Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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69 views

How secure is Wire?

I have stumbled upon this replacement for Skype, which claims to take privacy seriously. They recently open-sourced their client-side code. Is Wire secure? What data can be intersected and read by a ...
0
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2answers
86 views

Encryption - RSA vs. AES

I have a question regarding encryption and whether to use symmetric or asymmetric encryption. The idea is to implement a form of data encryption in a variety of software. This data will be exchanged ...
2
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3answers
58 views

Does a certificate authority use different private keys?

I was wondering whether a CA has different private keys to sign certificates with? Is there a risk of crypto-analysis (or something similar) when a CA signs thousands of certificates with the same ...
2
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1answer
346 views

Bypass SSL Certificate Pinning using SSL Vulnerablilities

I am wondering if it could be possible to sort of "bypass" the certificate pinning protection of Android or iOS using for example the POODLE SSL vulnerability. According to this blog Entry it is ...
3
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4answers
2k views

SSH: reusing public keys and known-man-in-the-middle

Usually, people recommend to use a single private-public key pair everywhere (if we're not talking about a possibility of compromising the private key): Best Practice: “One per-user ssh key” or “...
2
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2answers
158 views

number of ciphertext-plaintext pairs needed in double encryption

So I know in single encryption you would simply require at least 1 pair of plaintext-ciphertext, to carry out an exhaustive key search; you continue trying different keys until one is found that ...
1
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1answer
15 views

HPET effects on CSPRNG for Linux OS

HPET or High Precision Event Timer is a hardware built-in clock source available in most processors. I would use the computer to generate CSPRNG and do cryptographic operations. My question is: Is ...
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4answers
125 views

Which cryptographic algorithm should be used on client side to encrypt file before uploading to a cloud which is only for storing purpose?

I want to develop a website which will take the files from my computer encrypt it with my key and upload it on cloud which is only for storage purpose and decrypt it after downloading it on my ...
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1answer
57 views

Do current eCommerce systems provide sufficient security? [closed]

eCommerce systems are increasingly gaining importance in modern digital markets. Since most electronic transactions occur on a range of platforms, securing e-commerce transactions using Mobile Agents ...
2
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2answers
91 views

TLS Version specific cipher suites

I have come across that GCM, CCM, SHA-256 and SHA-384 Cipher suites are TLS 1.2 only. So TLS handshake can not be performed with lower TLS version using these suites. I am trying to figure out ...
3
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1answer
78 views

Recommended Crypto Security Setup (Implemented Algorithms)?

Firstly I'm not a crypto expert, however I know how to use algorithms that other people have defined before in practical usages, that is, as long as they live up to their promises. The thing is that ...
3
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2answers
98 views

Does a hash of a 32-bit integer make a better hash salt than the integer itself?

I have a scenario where I already have a table of resource passwords stored as unsalted 128-bit hashes. I'm unable to force owners to provide new passwords, so I'm trying to mitigate the situation by ...
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0answers
265 views

Reverse the encryption (part of the Labyrnith ctf challenge) [closed]

So my friend and I were trying to do this ctf challenge here http://labyrenth.com/ and when we were trying to solve the first part of the "Threat" challenges we stumbled upon a challenge we have no ...
51
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4answers
25k views

What is the use of a client nonce?

After reading Part I of Ross Anderson's book, Security Engineering, and clarifying some topics on Wikipedia, I came across the idea of Client Nonce (cnonce). Ross never mentions it in his book and I'm ...
0
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1answer
58 views

X509 / SSL certificates in practise

After learning the theory behind cryptography I'm having quite some problems understanding how SSL or X509 certificates works in practise and I simply cannot find useful information in the internet. ...
1
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2answers
918 views

Is SSH secure and what are the recommended modes of operation?

Given the recent confirmation of weakened and broken encryption schemes and implementations, how does the community feel about the security of SSH? It seems there has been very little discussion ...
80
votes
3answers
20k views

Amount of simple operations that is safely out of reach for all humanity?

Cryptographic primitives usually assert some security level given as number of operations to mount an attack. Hash functions, for example, give different security levels for collision attacks, ...
118
votes
8answers
23k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
10
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3answers
3k views

Suitable cipher for SMS encryption

I would like to create application for encrypting SMS messages. After long enough discussions I decided to use symmetric encryption, since handling public/private keys issue is too difficult for most ...
67
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5answers
20k views

Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for both)....
14
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5answers
12k views

What SSL key should I make for IIS: RSA or DH? What bit length is appropriate?

I'm creating an SSL cert for my IIS server and need to know when I should choose the Microsoft RSA SChannel Cryptographic Provider or the Microsoft DH SChannel Cryptographic Provider. Question 1 Why ...
1
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2answers
53 views

Why are primes reused in Diffie-Hellman key exchanges?

Reading about the Logjam attack, I learned that Diffie-Hellman exchanges often* rely on the same particular 1024-bit key. I understand that back when DH was invented, even 512-bit keys were considered ...
8
votes
3answers
608 views

How secure is HTTPS with weak ciphersuites?

Today I came across the website https://mtgox.com/, which claimed to be secure because of the Verisign certificate. I checked the certificate out of curiosity (it's the first thing they claim, let's ...
2
votes
1answer
172 views

How to enable ECDHE in openjdk-1.8.0 in CentOS 6.7?

I have seen many posts that hinted ECDHE is available in the SunEC provider way back in openjdk-1.6.0. My environment: CentOS 6.7 with openjdk 1.8.0.71-1.b15.el6_7. No ECDHE. Made 2 changes in jre/...
1
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4answers
107 views

What exactly is a key in cryptography?

After researching and reading I am not sure if I completely understand it. To my knowledge, a key is a password used to decrypt a message. However, the confusion comes in when it comes to the public ...
2
votes
2answers
187 views

Cloning problem of VM license keys

How do software companies ensure that their product or app can only run in a given number of bare-metal or VM instances? I'm curious about the cryptography behind the scenes. What prevents a user from ...
49
votes
9answers
6k views

Why is HTTPS not the default protocol?

Why is HTTP still commonly used, instead what I would believe much more secure HTTPS?
1
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2answers
83 views

Is is possible to shuffle an AES ciphertext without owning the key for it?

I would like to know if it is mathematically feasible to change an AES(CBC) ciphertext and IV without owning the key, so that the ciphertext would look totally different while still decrypting to the ...
2
votes
1answer
59 views

ECC for future IoT devices?

Elliptic Curve Cryptography(ECC) is one of the powerful cryptographic methods that requires less computational effort. IoT requires a cryptosystem that secures smart services and applications (5As i....
6
votes
2answers
710 views

Requiring 2 keys to access a content

I need to use an external service that can only be accessed by password. I don't like the idea of storing the plaintext password on the server, but AFAIK there's not much I can do. Considering this ...
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0answers
34 views

which type of encryption is RWJKeLBJTBfDc? [duplicate]

which type of encryption is RWJKeLBJTBfDc ? and how can you detect it
4
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1answer
109 views

ProtonMail: Would it not be much better if each user had their own private key?

ProtonMail keeps the encrypted private keys of all their users in their servers. The mailbox password for each user decrypts this private key, which is known only to that user. Would it not actually ...
23
votes
4answers
4k views

What are the chances to generate the same ssh key?

I could generate ssh keys on the client like (without password): ssh-keygen -b 8192 -t rsa -f /home/THEUSER/.ssh/id_rsa -P '' -v and copy the generated id_rsa.pub to the server: ssh-copy-id -i /...
2
votes
1answer
123 views

Can an attacker make in-app-purchases of my products in their app?

My iOS app needs to store a pre-shared secret. It cannot embedded within the App Bundle itself because it could be extracted by statically analysing the bundle. Apple's In-App-Purchase system allows ...
29
votes
4answers
2k views

How to encrypt in PHP, properly?

How do I encrypt data in PHP, properly, using symmetric-key encryption? I have a message M and a secret S. I'm looking for a solution that uses cryptography properly without making any of the usual ...
4
votes
0answers
30 views

UEFI Firmware integrity measurement

we know that UEFI measures the OS bootloader image integrity every time we power on our computer, if Secure Boot enabled. With the growing attacks and discoveries of UEFI vulnerabilities, the ...
2
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0answers
38 views

How do (broadcast-only/passive) RFID licence plates assert their identity?

I would have guessed by some kind of challenge-response, but there seem to be many claims of 'passive' or 'broadcast-only' tags in the plates. For example from http://www.e-plate.com/security.html: ...
9
votes
3answers
110 views

Where to find current information on cipher suite strength?

I am hardening the configuration for my /etc/ssh/sshd_config and have a few choices for Ciphers: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,...
0
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0answers
34 views

Is it safe to combine System.Random with cryptographically secure pseudo-random number generators? [migrated]

Have a look at the following codesample written in C#: private static byte[] GetRandomBytes(int size) { byte[] buff = new byte[size]; // Create an array of crypto-secure random numbers ...
1
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1answer
819 views

Prevent CryptoLocker on Server

Are there any ways to prevent files associated with CryptoLocker, to be propagated to a data server, by means of a back up? We use Cobian as our backup system, and it backs up the user's directory to ...
12
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3answers
7k views

Please help verify my understanding of Domain Validation (DV) SSL Certificate

This is what I understand so far from reading various knowledge bases and articles about DV SSL. Can anyone please help clarify if any of these is wrong? DV SSL (and SSL certificate in general) is ...
2
votes
1answer
241 views

Encrypting data before sending to SaaS tool and decrypting on browser view

I'd like to send data to a SaaS tool, where the data is stored in the cloud. I'll use Google Analytics as an example, but it applies to any similar service. Google Analytics does not allow you to ...
1
vote
2answers
169 views

Unencrypt Data Encrypted by Cryptolocker Virus [duplicate]

A while back my computer was encrypted by the cryptolocker virus. I ended up taking an image of the encrypted drive and then formatting it and installing a new operating system. Since I have the ...
38
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9answers
28k views

Feeding /dev/random entropy pool?

Which way of additionally feeding /dev/random entropy pool would you suggest for producing random passwords? Or, is there maybe a better way to locally create fully random passwords?
2
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2answers
2k views

Is it true that encryption bit “strength”, although numerically identical, may actually be different depending on the algorithm?

I was reading recently that for AES, the encryption strength is actually the key size/length, so 128-, 192- or 256-bit. While, for SHA-2, the encryption strength is measured against the message digest ...
3
votes
1answer
126 views

How to get a green certificate bar if I'm not a company?

I'm not a company and do not represent one, but I would like to have a green bar on my website for several reasons. One of them, for example, is that I want to ensure that the information displayed in ...
1
vote
3answers
197 views

Constant time compares when array sizes are not equal?

What is the preferred or recommended way to pursue contestant time compares when array lengths are not equal? Should we exit as early as possible? Something like: if (array1.size() != array2.size()) ...
1
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3answers
258 views

Why don't the majority of today's malware use strong cryptography?

While reading another story of botnet takedown, my wondering has reached its apogee: Why don't malware authors use cryptography (encryption + signing) provided by good libraries when their creations ...
1
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0answers
27 views

If a HSM RNG is FIPS 140-2 compliant, does that imply FIPS 186-2 compliance also?

If the RNG of an HSM is said to be compliant to FIPS 140-2 (approved DRBG - SP 800-90 CTR mode) does also imply that it is compliant to FIPS 186-2?
2
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1answer
67 views

What does “probability space is over coin flips of algorithm M” mean?

In the book The Algorithmic Foundations of Differential Privacy by Cynthia Dwork, Aaron Roth on page 16 (actually page 20 in the pdf viewer) it says at the very bottom of the page: Definition 2.2 (...