Questions tagged [aes-gcm]
Deprecated tag, see tag info. Advanced Encryption Standard Galois/Counter Mode, better known as AES-GCM is a mode of operation for symmetric key cryptographic block ciphers that has been widely adopted because of its efficiency and performance. GCM supports authenticated encryption, meaning that the mode not only offers privacy, but also integrity.
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Why was AES CBC removed in TLS 1.3?
I don't quite understand why AES CBC was removed in TLS1.3.
From what I know CBC is the most secure Mode of operation for the AES block cipher (if you can say it like that).
It only needs a TRND IV ...
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Can AES-GCM be broken if initialisation vector is known?
We are using AES encryption in GCM block mode in order to encrypt a number of different kinds of data at rest on a mobile device - Android.
The key used for encryption is stored in the protected key-...
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how does BearSSL's GCM modular reduction work?
BearSSL (in src/hash/ghash_ctmul.c) seems to be doing a modular reduction that I don't completely understand. Here's the code:
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What are the rules for using AES-GCM correctly?
When using AES-GCM I know that I am supposed to use a new initialization vector every time I call the AES-GCM algorithm with the same key. What are other rules must be followed to use AES-GCM ...
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Can a zero nonce be safely used with AES-GCM if the key is random and never used again?
I could generate a random nonce and prepend it to the ciphertext, but storage space is at a premium and the only constraint AES-GCM has on the nonce (if I'm reading correctly) is that the same nonce ...
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IV in Galois Counter Mode
I am looking at Wikepedia Galois Counter Mode article. I see this diagram
I am trying to figure out where the IV works its way in. Is it used to initialize the counter? If so, how does a sequence of ...
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TLS 1.2 Cipher Suites With AES-GCM – What data (if any) is passed to the AES-GCM cipher as the Additional Authentication Data?
TLS 1.2 defines a number of cipher suites that employ AES-GCM, e.g.:
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Key size, performance, and security tradeoffs for AES GCM / CCM
AES can be used with 128, 192 or 256 bit keys and each one appears to have a performance vs security trade-off (What is the effect of the different AES key lengths?, What are the practical differences ...
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GCM with reversed poly
These slides talk about how GCM can be sped up if one uses $x^{128}+x^{127}+x^{126}+x^{121}+1$ as the reduction polynomial instead of $x^{128}+x^7+x^2+x^1+1$.
When one is doing that one needs to ...
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What are the popular modes-of-operation (AES-GCM, AES-SIV, AES-GCM-SIV, etc.) geared for?
I'm interested in developing software capable of encrypting personal files (which will ultimately be backed up to the cloud) and have been doing my best to follow best practices.
There are many forms ...
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Deterministic Encryption with AES GCM - how to choose the IV (nonce)
I have not a very large background in cryptography so I hope these questions are not very dumb. I don't want to reinvent the wheel, I'm just looking for advise on the best practices about how to build ...
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Delayed tag checks in AES-GCM for streaming data
There is currently a GitHub discussion on .NET not supporting AES-GCM for any streaming data since releasing decrypted data prior to tag checks somehow reveals the plaintext or the AES key (or some ...
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How to encrypt files using AES256-GCM cipher under Linux? [closed]
I'm struggling to implement AES256-GCM on a Linux machine to encrypt files outgoing to another party.
We're usually exchanging files using PKI, but this particular party insists on AES256-GCM and ...
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What is Associated Data in AEAD?
I am trying to understand what is AEAD exactly. I am application developer not a cryptographer. I have been searching online for a while watched a bunch of Youtube videos, read through a couple of ...
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Why GCM operation mode with AES-128 is recomended and can we use AES-192 and AES-256 with GCM?
It happens that on the internet I often find that AES encryption should use a 128-bit key only if it is used in conjunction with the GCM mode of operation.
Why only with 128-bit keys?
What happens ...
user75600
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Apple secure notes. How secure?
In terms of cryptography, how secure is Apple Secure Notes? Can one store sensitive information there? The relevant section of the Apple white paper is quoted below:
The Notes app includes a Secure ...
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Is this a typo/error in the Galois/Counter mode specification or have I misunderstood?
I've been reading the following document describing Galois Counter Mode:
The Galois/Counter Mode of Operation
On page 7 of the document, the following diagram describes the ...
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What are the actual merits of Galois/Counter Mode?
GCM (Galois/Counter Mode), in particular in combination with AES, has been a de-facto gold standard for years. Encrypt and authenticate in one step, that's just too awesome, and terms like AEAD work ...
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Why doesn't GMAC/GCM encrypt its authentication tag?
As most know, a duplicate nonce with GMAC/GCM allows key recovery attacks against GMAC itself and thus the ability to forge messages. This is because GMAC computes GHASH and then just XORs this with ...
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How is NIST's Key Wrap (using AES GCM) different than normal AES GCM Authenticated encryption?
From what I could gather, it seems like that NIST's key wrap (publication) provides similar security like AES-GCM Authenticated encryption. If this is true, why did we need a separate specification ...
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The Rationale behind NIST's counter/LFSR recommendation on deterministic IV constructions on SP 800-38D
The NIST has a "SP 800-38D: Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC". This guideline is a base for AES-GCM from definition to security ...
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OpenSSL AES-GCM says 'bad decrypt', other block modes work fine?
If I do a simple encrypt and decrypt test like so:
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Is a stream cipher and a (cryptographically secure) PRNG nearly the same thing?
If I let the authentification tag aside (which is important), encrypting with AES-GCM and a fixed key and nonce:
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Is it possible to recover AES-GCM plaintext when having everything but the additional data?
I'm using the window.crypto library in browsers.
I use iv from window.crypto.getRandomValues...
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Real time video stream AES encryption with authentication
I am now studying AES encryption for real-time video streaming. It seems that Netflix uses the AES-GCM (or CBC + MAC) mode for real-time video encryption and authentication. With MAC authentication, ...
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AES-GCM conformance test
Is there any conformance tests/sequences to validate AES-GCM & GHASH() implementation?
Details: I'm implementing AES-GSM, that's just for better understanding of that stuff, nothing more. Well I ...
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Proper way of encrypting large files with AES-256-GCM
I would like to encrypt and decrypt files with AES-256-GCM. I need a solution that works with Java, PHP and JavaScript. In practice, users can upload, download files via web browser and/or desktop app ...
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Is GCM with zero-length AAD less secure?
In a previous question, it was made clear that in the case of GCM, there is no distinction between "no AAD" and "zero-length AAD". Since I have noticed "zero-length AAD" ...
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Patent Status & Usability of AE Modes [closed]
Post Structure:
Sources Cited
Question & Details
Before You Answer
Useful Info From Comments
Sources Cited:
https://blog.cryptographyengineering.com/2012/05/19/how-to-choose-authenticated-...
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What if an AES GCM nonce overflows and collides with the GHASH nonce (0^128)?
When using AES in GCM mode, the GHASH function uses E(0^128) as the initial value for H, the authentication key. The IV, for the underlaying CTR mode, is initialized with:
[prefix (application nonce)]...
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Is AES-GCM with static key and dynamic salt safe to reuse IV/nonce
Problem: want to encrypt messages/objects/files using AES-GCM with the same secret key in a safe way, but want to do it in distributed/stateless way, so the IV of previous encryptions with the same ...
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Extending AES-GCM initialization vector
We all know that applications of crypto primitives like to not think about the management of nonces, and initialization vectors and often prefer to just set them to random values. This sometimes leads ...
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Size of IV in AES-GCM according to RFC 4106
RFC 4106 specifies about nonce. It contains a salt of size 4 octets and an iv of size 8 octets. Further, RFC specifies that salt is assigned at the beginning of the security associations which is ...
farooq
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GCM-SIV vs CBC with fixed IV?
I keep hearing CBC with fixed IV mode is bad because it has similar issues to the codebook breakdown of ECB mode. However, people seem quite willing to recommend AES-GCM-SIV for deterministic ...
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Plain text size limits for AES-GCM mode at 2GB with Sun JCE implementation?
The Sun JCE implementation of GCM is hard coded to refuse to encode more than 2 Gb, through the function GaloisCounterMode.checkDataLength() that returns an error message : "SunJCE provider only ...
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AES-GCM secure against IND-CCA2
How would you prove that AES-GCM is secure against a chosen ciphertext attack (IND-CCA2), assuming that the attacker cannot forge AES-GCM MAC tags in less than brute force?
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AES 128 GCM - dynamic key with static IV/nonce
I'm working on a project to upgrade an existing system that currently uses RC4 to encrypt a payload with a random session key. The session key is then encrypted with asymmetric public key encryption (...
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What kind of hashing is GF multiplication in GCM cipher mode and GMAC?
In GCM, GMAC, the additional associated data (AAD) (as well as outputs of subsequent blocks) is multiplied by a polynomial H in GF(2^128). This appears to be doing some secure hashing.
Is that what's ...
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Why can't AES-GCM be used in IKEv1 phase 1?
I was configuring a VPN on a firewall (fortigate) and realized that I could use AES-GCM for encryption in the IKEv1 phase 2 but not in the phase 1 and I was wondering why knowing that in IKEv2 we ...
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Is a single md5 hash a good way to generate an AES key?
This site says how to encrypt data using a password in go using AES-GCM.
It says the following:
When encrypting and decrypting data, it is important that you are using a 32 character, or 32 byte key. ...
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Key generation for AES-GCM-256 file encryption
I am currently working on a file encryption software that works via AES-GCM-256 and I am looking for feedback on the encryption key generation process I intend to implement.
So far, I have come up ...
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AES - which cipher is the safest one out there and what are the best practices for creating and storing the key
I just started to learn cryptography. I've read a ton of articles but couldn't find a book or a course that is based on this subject (and also is not outdated).
Therefore I have a few questions (...
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AES-GCM with different IVs but close enough for counter to cause duplicates
I am planning to use AES-GCM or AES-CTR for encryption. However, I have read from several sources that the IVs must be unique for every piece of information encrypted. I have a doubt though, what if I ...
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Key Committing AES-GCM
There is a handful of attacks against AEAD, and GCM in particular, which demonstrates that it is feasible for an attacker $\mathcal{A}$ to obtain a ciphertext $C$ which encrypts to multiple key/...
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Can the AES-GCM authentication tag be used as a key derivation function?
I want to build a deterministic key derivation tree, where the root is stored securely in a centralized service and the leaves are embedded in a multitude of devices. When a device wants to ...
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Factorization of polynomial in GF(2^128) used in GCM
It is widely known, that using a GCM nonce twice or even more often can be used to disclose the authentication key H. I understand, why this is theoretically possible. However, I have no feeling about ...
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Why is counter mode encryption with a 16-byte cipher block not broken?
We determine a system IND-CPA secure when an adversary has a negligible advantage after any feasible amount of queries.
AES256-GCM uses a 128bit block cipher.
We know that the distinguishability ...
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Using keys as Additional Authentication Data in GCM
In my opinion, it's not a good idea to use (symmetric/asymmetric) keys as Additional Authentication Data (AAD) in GCM as AAD is only authenticated but not encrypted. The key will be protected from ...
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Is it safe to use a counter as IV for AES256-GCM
What if I will use 96-bit integer counter starting from 0 as IV for AES256-GCM cipher. Is it safe? Is there any other ways to ensure uniqueness of IV for GCM cipher?
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How is the time intereval calculated for symmetric key re-negoatition in UK Security Standard – Use of Cryptography?
According to point 10.6.4 (Encryption in Transit) in Security Standard –Use of Cryptography, one of the criteria for key renegotiation is timeout ,
Encrypted sessions MUST re-negotiate new symmetric ...
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