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 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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41 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
308 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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61 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
62 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 ...
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2answers
457 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
65 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 ...
3
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4answers
484 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 ...
2
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1answer
116 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
41 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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3answers
553 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 ...
2
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1answer
79 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
108 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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1answer
413 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
64 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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1answer
126 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 ...
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3answers
121 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 ...
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1answer
77 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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1answer
6k 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 ...
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1answer
71 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 ...
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2answers
150 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
172 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
102 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 ...
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1answer
654 views

Cascading Encryption Algorithm using mcrypt or GnuGP

I'm trying to a cascading cipher encryption algorithm to encrypt a textfile via mcrypt. I'm essentially trying to emulate the behavior of TrueCrypt, where it can cascade two or three different cipher ...
2
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1answer
289 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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1answer
100 views

Permutation in Block Ciphers

I was reading some e-books to understand the basics of block ciphers and how it works in AES. As i understood, Permutation plays a big part in AES and Block Ciphers, Here is what i understood by ...
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435 views

How to circumvent compromised CPUs in major FOSS operating systems

As Matthew Green puts it, "the NSA has been ... Working with hardware ... vendors to weaken encryption and random number generators." At this stage, however, there is little public knowledge of which ...
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1answer
29 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
571 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. ...
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1answer
73 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 ...
0
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2answers
331 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
595 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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220 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 ...
6
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1answer
671 views

What's the hash for in ECDHE-RSA-AES-GCM-SHA?

Presumably the SHA is for deriving the AES key from the shared secret. Where else is the hash used? ECDH just does ECC (no hashing). RSA does masking and padding but this doesn't involve the ...
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3answers
3k views

Can someone explain a little better what exactly is accomplished by generation of DH parameters?

I'm setting up a node.js server: https.createServer({ ... ciphers: 'ECDHE-RSA-AES128-SHA256:AES128-GCM-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH', honorCipherOrder: true }, app).listen(443); ...
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1answer
459 views

Salt usage for Spring security?

I use the Spring security for Java web applications and I have written an authenticationprovider which is working without salt and now I want to either add salt or alternatively use the builtin ...
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2answers
115 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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2answers
3k 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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155 views

Do I need to salt PBKDF2 when it's used for AES encryption

If I'm using PBKDF2 to stretch a password into a suitable key for use in encryption with AES, should I be using a random salt (for PBKDF2, not the AES IV)?
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3answers
232 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 ...
2
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1answer
859 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 ...
2
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2answers
2k 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
227 views

Can SHA-1 PRNG still create secure cipher keys?

I am concerned that a SHA-1 PRNG cannot produce an AES-256 cipher key with the expected 256 bits of security, or indeed any secure cipher key where over 165 bits of security are expected. The SHA-1 ...
4
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2answers
3k 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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521 views

Using AES to encrypt user data

I know next to nothing about cryptography, and I'm basically just looking for someone to look over what I'm doing and tell me if I'm screwing up. I have the user entering in some sensitive ...
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1answer
66 views

What key needs to be used to compute HMAC?

I use AES-128bit to encrypt files and I want to compute a HMAC for each one of the encrypted files to ensure their integrity. Can I use directly the AES KEY to compute HMAC or should I used a derived ...
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106 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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3answers
2k views

How long (in letters) are encryption keys for AES? [closed]

How long is the encryption/decryption key for an assymetric algorithm, such as AES? If I use AES 128-bit, how many characters should I type in for my key? What about AES 256-bit? Edit: Here is why I ...
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1answer
318 views

Using Apple NSKeyedArchiver class without encryption to save score data locally

first of all I'm sorry for my bad English! I have a question about the security of NSKeyedArchiver, a subclass of NSCoder of Apple Foundation.framework ...