Using Get-Random after using Where-Object creates a null valued expression - arrays

Question

I'm trying to create a 10 character password that includes a mix of numbers, letters (uppercase and lowercase), and symbols.
Below is the script I am using in the function:
Function Get-TempPassword {
$TempPassword = $null
$ascii = $NULL;For ($a = 33;$a –le 126;$a++) {$ascii +=, ([char][byte]$a | Where-Object {$_ -notin "'",'`','|','_',"`;",'"',','})}
Do {$TempPassword += $ascii | Get-Random; $loop++}
Until ($loop -eq 11)
return $TempPassword
}
If I remove the following section:
| Where-Object {$_ -notin "'",'`','|','_',";",'"',','}
The creation of the password works fine albeit including the symbols I don't want included.
Having the Where-Object function causes the Get-Random function to only use the first 5 characters in the array, and therefore I don't get letters of any case type, or numbers, or any of the other symbols.
I've found that if I use $ascii[26] (being the 25th character in the array) I get a null value, however I would think this would allow any character up to this character to be used, or none at all, not just the first 5. The 25th character just so happens to be a ; (ascii value number 59). I tried adding the symbol to the Where-Object exclusion, and it was removed from the array, but the 25th character still showed as a null value.
I performed a reverse lookup of the ascii value [int[]][char[]] of each character either side of where the ; symbol would appear and it returned values 58 and 60, leading me to believe it was value 59 that was offending, but the symbol at this point should have been excluded.
Adding characters to the 'where-object' exclusion list should be removing them from the array, and it appears to, however running $ascii.Count shows 49 characters, regardless of whether I add or remove characters to the Where-Object exclusion list.
I have looked for information on the web and can't seem to find any, although it may be the search terms I'm using, as it's a bit of a complex case that not many would be reporting on.
Any help is appreciated.

Answer 1

I didn't write this and i can't remember where i got it but i have built this into any scripts to create random secure Windows passwords, you can specify the length of the password returned by the param [int]$PasswordLength ( i have already set it to 10 ).
function New-SWRandomPassword {
[CmdletBinding(DefaultParameterSetName='FixedLength',ConfirmImpact='None')]
[OutputType([String])]
Param
(
# Specifies minimum password length
[Parameter(Mandatory=$false,
ParameterSetName='RandomLength')]
[ValidateScript({$_ -gt 0})]
[Alias('Min')]
[int]$MinPasswordLength = 8,
# Specifies maximum password length
[Parameter(Mandatory=$false,
ParameterSetName='RandomLength')]
[ValidateScript({
if($_ -ge $MinPasswordLength){$true}
else{Throw 'Max value cannot be lesser than min value.'}})]
[Alias('Max')]
[int]$MaxPasswordLength = 11,
# Specifies a fixed password length
[Parameter(Mandatory=$false,
ParameterSetName='FixedLength')]
[ValidateRange(1,2147483647)]
[int]$PasswordLength = 10,
# Specifies an array of strings containing charactergroups from which the password will be generated.
# At least one char from each group (string) will be used.
[String[]]$InputStrings = #('abcdefghijkmnpqrstuvwxyz', 'ABCEFGHJKLMNPQRSTUVWXYZ', '23456789', '!"#%&'),
# Specifies a string containing a character group from which the first character in the password will be generated.
# Useful for systems which requires first char in password to be alphabetic.
[String] $FirstChar,
# Specifies number of passwords to generate.
[ValidateRange(1,2147483647)]
[int]$Count = 1
)
Begin {
Function Get-Seed{
# Generate a seed for randomization
$RandomBytes = New-Object -TypeName 'System.Byte[]' 4
$Random = New-Object -TypeName 'System.Security.Cryptography.RNGCryptoServiceProvider'
$Random.GetBytes($RandomBytes)
[BitConverter]::ToUInt32($RandomBytes, 0)
}
}
Process {
For($iteration = 1;$iteration -le $Count; $iteration++){
$Password = #{}
# Create char arrays containing groups of possible chars
[char[][]]$CharGroups = $InputStrings
# Create char array containing all chars
$AllChars = $CharGroups | ForEach-Object {[Char[]]$_}
# Set password length
if($PSCmdlet.ParameterSetName -eq 'RandomLength')
{
if($MinPasswordLength -eq $MaxPasswordLength) {
# If password length is set, use set length
$PasswordLength = $MinPasswordLength
}
else {
# Otherwise randomize password length
$PasswordLength = ((Get-Seed) % ($MaxPasswordLength + 1 - $MinPasswordLength)) + $MinPasswordLength
}
}
# If FirstChar is defined, randomize first char in password from that string.
if($PSBoundParameters.ContainsKey('FirstChar')){
$Password.Add(0,$FirstChar[((Get-Seed) % $FirstChar.Length)])
}
# Randomize one char from each group
Foreach($Group in $CharGroups) {
if($Password.Count -lt $PasswordLength) {
$Index = Get-Seed
While ($Password.ContainsKey($Index)){
$Index = Get-Seed
}
$Password.Add($Index,$Group[((Get-Seed) % $Group.Count)])
}
}
# Fill out with chars from $AllChars
for($i=$Password.Count;$i -lt $PasswordLength;$i++) {
$Index = Get-Seed
While ($Password.ContainsKey($Index)){
$Index = Get-Seed
}
$Password.Add($Index,$AllChars[((Get-Seed) % $AllChars.Count)])
}
Return $(-join ($Password.GetEnumerator() | Sort-Object -Property Name | Select-Object -ExpandProperty Value))
}
}
}
New-SWRandomPassword
EDIT:::
https://gallery.technet.microsoft.com/scriptcenter/Generate-a-random-and-5c879ed5
The script can be found here.

Answer 2

Short version (best method for me):
$possible=36..38 + 40..43 + 45..58 + 60..94 + 97..123 + 125..126 + 33
(get-random -count 10 -input $possible | % {[char]$_}) -join ''

Answer 3

Using the following script seems to have worked exactly how I want.
I removed the comma (,) from after += on this line:
$ascii = $NULL;For ($a = 33;$a –le 126;$a++) {$ascii +=, ([char][byte]$a | Where-Object {$_ -notin "'",'`','|','_',";",'"',','})}
I created a blank array before the array is added to:
$ascii = #()
The full code block is below:
Function Get-TempPassword {
$TempPassword = $null
$ascii = #()
For ($a = 33;$a –le 126; $a++) { $ascii += ([char][byte]$a | Where-Object { $_ -notin "'",'`','|','_',";",'"',',' }) }
Do {$TempPassword += $ascii | Get-Random; $loop++}
Until ($loop -eq 11)
return $TempPassword
}

Answer 4

Recursive method :
Function random-password ($length = 10)
{
$Assembly = Add-Type -AssemblyName System.Web
$password = [System.Web.Security.Membership]::GeneratePassword($length, 2)
$desablechar = "[``'|_;,`"]"
if ($password -match $desablechar )
{
random-password $length
}
else
{
$password
}
}
random-password

Answer 5

try Something like this :
Function random-password ($length = 10)
{
$possible=36..38 + 40..43 + 45..58 + 60..94 + 97..123 + 125..126 + 33
$password = get-random -count $length -input $possible |
% -begin { $aa = $null } -process {$aa += [char]$_} -end {$aa}
return $password
}
random-password

Answer 6

I have rectified my others propositions, but i propose an other method :)
Function random-password2 ($length = 10)
{
$Assembly = Add-Type -AssemblyName System.Web
$password = [System.Web.Security.Membership]::GeneratePassword(50, 2)
$possible=36..38 + 40..43 + 45..58 + 60..94 + 97..123 + 125..126 + 33
$newchar=[char](get-random -count 1 -input $possible)
$password=$password -replace "[`'|_;,]", $newchar
$password.Substring(0, $length)
}
random-password2