That’s fantastic.
This had been my solution and I do kinda like seeing the actual valid
characters cuz it makes it easy to edit out quotes or other possible illegal
values. But, it’s tough to beat the elegance of yours when valid characters
aren’t a concern.
$Chars =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()"
$Rand = New-Object System.Random
For ($i = 1; $i -le 20; $i++) {
$Password = $Password + $Chars.Substring($Rand.Next(0,
$Chars.Length), 1)
}
$Password
From: [email protected] [mailto:[email protected]] On
Behalf Of Michael B. Smith
Sent: Friday, February 5, 2016 7:07 PM
To: [email protected]
Subject: RE: [powershell] Random Password Generator
Interestingly enough, you can take Get-Random and get an even better random
password. Take a look at this:
( [char[]]( Get-Random -Input ( 33..126 ) -Count 20 ) ) -Join ''
Great solution using all of the printable ASCII characters (except for the
<space> character).
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Michael B. Smith
Sent: Thursday, February 4, 2016 3:39 PM
To: [email protected]<mailto:[email protected]>
Subject: RE: [powershell] Random Password Generator
That’s very nice. I never would have thought of that application of Get-Random.
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Sean Martin
Sent: Thursday, February 4, 2016 10:44 AM
To: [email protected]<mailto:[email protected]>
Subject: Re: [powershell] Random Password Generator
You make a good point. How about this?
$randombytes = new-object byte[] 15
(new-object
System.Security.Cryptography.RNGCryptoServiceProvider).GetBytes($randombytes)
$pass = [System.Convert]::ToBase64String($randombytes)
$a = ([char[]](get-random -input (33..47 + 48..57) -count 4)) -join ""
$password = $a + $pass
- Sean
On Wed, Feb 3, 2016 at 6:36 PM, Michael B. Smith
<[email protected]<mailto:[email protected]>> wrote:
The maximum entropy you get from Base64 is 2.58 bits per character, kinda by
definition( ln2( 6 ) ). Given that your maximum length is 15 digits, that
limits you to ~38 bits of entropy. At a thousand guesses a second, that’s about
8 years to brute force. Not bad.
However, you’ve GIVEN UP over 10 bits of entropy because of four constant
characters, taking you to about 28 bits of entropy. Believe it or not, having
constants makes a password far far easier to crack. (This is why the revelation
of a non-random non-prime in netcat/socat is such a big deal – it makes
Diffie-Helman much much simpler to crack.)
That’s about 3 days to brute force.
That is completely believable for someone to spend the time/energy to crack.
(And remember, the 3 days assumes that your password is the last one checked,
out of the entire “password universe” – on average, assume half that.)
So, the lesson here is that 15 bytes of base64 is fine (if impossible to
remember). But don’t use constants. Evah.
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]<mailto:[email protected]>]
On Behalf Of Sean Martin
Sent: Wednesday, February 3, 2016 3:24 PM
To: [email protected]<mailto:[email protected]>
Subject: [powershell] Random Password Generator
I don't get the opportunity to contribute all that often so I thought I would
throw this out there in case it helps anyone.
I got the method from this article:
https://www.scriptjunkie.us/2013/09/secure-random-password-generation/
I modify the resulting password by prepending/appending a couple of special and
numerical characters to ensure it meets complexity requirements in my current
environment.
Easy way to generate a secure password whenever the need arises. Critiques are
always welcome.
===================================================================
# Generate Random Password
$randombytes = new-object byte[] 15
(new-object
System.Security.Cryptography.RNGCryptoServiceProvider).GetBytes($randombytes)
$pass = [System.Convert]::ToBase64String($randombytes)
$password = "&#" + $pass + "82"
Write-Host ""
Write-Host "Your password is: " -ForeGroundColor Cyan -NoNewLine
Write-Host "$Password" -ForeGroundColor Yellow
Write-Host ""
Write-Host ""
Write-Host "Press enter to exit script..." -ForeGroundColor Cyan
$Pause = Read-Host
Exit
==================================================================
- Sean
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