Tagged Questions

Encryption is the process of transforming plaintext using a cipher to make it unreadable to anyone except those possessing the key.

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50 views

Is it safe to use private key encryption for lots of small blocks of data themselves?

I currently handle small JSONs of sensitive information which are guaranteed to be smaller than 100 bytes. You can encrypt up to ~500 bytes with a 4096 RSA key. Is it safe/secure to store these ...
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61 views

How negative are virtual machines (vms) to /dev/urandom?

I looked at the questions here and here. This then piqued my interest as I've recently been involved with looking into FIPS compliance, and in my vm environment /dev/urandom compliance testing ...
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1answer
50 views

Is Lock-a-Folder a secure and reliable way to encrypt information?

What are the properties of Lock-a-folder? does it create plain-text temporary files anywhere? (e.g. ntfs artifacts, etc) does it allow running a program from the folder as if it was a normal folder? ...
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1answer
51 views

Decrypt signature file based on plaintext

I have 2 text files used by an application. One is a very large "schema" array (approaching 100,000 lines, JSON format). The other is a .txt.sig file generated somehow from the contents of the schema ...
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1answer
66 views

Hardware Implementation of Encryption Algorithm

In the abstract of the AES-GCM RFC, the following passage is prominently included: [AES-GCM] can be efficiently implemented in hardware for speeds of 10 gigabits per second and above... Is the ...
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1answer
74 views

Can Cipher Suites defined in TLSv1.2 be negotiated by clients that only support TLSv1.0?

If my server has only the cipher suites enabled which are defined by TLSv1.2 does that force a client to also use TLSv1.2 or else not be able to connect or can the connection fallback to TLSv1.1 or ...
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2answers
35 views

PKI expired and renewed, do my correspondents have to do anything?

My PKI certificate (Digital ID for email from Symantec, issuer is "VeriSign Client External Certification Authority - G3") expired after 1 year and so I have renewed it. Do the people I correspond ...
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1answer
87 views

Hardware encrypted external HDDs

I'm planning to buy an external HDD with hardware encryption, namingly the WD My Passport Ultra 2TB. On the WD website the information about the encryption is sadly scarce so I'm asking here. How ...
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0answers
59 views

Database row level encryption scheme

I am wanting to secure some highly sensitive data in a database. This would mean that the data needs to be encrypted and remain secure for 100 years if it were to fall into adversary hands. I also ...
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2answers
840 views

Why is VeraCrypt more secure than TrueCrypt?

TrueCrypt retired with a mysterious "Using TrueCrypt is not secure as it may contain unfixed security issues" (source) Yesterday Slashdot reported VeraCrypt as a better replacement (source) since it ...
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23 views

Can Diffie-Hellman be scaled up or force-multiplied? [migrated]

I'm not too familiar with the math involved with the exchange of keys, I've read it over several times, but math isn't my strong point. My understanding is that smart people are hard at work to ...
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4answers
726 views

Why the symmetric key is added to the message?

Yesterday in my class we learnt how to send a message from Alice to Bob with the achieved goals of confidentiality, integrity and authenticity. In order to have a better performance we use a hybrid ...
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0answers
46 views

Is an anonymity network like Tor viable on top of the GPG web of trust?

The web of trust is a graph where the vertices are GPG users (actually, their keys) and the edges are cross-signatures. If we put issues of owner trust aside and assume that all participants only sign ...
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21 views

Protect file with digital signature that can be verified using public key

Sorry if the answer is obvious, I am really new to this stuff. I need protect a file from changing using public-key cryptography. The file should look like this: Filecontent ...
1
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1answer
55 views

is this data encryption scheme viable?

My goal is to be able to encrypt the data so that no one would be able to make use of it if it was stolen. User data - the one that will be encrypted - can be any type of data Data encryption key - ...
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1answer
27 views

Difference between sshv1 and 1.5?

I've been searching for the answer to this but haven't had much luck. What is the difference between SSH version 1 and 1.5? Is 1.5 a release of 1? As in 1.2, 1.3, 1.4, 1.5? Are there any ...
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0answers
39 views

Linux, TRESOR and XTS

I want to switch from using LUKS for full disk encryption to TRESOR. TRESOR tries to prevent cold boot attacks by storing the encryption key in the CPU's registers. It uses the kernel's crypto API for ...
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1answer
42 views

Flawed understanding of SQL Server Transparent Data Encryption (TDE)

We host a database for one of our applications on Microsoft SQL Azure. One of our clients was dissatisfied with the fact that TDE is not supported on SQL Azure (and the database is otherwise not ...
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2answers
126 views

Encrypt with private and decrypt with public

Above picture is captured from iOS Security overview at page 25. The path encrypt with public and decrypt with private makes sense. But the other path, encrypt with private and decrypt with public ...
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3answers
32 views

Do passphrases need to be run through PBKDF2? Almost impossible to brute force?

Passphrases normally contain more data then passwords and can provide more entropy. It seems like it would still be hard to brute force a passphrase w/o using PBKDF2, assuming a user didn't select a ...
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2answers
113 views

Would it be possible to create a zero knowledge social network?

I understand the concept behind a zero knowledge web application where only the user has access to their data. What about a social network where some circles of user have access to that data? Is it ...
3
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0answers
16 views

Serpent 256bit key wrong round keys [migrated]

Assume that we have this 256bit key: 15FC0D48 D7F8199C BE399183 4D96F327 10000000 00000000 00000000 On first 0-7 keys we can't apply formula wi=(wi-8 xor wi-5 xor wi-3 xor wi-1 xor phi xor ...
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1answer
130 views

Two takes on PHP two way encryption - which one is preferable?

I need to encrypt some data and have it decrypted on a later point in time. The data is tied to specific users. I've gathered two possible solutions... 1: The first one is derived from the official ...
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1answer
53 views

Problem with common factor in RSA [duplicate]

In the RSA key generation steps, what if two entities select a common factor to generate n (i.e. p*q1=n1 and p*q2=n2) resulting in gcd(n1,n2) <> 1 ? This will lead to a problem that everyone ...
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1answer
93 views

Secure Boot on Microsoft Surface Pro 3 (or modern PCs)?

Got a Surface Pro 3 today (it's awesome BTW!) and noticed in it's EFI that it's got TPM enabled, "Secure Boot" enabled (unsure what such an umbrella/catch all term actually covers) And then in ...
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1answer
44 views

Is it safe to store important data in an encrypted access token?

Is it safe to store important data in an encrypted access token? For example, instead of storing access tokens in a database, not storing them at all and putting their associated data into them before ...
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1answer
40 views

Securing an OAuth / OpenID Connect identity in a cookie for easy login

I have a website that uses Azure Active Directory or Google+ for logging in. I go through an OAuth2 login flow, and the users email along with their tokens are returned to me by their identity ...
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2answers
92 views

PCI Compliance - Encrypted Mobile Apps

My company (health care) went through a PCI audit and needs to solve some major issues. Our branches collect CHD on paper and saves them to a network drive as a pdf that our corp office accesses to ...
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2answers
135 views

With RSA, can one ensure that two entities will not have the same private key?

With the RSA encryption algorithm, is there any guarantee that two different entities will not be given the same private keys?
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0answers
19 views

FEAL-4 Fk Function 4 Rounds [migrated]

As I understood in FEAL-4 it needs 4 pair of round keys. Which means that we need to launch Fk function 4 times, but the problem occures on the 2nd round. At first round we have original 64 bits key ...
2
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2answers
79 views

Securing commands

For a project I'm working on, I need to securely send commands between servers. These commands should not be able to be altered, and there should be some security about not being able to just keep ...
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3answers
119 views

Can you have Secure encryption with a backdoor, and still be secure?

Is it possible to have an encryption algorithm/implementation that has a "backdoor", that also wouldn't introduce flaws into the encryption? For instance, if you have a master password, once that ...
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3answers
63 views

Can AES encryption prevent modifying bits in a wireless protocol?

I'm building an application with NFC which is a wireless communication protocol. An attacker can modify bits in a wireless communication protocol. I want to prevent this. I know we can't prevent an ...
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2answers
83 views

Key Size vs. Block Size: In Practice

I've seen a lot of confusion between encryption key size and block size. I feel like I completely understand the difference between the two, no need to explain what they are. But it's when put in ...
1
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1answer
103 views

Secure backup on online Cloudstorage

i own a small private server (@home) with all necessary features for my backup purposes (Owncloud, SVN, GIT). My target now is to ensure the safety of my data in emergency cases like fire/flood. For ...
0
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1answer
91 views

Improving stateless REST API authentication token - or ditch it for database persistence?

I'm looking to implement stateless REST authentication into an API. I've been reading up on articles here, and have implemented an idea that works, but I was hoping to get some feedback on its ...
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0answers
39 views

Serpent Cipher 128bits (Example rounds on any plaintext/key) [migrated]

Is there are any possibility to see trace(example) of Serpent Encryption/Decryption on concrete plaintext/key example, (not code implementation) or at least animation of steps. During reading of ...
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0answers
85 views

Encrypt in C# program, Decrypt in android application By RSA Keys

I used RSA Encryption for sending message between Server and client. The server program implemented by C# and the Client is an android application. I want to know is it possible a message that ...
2
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1answer
73 views

The most trusted hard problem [closed]

Is there a mathematical formalism to rank the hardness of the hard problems? In particular I am referring to the sort of hard problems that are typically used in cypher system; such as factorization ...
0
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1answer
136 views

How strong is PDF security/encryption?

I want to securely convey a PDF document containing sensitive information from my system to another system. The latter is operated by a different person, whom I trust. However, this person does not ...
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0answers
57 views

Is it possible to encrypt Word Docs with something other than default?

AES 128-bit advanced encryption is fairly simple to break and was wondering if there was any way to use a more secure one? And if so - any suggestions?
2
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1answer
136 views

Is knowing the decrypted and encrypted data enough to find the key?

Let's say an attacker knows the encrypted content, the decrypted content and the algorithm used: can he get the key that was used to encrypt the content or does it make it easier to find the key out? ...
2
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2answers
77 views

Anonymiszing sensitive data in MySQL DB while retaining searchability

I have a MySQL database that stores sensitive (personal) data about individuals; and have been tasked with ensuring that this data is encrypted in some way to protect the individuals and their data if ...
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votes
1answer
78 views

I want to encrypt content on USB or SD Card [closed]

I want to encrypt the content on a USB or SD card that can only be decrypted by an app installed on any device or TV. When the USB is not connected to that particular app, it should not be accessible. ...
0
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1answer
77 views

Protection of Private Keys

I've used mail encryption products like Mailvelope in the past, where you have to create a key pair to encrypt/decrypt data. I understand you have to hand out the public key to others that want to ...
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0answers
50 views

NaCL: Encrypt file to multiple recipients

I am trying to understand the Networking And Cryptography Library (NaCL). Consider i have a file that i want to send to multiple recipients. PGP or S/MIME supports multiple recipients by encrypting ...
1
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1answer
40 views

How can I hide proprietary elements of test data in tests that are automatically run?

I am writing automated tests for a web application that will be run periodically over night, and I am running into a moderate security issue. In order to make the tests thorough, I am hoping to ...
1
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1answer
65 views

Mapping of plaintext and ciphertext in DES

The plain text and the cipher text have a one to one mapping. Given a pair of those, can there be multiple keys used to generate the same pair? Or can a particular plain text - cipher text mapping be ...
1
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1answer
97 views

Chat encryption system avoiding protocol sniffing and then key+decryption replay?

I'm working on a chat system and I want to add it some kind of security (not just HTTPS with SSL since I've read it can be sniffed and decrypted with a few tools). Now, my knowledge in cryptography is ...
0
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1answer
92 views

How to decode/decrypt strings of text [closed]

So I'm trying to decrypt/decode some text strings. I don't believe they're hashes because they vary in length too much and the software they are used for is able to easily decode them and display them ...