(or Advanced Encryption Standard), a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.
0
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0answers
32 views
Security of .net AES implementation and security of a hash MAC
Hello I wanted to ask if there is any review about the security of the AES implementation of the .net Framework?
I found nothing concrete to that question, searching the Internet.
And, but this is a ...
2
votes
1answer
140 views
Visualization of cryptography
I think CrypTool is great software. And what I find most useful in it is visualization of algorithms such as Caesar, Vigenere, AES, DES. And my question is: does anyone know other tools which are ...
1
vote
1answer
118 views
Decryption a chunk of file with AES
We are having a requirement to store large files (~1GB) encrypted and decrypt them when reading. We are looking to use AES-CTR or AES-GCM mode to encrypt the data. There are scenarios where we want to ...
1
vote
1answer
97 views
How can encryption software accept password lengths which are not one of the AES key lengths?
AES comes with key sizes of 128, 192, and 256 bit.
But in Truecrypt or other crypto software we can use passwords of different length, even less than 128 bit or more than 256 bit.
How is this ...
10
votes
2answers
992 views
Why is MixColumns omitted from the last round of AES?
All rounds of AES (and Rijndael) have a MixColumns step, save the last round which omits it. DES has a similar feature where the last round differs slightly. The rationale, if I recall correctly, ...
1
vote
1answer
82 views
Understanding padding oracles - is an attack plausible in my scenario?
I have a scheme that, long story short, uses AES in CBC mode to encrypt third-party credentials for user accounts with a password-derived key. It's been mentioned that the use of CBC mode is a ...
2
votes
2answers
96 views
Does it take brute force to find a pair of plaintext and ciphertext that each follow a certain condition, given an AES encryption key?
Suppose that I have an AES key $K$, and I'm instructed to find a plaintext such that the first 32 bits of the plaintext are some string of bits $S_1$, and the last 32 bits of the ciphertext once the ...
2
votes
2answers
823 views
SHA-256 and AES-128
Does it make an encrypted string more secure if I use SHA256(x) instead of x as the secret key for AES-128 encryption? I do know that SHA-256 produces 64 characters of hashed string regardless of what ...
1
vote
1answer
54 views
Two files encrypted with related data versus one file
I have some code that takes a list of credit-card numbers, splits the number into two chunks, one chunk is 8 characters long, the other chunk is the remainder.
Each series of chunks is saved into ...
4
votes
1answer
66 views
Security for IV in AES-GCM mode
I'd like to use AES-GCM instead of HMAC for authentication and privacy in a token used in a web application, but I'm unsure how to securely tag each token with an IV. Is it safe for me to prepend the ...
3
votes
0answers
96 views
CBC with fixed IV but changing data [duplicate]
Possible Duplicate:
Using CBC with fixed IV
I am using AES in CBC mode.
For some reasons I have some issues for transmiting the IV. So I am using a fixed IV.
If the first 128bits of the ...
1
vote
2answers
237 views
Where i can find an AES implementation in python?
Where i can find a "reviewed" version of AES implementation in python. Not an API like PyCrypto whereby you can call AES algorithms in a single line.
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1answer
98 views
What encryption is this? [closed]
uwwmXzKSP0M7DHBHns3v2CtNZh0TOicb
uwwmXH6KGgVLjpnoWCk9I2A+
uwwmcv7JoND9WE6xwaXdN6fLXaecRPqf+m6WmqE
uwAm5NXph0c9hkFK
are originally:
001bboc@explorer.csc.com
001bocaj@gmail.com
...
1
vote
1answer
223 views
AES CBC mode or AES CTR mode recommended?
what's benefits and disadvantages of CBC vs CTR ? which one is more secure ?
6
votes
1answer
362 views
Difference between Rijndael 128 / 256 blocksize implementations? (and impact of block size in general)
Can anyone shed some light onto the advantages/disadvantages of using Rijndael with 256-bit block size, as opposed to the 128-bit (AES) implementation? (please note: I'm not referring to key-size ...
5
votes
2answers
222 views
Should I salt an AES password at each encryption?
I saw a sample code where the same password is salted with a different value (using PBKDF2) for each encryption. That means that the salt must be stored for each encrypted message.
I don't understand ...
2
votes
1answer
2k views
How to use RCON In Key Expansion of 128 Bit Advanced Encryption Standard
I have a question about RCON
here is my illustration...
this is the 128 bit key..
...
1
vote
2answers
197 views
Can one build a one-way function from AES?
We change the AES block cipher encryption:
we delete the key schedule algorithm
the user now provides a string of 1408 bits
we divide the string to 11 sub keys, and use them directly in the ...
3
votes
1answer
237 views
On-the-fly computation of AES Round Keys for decryption?
The usual implementation of AES first computes all the Round Keys sequentially starting from the key, and stores them in RAM for later uses. However, when enciphering a single block with a key that ...
0
votes
3answers
209 views
AES-GCM and its IV/nonce value
I was reading about the differences between the GCM and the CBC more here and I have a follow up doubt on the same.
In the CBC mode the person who performs the encryption is the one who provides the ...
0
votes
1answer
69 views
AES 128bit round level recommendation
we don't want change standard just after every attack, now for AES 128bit blocks i think 16 round is secure, but what is best round amount ? we had attack for 7 round then 10 round and it going so on ...
-1
votes
2answers
259 views
Double Encrypting with two different keys
In terms of security, would it be MORE or LESS secure to take, say, an RC4 output (or Serpent) or other, that is encrypted with one key, and to encrypt that output with AES (using a different key)?
...
2
votes
1answer
481 views
AES vs Blowfish taking key-length into account
I understand that Blowfish is getting old, but is still a secure algorithm, and that AES is very popular, and is recommended by most people. My question is, how do the two compare when a 256-bit key ...
0
votes
1answer
350 views
AES key length greater than 256 bits - is it dangerous to do an implementation outside of the standard?
I'm making a digital-asset manager written in ActionScript 3, it will be used to manage highly sensitive information. I'm using the AS3Crypto library (which has quite a good reputation) to implement ...
0
votes
1answer
227 views
0
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2answers
151 views
AES key expansion vs. a hash
Is there something special about the AES key expansion algorithm that makes it secure, or it is a compromise between security and speed? For example, say with a key I expand it by taking pbkdf2(key) ...
0
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2answers
289 views
decrypt AES without whole key
Is there a way to decrypt a AES cipher Text which was encrypted twice with some key, when having a part of this key? (the last 3 bytes of the key are missing)
0
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2answers
158 views
How can I add more rounds to AES?
I'd like to understand a bit more about the AES key schedule if anyone would mind explaining that. For instance, why is the way the schedule generated (with recursive xors and occasional ...
0
votes
1answer
137 views
AES Secure key generation and storage
I have a client-server application, which is transferring data between its components in a secure way. I currently use AES algorithm with CBC mode to transfer data and file. This is the scenario: ...
27
votes
4answers
5k views
What are the practical difference between 256-bit, 192-bit, and 128-bit AES encryption?
AES has several different variants (AES-128, AES-192, AES-256), but why would I use one over another?
1
vote
2answers
213 views
AES key padding
Is the initial AES key (expanded to the key schedule) byte padded if less than e.g. 16 bytes?
Is there a safe way of determining if decryption was successful (i.e. used the correct key)?
5
votes
2answers
141 views
AES encrypting multiple files
So if I want to encrypt all the files in a folder with AES (same password) I take each file and generate the key schedule using PBKDF2. As the PBKDF2 algorithm takes in a salt then this salt should ...
2
votes
1answer
73 views
Security implications of using constant string to verify AES key?
I know that you can use for example CBC-MAC to verify data integrity and thus the password upon decryption.
But would there be security implications of just adding a constant string to the plaintext ...
2
votes
2answers
154 views
Stopping timing attacks on AES: Why is it important to prevent the OS from interrupting the AES computation?
I read the paper Cache-timing attacks on AES (by Daniel J. Bernstein), but I don't seem to understand everything. The author dedicates a long section on how to prevent the OS to interrupt an AES ...
4
votes
1answer
200 views
AES timing attacks
I'm just interested in cryptography, so please don't expect me to be an expert. ;) I recently read about AES cache timing attacks and found it very interesting. I read the article Cache-timing attacks ...
-1
votes
2answers
129 views
Is the AES encryption scheme CPA secure?
Give a 256 bit key space and 128 message space would AES block cipher as the encryption scheme be CPA secure?
3
votes
2answers
155 views
Is storing the hash of a key together with ciphertext encrypted with that key secure?
Is it secure to store the hash of a symmetric cipher key along with data encrypted with that key? Are there any circumstances or algorithms in which this combination could lead to potential weaknesses ...
2
votes
1answer
114 views
Can I use my random IV (for AES) as a salt for PBKDF2?
Also, where do I store my salt (can I just store it at the beginning of the encrypted file)?
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0answers
39 views
NIST Standard for Advanced Encryption Standard Algorithm [duplicate]
Possible Duplicate:
Advantage of AES(Rijndael) over Twofish and Serpent
What is the reason of NIST why Rijndael choose as the Advanced Encryption Standard
3
votes
3answers
327 views
Relative merits of AES ECB and CBC modes for securing data at rest
I need to store several million Payment Card Numbers (PCNs) securely in a mainframe database (that is, 'at rest'). I assume that any attacker will have access to all of the stored data.
I assume the ...
0
votes
2answers
100 views
Is this how padding can work?
So for block ciphers you need a fixed size block.
If the plaintext length is not a multiple of the block length then you need to pad it.
One way you could do this is that for the last block you just ...
3
votes
2answers
352 views
Implementing AES in C++: 4x4 Array of unint8_t, or 4x1 array of uint32_t?
I'm implementing AES in C++, and, inspired by the way words are handled in SHA, I decided this time to handle the state as a one dimensional array of 4byte unsigned integers as opposed to a two ...
0
votes
1answer
184 views
Blowfish: hex digits of pi used for s-boxes?
Preface: here is the official site for the Blowfish algorithm:
http://www.schneier.com/blowfish.html
The Blowfish algorithm uses an s-box, which consists of hex digits of pi (found here: ...
2
votes
1answer
380 views
Advantage of AES(Rijndael) over Twofish and Serpent
I'm trying to figure out a suitable encryption technique and after reading a bit, I figured the current AES 128-bit encryption is suitable for what I'm trying to do. However, this is more due to the ...
9
votes
3answers
3k views
Why is AES resistant to known-plaintext attacks?
At least it's my understanding that AES isn't affected by known-plaintext. Is it immune to such an attack, or just resistant? Does this vary for chosen-plaintext?
4
votes
1answer
499 views
S-box design criteria and random sboxes
What are the disadvantages of using random s-boxes?
In AES, the s-boxes had to obey certain mathematical rules, which? And why?
What security does using hidden s-boxes (GOST) or generating them from ...
1
vote
4answers
341 views
How easily could this be cracked?
I'm looking into encrypting files like this: First, I SHA-1 hash the password. Let's say the password is something normal like "hello123", and then hashed. Then I encrypt a file using this:
...
-1
votes
1answer
81 views
What is the complexity of the Square attack against the reduced 4-rounds 128-bit Rijndael variant?
I'm looking at a square attack against a reduced version of AES-128 with only 4 rounds (with block and key size of each 128 bit). I have a set of 256 plaintext-ciphertext block pairs.
What is the ...
9
votes
2answers
539 views
Blum Blum Shub vs. AES-CTR or other CSPRNGs
Following on from D.W.'s comments on a previous question, what properties does Blum Blum Shub have that make it better / worse than other PRNGs? Are there significant implementation difficulties or ...
19
votes
4answers
2k views
Is AES-256 weaker than 192 and 128 bit versions?
From a paper (via Schenier on Security's Another AES Attack) (emphasis mine):
In the case of AES-128, there is no known attack which is faster than the 2128 complexity of exhaustive search. ...
