(or Advanced Encryption Standard), a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.
7
votes
2answers
416 views
Does AES have any fixed-points?
Is there any pair of 128-bit strings M and K such that AES$_K$(M) = M?
If yes, how do I go about (efficiently) finding such a pair?
6
votes
1answer
381 views
What causes first block of AES decryption to be garbled, even with correct IV?
I am attempting to duplicate wireshark's packet capture decryption for a TLS HTTP session, where I control the private key of the server.
The cipher suite number is 0x00002f, TLS_RSA_AES_128_CBC_SHA
...
5
votes
1answer
254 views
CBC key lifetime, or, “how big is too big?”
IPSec recommends rekeying SA's figuring in both time and amount of data sent. Even when using AES-256 in CBC mode, the key and IV commonly get re-negotiated after 100MB.
My case isn't using IPSec, ...
3
votes
1answer
231 views
Is it safe to encrypt a public key alongside a message with AES?
If I have a message M and a public key P, and I encrypt them alongside one another:
CIPHER = AES(M + P, aes_key)
Is CIPHER now weakened if someone knows what P ...
5
votes
1answer
289 views
XSL on serpent and rijndael - which is most affected?
So I've often looked at serpent and thought it was a very strong contender in AES. Not so long ago I was looking for evidence as to why it didn't beat rijndael. So far, the closest I've got answering ...
2
votes
1answer
596 views
AES-NI implementation examples
Newer Intel and AMD processors have hardware support for implementing AES using the instruction set AES-NI (instructions AESENC, AESKEYGENASSIST etc). Do you know of any clean example implementation ...
3
votes
2answers
7k views
How secure is AES-256?
The cipher AES-256 is used among other places in TSL/SSL across the Internet. It's considered among the top ciphers.
In theory it's not crackable since the combinations of keys are massive.
Although ...
1
vote
1answer
740 views
Is AES restricted to only 64 characters for the key/password?
I am wondering if AES only supports 64 character passwords?
When using truecrypt, the maximum character limit on passwords is 64 characters; however, when using WinRAR, the limit is 128 characters.
...
3
votes
2answers
205 views
Does AES specify error messages when using the wrong password to decrypt?
I am writing a small program which uses AES. In testing it with wrong passwords, I get error prompts from Microsoft C# component saying "the padding is bad"; whereas I expect wrongly decoded texts. Do ...
2
votes
2answers
230 views
AES with whitening mode
This mode is that each time generate a random number K, xor with plaintext M and the pass the result to AES. My question is that since AES is pseudo random permutation, does AES have the following ...
-2
votes
2answers
219 views
Factoring a polynomial over a GF [closed]
I have the following question:
What polynomial, when factored over the field $GF (2^8)$ based on the irreducible polynomial that is used in Rijndael, will factor into all the polynomials in the ...
5
votes
2answers
651 views
How to calculate an IV when I have a shared private key?
I'm working with a server/client system that has securely negotiated a private key. I need to encrypt/decrypt messages passing in both directions which are typically between 100 bytes to 100 KB. I'm ...
0
votes
0answers
46 views
Elliptic curve Cryptography [duplicate]
Possible Duplicate:
Can we use elliptic curve cryptography in wireless sensors?
How to map message character to point lies on Elliptic Curve? how to ecc used in wireless sensor networks? ...
5
votes
2answers
2k views
Rijndael vs. Serpent vs. Twofish: General comparison
Can anyone explain (or give a link to document about) why Rijndaal won the AES, especially comparing it to other finalists (Serpent and Twofish)? What criteria were used to make decision?
Or is there ...
13
votes
2answers
2k views
Why does nobody use (or break) the Camellia Cipher?
If Camellia is of equivalent security and speed to AES, concerns arise.
First of all, assuming the above, why is Camellia so rarely used in practice?
Why aren't there any breaks in Camellia? Does ...
6
votes
2answers
498 views
Can one implement AES on 4-bit microcontroller?
It is possible to implement AES on 4-bit microcontroller? As far as I know, AES on 8-bit microcontroller are common especially for light weight application such as the RFID.
I have yet to come across ...
3
votes
1answer
209 views
Best choice of finite field for AES on a 4-bit microcontroller?
As the finite field of $GF(2^8)$ are isomorphic to $GF((2^4)^2)$, $GF((2^2)^4)$ and $GF(((2^2)^2)^2)$,
which of the fields is best suited and most efficient for 4-bit MCU and why? Would it be ...
5
votes
1answer
1k views
How do I correctly derive a Key and IV?
Mainly I'm trying to understand how to correctly create the Key and IV for use with the .NET Implementation of AES (AesManaged class).
This encryption code will be used in conjunction with existing ...
5
votes
1answer
578 views
Is the AES Key Schedule weak?
After reading this paper entitled Key Recovery Attacks of Practical Complexity on AES Variants With Up To 10 Rounds I was left wondering why the key schedule of AES is invertable.
In the paper the ...
6
votes
3answers
403 views
Is it possible to distinguish a securely-encrypted ciphertext from random noise?
Say I have a bunch of data encrypted with a secure block cipher (such as AES). An attacker has unlimited access to this encrypted data. The attacker doesn't know whether the data is encrypted or if ...
5
votes
1answer
334 views
Related-key attacks on AES
According to Wikipedia:
Related-key attacks can break AES-192 and AES-256 with complexities $2^{176}$ and $2^{99.5}$, respectively.
What are the requirements for these attacks (i.e how many ...
2
votes
2answers
214 views
AESManaged Trade Compliance Issue in United States
I am currently using AESManaged encryption for my silverlight application. Does AESManaged encryption have a severe trade compliance issue in Bureau of Industry and Security in terms of shipping the ...
3
votes
1answer
725 views
Does AES-CTR require an IV for any purpose other than distinguishing identical inputs?
I'd like to encrypt files deterministically, such that any users encrypting the same plaintext will use the same key and end up with the same ciphertext. The ciphertext should be private as long as ...
4
votes
2answers
209 views
Is it safe to store initial counter value for AES-CTR alongside with ciphertext?
The initial counter value can actually be thought of as a sort of IV, which I assume is safe to transmit with the ciphertext, but I really want to be sure that this is indeed safe.
9
votes
2answers
518 views
Design properties of the Rijndael finite field
So we've already had a question on replacing the Rijndael S-Box. My question is - can we use a different finite field other than the one given by $x^8 + x^4 + x^3 + x + 1$ in $GF(2^8)$. In other ...
6
votes
1answer
580 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 ...
9
votes
3answers
399 views
Are these emerging threats against AES affecting your designs?
Recentally, an attack on AES was discovered which reduces its computationally complexity, by a very slight amount.
The first key recovery attack on the full AES-128 with computational
complexity ...
3
votes
2answers
534 views
Encrypted text length in AES
I have created an application that will be able to read any file and encrypt it using AES Encryption. For efficiency, I am reading a block of data, encrypting it and so on. So for decrypting, I just ...
4
votes
4answers
474 views
How to require two keyholders to decrypt a document?
I want to create a system to encrypt a document and store it with a 3rd party, but not have the 3rd party be able to decrypt it until some unspecified later date. It seems like the solution would be ...
7
votes
2answers
2k views
AES in ECB mode weakness
In a project that I'm currently working on, we are encrypting some data using AES with ECB mode in a database. Each piece of data being encrypted is very small, no more than 10 characters long.
Very ...
5
votes
2answers
382 views
Where can i get the info to implement AES?
I know there are 100's of AES programs and websites out there but I can't seem to find a site that give me the detail I think I would/should need to write my own java program.
I was to write AES form ...
10
votes
3answers
544 views
Is CBC really dead?
I developed a p2p-app in C# which sends and receives encrypted text messages (50KB). For encryption, my app uses AES 128 bit in CBC cipher mode. For each message it uses a new randomly-generated IV.
...
9
votes
5answers
482 views
How do I construct a 256-bit hash function from 128-bit AES?
I would like to generate a 256-bit hash on a microcontroller that has a 128-bit (only) AES engine. How can I construct a 256-bit hash function from a 128-bit cipher?
5
votes
1answer
626 views
GPG symmetric encryption and javascript
I have a use case where I need to encrypt some text in the browser using javascript. Only the encrypted text will be stored on the server.
The user should then be able to take the encrypted result ...
5
votes
3answers
1k views
Is there any opensource white-box implementation of AES or DES?
I googled it and give me no result. There is a binary executable of white-box implementation of DES (scroll down), but no source code provided.
The same page also links various papers about ...
2
votes
2answers
246 views
Are there public slow-but-strong algorithms out there that resist brute-force attacks better?
I'm reading that AES uses 4x4 bytes (4*4*8 = 256 bits key) matrix for performances matters (since it's a requirement for common standard encryption algorithms), but are there implementations with ...
10
votes
3answers
898 views
Known methods for constant time (table-free) AES implementation using 'standard' operations?
There are several known methods for implementing AES in constant time using SIMD operations, mostly based around fast byte shuffling (for instance Hamburg and Kasper/Schwabe). Are there any similar ...
2
votes
2answers
504 views
Using an RSA private key simultanously as an AES encryption key to generate random numbers?
Currently I'm implementing a PRNG for an embedded system. Using the RFC 4086 I've decided to use the X9.17 - to be more specific the succesor X9.31- standard to implement my PRNG. X9.17 uses DES, but ...
5
votes
3answers
464 views
How can my application make sure the right symmetric key is used for decryption?
I am developing an Encryption/Decryption Utility using Adobe AIR. I have chosen the AES algorithm and currently use the as3crypto library for this. My query is in ...
7
votes
1answer
450 views
Replacing the Rijndael S-Box?
The Rijndael S-Box design generates a permutation cycle of type $2+27+59+81+87$. What effect would replacing that permutation with a cycle of type $256$ have on the security of AES?
