusted party want to exchange data: how to insure each one gets the data it needs?
I am trying to come up with what could maybe be a novel algorithm for an ...
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1answer
92 views
What length should the padding be when encrypting or signing with RSA?
Does it matter what length the padding is? If so - what length should it be?
(Another point: Should it be random?)
-3
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1answer
433 views
Advantages of each encryption mode [closed]
What is the advantages of each encryption mode to other encryption mode..
for example what are advantages of CBC to PCBC, CBC to CFB
just like that.
so that I can filter what would be the best ...
