The Advanced Encryption Standard (AES) is a symmetric-key encryption standard adopted by the U.S. government. The standard comprises three block ciphers, AES-128, AES-192 and AES-256, adopted from a larger collection originally published as Rijndael.

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Is it possible to construct a specific AES collision?

Suppose I have a plaintext message P, and I encrypt it using key K to get ciphertext C. It's trivial to find a different plaintext message P' and a key K' so that the encryption results in C: just ...
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258 views

When to use HMAC alongside AES?

One of my clients wants to provide an URL to each of his customers to register in a system. This URL would contain a query string parameter with some data (e.g. code, email and name) from his clients ...
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696 views

Is AES(Rijndael) faster than Blowfish?

I know theoretical that blowfish is much faster than aes. But I benchmarked several algorithms including aes and blowfish for 1MB, 5MB, 10MB etc. files in java 8 platform and bouncy castle library. In ...
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1k views

Is OpenSSL AES GCM standardized?

I have been reading about the perils of not going the pages of my own encrypt-then-mac implementation, because there so many things can go awry. So decided to use EVP_aes_256_gcm. But some questions ...
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304 views

Remedy for not having filled the disk with random data?

Filling a large HDD with /dev/urandom prior to encryption can be extremely slow (even with netcat, multiple instances in parallel, etc) and for this reason I'm sure a lot of users skip this advice ...
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539 views

AES CBC over TCP - when is new IV needed

I am working on a project where two devices will be communicating with AES with CBC over TCP. We already have a secure mechanism for sharing the encryption/decryption key. I am not sure if we need to ...
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413 views

Hybrid key management doing it wrong?

I'm currently working on a project that needs be as secure as possible key-management. My experience with encryption, decryption and key-management are none whatsoever so i did some research on the ...
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211 views

Is there any security gain / risk by adding additional padding (beyond what is required) when using AES-256 to encrypt very short strings?

I would like to encrypt some authentication tokens using AES 256 (not tied to this algorithm but it seems to be a reasonable choice). These messages are usually very short at 128-256 bits. I'm ...
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599 views

How to Conceal/Detect PGP Symmetric Algorithm Used

When Symmetrically encrypting a file, (not signing, not an asymmetric encryption question), is it possible to conceal the encryption algorithm used, or is it already concealed, but just showing on ...
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860 views

Using AES to encrypt user data

I know next to nothing about cryptography, and I'm basically just looking for someone to look over what I'm doing and tell me if I'm screwing up. I have the user entering in some sensitive ...
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2k views

static IV and random keys using aes-256-cbc

Are there any security risks in using a static IV if I generate a new random KEY for each set of data to encrypt? If I understand correctly what the purpose of the IV is in Cipher-block chaining mode ...
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289 views

Are credit card number look ups more secure with a hash function than with a deterministic encryption algorithm?

I understand PCI DSS 3.0 allows hashes of cardnumbers to be stored separately from encrypted values, but I'm startled at the efficiency of tools like hashcat in discovering card numbers from hashed ...
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140 views

Encryption and HMAC with the same password

I need to send authenticated ciphered messages by using a single password. Reusing the same (derived) key for the block cipher and the HMAC is not a good practice, I know. My initial idea is to ...
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179 views

Do we have to take algorithm substitution attacks seriously?

Bruce Schneier's blog drew my attention to algorithm substitution attacks which may leak symmetric keys through IV or padding or other covert channels, encrypted with escrow keys. The major premise is ...
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aes cfb 128 decryption /encryption problem between Erlang and PHP

Update 2 - it works Thanks to Tom Leek for his answer. The CFB mode of mycrypt for Rijndael uses a 8-bit feedback loop and not a feedback loop the length of the key/iv. You have to force it to use ...
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74 views

Consequences of putting a serial number into an AES key

I have an embedded device with a secure memory of only 128 bits. I have to store the serial number (16 bits) and the AES key (128 bits) into this space. What are the consequences of putting the 16 ...
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594 views

What is the point of AES key wrap (with JSON Web Encryption)?

I'm looking at JSON Web Encryption (JWE) and am left a bit confused about why you would use AES key wrapping. The document even talks about using matching key algorithm strengths: Algorithms of ...
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1k views

How easy is it to crack gpg with private key, but without password

I was wondering if an adversary have your private gpg key but not the password/phrase, how easy/difficult would it be to crack a encrypted file compared to a encryption that only use password and not ...
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326 views

Is it a good idea to do double AES encryption with 2 different keys, when one is held by the user and one stored on the server?

I'm building a web app. The app needs to keep certain data within the database very secure. Please assume for the moment that I don't have a HSM or Key-Management facility and can't afford to ...
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2answers
612 views

Is AES encryption vulnerable?

I was reading weaknesses in AES encryption. Unfortunately, I have a website that uses AES: Its database is almost entirely AES encrypted. Is there a real threat? Would it be worth to refactor the web ...
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1answer
85 views

Confused about symmetric 128,256 key and the secret provided

I have searched and searched but cannot locate an answer to my question so I am hoping the experts here can. When I read about symmetric encryption like AES I see mention of the key and key size such ...
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1answer
1k views

Using GPG or PGP for symmetric database encryption/decryption in c#

I am looking to symmetrically encrypt/decrypt information in a database. This info consists of short pieces of information, which need to be individually encrypted when a specific method is called. I ...
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38 views

Can EAP-TLS and AES256 encryption be used together?

What is the difference between EAP-TLS and AES 256 encryption? Can they be used together? Or are they separate protocols?
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How can the parallelization in CTR mode be attained?

I am using CTR mode to encrypt/decrypt files. Theoretically CTR mode is faster than CFB or CBC because of its individual operations on blocks. In my case CTR mode takes almost as long as CFB. How can ...
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93 views

Do I have to use an IV when using GPG with AES 256?

Do I have to use an IV when using GPG with AES 256? Or does GPG handle that for me? I've noticed that I get different results each time I run the encryption, i.e. gpg --symmetric --cipher-algo ...
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Hardware encrypted external HDDs

I'm planning to buy an external HDD with hardware encryption, namingly the WD My Passport Ultra 2TB. On the WD website the information about the encryption is sadly scarce so I'm asking here. How ...
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233 views

Remote System Administration of an Encryption-Switch-Encrypted Infrastructure

I can't seem to find a decent explanation anywhere of the practicalities of remote system administration (e.g. SSH) of an encryption-switch-encrypted SAN-stored infrastructure. The environment will ...
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180 views

How does Silverlight protect the AES keys it gets from PlayReady? [closed]

I'm doing some research about how Silverlight protects AES keys. Here is the scenario: There is a smooth stream live encrypted channel service. When i log in to the service and tune the channel, ...
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328 views

Encrypting USB traffic: Is RSA necessary for AES session key exchange when using pre-installed secret keys?

I need a solution to encrypt USB communication between device A and device B. I was thinking about configuring each device with a secret RSA-2048 key, which would be used to exchange an AES-256 ...
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5answers
307 views

A secure way to encrypt a connection between 2 clients securing against both passive and active adversaries

Recently I got interested in encryption and the methods behind them. So for a fun / school project I am building a program in python to encrypt data between two clients (chat and files). I'm just ...
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1answer
140 views

Strange Finished message in TLS

I've tried to understand the content of the Finished message of TLS. I'm using WireShark to capture the traffic between my browser and the internet. I noticed a "strangeness" when the chosen ...
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2answers
596 views

7zip AES encrypted archive, padding oracle attack

I created an encrypted but forgot the password. When I attempted a pattern based brute force it said it had over a 100 trillion passwords to check. And to my knowledge that could take a few years. ...
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6k views

Is 4096 bit good enough to encrypt data?

I need to store encrypted information in a mysql table. I would like to use the AES algoritm but I don't know if 4096 is supported and if it is a good length to encrypt data like: credit card, email ...
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Are RSA 2048, ECDSA, and the SHA uncrackable in the sense that AES-256 is uncrackable?

The answer http://security.stackexchange.com/a/25392 has seemingly shown that AES-256 will not be directly cracked for at least the next 200 years (unless we manage to harvest the energy output of ...
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1answer
3k views

Why is GPG file encryption so much slower than other AES implementations?

Correct me if I'm wrong: When encrypting a file, GPG creates a one-off AES encryption key and encrypts that key using RSA. This is supposedly to take advantage of AES's superior performance when ...
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238 views

Slow down symetric encryption

I'm developing a program in Java. In one step data should be encrypted and exported in a file. As of now we are encrypting in AES-256 I want to slow down a possible brute force attack as much as ...
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1answer
600 views

Can I encrypt a file incrementally?

Is there any way to encrypt a file incrementally? The problem is that I receive a file a chunk at a time via Internet (it's a client-server application and I send byte arrays via a WCF service) and I ...
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How long would it take a single Processor with the AES-NI Instruction Set to bruteforce an AES Key?

I know that it seems like a stupid question - since it's note feasable to break AES without a quantum computer but I'm curious anyway. I read on wikipedia that the best known attack on AES-128 takes ...
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1answer
102 views

Is it insecure to provide a hash of an AES password?

I have made some software that encrypts and decrypts files using AES. I was wondering if it is safe to write a hash of the password to the file so that the program can check if a password is correct. ...
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Is Aescrypt a valid tool for encryption or not?

I'd like to know if Aescrypt is a valid tool, or if for a very secure protection, the only choice is to use a software like gpg, or similar. More I've another curiosity, if one doesn't want to use ...
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182 views

AES Key Management / How To Swap Encryption Key

I'm currently using AES 256 for the encryption of my web application and the security policy context specifies that the encryption key must be replaced once every few months. When that happens what ...
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2answers
9k views

How long would it take to bruteforce an AES-128 protected pdf knowing the key is 20 letter long and that the charset is A-Z,0-9?

The question says everything, knowing that a pdf is protected using standard Adobe password encryption that comes with Acrobat Pro (which as far as i know is AES 128) how much would it take to ...
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1answer
107 views

Does padding an AES key hurt security (besides lowering the strength of the key)? [closed]

I've been reading about solitare and its weaknesses, and thinking about clever ways of hiding keys. It seems like you could encode an 52-bit AES key in the vertical orientation of cards in a deck (or ...
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1answer
2k views

Should WPA2-AES be presumed insecure? (What is the “Hole196” vulnerability?)

I saw it mentioned in an answer here about firesheep, but I've never heard of it -- Should WPA2 be presumed insecure?
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1answer
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Aes encryption algorithm life time [closed]

How many years from now will we stop using aes encryption algorithm, as of now aes seems to be virtually immune to brute force attacks and not showing any weaknesses, will quantum or optical computing ...
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1answer
129 views

OpenSSL implemented AES not according to NIST?

I have been using the Encryption/Decryption code from https://wiki.openssl.org/index.php/EVP_Symmetric_Encryption_and_Decryption. The NIST test vectors (http://csrc.nist.gov/groups/STM/cavp/) for AES ...
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110 views

Encrypting files securely using user supplied password

I'm currently trying to build a (sort of) secure, desktop based RTF text editor written for node-webkit using node.js. Based on some answers that I read here, such as How can I securely convert a ...
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372 views

Is there a widely used protocol which builds on AES/GCM, and defines serialization formats of A, IV, C and T together?

note: Title edited to make the answer more useful to a wider audience I'm reading source code for encrypting files with AES GCM and see the following binary output. AdditionalAuthData IV ...
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Is Salt, IV and Key necessary when encrypting password in a database using AES? If so, how should they be used?

Imagine I have a website with user accounts. I want to authenticate users, so I need to know if the password they provide matches the one stored in my database. To protect the passwords from prying ...
2
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1answer
857 views

AES key management

I am encrypting a secret in a db field. I am encrypting using AES with a 256-bit key and a random IV per encryption. They AES key is hard coded in the code. Each IV is stored in clear in another ...