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.

learn more… | top users | synonyms

7
votes
1answer
10k views

Which is the Best Cipher Mode and Padding Mode for AES Encryption? [closed]

As per PCI-DSS 3.4 requirement: For storing Credit Card Data Strong Cryptography should be used. I decided to use AES Encryption which is a strong and mostly recommended crypto for encrypting ...
7
votes
3answers
3k views

Is AES 256 secure enough for putting Backups to AWS or Dropbox?

How long would it take with current hardware to hack an Disk Image which was encrypted with AES 256? I ask because i want to backup personal files (contracts, tax-things, code, keys, private ...
7
votes
1answer
339 views

I stored a copy of my KeePass database on a portable hard drive and I lost the drive. Should I worry about that?

I've been using KeePass for years, and I have a lot of accounts. I need to access them anywhere I work, so I store one copy of my database on a portable hard drive. The drive isn't encrypted. The ...
7
votes
6answers
1k views

Is leaking the hash of your encryption key a security risk?

I've been trying to design a simple archive format, that allows me to just bundle a bunch of encrypted files together. The idea, I currently have is to embed not the encryption key but a truncated ...
7
votes
1answer
2k 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) ...
7
votes
3answers
2k views

Does the endianness used with an encryption algorithm affect its security?

I'm implementing the AES block cipher, which reads/writes data in 16 byte blocks. The implementation I'm working with usually read data in the little endian format. But in my platform the endianness ...
7
votes
2answers
54 views

Are any inherently insecure AES-CBC keys or key-IV combos known for properly generated random values?

This is mostly a theoretical question. I am using AES128 CBC to encrypt small files. Both my keys and my IVs are randomly generated per file using iOS's secure random value generation ...
6
votes
2answers
1k views

Can I use SHA-512 hash as AES key?

I want to combine hashing and encryption for better security. So can I use a hash key generated from SHA-512 as a key in AES. For example, I have a password "secret", I calculate SHA-512 hash for it ...
6
votes
4answers
5k views

TrueCrypt -vs- MacOS encrypted sparse image - equally secure? Other alternatives?

I'm currently trying to find my personal best solution for storing passwords and other sensible data. Recently I've used 1Password on iPhone and Mac but I'm not really satisfied with its predefined ...
6
votes
2answers
579 views

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 ...
6
votes
1answer
332 views

What cryptosystem makes the encrypted text look like random noise?

Suppose one wants to setup a cryptographic protocol in which 2 parties communicate using an encryption scheme that produces encrypted messages indistinguishable from random data (the desired property) ...
6
votes
1answer
219 views

AES-ECB chosen plaintext attack with long secret

I'm having some trouble understanding the methodology for a crypto exercise I'm doing. The goal of the exercise is to recover an encrypted secret string through a chosen key attack on AES in ECB mode. ...
6
votes
1answer
2k views

How are chosen plaintext attacks against ECB implemented in the real world?

Reading up on attacks against AES i have seen countless examples of why ECB is bad, and the logic behind it i can understand, but i can't get my head around how these attacks actually work in the real ...
6
votes
2answers
591 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. ...
6
votes
1answer
77 views

Using AES with same salt / IV - required for pattern matching algorithm

I need to securely encrypt data we are storing, but for each client I need the same plaintext to encrypt into the same cypher text. The reason for this is the data is still required for a pattern ...
6
votes
1answer
970 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 ...
6
votes
2answers
259 views

Is there any reason to use AesManaged over DPAPI in this scenario?

I have a situation where my web application is going to be deployed on multiple web servers, and I'll be wanting to store some securely encrypted data on the DB servers (each web server has a DB ...
6
votes
3answers
102 views

What is the benefit of adding data encrypting key then store it (encrypted) along with data

To protect user's sensitive data, I am considering the following 2 approaches: Create 1 data encrypting key (DEK) for each user, use it to encrypt (using AES CBC mode with a random IV for each ...
6
votes
3answers
1k views

Are temporary files an issue when opening and editing an encrypted 7z file?

I am new to security and encryption. I want to store important information like passwords and pin codes so I don't forget them. So far I have been using LastPass but I would prefer a solution I ...
5
votes
2answers
1k views

Designing a cryptographic file-sharing protocol

As a learning project, I am trying to implement a secure way to share files with a friend over dropbox. (I am not looking for existing software, I am doing this in order to learn how to do this ...
5
votes
1answer
5k 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 ...
5
votes
3answers
6k views

Encrypting using AES-256, can I use 256 bits IV?

I want to encrypt data using AES in java, and I want to intialize the cipher with Initialisation Vector. Can I use 256-bits IV ? Or I must use only 128-bits IV ?
5
votes
2answers
2k views

How to encrypt more than 16 bytes using AES?

I am trying to implement AES on an image of size 256x256 (65536 bytes) but AES works on 4x4 size of image (16 bytes). What should I do? Can it be implemented or not? And if yes, then how?
5
votes
2answers
12k 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 ...
5
votes
1answer
2k views

Why does openssl enc -aes-256-cbc -a -salt increase the file size?

I'm using openssl enc -aes-256-cbc -a -salt for automated differential backups to Amazon Glacier. But I noticed that using this command increases the file size almost perfectly by 35%. In my ...
5
votes
2answers
244 views

Security sanity check

A company whose services I'm trying to integrate uses this protocol: An AES key is embedded in an Android library. To authenticate itself, the library sends a SHA1 hash of the key over plain HTTP. ...
5
votes
1answer
917 views

How did SSLv3 get AES?

IANA maintains a registry of TLS cipher suites at TLS Parameters. TLS provides TLS_RSA_WITH_AES_128_CBC_SHA, its value is {0x00, 0x2f}, and its available in TLS 1.0 and above. The AES cipher suites ...
5
votes
1answer
2k views

What difference between AES_128_GCM and AES_128 and AES_128_CBC ciphers?

I encountered AES_128_GCM cipher, tried to find it in specifications of TLS1.2 and nothing, any mention. Could some one explain the difference between AES_128, documented AES_128_CBC and this new kid ...
5
votes
2answers
683 views

Why do the banks all use weaker TLS suites? [closed]

I've been checking out various TLS certificates lately and noticed that most of the banks seem to have the following two issues: 1) They do not offer perfect forward secrecy 2) They are still using ...
5
votes
2answers
2k views

How much does unknown PBKDF2 iteration count improve security?

We are crackers who get our hand on an encrypted file. We know the whole file is AES-256 encryption of the original plaintext file. We also know that PBKDF2 was run 1000 times on the original plain ...
5
votes
1answer
3k 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 ...
5
votes
2answers
163 views

Is AES 128 encryption weak for very small payload size?

If I have a payload of e.g. 8 bits and I want to encrypt it using AES 128, I will need to add some random padding to make the plaintext 128 bits long. Does this padding affect the security of AES?
5
votes
1answer
76 views

Why is the Key Derivation Function important?

Let's consider this openssl command : openssl enc -aes-256-cbc -pass pass:PASSWORD Why is it important to have a good Key Derivation Function? This answer to another question suggest that GnuPG is ...
5
votes
2answers
334 views

Benefit to using PBKDF2 on key generated by RNGCryptoServiceProvider?

I have a program that generates a fixed-length 32 byte (256-bit) password using RNGCryptoService provider and then uses Rfc2898DeriveBytes on that password to arrive at an encryption key. However, to ...
5
votes
2answers
2k views

Incrementing Initialization vector by 1

Suppose that we do not generate initialization vectors randomly (using AES in CBC mode). Instead it is initially all zeroes and we increment it by 1 each time a message is encrypted. How can this ...
5
votes
3answers
231 views

Secure Hash of a very short payload - is it possible?

I am looking to verify the integrity of a very small payload, approx 64 bytes, which will be stored in a QR code. I need to verify that the payload has not been generated or altered by an attacker. ...
5
votes
1answer
2k views

When do I use NIST AES key wrapping?

Key Wrap constructions are a class of symmetric encryption algorithms designed to encapsulate (encrypt) cryptographic key material. The Key Wrap algorithms are intended for applications such as (a) ...
5
votes
2answers
141 views

Serving data from an encrypted database over an encrypted connection

There is encrypted data in the database (asymmetric FYI). It is to be viewed as decrypted on the website. The data can be sent to the client as encrypted to be decrypted on the client's computer, or ...
5
votes
2answers
188 views

Securely store session data in cookies

I'm trying to create a stateless application server architecture and I would like to store session data in cookies. All pages using the session would be served over HTTPS. I was planning on using ...
5
votes
3answers
167 views

AES256, repeated IVs and mostly-costant payload: how ok/bad is that?

I recently came across an application that more or less does this: starts from a (supposedly unknown to others) key generates a random IV encrypts some smallish (~ 160 bytes) payload with the key ...
5
votes
1answer
7k views

How safe is the new iOS Keychain that stores credit card numbers?

iOS7 includes iCloud Keychain which syncs your stored passwords across devices. Not only that but it also syncs credit card numbers. The only information I can find about encryption is that they are ...
5
votes
1answer
5k views

What block ciphers and algorithms are now safe? [closed]

I work for a large non-US based international organisation. Regarding the recent leaks about the NSA breaking most encryption on the internet, we now know the US and UK governments are actively ...
5
votes
2answers
281 views

JSON data decryption

Context I am trying to learn more about web security through looking into how various iOS native apps work under the hood. I have been using Burp Suite as the MITM tool to sniff out the network ...
5
votes
2answers
2k 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 ...
5
votes
1answer
608 views

Keyboards using 2.4GHz with AES

I got a Microsoft Sculpt keyboard, as it seems to be a small improvement over the much loved Ergo 4000. (What I'd give to have an Ergo 4000 with CheryMX Blues...) On various sites, they have this one ...
5
votes
3answers
5k views

Where do I securely store application-specific symmetric key?

I am writing an application App1. This application uses SQLite database and I plan to encrypt it using AES256. For symmetric encryption I need a key, which I need to store somewhere. From a similar ...
5
votes
2answers
147 views

What encryption and signature systems (don't?) allow for plausible deniability of the OP's key being used?

I need to prevent Mallory from blindly matching encryption and signing keys to messages Hypothetical scenario: A user creates a public key An encrypted or signed payload exists. With only public ...
4
votes
2answers
834 views

How secure is AES-256-CBC with user provided password and initialization vector

From my understanding the IV is used as a previous block for the first block only. But since each block is used by the following this adds significant security is a IV is provided and not based on the ...
4
votes
1answer
129 views

Has there been a breach of AES?

Are there any known logical flaws of AES Cryptography? I understand that you can always break the encryption by brute-force or by having backdoors, but I have not come across any sources that show a ...
4
votes
4answers
3k views

How to securely share key between two remote devices?

Assuming I have a server/client topology, currently I'm facing the problem that I want to generate some key on the client side and somehow make the remote server get it securely. I'm using AES on ...