AES (Advanced Encryption Standard) is a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.

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How many bits of entropy can I expect from /dev/urandom in iOS?

Apple's latest security documentation indicates that it now uses CTR_DRBG for generating pseudo-random numbers (previously Yarrow instead of CTR_DRBG), using "timing variations during boot" and ...
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Are pseudorandom permutation really permutation in mathematical sense?

In security, and specifically Block Cipher (AES, DES, etc), when we talk about pseudo random permutations, is the term "permutation" refer to the same meaning as in discrete mathematics. That is, the ...
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A software for test and performance analysis of cryptographic algorithms

I'm new to cryptography and I have been assigned at college to do a comparison study between AES, DES, RC6 and SERPENT ciphers. Is there any graphical software than can help me analyze speed and ...
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application for cryptography algorithms [closed]

i am working on an article named "Performance Analysis of Data Encryption Algorithms" and i am going to compare AES , DES , 3DES and etc performance. implementing all these algorithms is a time ...
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Post-quantum authenticated encryption

It is well-known that the Grover's algorithm reduces cryptographic strength of symmetric ciphers to a square-root - e.g. AES-256 becomes only 2128 strong. However, these statements are always made ...
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60 views

AES process candidates implementations and usages

There were fifteen candidates in the AES selection and I suppose that Rijndael wasn't the single good algorithm. I know that Camellia is an evolution of E2 candidate and can be used as symetric ...
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How can one improve Rijndael's with more efficient SBoxes?

Knowing that the Rijndael's SBox is a pre-calculation from a composition of two operations (an inversion in a polynomial field, and an affine transformation that can be saw as a product and an ...
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2answers
89 views

DH with AES - is that an acceptable security scheme over UPnP?

I'm trying to devise a good security scheme to protect comms over Wi-Fi. Right now, I have 2 devices that already communicate via UPnP but I need to secure this communication. I've come up with this: ...
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32 views

Segmenting encryption to get the same results with the same key

The given examples below are dummy and in English. They are mainly for place holding as this is a concept question rather specific example based Given AES has a block size of 128 bit (16 letters of ...
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24 views

How openssl padding for AES cfb IV?

From a few documents I have read and a few questions about padding here, I think if I passed a encrypted text fewer than BLOCK SIZE, openssl would pad it per PKCS7. And use that padded encrypted text ...
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75 views

where can i learn the basics of AES?

i was tasked with making an expo about AES and its steps, but i still cant grasp it, especially when it comes to "key schedule". anyone knows some good material to start learning? or someone can give ...
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RFC 5297 implementation [duplicate]

I am looking for an implementation of RFC 5297 algorithm using javascript. I would like to see how to wrap a key on client side web browser, like Mozilla's fxa-auth-client (That uses a xor to wrap) ...
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54 views

Clefia Vs AES 128 bit

I am running a comparison between Clefia (Lightweight cipher from Sony Corporation which is a standard now http://www.sony.net/Products/cryptography/clefia/standard/index.html) and AES 128 bit. The ...
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Can I use the output from a DRBG directly as K for AES, or do I need to use a key generator algorithm?

NIST has 3 validated "Recommendation for Random Number Generation Using Deterministic Random Bit Generators" (DRBG's) that are based on NIST SP 800-90A: Hash_DRBG (based on hash functions) ...
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45 views

Where is the authentication tag stored in file encrypted using AES-GCM?

So I am using cryptopp to encrypt a file in a project and I am using AES-GCM. I have a 256bit key and a 128bit ivec and a 128bit tag that I use to encrypt files. However, I want to know where the ...
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1answer
42 views

How to generate the APA SBox?

I am trying to generate the S-Box provided in the Affine Power Affine paper (PDF) but I'm not sure I understand it fully. The essence of the paper is this: ...
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1answer
27 views

SSL certificate / SSL configuration - FIPS-197 compliance

What does it mean when we talk about FIPS-197 compliance in the context of SSL certificates, their deployment and usage ? I am almost certain that the FIPS-197 compliance in the context of SSL ...
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50 views

side channel attacks against TDES (compared to AES)

We all know AES has some pretty strong side channel attacks, some where (with a couple of hundred know plain- and ciphertext combinations) a key can be derived in a matter of minutes. Others may take ...
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Is a padding oracle attack possible if data is only encrypted internally on a server (e.g. for storage)?

I read something about the padding oracle attack when analysing the use of an AES-encryption of data in a database and was "scared" it could be a serious issue. But after investigating a bit further, ...
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52 views

How is the MAC or HMAC secret shared with the other party for verification?

I've seen people everywhere say to use a MAC or HMAC with block ciphers. I think I understand the basics, but I'm still not sure how the HMAC secret is distributed so the other party can verify that ...
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120 views

Multiple AES/ECB encryptions of different data with same key all end with same pattern

We have used "AES/ECB/PKCS5Padding" with a 256 bit key. We encrypt different streams of data (blockwise) with the same key. Each encrypted stream ends with same pattern. What is the reason for this?
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128 views

nonce of AES-GCM in SSL

It seems that the nonce of AES-GCM in SSL has 3 parts: salt, 4 bytes, generated in handshake, not changed in whole session nonce_explicit, 8 bytes, chosen by the sender and carried in each SSL ...
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25 views

AES-XTS: find key from ciphertext and plaintext [duplicate]

Let's say I have a plaintext, the corresponding ciphertext encrypted using AES-XTS, and the initialization vectors. Is there any way - not brute force, of course - to compute the key? Even if there's ...
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66 views

AES Mix Columns and Shift Rows

Why we use Mix Columns and Shift Rows in AES? FOr example, if i want implement an AES algorithm without Mix Columns and Shift Rows what is the difference in the ciphertext?
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102 views

What do I use as the encryption key and initialization vector in AES cfb128

I'm writing a program that can encrypt a file using AES cfb128 (using Openssl and C++). The scenario of the program is this: Person A visits computer, encrypts a file they make, takes away a key ...
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40 views

AES inversion operation in sub byes

I was wondering why in the AES sub-bytes operation one can represent the inversion as computing $x^{254}$. What is the reason for this? Moreoever, I was wondering what the text on page 212 of ...
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86 views

Affine transformation in AES: Matrix representation

I know that the affine transformation of the AES can be represented both as a polynomial evaluation over $\operatorname{GF}(2^8)$ and as a matrix-vector multiplication (see, e.g., p.212 C.4 of The ...
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Decrypt AES-encrypted data with another key

Here is a plain question, all filled with pseudo-real data :) We have a string: "hello" and two keys for AES: GoodKey and BadKey. We encrypt our string with GoodKey, and receive something like ...
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23 views

Device intercommunication with commands

I want to create a smart house project, and in that i bought some simple RF modules. Those modules don't support crypto out of the box but i want to connect them to a device that i would program to ...
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102 views

Can Poly1305-AES be used with AES-256?

I'm reading through Bernstein's The Poly1305-AES message-authentication code. The MAC is predicated on 16-byte block ciphers like AES and produces 16-byte authentication tags. However, Bernstein does ...
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AES product function

Small description: consider a polynomial in GF($2^8$) , which has the form $$f(x) = b_7x^7 + b6x^6 + b_{5}x^5 + b_4x^4 + b_3x^3 + b_2x^2 + b_1x + b_0 $$ If we multiply by x , we have $$x * f(x) = ...
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About the Security of PCBC Encryption Mode

We are designing an encrypted file system. We plan to use the PCBC (Plaintext Cipher Block Chaining) encryption mode for encryption. This is because we desire the feature ("small changes in the ...
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How dangerous is it to encrypt with AES 256 if the end user knows the unencrypted value?

I am implementing a bit of security in a system that was originally built without encryption on a specific piece of data. The plan was to encrypt this piece of data and include it as part of the ...
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31 views

Determining nonce between unsynced systems

It's my first venture into cryptography, and I'm struggling with how to use a nonce in an encryption standard between two digital radios. The two radios support AES encryption, only requiring a ...
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Requested to encrypt data with AES256, digital certification, timestamped

at my job we have been tasked by gov to encrypt some data we send to them. The "law" says we have to do the title above, but they only need us to do the AES256 thing because the data is not really ...
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133 views

Differential Fault Analysis of AES

Let's say: an error is induced into an implementation of the AES-128 to produce a faulty ciphertext. The error is a one-byte eror and is always induced on the last state byte, during round9, before ...
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129 views

decrypt a saml 2.0 response having aes 128 and rsa [closed]

I need to decrypt a saml 2.0 response. But, the response object has reference to aes 128 and rsa algorithms, and I am having hard time in finding a way to decrypt. Below is the structure of the ...
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113 views

Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?

I've asked some other questions before about Rijndael's S-boxes, and step by step I'm coming to an understanding; but those steps often guide me to new questions. I did some lines of code to ...
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83 views

Block cipher mode with diffusion on ciphertext

As I understand, diffusion property in AES-CBC ensures that one-bit change in plaintext will yield changes in all following blocks in ciphertext upon encryption. I'm looking for algorithm that will ...
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FileVault AES-XTS decryption with cipher text that's missing a part

My mac was recently upgraded to OS X Yosemite and FileVault2 full disk encryption was turned on. Encryption finished, but things went horribly wrong and key parts of the disk are filled with all 0s ...
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112 views

Repair AES-128 decrypted file

I decrypted a file which was encrypted with OpenSSL and AES-128 with the wrong password. Before I noticed it was the wrong password I removed the original file. Is there a possibility to reproduce the ...
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657 views

Encrypt-then-MAC: Do I need to authenticate the IV?

In the setting of Encrypt-then-MAC, do I need to include the IV in what I'm HMACing, or is authenticating just the AES-encrypted data sufficient?
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124 views

CTR HMAC SHA256 implementation

After trying to invent my own AES mode, I decided to just implement something that's known to work, namely CTR with HMAC SHA256. From what I understand, I can use the IV as a counter, and the IV ...
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AES-128/192 safer than AES-256 in practice? [duplicate]

Related-key attacks can break AES-192 and AES-256 with complexities 2^176 and 2^99.5, respectively. Quote from: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard It seems that more ...
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1answer
84 views

Keeping the key and IV safe when AES256 encrypting publicly known data

I am encrypting some publicly known data, and some private data using the same key, using AES256 with CBC. An attacker does not have the ability to choose what the public data is. Is this safe? (It ...
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255 views

Why is AES unbreakable?

Why is it said that AES is unbreakable? Brute force attacks would take years to crack it, so is it possible to crack it if the computational speed of machines increase in the following decade?
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AES mode scheme feedback [duplicate]

I've been studying encryption on a hobby basis, and wanted to know if I got this basic cypher construction right (this is another experiment, see the AES ECB experiment thread earlier). Encryption: ...
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82 views

AES key from encrypted text and VI

So I'm trying to figure out if it's possible to extract the private key if you have the ciphertext and the IV corresponding to that ciphertext. It's for some kind of a challenge, and can't really ...
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1answer
43 views

AES different modulo operations

I don't get the modulo 10001 operation in mixColumns so much. If I have to take the byte computations mod 100011011 anyway what leads me to a result of 4byte length, why do I need the mod 10001 ...
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232 views

AES as Integer Program

I read that AES can be broken by solving a Linear Integer Program (IP). From a given encrypted text, how can one construct this IP? How big is the system?