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 to use Truecrypt AES keys to decrypt a Truecrypt volume

I am performing a forensics experiment. I have access to a '.mem' memory dump and I am successful in extracting 2 AES keys from the dump. Now I wish to use these AES keys to decrypt a volume encrypted ...
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174 views

Why do the banks all use weaker TLS suites?

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 ...
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3answers
157 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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20 views

Possible CPA or CCA attack when using AES-CBC mode under the following situation?

Both client and server know a shared key in advance. Both sides us EVP_BytesToKey() derive a pair of same key and same IV. Then, client and server start transferring data encrypted by AES-CBC mode ...
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41 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 ...
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3answers
158 views

Java AES encryption output length

I am trying to encrypt few database columns (string values) using Java AES algorithm. This is to protect certain sensitive data. For some users these data should decrypted. In Java AES encryption, if ...
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2answers
46 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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2answers
959 views

Extract AES key by comparing plaintext and encrypted data

Is there a kind of analysis which would enable me to get AES key which was used for encrypting arbitrary data while I have both original and encrypted version of data ? The problem is that the AES ...
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2answers
62 views

Client-server encryption technique explanation (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 128 bit keys)

I opened a web page using https. When I looked at the page info provided by my browser (Firefox) I saw following: Connection encrypted: High-grade Encryption ...
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25 views

How does Spideroak manage encryption keys

I'm trying to understand the following from SpiderOak's engineering page (sorry I'm on a mobile phone so have no access to formatting functions like quote blocks): "SpiderOak uses a nested series of ...
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2answers
108 views

File encryption for a storage API

I'm implementing a Dropbox-like API, and one of my requirements is to have the files stored encrypted on the server. It is not required that the files are made unreadable by the server, only that they ...
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161 views

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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1answer
155 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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1answer
54 views

Will obtaining password hash compromise derived encryption key?

I've been looking at how PBKDF is used to generate encryption key for AES. One thing I couldn't get my head around is that how those OS keep the encryption key safe apart from using hardware modules. ...
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1answer
536 views

Salt usage for Spring security?

I use the Spring security for Java web applications and I have written an authentication provider which is working without salt and now I want to either add salt or alternatively use the built-in ...
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1answer
81 views

PHP/Ajax Data transmission security

I'm learning about web security mechanisms. I have developed the following system in PHP and JavaScript: assuming that I have a page named: messages.php which is a real-time chat system. first when ...
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2answers
110 views

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 ...
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97 views

Saving passwords decryptable for later usage

I'm in a situation where I need to calculate a hash of the result of the password in plain text plus some random chars representing a session. The gained hash will be compared to another hash that is ...
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142 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. ...
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1answer
32 views

In TLS1.2 AES-GCM mode, what happened when input is not exactly the multiple of its block size?

I know that AES-GCM mode does not need padding, and its output are exactly the length of input data plus the tagging. But I am a little bit lost, as AES itself is block cipher, it could only operate ...
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1answer
141 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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1answer
85 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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1answer
90 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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111 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 ...
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56 views

get encryption key from encrypted and decrypted data

I used encfs to encrypt some important files on my system , But sadly i forget the encryption key , i still have a version of some of the the encrypted files .so my question is : is there there a way ...
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1answer
103 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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Is “Why Should You Avoid AES In MySQL?” true?

From a 2012 Smashing Magazine article quite a bold statement is made to avoid AES in MySQL itself. Or as they put it "Why Should You Avoid AES In MySQL?". However, if you search for SQL encryption, ...
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127 views

Cracking Kingston DataTraveler vault privacy - is it possible?

I have Kingston DataTraveler vault privacy USB flash drive (DTVP/2GB). Here is tech specs. Flash drive has a 256-bit AES hardware based encryption. My flash has password protected and I do not know ...
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212 views

How to treat/hash ECDH shared secret to use as keys for AES?

I'm doing some studies/development for a security system that would use ECDH with ephemeral keys. In my code I'm currently using a 256-bit EC, so when the two parts compute the shared secret, I get a ...
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1answer
113 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 ...
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1answer
94 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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1answer
57 views

Gmail Voicemail Encryption

I want to listen to my voicemails in a secure but convenient fashion. I plan do this by having my PBX encrypt the voicemail using openssl aes 256 cbc with salt and a single static password. The ...
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1answer
102 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 ...
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144 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
108 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) ...
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94 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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1answer
161 views

Crazy 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 "stangeness" when the chosen ...
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1answer
848 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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1answer
97 views

How to do Rijndael MixColumns step

I am trying to go through all of the the steps in the Rijndael Encryption Algorithm using pencil and paper. I have been using ...
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4answers
4k 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 ...
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42 views

BKSQ block cipher

I'm trying to implement the BKSQ block cipher (similar to AES) but to do so I need the inverse mixcolumns operation, therefor I need to inverse the 2x^2+2x+3 operation. e.g for the AES it is c(x) = ...
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116 views

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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2answers
168 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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70 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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6answers
6k views

Is AES encrypting a password with itself more secure than SHA1?

This isn't really a practical question, but more a question of curiosity. I heard a CS professor recommend stepping up from md5ing passwords not to SHA1, but to AES encrypting the password using ...
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3answers
4k 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
337 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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1answer
246 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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1answer
156 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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53 views

Is saving a list of passwords in Acrobat XI with 256bit AES encryption as secure as something like KeePass?

I would like to just have a single .pdf document that has all of my passwords and sensitive info included, but have it password protected so that I could store it in Dropbox and sync it to multiple ...