Questions tagged [gcm]

The Galois Counter Mode, an authenticated encryption mode of operation for a block cipher.

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Why does the Signal protocol use AES/CBC instead of AES/GCM?

AES/GCM has obviously proved itself to be better than AES/CBC. Unless the key is re-used with the same initialization vector (see disadvantages of GCM). More information on its advantages against CBC ...
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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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Are there any test vectors for the CMS content type AuthEnvelopedData (for AES-GCM)?

I am looking for CMS AuthEnvelopedData test vectors for AES-GCM mode. I haven’t seen any ready-to-use test vectors for it. There are test vectors for AES-GCM mode but not for its CMS support. I even ...
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How does GHASH used in GCM behave as a universal hashing function?

As per my understanding, a Universal Hash Function isn't a cryptographic hash function & it's output isn't uniformly distributed. However, this is still secure because it's actually a family of ...
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Is AES-GCM-SIV with fixed IV deterministic authenticated encryption?

Is there any functional or strong security difference beyond speed between AES-GCM-SIV with implicit fixed public IV and no additional data AES-CTR (or AES-OFB) with 128-bit IV computed per HMAC-SHA-...
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How to break GCM that uses the same IV

I have an implementation that natively uses the same IV (12 bytes of 0) for all encryption. The key is always a 32 byte SHA-512 hash. I know via this post that I ...
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Can GCM auth be bitsliced?

Is it possible to use bitslicing for GCM? This seems like a way to allow for a way to avoid cache-timing attacks without PCLMUL instructions and with good performance.
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Does the size of data to be encrypted influence the security of Gmac?

In this link: Has GMAC mode a future outside GCM?, the last comment given by the user Demi, indicates that the larger the size of the text to be encrypted, the lower the security of the gmac. Why is ...
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Conforming to best practices in password file (keyring) encryption

In order to implement a plaintext password file safe (keyring), while adhering to best Crypto practices today, I came up with this scheme: A user's master password is hashed with Argon2 (\$argon2id\$...
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Is OCB the state of the art in authenticated encryption modes of operation for block ciphers?

OCB mode seems to represent the state of the art in authenticated encryption modes, largely due to its speed – it is faster than GCM even when GCM has hardware support. Its only drawbacks seem ...
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Defending hybrid encryption schemes against padding oracle attacks

I intend to use a generic integrated/hybrid encryption scheme for transmitting information between a client and a server. Key encapsulation: a 128-bit symmetric key is generated and asymmetrically ...
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AES-GCM - what are “Payload Length” and “AAD Length”

For the AES-GCM mode within many cryptomodules, their FIPS-validation certificates list the options: Payload Length: 504, 512, 1016, 1024 AAD Length: 0, 504, 512, 1016, 1024 For example in OpenSSL, "...
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Authenticating a range of a ciphertext

I have some data that I CTR-AES-256 encrypt already. I am aware of ways to validate the integrity of the entire file (ie: a separate MAC of the plaintext, or encrypt then MAC, etc). But none of ...
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AES-GCM Hash sub key parameter in Intel's IPsec library

I am trying to use Intel's optimized AES-128-GCM implementation (from the Intel white paper “Fast Multi-buffer IPsec Implementations on Intel Architecture Processors”, you can find the code here). ...
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Is this a reasonable design for encrypting records in a key/value database?

A while back I designed a protocol for en encrypted key/value service. My main goal was to minimize the value of a breached database by using cryptographic algorithms where a brute-force cracking ...
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Authenticating and encrypting data for an automated system

I wish to distribute a file from A to an automated system B. The requirements are: Contents are encrypted Contents are tamper proof Contents origin is verified To do this I have devised the ...
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GCM Create M tables and R

I am trying to optimize GCM multiplication. This PDF explains GCM: The Galois/Counter Mode of Operation (GCM) The algorithms are in section 4.1 In algorithm 3 I have to multiply table M [128] ...
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Can I use aes-gcm to authenticate a user based on his ability to decrypt a payload?

I'd like to authenticate my users without storing their password, even in a derived form with scrypt/pbkdf or other derivation methods. I'm exploring the idea of encrypting a random payload with AES ...
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Generating the Backup Exec AES-256 GCM key used to encrypt/decrypt LTO5 tape drive data

I've got an LTO5 tape that was backed up using Backup Exec (BE), which used hardware compression when writing to the tape. I've been given the passphrase that BE used to create the actual encryption ...
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327 views

Can I Achieve Deterministic Encryption Using AES-GCM with Nonce = HMAC [ message ]

I would like to implement a deterministic encryption scheme within .NET. From the following post it is established using AES-SIV mode is appropriate. As AES-SIV mode is not implemented within the ...
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Using OpenSSL to emulate LTO 4 tape encryption

I have a mix of LTO 4 and LTO 3 tapes I would like to encrypt data on to. LTO 4 has built in encryption - load they key into the drive, and it handles the AES-256-GCM encyption transparently. LTO 3 ...
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Is there a reduction of security if I XOR Pkcs5S2 and SecureRandom?

I'm using this codereview sample to encrypt data. I would like to provide hardware protected encryption and a user password as the key. Is it acceptable to XOR the KDF Pkcs5S2 in Bouncy Castle with a ...