---
title: Search and strip byte-array headers
summary: Locate a byte or text pattern within a byte array and optionally strip bytes preceding it, for example removing junk bytes before a PDF file header.
status: draft
owner: Framework.NCore maintainers
last_reviewed: 2026-10-02
library: SAIF.NetCore.Common
reference_type: package
operation_id: OP-09
trigger: A consumer calls `ByteExtensions.Search` or `.StripHeader` on a `byte[]`.
---

# Search and strip byte-array headers

Locate a byte or text pattern within a byte array and optionally strip bytes preceding it, for example removing junk bytes before a PDF file header. This operation is triggered when a consumer calls `ByteExtensions.Search` or `.StripHeader` on a `byte[]`.

| Field | Value |
| --- | --- |
| **Operation ID** | OP-09 |
| **Trigger** | A consumer calls `ByteExtensions.Search` or `.StripHeader` on a `byte[]`. |
| **Inputs** | `bytes` (byte[]), `searchFor` (string or byte[]), optional `start` (int, default 0), `maxBytesToSearch` (int) |
| **Outputs** | `Search` returns the match position or `-1`; `StripHeader` returns a (possibly trimmed) `byte[]` and an `out bool found`. |
| **Primary components** | `ByteExtensions.Search`, `.StripHeader`, `.GetMD5Hash` |
| **Entry point** | `src/SAIF.NetCore.Common/SAIF.NetCore.Common/SAIF.NetCore.Common/Extensions/ByteExtensions.cs` |

## Steps

1. `Search`: perform a linear search for `searchFor` starting at `start`; when `maxBytesToSearch > 0`, it is treated as a positive absolute inclusive candidate-start limit — the search still examines the candidate position exactly at `maxBytesToSearch`, it just stops considering any later start position. A non-positive `maxBytesToSearch` disables the limit entirely. The string overload encodes the search text as ASCII.
   - Return the match position, or `-1` if not found.
2. `StripHeader(bytes, searchFor, out found, max=100)`: call `Search` for the header text, forwarding the same `maxBytesToSearch` candidate-start limit.
3. If the match position is greater than `0`, return the bytes from that position onward and set `found = true`. ([BR-021](../business-rules.md#br-021-a-header-is-stripped-only-when-found-strictly-after-position-zero))
   - If the position is `0` (header already at the start) or `-1` (not found): return the original array unchanged and set `found = false`.
4. `GetMD5Hash`: compute and return the raw 16-byte MD5 digest of the byte array (`byte[]`, not a hex string). Callers that need a hex-encoded representation must format the bytes themselves.
   - MD5 is cryptographically broken; acceptable for checksums only, not for security purposes*.

## Process flow

The following diagram visualizes this operation's control flow.

```mermaid
flowchart TD
	Start([Call StripHeader]) --> Search[Search for header text]
	Search --> PosCheck{position > 0?}
	PosCheck -->|Yes| Strip["Return bytes from position<br>onward, found = true"]
	PosCheck -->|No| Unchanged["Return original array,<br>found = false"]
	Strip --> End([Return result])
	Unchanged --> End
```

## Failure and edge-case behavior

- Header located at position `0`: treated the same as not-found (`found = false`), per [BR-021](../business-rules.md#br-021-a-header-is-stripped-only-when-found-strictly-after-position-zero).
- `GetMD5Hash` is suitable only for checksums, never for security-sensitive integrity checks*.
- `maxBytesToSearch` is an absolute inclusive candidate-start index, not a count of bytes relative to `start`; the matched header's remaining bytes can extend beyond it since only the starting candidate position is bounded.

## 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. Statements marked with `**` could not be confirmed; treat
> as unknown until verified.

## Sources
- `src/SAIF.NetCore.Common/SAIF.NetCore.Common/SAIF.NetCore.Common/Extensions/ByteExtensions.cs`