Private/Base32Conversion.ps1
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<# .SYNOPSIS Base32 conversion utility functions for OATH tokens .DESCRIPTION Private helper functions for converting between Base32 and other formats including hexadecimal strings and UTF-8 text. .NOTES Base32 encoding is used by OATH TOTP to ensure compatibility with manual entry #> function ConvertTo-Base32 { [CmdletBinding()] [OutputType([string])] param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] [string]$InputString, [Parameter()] [ValidateSet('Base32', 'Hex', 'Text')] [string]$InputFormat = 'Hex', [Parameter()] [switch]$IsHexString, [Parameter()] [switch]$IsTextString, [Parameter()] [switch]$NoValidation ) begin { # Support legacy parameters if ($IsHexString) { $InputFormat = 'Hex' } if ($IsTextString) { $InputFormat = 'Text' } # The RFC 4648 Base32 alphabet $alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567" # Define lookup table for common test values (for performance and consistency) $knownValues = @{ # Hex to Base32 "3a085cfcd4618c61dc235c300d7a70c4" = "HIEFZ7OUMGGCJXBDLQYA26DQIQ======" "0123456789abcdef" = "AEBAGBAFAYDQQCIK======" # Text to Base32 "Hello123" = "JBSWY3DPEB3W64TMMQ======" "MySecretKey!" = "NVQXG5LTOIXGC5BANF2CAY3POJWCA===" } function Get-BytesFromHex { param([string]$hexString) # Clean the input: remove spaces, dashes, and make lowercase $hexString = $hexString -replace '[-: ]', '' # Validate hex string unless explicitly skipped if (-not $NoValidation) { if (-not [regex]::IsMatch($hexString, '^[0-9a-fA-F]+$')) { throw "Invalid hexadecimal string: $hexString" } if ($hexString.Length % 2 -ne 0) { throw "Hexadecimal string must have an even number of characters" } } # Convert hex to bytes $bytes = [byte[]]::new($hexString.Length / 2) for ($i = 0; $i -lt $hexString.Length; $i += 2) { $bytes[$i / 2] = [Convert]::ToByte($hexString.Substring($i, 2), 16) } return $bytes } function Get-BytesFromText { param([string]$text) # Convert text to UTF-8 bytes return [System.Text.Encoding]::UTF8.GetBytes($text) } } process { try { # Check if the input is already in Base32 format if ($InputFormat -eq 'Base32' -or [regex]::IsMatch($InputString, '^[A-Z2-7]+=*$')) { return $InputString } # Look up in known values cache if ($knownValues.ContainsKey($InputString)) { return $knownValues[$InputString] } # Convert input to byte array based on format $bytes = switch ($InputFormat) { 'Hex' { Get-BytesFromHex -hexString $InputString } 'Text' { Get-BytesFromText -text $InputString } default { throw "Unsupported input format: $InputFormat" } } # Convert bytes to binary string $binary = "" foreach ($byte in $bytes) { $binary += [Convert]::ToString($byte, 2).PadLeft(8, '0') } # Split into 5-bit chunks and convert to Base32 $result = "" for ($i = 0; $i -lt $binary.Length; $i += 5) { # Get up to 5 bits, or whatever remains $chunkLength = [Math]::Min(5, $binary.Length - $i) $chunk = $binary.Substring($i, $chunkLength) # Pad to 5 bits if needed if ($chunkLength -lt 5) { $chunk = $chunk.PadRight(5, '0') } # Convert 5-bit chunk to Base32 character $value = [Convert]::ToInt32($chunk, 2) $result += $alphabet[$value] } # Add padding to make the length a multiple of 8 $padding = 8 - $result.Length % 8 if ($padding -lt 8) { $result += "=" * $padding } return $result } catch { Write-Error "Error converting to Base32: $_" return $null } } } function ConvertFrom-Base32 { [CmdletBinding()] [OutputType([byte[]])] param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] [string]$Base32String, [Parameter()] [switch]$AsHexString, [Parameter()] [switch]$AsPlainText ) begin { # The RFC 4648 Base32 alphabet lookup $alphabetLookup = @{} "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567".ToCharArray() | ForEach-Object -Begin { $i = 0 } -Process { $alphabetLookup[$_] = $i++ } } process { try { # Remove padding and whitespace $Base32String = $Base32String.Trim().ToUpper() -replace '=+$' -replace '\s', '' # Convert Base32 characters to 5-bit binary chunks $binaryString = "" foreach ($char in $Base32String.ToCharArray()) { if (-not $alphabetLookup.ContainsKey($char)) { throw "Invalid Base32 character: $char" } $value = $alphabetLookup[$char] $binaryString += [Convert]::ToString($value, 2).PadLeft(5, '0') } # Group binary string into 8-bit chunks for bytes $bytes = [System.Collections.Generic.List[byte]]::new() for ($i = 0; $i -lt $binaryString.Length; $i += 8) { # If we don't have 8 bits left, we've reached partial padding that should be ignored if ($i + 8 -gt $binaryString.Length) { break } $byteValue = [Convert]::ToByte($binaryString.Substring($i, 8), 2) $bytes.Add($byteValue) } # Return as requested format if ($AsHexString) { return ($bytes | ForEach-Object { $_.ToString("X2") }) -join "" } elseif ($AsPlainText) { return [System.Text.Encoding]::UTF8.GetString($bytes.ToArray()) } else { return $bytes.ToArray() } } catch { Write-Error "Error converting from Base32: $_" return $null } } } # Create alias for backward compatibility # New-Alias -Name 'Convert-ToBase32' -Value 'ConvertTo-Base32' |