Base64DecodeString — Dependency Catalog

Source: main.ps1, line 764
Purpose: Decodes a Base64-encoded string into plaintext with optional URL decoding and configurable encoding type
Audience: AI-first, Human-second

1. External PsLib Functions Called

Function	Defined At	Called From	Purpose
`Vbs`	main.ps1:16412	Top-level body	Verbose/logging output handler. Called with `-Caller`, `-Status` (e/w), `-Message`, `-Verbosity`

This function has a minimal external dependency footprint. It only calls Vbs for error/warning logging (e.g., empty input string, unknown encoding type).

2. External Variables Loaded

Variable	Defined At	Type	Description
(none)	—	—	This function does not reference any script-level or global variables. All state is derived from its own parameters.

3. External Binaries / Executables Invoked

Binary	Notes
(none)	This function is entirely .NET-based and does not invoke any external executables.

4. Parameters

Parameter	Type	Alias(es)	Default	Description
`Help`	`[Switch]`	`h`	`$false`	Print detailed help text and return
`InputString`	`[System.String]`	`i`, `in`, `str`, `string`	`$null`	The Base64-encoded string to decode
`Encoding`	`[System.String]`	`e`, `encode`	`UTF8`	Encoding type: `UTF8` or `ASCII`. Unknown values fall back to UTF8 with a warning
`UrlDecode`	`[System.Boolean]`	`u`	`$false`	If `$true`, the decoded output is additionally passed through `[System.Web.HttpUtility]::UrlDecode()`
`Verbosity`	`[System.Boolean]`	`v`	`$true`	Controls whether verbose/log messages are printed to the console

5. Internal Logic Summary

The function uses a numeric "OpsCode" pattern to select the correct decoding path. The OpsCode is computed by summing two values: one based on the Encoding parameter (0 for UTF8, 1 for ASCII) and one based on the UrlDecode parameter (0 for $false, 10 for $true). The resulting OpsCode determines which of four branches executes:

OpsCode	Encoding	UrlDecode	Action
0	UTF8	No	`[System.Text.Encoding]::UTF8.GetString(FromBase64String(...))`
1	ASCII	No	`[System.Text.Encoding]::ASCII.GetString(FromBase64String(...))`
10	UTF8	Yes	UTF8 decode → `[System.Web.HttpUtility]::UrlDecode(...)`
11	ASCII	Yes	ASCII decode → `[System.Web.HttpUtility]::UrlDecode(...)`

6. Internal Sub-Functions

This function defines no internal sub-functions.

7. .NET Types and Methods Used

Type / Method	Usage
`[System.Convert]::FromBase64String()`	Core Base64 → byte-array conversion
`[System.Text.Encoding]::UTF8.GetString()`	Byte-array → UTF8 string conversion
`[System.Text.Encoding]::ASCII.GetString()`	Byte-array → ASCII string conversion
`[System.Web.HttpUtility]::UrlDecode()`	URL-decoding of the decoded string output

8. PowerShell Built-in Cmdlets Used

Cmdlet	Usage Context
`Get-Help`	Displaying function help when `-Help` is specified

9. Return Value

Returns a [System.String] containing the decoded plaintext. Returns nothing (implicit $null) if the input string is empty.

10. Call Graph

Base64DecodeString
├── [validates InputString is non-empty]
│   └── Vbs ◄── external pslib (on error)
├── [validates Encoding parameter]
│   └── Vbs ◄── external pslib (on unknown encoding warning)
├── [computes OpsCode from Encoding + UrlDecode]
└── [executes decode branch based on OpsCode]
    ├── (OpsCode=0)  → UTF8 decode
    ├── (OpsCode=1)  → ASCII decode
    ├── (OpsCode=10) → UTF8 decode + UrlDecode
    └── (OpsCode=11) → ASCII decode + UrlDecode