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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How less secure is an encryption if we know something about the original data?

I have a number of files encrypted with a key derived from a password. In line with standard practice, I use a random salt and password and do many PBKDF2 iterations to obtain an encryption key and ...
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1answer
4k views

How does PKCS#7 padding work with AES-256, CBC mode?

I'm a bit confused with AES-256, CBC, and how it works with padding (PKCS#7). Whenever I encrypt data of multiples of 16 bytes (the block size), extra 16 bytes are always padded at the end. For ...
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2answers
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LastPass One Time Recovery Passwords--How?

The LastPass password manager stores One Time Recovery Passwords locally in each browser you use the plugin with: http://helpdesk.lastpass.com/account-recovery/ My question is, how can you have more ...
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1answer
1k views

Key length and hash function in PBKDF2

On this page: http://www.ruby-doc.org/stdlib-2.0/libdoc/openssl/rdoc/OpenSSL/PKCS5.html they make a statement that strikes me as rather weird: Key Length Specifies the length in bytes of ...
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4answers
598 views

Is it safe to have the salt equal to IV?

If I'm using AES-256 CBC to encrypt, getting the 32 byte key using multiple iterations of the PBKDF2 function with a 16 byte salt, is it safe for me to let IV be equal to the salt? (Edit: The salt is ...
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1answer
239 views

Key distribution advice

I have been thinking for days about that problem! The application is based on a student system management. I am implementing database encryption on a column level and The encryption occurs at the ...
3
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2answers
264 views

Confidentiality and integrity for web session

When the client authenticates with our service, he is issued an opaque "token". This token includes the information, that identifies the client and some other information about the client ("payload"). ...
0
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1answer
787 views

What AES mode does SQL Server 2012 use?

I looked at this link that shows how to encrypt a SQL column via a certificate (RSA??) and AES256. I created a dummy table (script at GitHub) intentionally using identical plain text (Credit Card = ...
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2answers
6k views

How X509 Certificates are used for Encryption

I have small doubt regarding the process of X509. I am aware of OpenPGP Encryption/Decryption, where we generate the public key and private key. We can share the public key to vendors and they can ...
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1answer
316 views

AES encrypt secret key with plaintext

We need to be able to retrieve password. Hashing is one-way, we can't do that. So we ended up using AES. We want to know if the following schema is safe or not. I am only familiar with modulo PK ...
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2answers
222 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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2answers
5k views

Why does OpenSSL not include AES-256-GCM? [closed]

I'm trying to implement AES-256-GCM in Ruby. Ruby's OpenSSL wrapper library and aead library both clearly seem to believe that OpenSSL itself supports this. However, neither 0.9.8r (which I had ...
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1answer
2k views

Weakness of AES OFB mode

I found these comments regarding AES OFB Mode "This mode is a slightly less common mode, quite similar to CFB above, but which should not be used as a stream cipher due to inherent weaknesses when the ...
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1answer
120 views

Securing the SOAP Messages

One of my clients wants to encrypt few sensitive information which will be transferred through webservices / SOAP. My client has the following suggestions: Encrypt the sensitive data with AES ...
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2answers
3k views

After How Much Data Encryption (AES-256) we should change key?

Considering AES-256 encryption, what is the maximum amount of data should be encrypted with one key? Does Block cipher modes/IV/counters also governs the limit? If say the maximum amount is 50GB, ...
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1answer
2k views

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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3answers
11k views

AES CBC padding when the message length is a multiple of the block size

Assuming that a 32-byte plaintext is encrypted by AES 128 CBC - is it mandatory to add 16-byte padding, according to the different padding schemes?
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2answers
715 views

How to correctly implement AES in a backup application

I am writing a back-up application which should have the feature of encrypting the back-up. It must encrypt file data, paths and filenames. The application is being written in C# (.NET). Target is ...
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2answers
251 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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1answer
6k views

Is AES-GCM recommended for SSL?

I'm looking at turning on site-wide SSL for a website I manage, and I'm wondering what the best practices for SSL configuration. I'm not too worried about compatibility with old browsers and more ...
5
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1answer
2k views

Security of bcrypt/sha256 key used with AES to encrypt a file

I'm looking to encrypt files using secure hashing and encryption algorithms in Python. Having used bcrypt in the past, I decided to use it for my passphrase calculator, then pass the output through ...
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1answer
199 views

Need advice on Cryptography digital files project

I have to choose a topic for my end-of-year school project and I need some advice. I was thinking of implementing an online tutorial materials (digital files) project. I have been researching on ...
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2answers
442 views

Implications of having a service account in AD use RC4 rather than AES for Kerberos?

Bear with me, I know this is sloppy, but here is the back story: We have a partner that uses Jira and is using spnego with a custom auth back-end that expects certain group membership in the token. ...
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1answer
216 views

Implementation review - Independent key, admin side and user side

The admin of the website needs to read user data. So, if the key is derived from the user pass, then the admin has to know the user pass, not exactly a good idea. The following encryption scheme was ...
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2answers
8k views

openssl: recover key and IV by passphrase

A large amount of files were encrypted by openssl enc -aes-256-cbc -pass pass:MYPASSWORD Openssl should derive key+IV from passphrase. I'd like to know key+IV equivalent of that MYPASSWORD. Is ...
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2answers
4k views

Pitfalls of SSD encryption

Encrypting an SSD is a process that is sometimes warned should be done with caution. E.g. http://en.gentoo-wiki.com/wiki/DM-Crypt_with_LUKS mentions how the SSD may keep hidden space used for wear ...
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2answers
726 views

Filling the disk with random data prior to encryption?

Filling the disk with random data prior to encrypting it will supposedly make it harder for the attacker to perform any cryptanalysis. Most sources seem to state this is because it will be harder for ...
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33k views

Security comparsion of 3DES and AES

Which one is more secure and least possible to be broken through cryptanalysis AES or 3DES (no matter performance)? I need to use encryption for my projects to store and secure sensitive information ...
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1answer
244 views

Password protection of encryption and signature keys

I would like to store encrypted backup of text files on my computer. I'm developing a python script using Pycrypto to achieve that, based on this code to use the library. (current code) The basic ...
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2answers
4k views

WPA2 Enterprise AES encryption key size?

I have recently set up a RADIUS server with EAP for my wireless router, however, I have some questions about the key size and how WPA2 enterprise (AES) works in general. I have read that in ...
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490 views

RSA and encrypted authentication

Symmetric algorithms such as AES provides modes such as GCM which can be used for authenticated encryption. Assuming that I'm using RSA instead of AES, does it still make sense to add authentication ...
2
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1answer
221 views

Design of Initialisation Vector

I understand that an IV (initialisation vector) should be both unique and unpredictable, but I have found little guidance as to which is most important. For an AES cipher I have a block size of 128 ...
9
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3answers
941 views

AES using derived keys / IVs. Does it introduce a weakness?

I'm looking for an efficient way to encrypt multiple fields in a database with AES using a single global key, used throughout a large web application. Obviously in order to re-use this key, a unique ...
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2answers
699 views

User authentication + database encryption with same password

I'm working on a private project where I need to store a users financial data in a database. I'll encrypt this data using AES, and I'll be using scrypt to generate a AES ecnryption key from a more ...
2
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1answer
513 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 ...
6
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1answer
739 views

Android and AES side channel attacks

I am working on a project that will involve symmetric AES 128 bit encrypted communication between an Android application and a bluetooth device. Are there any public AES libraries available for ...
9
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3answers
2k views

How can I encrypt a file with .NET and have the same file size of the original file?

I'm using .NET and I've written an awesome routine (xD) that encrypts and decrypts a file using AES256 CBC. It works perfectly, but now they told me that the encrypted file must be of the same size of ...
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3answers
3k views

I don't see how “-salt” in the openssl command line tool enhances security at all

I do this to encrypt a single file: openssl aes-256-cbc -a -salt -in file.txt -out file.enc and then type in some regular plaintext password. I do not understand how -salt enhances the security of ...
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2answers
2k views

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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2answers
2k views

Decryption on AES when the same key and IV are used

Let's say that I have three messages being encrypted by AES-128 with the same key and IV every time. Is it possible to decrypt the key being used? And more importantly, is it possible to decrypt the ...
2
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2answers
4k views

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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1answer
764 views

How does Cipher Block Chaining relate to AES?

I was reading FIPS197 for a class (found here: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf ) trying to find some sort of specific relation between CBC and AES. I guess my problem is ...
3
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3answers
2k views

User data encryption/decryption in a database (PHP)

I was wondering which is the best way to encrypt and decrypt user data in a database, to make it much more secure as it is possible? I was reading about AES but I would like to know if is really the ...
11
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1answer
8k views

Where is the salt on the OpenSSL AES encryption?

I'm interested in knowing how and where OpenSSL inserts the generated salt on an AES encrypted data. Why? Im encrypting data in Java classes and need to guarantee that I can use OpenSSL to decrypt ...
2
votes
2answers
457 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 ...
10
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3answers
5k views

How secure is Intel SSD Encryption?

Are there any known flaws in the full disk encryption on Intel 520 series SSD drives? Specifically, it seems these drives generate an internal AES key automatically, even when no password is set. But ...
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1answer
1k 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
879 views

AES Key Generation Strategy/Algorithm For Offline System

Let say I have several application that aren't connected to any network, and I have one requirement that says each application could produce a token from an input that other application could validate ...
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2answers
2k views

Does AES-192 provide better encryption than AES-256?

this wikipedia article describing AES says: Related-key attacks can break AES-192 and AES-256 with complexities 2^176 and 2^99.5, respectively. Does this mean that AES-256 is actually a weaker ...
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1answer
1k views

OpenSSL fails NIST AES-128-ECB test vectors?

I'm having trouble getting OpenSSL's ciphertext to match the NIST test vectors. Example : in "ecb_e_m.txt" from http://csrc.nist.gov/archive/aes/rijndael/rijndael-vals.zip, the first test is (in hex) ...