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

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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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0answers
25 views

Ring Oscillator: TRNG vs 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
96 views

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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0answers
70 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
77 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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1answer
34 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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3answers
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License key / Serial number generator and checker

I need a serial number generator and accompanying checker. I would like to be able to set a salt (and maybe a length). The generator should only produce serial numbers that pass the test of the ...
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7answers
4k 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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21 views

How is the random string of Thunderbird's profile folder generated? [closed]

As per this link, Thinderbird creates a folder by name in the format ".default” where ”” is an eight digit string randomly generated by Thunderbird. But how is it generated? Which random generator ...
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3answers
12k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Or should ...
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4answers
4k views

Generate cryptographically strong pseudorandom numbers in Javascript?

Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript? The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
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1answer
807 views

Using Random Numbers As Session variables

I am using randomly generated numbers as session variables to identify the sessions in a PHP application. To make further security proof what ways should I follow?
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5k views

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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73 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 = ...
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2answers
308 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 ...
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1answer
144 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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2answers
2k views

Flaw in encryption through pseudorandom number stream (from PGP documentation)

I was reading PGP docs and came upon a part written by Phil Zimmermann (PGP's creator) that piqued my curiosity: When I was in college in the early 70s, I devised what I believed was a brilliant ...
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3answers
2k views

Java SecureRandom doesn't block? How?

I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
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1answer
162 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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4k 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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2answers
82 views

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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1answer
132 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
218 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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9answers
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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?
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2answers
310 views

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 ...
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2answers
98 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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121 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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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
65 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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3answers
459 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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40 views

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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2answers
223 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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3answers
703 views

Why CSRF Token has to be a Cryptographically Strong Random number, in Double Submit Cookies method?

I was just going through the OWASP's Cheat Sheet for CSRF Prevention. In the Double Submit Cookies method, I saw this the site should generate a (cryptographically strong) pseudorandom value ...
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1answer
161 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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312 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 ...
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2answers
142 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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2answers
676 views

Correct way to get a number from 0-9 from a random byte?

If I have a good random number generator that gives me a byte of data at a time, and I want to extract a random decimal digit of 0 to 9 from that byte stream, what is the correct way to do that? At ...
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6answers
6k 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 ...
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1answer
96 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 ...
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1answer
253 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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987 views

Java SecureRandom generate secure random number

How to generate a secure random number bit length is 256 bits using Java. What is the different between: SecureRandom random = new SecureRandom(); and SecureRandom prng = ...
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3answers
554 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
191 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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4answers
2k views

Is generating random numbers using a smartphone camera a good idea?

Forgive my ignorance on the subject, but I wish to know more and asking (stupid) questions are one way. I was reading http://www.random.org/randomness/ and this idea popped into my head (before the ...
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1answer
231 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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7answers
2k views

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
120 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 ...
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1answer
224 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
65 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
160 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 ...