Questions tagged [random]

The generation of random or pseudorandom data, and the use of randomness in security protocols

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1answer
3k views

Is it fine to store single-use beta keys plain-text?

Is it okay to store single-use beta keys in plain-text in the database? I'll be pre-generating and storing about 2M keys. The keys get passed around so that people can sign up with it, rather than let ...
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2answers
2k views

Ring Oscillator: True Random Number Generator (TRNG) vs Physically Unclonable Function (PUF)

Ring oscillators can be used in hardware true random number generators (TRNG), and also in physically unclonable functions (PUFs). The designs seem fairly similar: TRNG based on ring oscillators: ...
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2answers
2k views

AES encryption on embedded device: Can this be secure?

I plan to create an encryption program for an embedded device with the following characteristics: CPU is Intel 80186 compatible @ ~20 MHz 128 KB RAM, of which I have ~20 KB at my disposal for ...
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3answers
255 views

How to compare passwords with duplicate password

On Steam, the gaming client, I have this habit of creating multiple "smurf" accounts. I have a randomly-generated, unique password, and I decided to use the same password for all of my multiple ...
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2answers
2k views

Initialization of a LUKS encrypted partition with cipher or /dev/urandom

I've created a few encrypted devices with LUKS and cryptsetup on Linux and am pretty comfortable with disk encryption in this regard. I've seen it mentioned in many different places that when setting ...
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7answers
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Is it possible to make a more secure random number generator algorithm by XORing two or more less secure random number algorithms?

Is it possible to make a more secure random number generator (e.g. for cryptologic purposes) by combining two or more less secure random number generator algorithms using XOR? Here is an example of ...
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7answers
6k views

Are humans a strong or weak RNG? [duplicate]

Thomas Pornin has stated in the past on multiple occasions (I'm not going to source them, he can argue with me if he wants) that humans are bad RNGs. While I agree that human RNG for password ...
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1answer
1k views

Creating secure PIN in Java

I need to create cryptographically secure PIN number in Java using secret id for each user. This simple approach comes to mind: int getPin(String secretUserIdStr) { String pepper = "randomPepper....
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2answers
491 views

Including and storing the order of character entry in a password as an enhanced security measure

I'm sure I will be quickly corrected if this is a stupid idea, or if it has already been tried. My question is: has this idea been tried before? If not, are there good reasons it would not work, or ...
2
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1answer
978 views

Key's random art image is mostly black

I have generated an SSH key on Ubuntu 10.04 with ssh-keygen -t rsa -C "example@example.com" and the key's random art image comes out mostly empty (modified slightly): +--[ RSA 2048]----+ | ...
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1answer
892 views

Where does /dev/random get its entropy?

I read over and over about how /dev/random gets its entropy from "hardware events." What exactly are these hardware events and how can we be sure that it is random enough?
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2answers
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2 way encryption of a string into numerical string using random number

I have a random number like 0.323978544752212. I want to encrypt a string using this random number into to numerical string i.e. final string is like ...
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11answers
10k views

One liner to create passwords in linux?

How do you create a readable password using bash with one line? What if i'm looking for 128 bits of entropy? EDIT By readable I mean the 94 printable ascii characters (without space). It can use ...
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1answer
179 views

Why is using [x] to generate random keypairs a bad idea?

Anyone who has generated large GPG public/private keypairs has come across this annoying message: "Not enough random bytes available. Please do some other work to give the OS a chance to collect more ...
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4answers
11k views

Add a file as entropy source for /dev/random

What I have: A large file containing lots of secret, true-random bytes (yes, I'm sure they're not merely pseudo-random). I'll call it F. What I want to do: Tell Linux that it can use this file as an ...
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1answer
90 views

Secure shuffles and the rand() function

I'm trying to understand one aspect of a secure shuffle using Fisher-Yates. For reference, here is Fisher-Yates to shuffle an array x of n elements (numbered from 0 to n-1) (from Securing a Shuffle ...
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2answers
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Can the human brain generate cryptographically secure random numbers?

A security conscious friend of mine was attempting to generate entropy using random dice rolls to generate a random password, and I became curious about the security of random number generators and ...
4
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1answer
565 views

Do I need a salt when hashing a randomly generated password?

I have passwords stored in my database that are very long, unique and generated by a CSPRNG. Do I need to use a salt before hashing them? My understanding is that usually you use a hash function in ...
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2answers
310 views

Do DES keys have to be random?

In stream cipher (namely the OTP ) . The pad which the plain text is Xored with has to be random to achieve perfect secrecy , or psudorandom to ensure semantic security Dose this apply to DES or ...
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2answers
208 views

How does an insecure RNG affect cryptography, and how do I measure the corresponding loss of security?

Suppose a given random number generator has poor entropy, and is compressible by any compression algorithm (zlib, bzip2, lzma, etc). Specifically the issues with this RNG are: Bad entropy Bad seed ...
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2answers
102 views

Is there something similar to pseudorandom generators but in the opposite direction?

Pseudorandom generators (PRG) are functions that takes a random small input (called the Seed) and maps it into much larger output . However, the mapping process must be unpredictable in order for the ...
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1answer
185 views

Usefulness of bcrypt(UUIDv4())

One of my colleagues is working on securing OAuth 2 client IDs and secrets for our OAuth server and he has come up with this scheme where he would not only use UUID v4 to generate random values, but ...
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0answers
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Steps for creating a test environment where GUIDs are exploitable?

I have been using GUIDs as un-guessable tokens in various situations for some time. I came across this question/answer which seems to suggest that while this is ok in some situations, it should not ...
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3answers
5k views

Would it be secure to generate random number using AES?

I know that there are already tools out there to generate cryptographic random number, but I was wondering if using AES could do the same. For example, I have a secret key for AES on my server and a ...
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2answers
2k views

How to generate an unpredictable but short string? [closed]

I want to built some short urls for uploaded files and links on my own server. Simple enough, I upload files and my script returns me a link. On access, the link is translated to the file and download ...
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2answers
880 views

Securing a Shuffle Algorithm

After reading about writing a secure shuffle algorithm, I realized that my module that generates a password is only as strong as my PRNG, which in this case is Math.random(). I'm confused as to how to ...
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1answer
732 views

What cryptosystem makes the encrypted text look like random noise?

Suppose one wants to setup a cryptographic protocol in which 2 parties communicate using an encryption scheme that produces encrypted messages indistinguishable from random data (the desired property) ...
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2answers
559 views

Reliable random seed for RNG

I want to create my computer passwords with a RNG, but I am thinking about one thing: I would use python to write that script and the RNG is controlled by one seed, most likely the time. If I would ...
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7answers
15k views

Are random URLs a safe way to protect profile photos?

I would like to move from sequential to random user IDs, so I can host profile photos publicly, i.e. example.com/profilepics/asdf-1234-zxcv-7890.jpg. How long must user IDs be to keep anyone from ...
2
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1answer
324 views

Does RAND_add(&Time,sizeof(Time),0) at each ssl connect reduce randomness or not?

Reviewing openssl 1.0.1g s23_clnt.c code i see that : int ssl23_connect(SSL *s) { BUF_MEM *buf=NULL; unsigned long Time=(unsigned long)time(NULL); void (*cb)(const SSL *ssl,int type,...
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1answer
1k views

How secure is Vigenere cipher for random data?

Traditional situation It is easy to crack a ciphertext encrypted by Vigenere cipher, if you know the plaintext is in a natural language like English. There are two methods to discover the key used to ...
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2answers
2k views

MySQL ENCRYPT salt is not random?

I know there's little reason to still use ENCRYPT() nowadays, what with bcrypt being almost ubiquitous and MySQL providing better hashes such as SHA1. But while dabbling with ENCRYPT() on MySQL 5.6....
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3answers
595 views

Hashing speed with true random passwords

Just a theoretical question: If I had ideal users, who all provide fully random 128-bit passwords, And also, I invalidate every password shorter than 128 bits. Then would I still need a slow hash ...
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1answer
903 views

SSL Handshake random number?

I realized all of the phase of the handshake but I do not understand how it does that from the two randomly generated numbers are unable to generate a session key that the client and the server uses ...
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1answer
2k views

Is the following code seeding OpenSSL's PRNG necessary, superfluous, or harmful?

As I was going through Crypt::SSLeay, preparing it for the next release, I noticed the following code, written way before my time, ... int rand_bytes_read; static int bNotFirstTime; char buf[ 1024 ];...
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2answers
247 views

How can you detect an insecure, non-random token?

I know that some of PHP's random functions are insecure due to them not being completely random and are considered a bad practice. My question is how an attacker go about finding that the developer ...
2
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1answer
929 views

-bash: -sudo: command not found [closed]

Some dependencies were missing when I installed THC Hydra. I found this site which directs me to install the missing package: sudo apt-get install libsvn-dev libapr1-dev libaprutil1-dev But when I ...
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1answer
208 views

Are the problems with Window's CSPRNG still an issue on modern Windows?

The paper Cryptanalysis of the Random Number Generator of the Windows Operating System describes some problematic aspects of the Windows CSPRNG. However the paper was written in 2007, and looked at ...
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2answers
1k views

What does the “period” of a random number generator measure?

What is "period" in the context of pseudo-random number generators? For example when someone says "The Mersenne Twister has a 2^19337−1 period" what does it mean? I would appreciate a simple as ...
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2answers
233 views

Does RNG play a role in PGP signing?

We have a Jenkins system that builds and PGP-signs software releases, and we are considering moving the signing component to an isolated VM instead of running it as part of the overall builder ...
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1answer
356 views

Should generating gpg keys ever result in an identical key to an older key?

I recently had a situation where I lost an old private key (write error; realized this too late). In regenerating keys and replacing the public keys on various sites, I noticed that the public keys ...
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3answers
885 views

How secure is to seed PRNGs with the sequences from CSPRNG?

Background: Implementing online casino, I would like to use a number of PRNGs with high throughput, like MersenneTwisterFast. I know it is not cryptographically strong, but quite unpredictable when ...
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1answer
143 views

is this code valid for securing passwords? [duplicate]

i was wondering if this is a secure method for a hashing password.if it is not secure please tell me what to do in order to make it secure $pass='test'//the password $salt=openssl_random_pseudo_bytes(...
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1answer
63 views

bin_random_table and RANDOM_BOOT_ID

The Linux kernel has a few sysctrl's related to random devices packaged in a bin_random_table (http://lxr.free-electrons.com/source/kernel/sysctl_binary.c?v=3.2): static const struct bin_table ...
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3answers
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Does (online) poker require cryptographically secure randomness?

Here’s a quote from a reddit discussion: … for poker [a cryptographically secure RNG] is completely unnecessary. If you have an appropriate unpredictable seed, and you are throwing away a lot of ...
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1answer
7k views

How securely random is Oracle's java.security.SecureRandom

There was a lot of news in the past year about exploitable weaknesses in cryptography which originated from weak random number generators. In some cases it was negligence on side of the developers, in ...
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4answers
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Why OpenSSL can't use /dev/random directly?

I couldn't find the answer for the reason anywhere, even the wiki page doesn't explain it. This seems like using a PRNG for seeding an another PRNG. The first one (/dev/random) may itself be seeded by ...
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7answers
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Testing a hardware random number generator

The Raspberry Pi has a built in hardware random number generator but there doesn't appear to be any public documentation on the hardware, and even if there were it would be questionable (what company ...
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2answers
2k views

Can the xor of two RNG outputs ever be less secure than one of them?

Suppose I'm suspicious that one or more (pseudo)-random number generators is cryptographically flawed, perhaps even deliberately backdoored. The RNGs in this case might be either PRNG algorithms, ...
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2answers
548 views

Benefit to using PBKDF2 on key generated by RNGCryptoServiceProvider?

I have a program that generates a fixed-length 32 byte (256-bit) password using RNGCryptoService provider and then uses Rfc2898DeriveBytes on that password to arrive at an encryption key. However, to ...