Tagged Questions

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 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 ...
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0answers
43 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 "stangeness" when the chosen ...
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1answer
176 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 ...
1
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1answer
204 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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2answers
166 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
164 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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3answers
400 views

AES encryption do I need to use a Mode?

I am currently working on a file encryption program using Java Cryptography Architecture. My plan is to have a number of encrypted files where each file has a different AES key. To keep track of the ...
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2answers
434 views

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
577 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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1answer
682 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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2answers
100 views

openssl aes 256 cbc strange bug

This is extremely strange but I have already tried this twice and am completely sure it is openSSL and not me doing the bug. I am encrypting the data 'Hygiene' with the password '*' (sorry can't tell ...
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0answers
97 views

Gladman's file encryption library = AES in counter mode with HMAC-SHA1 authentication?

I would like to use Gladman's algorithm to create AES encrypted data in JavaScript. I use the Crypto-JS library, but its performance is horrible. PBKDF2 is terribly slow, so I switched to another ...
2
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1answer
169 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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1answer
200 views

What is default mode for AES encryption [closed]

What will be the default mode for AES encryption if we don't use any specific mode like ECB, CBC, OFB, CTR, etc. and just carry out the encryption without specifying any AES encryption mode.
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1answer
263 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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2answers
261 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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1answer
122 views

I get the feeling that Microsoft and Mac use two different forms of AES

I have an AES string being produced with this class, the AesCryptoServiceProvider Class provided by Microsoft. And I need to decode this encryption with Ruby's SSL::Cipher class . The problem is ...
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1answer
45 views

Are there limits (or, what are the limits) to our understanding of AES's resistance to known plaintext attacks?

Let's assume the same message is encrypted many times, each time with a different IV but the same key. Do we reach a point where just knowing what that message is gives us a plausible attack by which ...
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4answers
869 views

When should I use symmetric encryption instead of RSA?

I'm currently using GPG RSA keys to encrypt binary files. Many people recommend using symmetric keys to encrypt large files, and then encrypt the symmetric key with a public key. At what file size ...
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0answers
82 views

P2P sharing of uniquely encrypted files

I need a way to share large, uniquely encrypted files (AES256) that are actually the same file when decrypted, through P2P, to optimize download speeds. For instance, a centralized server would ...
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1answer
82 views

Need help designing an encryption workflow

Background: I'm building a .NET application, a very small part of this application allows for users to communicate with a third party application. I am designing this aspect. The third party simply ...
2
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1answer
74 views

What is the purpose of derivation of encryption and authorization keys from master key?

We're using AES-CBC and HMAC to encrypt and authenticate our messages (using encrypt-then-authenticate method). Sometimes I see solutions (like this one) which are deriving encryption and ...
2
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1answer
159 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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1answer
43 views

Generate Passphrase from the data & encrypted data

right now I'm thinking about how to secure some data inside an Application... Now i have the following problem: Is it possible to generate the passpharase from a decrypted message and the same ...
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4answers
704 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 ...
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2answers
133 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 ...
2
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1answer
97 views

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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1answer
117 views

What would be a valid approach to store private keys?

I'm implementing a mobile app which uses AES encryption algorithm to encrypt some critical values being sent to a remote server (basically, the user password), and then decrypted on the server side ...
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3answers
1k views

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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1answer
1k 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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1answer
66 views

two encrypting / hashing case, which one is best

Thinking about these below two cases, which one is best and most secure one 1st case //key1 generated from static salt and user password, because in case attacker don't know about source code (bad ...
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2answers
273 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 ...
5
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2answers
642 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?
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1answer
184 views

How to best use JavaScript to encrypt client side so the server never sees it?

I don't want the server to ever see the raw input and would rather have the client do the encryption and then pass the data (over https) to the server for storage. If I use a JS library to AES ...
3
votes
3answers
136 views

How to simply and efficiently generate different keys from one password?

I saw here that using the same key to encrypt and mac (in that order) a message could eventually be unsafe. What is the best way to generate two different keys from the same password (using a PBKDF ...
0
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1answer
82 views

Encryption key generation performance

A question for cryptography experts. Imagine we have a conceptual Notes.app: There are notes (title|content) stored as AES-256 encrypted strings Application has to present a list of all notes ...
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2answers
191 views

Have I crossed my t's and dotted my lower-case j's? (or, implementing AES, please help get some eyes on my code)

So, I used the crypto module in node.js to implement a secure key generator and encrypt/decrypt functions. Knowing that security's best friend is a spotlight on the implementation, I want to throw it ...
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3answers
2k views

Is it safe to write the salt AND/OR the IV at the beggining of an encrypted file?

I want to encrypt a file with AES in CBC mode (maybe another mode is better for file encryption...I don't know, but suggestions are welcome!). What I usually do is that I first write a few random ...
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2answers
201 views

Is AES feasible for secure hashing files? [closed]

There was already a similar topic "Why AES is not used for secure hashing, instead of SHA-x?", but it was not about files specifically, and I, personally, am not convinced by the answers in it. "AES ...
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1answer
113 views

Sending Salts For Key Generation

I am working on a project that uses a combination of a web based framework (Django) and an installed app (Python) for the purpose of data entry/upload. I will have to send medical records over the web ...
0
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1answer
32 views

Is embedding the EAX nonce inside the Associated Data considered safe?

As the nonce bits would be used twice in that case, does that break EAX security? The examples I've seen using EAX have separated the nonce from the Associated Data, but to me it makes more sense to ...
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2answers
805 views

What is the advantage of using a symmetric cipher like AES to generate a keystream?

I see examples of AES (with a shared secret key) being used to encrypt shared secrets (e.g. nonce + counter) to produce a keystream against which the plaintext is XOR'ed to produce the ciphertext. ...
0
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1answer
78 views

Encrypting data in a load-balanced application - am I doing this right?

A web application I'm developing needs to store some sensitive data in a database. I need to be able to retrieve and use this data later on so hashing isn't enough. The web application might, at some ...
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2answers
536 views

Security of several files all using same password/key (7zip, AES256)

I'm working on a simple secure mirror for potentially untrusted services like Dropbox, Owncloud and so on. (Current code may be seen here: http://www.codeduce.com/extra/secure_mercurial) Currently ...
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2answers
1k views

Why would you need a salt for AES-CBS when IV is already randomly generated and stored with the encrypted data?

I was looking at this code and came across these comments which says encrypting without a salt is insecure. Why would it be insecure when you are already using a random IV for each value? I think the ...
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4answers
221 views

Is knowing 'a' encrypted with 'b' and 'b' encrypted with 'a' a possible threat?

Excuse me for question name, but I couldn't find any other suitable title. I want to validate client connecting to the server. My algorithm looks like that: Clients sends his login - plaintext ...
3
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1answer
657 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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2answers
142 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 ...
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3answers
306 views

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 ...
3
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1answer
74 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 ...