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 authentication tag is calculated in AES-GCM-256

I have a sample code,which encrypt and decrypt a string using AES-GCM-256. I am unable to understand,how authentication tag is being generated on encrypter side and how is that being used on ...
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Question about AES-CBC IVs

I'm writing a Java program that encrypts strings with AES-CBC encryption. (Eventually I'm going to add steganography functions too). As you are well aware, CBC needs an IV in order to encrypt the ...
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Key-exchange over the network with more than two peers

Me and my team is developing a multiplayer videogame with a Client/Server-Topology. This secures the match from clients who have the intention to cheat because of server authority but still allows the ...
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Encrypt a file with Block Cipher in CBC mode in c++ [on hold]

I have using Crypto++ Library in C++ for encrypting files, and use of AES Standard and CBC encryption mode. i know comparison between Block Cipher and Stream Ciphers and Operations of each modes, so ...
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How to use a different key and IV for encrypting a file with AES in C++?

I know how AES encryption works, and different modes (for example EAX, CBC, CCM, ...), and also about CipherBlock and StreamTransformationFilter methods and their implementation in C++. I am using ...
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LENGTH Parameter in the EEA2 AES-128 of LTE [migrated]

In the EEA2 option for encryption in LTE the AES-128 algorithm is mechanized. There, the nonce used in the CTR Mode is a 128-bit value. The first 64-bits are covered by a COUNTER, a BEARER, a ...
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Calculate time taken to break AES key

A 256 bit AES key is required to be broken using the brute force method on a 2GHz computer. How long would it take to break the key in the best case and in the worst case situations? Assume that 1000 ...
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143 views

MasterSecret expansion into keys

I'm trying to deeply understand the steps during a TLS handshake. I've read this answer (which is btw pretty complete), but I stil got a question about the utilisation of the MasterSecret, in the ...
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71 views

Security of an IoT network using AES (LoRaWAN)

I am studying the security of LoRaWAN. Here is a simplified architecture of the network: As you can see, there are two keys: one for the network security (no mitm, no modificatiof the messages). ...
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63 views

Firmware protection scheme

Edit: I have found a scheme that fits my limits (little memory, only AES is available): AES-CMAC described in RFC 4493 (just remember to use different key for encryption and MAC ;) . I am working ...
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179 views

How to wipe disks before encryption with dm-crypt if CBC or XTS is used internally?

First, please forgive me if I'm posting this question to the wrong community. Feel free to migrate this post to the right community if I was wrong. I'm quite new to whole disk encryption (but not ...
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61 views

How could I encrypt an SD card to store data on it?

I have some data I'd like to carry with me in an encrypted form onto an SD card, so I (and only I) can access it easily from any OS (or at least Windows, OSX and Ubuntu). My idea was like: Two ...
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46 views

Is using trim on a ssd with LVM LUKS safe?

I know that it can allow an attacker to know the filesystem and file size, but can it allow an attacker to decrypt any files?
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88 views

OpenSSL key derivation

I'm trying to manually decrypt DTLS packets sent by OpenSSL. The cipher suite used between the server and the client is TLS_RSA_WITH_AES_256_CBC_SHA256 and my understanding is that the IV used by ...
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43 views

Choosing Key and IV in AES-256

I am working on a real-life project for a firm. I have to encrypt data using AES 256 as per specification. I want to know how are the key and IV are really chosen in real world projects. /dev/urandom ...
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How long does it take to brute force a 7 character long password taken from 16 character set

A database file is encrypted with 256bits AES and the key is the first 7 characters (from the character set 0-9, a - f, all small letter) of MD5 hash . This implies 2^28 bits (268,435,456) possible ...
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48 views

Does use of fixed padding pattern compromise AES-ECB

I'm working on an application where AES-256-ECB has been specified. It has been asked that a fixed pattern is included at the end of the message to allow the decoding end to ensure the decryption has ...
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1answer
24 views

Is it ok to append the nonce/iv to the ciphertext when using AES GCM?

I want to use AES GCM to encrypt data at rest. When retrieving the data, I want to make sure that the key is valid and the data has not been tempered with. Can I store the nonce/iv along with the ...
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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 ...
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24 views

AES256 nopadding vs PKCS7Padding

I was looking over AES Crypt's Java lib which seems like a secure AES encryption software and I noticed that they are using nopadding. Can somebody explain to me what the benefit of using nopadding as ...
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67 views

Questions regarding AES 256

i have googled and searched quite alot but most things just state the same things but not answering my questions so hopefully you guys can help me out abit Story: i am looking at creating an ...
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Is it secure to use a part of the key as IV in AES?

I seen a lot of AES implementation samples wide spreaded over the Internet in almost every language I can recognize. There is one difference that I reflect to be repeated between all. Some of them ...
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147 views

store passwords as one-way-hash, or just use it as an AES key?

I want to store some data so the only one who'll be able to access it is the user itself. Here is my idea: when user registers, his password will be hashed in SHA256 (so it'll fit as an AES key), and ...
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62 views

OpenSSL brute-force attacking and file size

I use OpenSSL with aes-256-cbc to encrypt a 30 GB tar file containing a recent backup of my hard drive. Now suppose somebody wants to run a brute-force attack on this file, trying out all possible ...
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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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Why would I use at-rest encryption over a DB's key-based encryption?

Goal I want to store encrypted data in a database. Constraints Application-level encryption (encrypting before sending to the DB) is not a reasonable option for my use case. The DB providers I'm ...
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Create a TLS Application Data Message for AES-GCM

I was wondering if anyone could help me with structuring a TLS Application Data message for AES-GCM. I don't know how the IV, CipherText, Additional Data, and Tag fit together in a message. Thanks.
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Which block cipher should be used in TLS 1.2 (while keeping 1.3 in mind)?

I have been looking a bit at the various block ciphers for TLS. As everyone should (pipe dream) have migrated to TLS 1.2 by now it should be considered how to prepare for TLS 1.3, when it has been ...
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26 views

Clarification of RSA Key Exchange (TLS 1.2) and AES for On-Going Message Excahnge

I'm trying to understand the full flow of key exchanges for secure communications. As a potentially incorrect premise, I am under the impression that RSA is a good asymmetric technique for ...
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66 views

Stateless AEAD (AES-GCM) based tokens

I want to generate secure data tokens which can be shared with the client for uses like password reset, etc. which involves low storage overhead at server end. Ideally I am interested only in managing ...
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51 views

How can AES-CBC be used for LUKS encryption, when the ciphertext is not static?

In CBC mode of operation, ciphertext from previous block is used as IV in next block. How then can AES-CBC be used for disk encryption (LUKS), when the data on the disk (ie the ciphertext) keeps ...
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Is AES-GCM recommended for SSL?

I'm looking at turning on site-wide SSL for a website I manage, and I'm wondering what the best practices for SSL configuration. I'm not too worried about compatibility with old browsers and more ...
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Why does IV not need to be secret in AES CBC encryption?

According to Wikipedia, the initialization vector (IV) does not have to be secret, when using the CBC mode of operation. Here is the schema of CBC encryption (also from Wikipedia): What if I ...
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Why is 128bit AES considered very strong but 160bit SHA depreciated?

Why is 128bit AES considered very strong but 160bit SHA 'insufficiently secure'? Google/chrome/browsers seems to drop support for SHA1 SSL certificates. I assume it's more simple to calculate SHA than ...
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66 views

Store password ciphers using Powershell ? DPAPI/AES

Hi and sorry if it is in wrong place I am making a script that requires to have a lot of server's IP and their passwords stored into a file. I wanted to use Windows DPAPI, but as we can easily ...
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Is this RSA/AES combination good?

The team of developers I am part of is trying to develop a safe way to exchange sensitive data between a server and mobile devices. We have come up with the following algorithm: Device generates ...
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AES step by step

I can't seem to find an AES tutorial that starts from Unicode to Cipher text. All of the tutorials I found starts with 128 bit block already. Also, where do I start or what topics do I have to start ...
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Designing my own HSM using an Arduino

I am attempting to build from scratch something similar to Apple's Secure Enclave. What I've done is use an AES library for the Arduino to create a security appliance. A random crypto key and the ...
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Different performance of openssl speed on the same hardware with AES 256 (EVP and non EVP API)

If I run openssl 1.0.1e like this : $ ./openssl speed aes-256-cbc (i.e without EVP API) Doing aes-256 cbc for 3s on 16 size blocks: 14388425 aes-256 cbc's in 3.00s Doing aes-256 cbc for 3s on 64 size ...
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Is it safe to reveal AES encrypted password?

Please correct me if any of my statement is incorrect. It is probably more good practice to not show any hint of the password. However, AES encrypted passwords by itself cannot be used to decrypt ...
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How is WhatsApp sending end-to-end encrypted messages in push notifications?

WhatsApp implemented end-to-end encryption (whitepaper) in their latest update. How is it possible for WhatsApp to send push notifications with message contents to the Apple Push Notification service?...
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843 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 ...
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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 ...
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Authentication tag lengths of AES-CCM in TLS

I'm catching up on understanding some of the new cipher suites that are appearing in TLSv1.2 and will be making an appearance in 1.3. While looking through AES-CCM, I discovered that it offers a ...
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87 views

Diffence between AES-128 CMAC & AES-128 ECB/CBC?

Automotive standard for encryption use to talk about following algorithm AES-128 CMAC & AES-128 ECB/CBC. AES-128 CMAC use to provide Security service Authenticity AES-128 ECB & CBC used to ...
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Is webkey a reasonably secure authentication system?

I just created Webkey in the last couple days. It's built to do client-certificate auth without using the (in my opinion unusable) client-cert functionality built into browsers. It would allow single-...
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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 (...
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108 views

Why does this key get Base64 encoded prior to use?

I wish to have my server encrypt messages to clients who have each provided the server with an RSA public key, as well as having the clients authenticate their messages to the server using their ...
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Is symmetric encryption with one time pre-shared key secure?

Suppose I have a secure channel between client and server, with proper certificate validation etc (actually, ssh session). I want to establish a secure connection between my own application on a ...
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when/how does an encrypted volume .dmg change to reflect the file system it stores

I'm trying to verify that storing a .dmg file stays encrypted while only the mounted file system is unencrypted (see here). My thought was to create a .dmg containing a text file, make a copy of the ....