crypto challenge

Get-DecryptedMessage.ps1

$crypto1 = @"
g-25Retopc7-
hv1QnelbedEp
"@

$crypto2 = @"
PkTr2sz2*cF-
raz7GuD4w6U#
gctK3E@Bt1aY
QPic%705ZvAe
W6jePRfpmI)H
y^LoowCnbJdO
Si9Mber#)ieU
*f2Z6MSh7VuD
5a(hsv8el1oW
ZO7lpKyJlDz$
-jI@tT23Raik
q=F&wB6c%Hly
"@

function Get-DecryptedMessage {
    Param(
        $message,
        $index = 0,
        $offset = 5
    )

    $arr    = @()

    $string = $($message -split "`r`n") -join ''
    Do {
        $arr += $string[$index]
        $arr += $string[$index + $offset]
        $index = $index + $offset + 1

    } While( $index -lt $string.Length )

    $arr -join ''
}

Get-DecryptedMessage -message $crypto1

#Brute force to figure out which pair is the winner
0..12 |
ForEach-Object{
    $index = $_
    0..12 |
    ForEach-Object{
        $offset = $_
        "{0},{1} - {2}" -f $index,$offset, $(Get-DecryptedMessage -message $crypto2 -index $index -offset $offset) 
    }
}

#Winning pair 0,12
Get-DecryptedMessage -message $crypto2 -index 0 -offset 12