The tag has no wiki summary.

learn more… | top users | synonyms

0
votes
1answer
29 views

Not quite grasping /dev/random and /dev/urandom

I am not quite understanding the difference between /dev/random and /dev/urandom on Linux systems. What does it mean to run out of “entropy” and how does the system get more? What does it mean when ...
0
votes
1answer
37 views

How to generate inverted normal random numbers in VBA?

I am trying to generate 5.000 random variables using these excel functions: normsinv(rand()). This is the code I wrote: Dim r As Integer r = 1 For r = 1 To 5001 .Cells(r + 1, 1) = ...
1
vote
1answer
167 views

How do computers generate random numbers? [closed]

How does a computer generate 'random' numbers? How close to truly 'random' can a number generated by a computer actually be? Is there software / programming language out that that might generate a ...
1
vote
3answers
460 views

Creating a large file of random bytes quickly

I want to create a large file ~10G filled with zeros and random values. I have tried using: dd if=/dev/urandom of=10Gfile bs=5G count=10 it creates a file of about 2Gb and exits with a exit status ...
0
votes
0answers
24 views

Seeding RNG with clock in application running on virtual machines, reliability issues?

How reliable is using the current time to seed random number generators for applications to run inside a virtual machine. The application is not related to security, and the virtual machine settings ...
553
votes
18answers
63k views

How are pseudorandom and truly random numbers different and why does it matter?

I've never quite got this. Just say you write a small program in any language at all which rolls some dice (just using dice as an example). After 600,000 rolls, each number would have been rolled ...
2
votes
1answer
937 views

Is reading from /proc/sys/kernel/random/entropy_avail draining entropy?

When I'm doing watch cat /proc/sys/kernel/random/entropy_avail, the amount of entropy steadily decreases, until I get about 150-200. Initially I get over 2000. When I stop reading that value and wait ...
0
votes
0answers
34 views

Is it possible to use custom random sources directly in gnutls or in openssl clients?

I've only saw the -rand option in openssl which is used to seed their custom random number generator. The help page are divided, so it is easy to miss an option. I couldn't get a list of options for ...
0
votes
1answer
350 views

Excel VBA: Rnd() method isn't random enough

I'm using Excel and VBA to simulate a large number of dice rolls. The problem I'm having is after a certain period of time, the rolls start repeating, and I start getting results that are anything ...
2
votes
1answer
256 views

Randomly reorder pages in PDF document

I'm looking for a series of commands to randomize the order of pages in an existing PDF document.
4
votes
4answers
3k views

Why does `cat /dev/urandom` break your terminal?

In reference to this question: http://serverfault.com/questions/534449 How does cat /dev/urandom make some terminal emulators go wonky?
1
vote
3answers
12k views

excel: how to use vba to repeatedly generate random numbers?

I know that in Excel one can use "rand()" function to generate random numbers, and each time pressing F9, all "rand()" results on that sheet will be refreshed. However, now I need to repeated ...
0
votes
2answers
7k views

MS Excel: Unique random number generator within a range

I searched for a similar question but couldn't find one.. I want to generate 10 groups out of numbers ranging from 1-60 (including both), with each and every group containing random and non-repeating ...
2
votes
1answer
217 views

Calculating mean of value across random trials/refreshes in Excel?

Say I have a 1000 cells filled with random values and a particular cell that computes a final answer based on those 1000 values. Now I wish to track the value of the answer over 1000 trials i.e., I ...
1
vote
3answers
558 views

What's the best way to get a random(ish) sequence of printable/alphanumeric characters?

I know I can get random (well, pseudo-random) characters, unconstrained, from '/dev/random' (or /dev/urandom). But what if I need these characters to generate a filename? I need to somehow have a ...
3
votes
1answer
445 views

How can I know whether my machine have RNG hardware support?

I came across a blog concerning entropy pool problem and learn that there are a special hardware called RNG. I have read this kernel RNG page but I still wonder whether there is a way to find out if ...
-2
votes
3answers
361 views

Random Number in Linux

In linux /dev/random is based of "environmental variables" and /dev/urandom is based off an algorithm and the time. My questions are: Where does /dev/random gather these variables from. And if you ...
2
votes
3answers
1k views

how to record mic input and pipe the output to another program

Hi everyone Im trying to follow a tutorial on generating truly random bits How To Generate Truly Random Bits This is the command from the tutorial but it does not work rec -c 1 -d /dev/dsp -r 8000 ...
5
votes
2answers
368 views

How to generate random numbers with a .wav file?

I want to generate random numbers within a certain range (1 to 26) using a .wav file with only static noise. The results need to be repeatable. Is there any service/program/method of accomplishing ...
0
votes
1answer
217 views

Are GPG keys generated on windows as secure as ones generated on linux?

Under linux you run out of system Entropy when trying to generate GPG keys unless you use /dev/urandom. Under windows, you get the speed of /dev/urandom without any tweaks. Does windows have that ...
5
votes
2answers
4k views

Why is GNU shred faster than dd when filling a drive with random data?

While securely erasing a hard drive before decommissioning I noticed, that dd if=/dev/urandom of=/dev/sda takes nearly a whole day, whereas shred -vf -n 1 /dev/sda only takes a couple of hours with ...
3
votes
2answers
1k views

How to determine a coin toss online? [closed]

What resources can I use if I'm trying to settle a coin flip online? Obviously, a coin toss app won't work if it only displays the result to me - the other party should also see it. And we can't meet ...
1
vote
2answers
369 views

Have a script execute a command randomly every now and then

I have a script which I am scheduling to run daily with Cron. However I want a certain section of the script to only run randomly occasionally, with a certain probability of executing on any given ...
18
votes
5answers
13k views

Why is my /dev/random so slow when using dd?

I am trying to semi-securely erase a bunch of hard drives. The following is working at 20-50Mb/s dd if=/dev/zero of=/dev/sda But dd if=/dev/random of=/dev/sda seems not to work. Also when I ...
6
votes
4answers
5k views

how do you make a letter password generator in batch?

I'm having a hard time figuring out how to make a password generator with random letters in it. For example, ASWED-ASDWAD-EFEST. So far I can only make random numbers by using the code @echo off ...
1
vote
1answer
1k views

Math Round multiple cells, generate integers and histogram integer values

I want your help for the following points: How generate integer values using Data menu > Data Analysis > Random Number Generation or (if this action can't be done) how round multiple cells in same ...
3
votes
4answers
448 views

Does 'urandom' share the same entropy of 'random'?

Does the entropy pool /dev/random used the same to /dev/urandom? I want to mknod /dev/random 1 9 to replace the slow random, I think the current entropy is randomly enough, if urandom is based on ...