Functions/Get-CeasarCipher.ps1
|
function Get-CeasarCipher { <# .SYNOPSIS Shifts letters in string by a certain number of positions. Default shift is 13 characters or the classic ROT13. .DESCRIPTION Shifts letters in string by a certain number of positions. Default shift is 13 characters or the classic ROT13. .PARAMETER Text A string array of plaintext that you want to run through the cipher. Aliased to 'String' to provide backward compatibility. .PARAMETER Key The number of positions you want to switch. Defaults to '13', valid range '1' through '25' .PARAMETER Decode Switch used if you want to decode cipher text by a certain number of characters. .PARAMETER IncludeInput Switch that will include the input in the output .EXAMPLE Get-CeasarCipher -Text Zoo, human -IncludeInput -Verbose VERBOSE: Starting [Get-CeasarCipher] VERBOSE: -Key [13] -Decode [False] -IncludeInput [True] VERBOSE: Processing [Zoo] VERBOSE: Processing [human] VERBOSE: Ending [Get-CeasarCipher] PlainText Key CipherText --------- --- ---------- Zoo 13 Mbb human 13 uhzna .EXAMPLE Get-CeasarCipher -Text Zoo -Key 10 Jyy .EXAMPLE Get-CeasarCipher -Text Jyy -Key 10 -Decode Zoo .NOTES Inspired by: https://titanwolf.org/Network/Articles/Article?AID=99197fe0-0b0e-4a9c-883e-49f4273a59ad#gsc.tab=0 #> [CmdletBinding()] [alias('Convert-ROT13')] Param ( [Parameter(Mandatory, HelpMessage = 'Please enter text to pass through cipher', ValueFromPipeline)] [Alias('String')] [string[]] $Text, [ValidateRange(1, 25)] [int] $Key = 13, [switch] $Decode, [switch] $IncludeInput ) begin { Write-Verbose -Message "Starting [$($MyInvocation.MyCommand)]" Write-Verbose -Message "-Key [$Key] -Decode [$Decode] -IncludeInput [$IncludeInput]" $LowerAlpha = ([char] 'a')..([char] 'z') $UpperAlpha = ([char] 'A')..([char] 'Z') } process { foreach ($Line in $Text) { Write-Verbose -Message "Processing [$Line]" $Chars = $Line.ToCharArray() $LineOutput = '' foreach ($Char in $Chars) { if ($Char -cmatch '[A-Z]') { $Position = $UpperAlpha.IndexOf(([int] $char)) if (-not $Decode) { $LineOutput += [char] $UpperAlpha[(($Position + $Key) % $UpperAlpha.Count)] } else { $LineOutput += [char] $UpperAlpha[(($Position - $Key + $UpperAlpha.Count) % $UpperAlpha.Count)] } } elseif ($Char -cmatch '[a-z]') { $Position = $LowerAlpha.IndexOf(([int] $char)) if (-not $Decode) { $LineOutput += [char] $LowerAlpha[(($Position + $Key) % $LowerAlpha.Count)] } else { $LineOutput += [char] $LowerAlpha[(($Position - $Key + $LowerAlpha.Count) % $LowerAlpha.Count)] } } else { $LineOutput += $char } } if (-not $IncludeInput) { Write-Output -InputObject $LineOutput } else { New-Object -TypeName psobject -Property ([ordered] @{ PlainText = $Line Key = $Key CipherText = $LineOutput }) } } } end { Write-Verbose -Message "Ending [$($MyInvocation.MyCommand)]" } } |