---
title: Generate random password
summary: Produces a random password of a caller-specified length drawn from a restricted, visually-unambiguous character set.
status: draft
owner: SAIF
last_reviewed: 2026-07-30
library: SAIF.Business.Security.SystemUser
reference_type: package
operation_id: OP-SU-11
trigger: Caller calls clsSystemUser.GenerateRandomPWD([inLength])
---

# Generate random password

`GenerateRandomPWD` builds a random password character-by-character from the `PWDCHARLIST` constant, re-seeding the random-number generator partway through the loop to reduce sequence predictability.

| Field | Value |
| --- | --- |
| **Operation ID** | OP-SU-11 |
| **Trigger** | Caller calls `clsSystemUser.GenerateRandomPWD([inLength])` |
| **Inputs** | Optional `inLength` (defaults to `6`) |
| **Outputs** | Randomly generated password string of the requested length |
| **Primary components** | `clsSystemUser.GenerateRandomPWD(...)` |
| **Entry point** | `Business\SAIF.Business.Security.SystemUser\clsSystemUser.vb` |

## Steps

1. **Determine the character range.** `charLen` is set to `PWDCHARLIST.Length - 1`, the maximum valid index into the constant character list ([BR-015](../business-rules.md#br-015-generated-passwords-exclude-visually-ambiguous-characters)).
2. **Seed the random-number generator.** `Randomize(Now.Millisecond)` seeds VB's shared random-number state using the current millisecond value.
3. **Loop once per requested character.** For `i` from `1` to `inLength`:
   - Compute `newPos = CInt(Rnd() * charLen)`.
   - Append `PWDCHARLIST.Substring(newPos, 1)` to the output string.
   - If `newPos > (charLen * 0.5)`, re-seed with `Randomize(Now.Millisecond)` again before the next iteration.
4. **Return the assembled password.** The completed string is returned once the loop finishes.

## Process flow

The following diagram visualizes this operation's control flow.

```mermaid
flowchart TD
	Start([Caller calls GenerateRandomPWD]) --> Seed[Randomize with Now.Millisecond]
	Seed --> Loop{More characters needed?}
	Loop -->|Yes| Pick[Compute random index and append character]
	Pick --> ReseedCheck{Index > half of charLen?}
	ReseedCheck -->|Yes| Reseed[Re-seed random generator]
	ReseedCheck -->|No| Loop
	Reseed --> Loop
	Loop -->|No| Return([Return assembled password])
```

## Failure and edge-case behavior

- `PWDCHARLIST` excludes visually ambiguous characters (`0`, `O`, `I`, `l`, `1`) by construction, per [BR-015](../business-rules.md#br-015-generated-passwords-exclude-visually-ambiguous-characters), but the constant repeats its character set twice within the same string, which affects the relative frequency of characters rather than which characters can appear.*
- Seeding with `Now.Millisecond` provides limited entropy — the seed range is bounded to a single millisecond value (0–999), which is a cryptographically weak seeding strategy for password generation.*
- The re-seeding condition (`newPos > charLen * 0.5`) is a purely internal implementation detail with no externally observable effect beyond potentially altering the random sequence for subsequent characters.*
- A caller-supplied `inLength` of `0` or negative produces an empty or unpredictable result since the loop bounds are `1 To inLength`.*

## Related documentation

- [Operations and processes](../operations-processes.md)
- [Business rules](../business-rules.md)

> **Note:** Statements marked with `*` were inferred from code structure, naming
> conventions, or contextual evidence where direct confirmation was not available
> in source artifacts.

## Sources

- `Business\SAIF.Business.Security.SystemUser\clsSystemUser.vb`