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Questions tagged [disk-encryption]

Disk encryption protects information by encrypting every byte that is written to a HD or virtual disk volume.

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Cascaded XTS vs XTS with cascaded block ciphers

The popular VeraCrypt encryption utility, as well as its precursor TrueCrypt, has the option to cascade multiple ciphers on top of each other, such as AES-Twofish-Serpent. It works by cascading three ...
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confusion about LUKS encryption

from Can I clone a LUKS container? You can, but it breaks security, because the cloned container has the same header and hence the same master key. You cannot change the master key on a LUKS ...
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How to determine the fastest OpenSSL cryptographic algorithm

This question does have to do with cryptography, but not necessarily with encrypting meaningful data. This is my first post here, so if I'm going about this question incorrectly please let me know. ...
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LUKS: decrypting with master-key rather than with passphrase

It's my understanding that LUKS encrypts data by using a randomly-generated master-key, which is then itself stored encrypted by my passphrase. When I want to access the data, I use my passphrase to ...
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1answer
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Using YubiKey to store a PIN-protected secret for disk encryption

I want to store a secret on YubiKey and use it for disk encryption. It's crucial that it be PIN protected. There are a limited number of PIN tries, and after three attempts the YubiKey would be ...
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Combining stream cipher with block cipher for disk encryption

You take something like chacha20 and use the disk block # to seek it, xor it with the data block and then encrypt it with a block cipher in ECB mode. Would this be secure? Edit: To avoid getting ...
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1answer
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Can wiping a disk writing zeros on an encrypted device be a weak point?

Can cryptsetup suggestion of wiping a disk before encryption with zeros written to an encryted device as described in question 2.19 as the recommended method on the CryptsetupFAQ (the part that starts ...
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Why does the Content Scrambling System have two different length LFSRs

CSS uses two LFSRs of length 17 and 25. If we have two periodic functions $f(t)$ and $g(t)$ and consider the function $h(t) = (f(t), g(t))$, then $h$ will have period $pq/\gcd(p, q)$ where $p$ and $q$...
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How can XTS be used to detect the presence of TrueCrypt hidden volumes?

According to a thread on the VeraCrypt discussion forum, and a single-post followup, it is possible to detect the presence of a hidden volume in certain conditions due to a flaw in the cryptography or ...
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Has anyone seen a stream cipher being used for FDE

So I am a newbie to this. Has anyone experimented implementing a stream cipher for full disk encryption? EDIT With the caveats that come with using a stream cipher over a block cipher of course! I ...
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XTS-AES-128 and Grover's algorithm

AES-128 is considered weak against quantum computers because Grover's algorithm effectively halves its key length to unacceptable 64 bits. XTS-AES-128 as described in IEEE 1619-2007 doubles key ...
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What are the malleability properties of block device encryption with multiple modes of operation?

When encrypting a block device with a given symmetric cipher with a 128-bit block size in CBC mode, every second plaintext block in a sector can be changed to contain arbitrary data, with the blocks ...
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Does observing amount of changes in encrypted disk ciphertext have a well-known attack name?

Let us assume that I have two partitions on my hard disk, and unencrypted one and an encrypted one. Let us also assume that I shut down the computer when sleeping or away, and an attacker has physical ...
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Why not authenticate full-disk encryption?

Common FDE software (TrueCrypt, BitLocker, dm-crypt) doesn't authenticate ciphertext stored on the disk. The commonly cited reason is "it would take too much space", reasoning that you would need an ...
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1answer
160 views

Does passphrase length impact read-write speed?

I'm using Diskcryptor to encrypt a 2TB external USB HD and the process is taking over 2 days. I chose a 100-character strong encryption key passphrase (because, why not?) and am now wondering if the ...
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1answer
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Ephemeral Encryption Keys

My understanding is, ignoring implementation details, iOS disk encryption works like this: On boot (and/or every time you unlock your phone) an ephemeral session key is created that can decrypt ...
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1answer
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Are Iphones' content encrypted?

Recently I heard that the content of an Iphone is stored in encrypted form meaning that if I were to take apart the Iphone and managed to extract the memory and read it, I wouldn't be able to get any ...
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Should I use XTS or GCM to encrypt my hard drives?

I want to start encrypting all of my hard drives, but I don't know whether to choose XTS or GCM mode. Why is it that XTS is recommended (since the most websites I visit use GCM in their HTTPS ...
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1answer
353 views

Disk encryption using AES-CBC: is reliance on previous block data a downside?

I have seen drives that boast that they use AES with CBC mode, which doesn't really make sense in my opinion, sure it's more secure than ECB (but actually, leaving security aside, ECB is better suited ...
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Can XTS + checksum be used for authenticated encryption?

Is it possible to use XTS + a checksum for authenticated encryption? Specifically, it seems like a good $n$ bit checksum applied before encryption should ensure that any change to the ciphertext will ...
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High-level overview of system architecture of LUKS/cryptsetup (how it works vs. how to setup) [closed]

I've been searching (unsuccessfully) online for a high-level overview of how LUKS/cryptsetup disk encryption works. I am reading through the cryptsetup source code to try to understand what is going ...
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1answer
2k views

Effect of ESSIV when used with XTS

I looked everywhere on the web and I did find a lot of information about full disk encryption, but nothing really answered my question. When formatting a partition to use LUKS, the two most common ...
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How does FileVault2 Recovery actually work?

I'm a crypto-enthusiast but no expert at all, that'll explain why i didn't understand. Also please consider english isn't my native language :) I am about to enable FileVault2 FDE on the new macbook ...
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1answer
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Does XTS provide random write access?

I'm trying to find a sufficient encryption mode that supports random read and write access. It seems like XTS is a perfect fit, since in my use case authentication and integrity insurance are handled ...
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Encrypt-Mix-Encrypt: Full Diffusion?

I've read "A Parallelizable Enciphering Mode" by Halevi and Rogaway about the encrypt-mix-encrypt mode for ciphers and was asking myself if this mode provides "full" diffusion. So if an attacker ...
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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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LUKS multiple key slots - what's the intuition?

LUKS volumes have the ability to allow multiple independently usable passwords, as explained here: [https://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions] The intuition behind basic ...
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Modes of encryption for hard drives?

What are the currently recommended modes of encryption for large disks? Basic requirements would seem to be that you can update an encrypted sector independently of others, which rules out most ...
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1answer
3k views

what are the security benefits of LUKS?

Aremed with only basic crypto knowledge, I'm trying to understand the security benefits of LUKS over plain-mode dm-crypt. Hopefully this is a good place to ask. Given the LUKS header contains ...
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2answers
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How do disk encryption programs solve the “IV problem”?

I was reading a paper on the "elephant diffuser" used in BitLocker and it got me wondering how other systems (e.g. TrueCrypt before it shutdown) solved the problem the elephant diffuser was meant to ...
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1answer
324 views

Galois field step in XEX mode

I'm reading through the XEX mode spec, and I want to make sure I've understood the $\alpha^j$ step correctly: $X = E_K(I) \oplus \alpha^j$ $C = E_K(M \oplus X) \oplus X$ where: $M$ is the ...
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1answer
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Why is Serpent faster than AES in this benchmark?

I have a laptop without the AES-NI CPU instructions but with SSE4.1. I'm using Linux and tried the (in-memory) cryptsetup benchmark to get the rough tendency which returned: ...
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Is there a flaw in whole disk encryption vs volume or folder encryption? [duplicate]

My company just implemented whole disk encryption on all laptops (Symantec) and the concept seems flawed. Please correct me if I'm wrong, but if I have known file in plain text and that same file in ...
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Why do we use XTS over CTR for disk encryption?

I'm taking Prof. Boneh's crypto class from Coursera, and am unsure on the requirement for XTS mode for disk encryption. It seems that CTR mode would do exactly what XTS can do, but is simpler to ...
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1answer
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How is LUKS dm-crypt secure if the key is stored with the encrypted data?

I've posted this question over at superuser, but haven't had any success at getting answers. That's why I've posted it here. Furthermore, I believe this is a more appropriate place for it as it is ...
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Is it possible to tweak AES-GCM so that it is satisfactory for whole-disk encryption (like XTS mode)?

Is it possible to leverage a preexisting implementation of AES-GCM to provide the key security benefits essential for full-disk encryption (similar to AES-XTS)? GCM is a popular encryption mode ...
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1answer
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Testing if a password for an eCryptfs mount is valid [closed]

I'm using "eCryptfs" on several directories on my dedicated Debian server. I mount them manually via mount -t ecryptfs [dir] [mountpoint] But after some weeks ...
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2answers
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What can a master password also be called?

When having a company computer that is full disk encrypted, it is common that the boss have a master password / backdoor, so the data always can be decrypted. I have heard some call this for "scrow" ...
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1answer
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How can disk encryption systems (like Truecrypt) resist frequency analysis when they allow random access?

I don't understand how disk encryption (e.g. TrueCrypt) is supposed to resist frequency analysis. If blocks can be randomly accessed (which they can), doesn't that mean that frequency-domain ...
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Information leakage from the ecryptfs filesystem

I'm wondering what information might be leaked from the ecryptfs filesystem. This is what Ubuntu uses if you check the box for "encrypted home directory" when using the desktop installer, so is ...