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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What to do with the extra bytes in ECDHE-RSA-AES-GCM-SHA?

I'm trying to implement, as an exercise, a protocol based on the cipher suite ECDHE-RSA-AES256-GCM-SHA384. As I understand things, ECDHE is used for the key exchange, RSA for the authenticity of the ...
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114 views

Is it safe to derive an IV partially from the secret data if it is hashed before use?

To help ensure uniqueness of IV's used in a CFB AES-256 cipher, software I know of gathers bits from various sources including the plaintext being enciphered, and runs that through an SHA-256 hash. ...
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622 views

AES in CTR mode with same random IV to create same ciphertext

I am currently working on a little project. I am trying to generate an AES key with that I would like to encrypt a private RSA key. I have to do it this way. However, I do not want to save the AES ...
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Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?

I recently found out that active attacks are a threat against AES-256, CBC mode, padded with PKCS#7 (the CBC mode in particular. I should supposedly change to EAX to guard against these attacks). ...
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231 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 ...
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61 views

Clarification about IV in PBKDF2 to generate encryption key

I've realized that the following implementation isn't truly safe: $pb = pbkdf2('sha256', $_POST['pass'], "enc_salt", 100, 100); $d = openssl_decrypt ($data['container'],'aes-192-cbc', $pb, true, ...
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48 views

What is the output length of CBC with zero input?

Given this formula for CBC encryption from 6.2 The Cipher Block Chaining Mode what is the output length of CBC if plaintext P is of length 0?
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422 views

Python implementation of AES and SHA256/512 that are FIPS-140-2 validated?

For security purposes I need to use AES encryption and SHA256/512 in my Django/Python project. I know there are various libraries out there that provide different encryption methods but I can't seem ...
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287 views

Properties of AES Encryption

First of all, I apologize if these questions can be answered using a web search, but I'm sort of a crypto noob and don't know what to search for. Given N AES encrypted messages (where the message ...
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350 views

What can I do with private 128 bit AES Keys?

For my studies, I am required to do an investigation on a fictional criminal VMWare image. The image is suspected of participating in DDoS attacks and other illegal activities. On this PC TrueCrypt is ...
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141 views

How safe is Money Toolkit?

Money Toolkit is a smartphone app that can alert you to your balances and transactions across multiple accounts. I was reading their site and whether their practises are as secure as they claim to ...
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Login system using authenticated encryption without storing user password

I'm not a security expert, so I might be asking a silly question, but let me describe what I am thinking about. First, I know that a lot of web sites store hashed/encrypted passwords which could be ...
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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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Authenticated encryption (Symmetric encryption) for .NET applications [closed]

Is there an implementation of Authenticated encryption for .NET applications? The AES API from .NET does not include mode such as GCM. In the documentation, I can only see insecure modes (ECB, CBC, ...
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48 views

Is a Fernet token's timestamp a security risk?

A Fernet token has the following format: Version ‖ Timestamp ‖ IV ‖ Ciphertext ‖ HMAC As the above shows, the timestamp is not part of the ciphertext, so anyone can read the time the token was ...
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70 views

How to implement encrytion/decryption system using IV between mobile app and web service

In my app we are going to send encrypted data to the web service. I am using the following code to encrypt and decrypt the data - public class DecEn { private static final String password = ...
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27 views

Does endianness affect encryption keys and initialization vectors?

When encrypting (specifically when using AES) content, will endianness affect how the key (and/or initialization vector) should look when encrypting/decrypting content? And could this depend on the ...
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830 views

Creating a private key with OpenSSL and encrypting it with AES GCM

My goal was to create a private key and to encrypt it with a strong cipher. That key would be used as a root certificate for an internal Certification Authority. However, eventhough openssl supports ...
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331 views

PGP as method of sharing AES key?

Would PGP work as a method of sharing the AES key, as shown below, and what would be the flaws with this method of encryption? Server sends PGP public key Client generates (uses as AES key for ...
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1k views

Storing encryption keys on a server using Node.js and MySQL

I am writing a web backend/api for an iOS application using Node.js and MySQL. In my database I have a table for posts. I would like the posts content to be encrypted. Let's say I'm using this AES for ...
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224 views

HIPAA compliant blob storage architecture

There is a task to design a system to store sensitive data securely (should be HIPAA compliant in the future). It's just a draft - this will not be used in production in a foreseeable future. I have a ...
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316 views

An attacker got a few 128bit TrueCrypt keys from a RAM analysis. What can he do?

I'm trying to simulate a possible attack scenario for my studies. I've got a image, which has a encrypted disk, encrypted by TrueCrypt (confirmed). TrueCrypt is installed on the image itself too. ...
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Kik | WhatsApp - Encrypted? iOS / Android Message encryption tips [closed]

Kik says that their client is using ssl etc. But it's kind of hard to tell if the messages is actually encrypted between the devices. What i can understand is that they don't got device-to-device ...
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AES-256 Decrypt a VHD File

I recently messed up with my McAfee Encrypted Laptop (2 Drives) and got MBR overwritten by Linux (Ubuntu). I used DETech CD on C: but after 2% it failed due to Bad Sector. Using a safety precaution ...
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A simple HMAC question

Suppose I use a key (and IV) to encrypt a piece of binary data with AES-256-CBC to produce the corresponding encrypted data. Suppose I then throw this encrypted data into HMAC-SHA512 using the same ...
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Security implications of providing an encryption/decryption oracle

I need to provide a service that acts as a symetric encryption/decryption blackbox : the box get a secret key k users send datas d, and get ciphertext c = Encrypt(d,k) users send ciphertext c, and ...
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How is Tresorit client-side encryption key stored and managed?

I am using Tresorit on Mac OS X and iPhone. When I am using it there is always applied client-side encryption before posting the file to cloud. The key used for encryption is AES-256 and CFB mode of ...
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479 views

Steps for building a good File Encryption on Android

I want to be able to build a good file encryption on android for a cloud app. The files used are mainly pdfs, pngs, docs, audio, video, etc (all sorts of files). Edit: My constrains are that it ...
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Using GPG or PGP for symmetric database encryption/decryption in c# [duplicate]

Possible Duplicate: 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 ...
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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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4k 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 ...
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Is applying AES multiple times safer?

The KeePass security help page talks about preventing dictionary attacks To generate the final 256-bit key that is used for the block cipher, KeePass first hashes the user's password using ...
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Storing AES password for verification

I was wondering if such practice would be safe: I have a table that stores encrypted notes Every note has a data field and a password field When a password is entered, i want to select all notes, ...
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737 views

Is symmetric encryption vulnerable to known plaintext attack?

If Bob sends some plaintext to Alice for encryption before sending the ciphertext to Carol, can Bob deduce the key by comparing the plaintext and ciphertext assuming only Alice and Carol knows the key ...
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Using AES as a Stream Cipher

I need to send a lot of small messages that are usually between 128 bits and 256 bits long, and each message is encrypted with a separate 128 bit AES key. Therefore, to send each message with the key ...
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253 views

Expiring AES Key

Is there any way to make an "expiring" AES key? Here's scenario to give a better picture: Say Bob has some data which he would like to share with Alice. Alice has a public and private key, let's say ...
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446 views

Real time application of AES and DES [closed]

I am writing a paper on reducing the power consumption of security protocols. I am having trouble identifying sources that describe real-time usage of DES and AES, and how often they are used. I plan ...
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186 views

Hardware Implementation of Encryption Algorithm

In the abstract of the AES-GCM RFC, the following passage is prominently included: [AES-GCM] can be efficiently implemented in hardware for speeds of 10 gigabits per second and above... Is the ...
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476 views

Which encryption technique should be used for cloud computing data transfer?

I want to setup my application for cloud computing for Software as a Service. There is going to be a lot of data transfer between my server and client, to and fro. The technique I have envisaged is: ...
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313 views

How to decrypt a file when I have its key?

How could I decrypt a file (encrypted with AES-128) using openssl ? I do not remember the passphrase I used to encrypt it, but I saved the key generated and used to encrypt my file. How could I use ...
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385 views

256 Bit Key into AES 128 same output as 256 Bit Key into AES 256

I have two different crypto libraries I created, one is in java and uses the standard built-in java crypto libraries. The other uses openssl and has been wrapped in java through the JNI. I'm ...
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119 views

How can I encrypt compressed data safely?

As mentioned in this particular answer, compressing data before encryption may lead to the CRIME attack, especially if the hacker has collected many similar versions of the transmitted data. Let's ...
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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 ...
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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 ...
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Questions to hybrid encryption. RSA with AES

I want to use a hybrid encryption in my application, so after reading a lot of lines I ended with this implemantation, please critizie it ;) (I want to stick to .Net) byte[] aesKey = ...
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616 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 ...
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196 views

Protecting passphrases within an application

First off, I'm not very familiar with encryption best-practices. My use-case is simple: I'm creating an application that will be reading encrypted documents and decrypting them dynamically to do some ...
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382 views

How to check for a key *and* store encrypted data?

I wish to create a system wherein I store encrypted data. Users can access this data if they have the key. If they give a wrong key, they don't get access at all. If they give the right key, they get ...
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Which AES key length to choose for OpenVPN?

I plan on using OpenVPN on client devices which are small embedded machines, so I must balance between speed and security. The OpenVPN documentation says that it is "general wisdom that 1024-bit keys ...
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Cryptanalysis of encrypted data at rest

Imagine I have a file encrypted using AES CBC mode with a key and a random IV. The attacker access to the encrypted text and the IV used but not the key. In this scenario there is no vulnerability ...