Digital Evidence Laboratory • Houston, Texas
Forensic Bit-Stream Imaging & Write-Blocking
Non-destructive physical disk acquisitions, Master File Table (MFT) preservation, and dual cryptographic verification (MD5 / SHA-256) under Federal Rule of Evidence 902(14).
What Is Forensic Bit-Stream Imaging and Why Is Hardware Write-Blocking Mandatory?
Forensic bit-stream imaging creates an exact bit-for-bit physical clone of hard drives, solid-state drives, virtualized servers, and RAID arrays without altering evidence media. At E-Investigations, lead examiner Gary Huestis utilizes hardware write-blockers (Tableau, Atola TaskForce) to preserve bit-level unallocated space, volume slack, and Master File Tables (MFT) with simultaneous dual-hash MD5 and SHA-256 verification under Federal Rule of Evidence 902(14).
Bit-Stream Physical Imaging vs. Standard Logical Copying
Standard Windows copy-and-paste or drag-and-drop operations alter file metadata, overwrite volatile last-accessed timestamps, and fail to copy unallocated clusters where deleted evidence resides. Furthermore, simply connecting an evidence drive to a standard Windows computer modifies Registry mount points, volume GUIDs, and file system journals.
E-Investigations performs forensically defensible bit-stream acquisitions adhering strictly to NIST SP 800-86 standards:
1. Hardware Write-Blocking
Physical forensic bridges (Tableau T8u USB 3.0, T35u SATA/IDE, PCIe) intercept all write commands sent from the host operating system, guaranteeing absolute 100% read-only integrity.
2. Unallocated Space & Slack Recovery
Bit-stream images capture every physical sector, including drive slack, unallocated clusters, file system journals, and Volume Shadow Copies (VSS) where deleted files remain intact.
3. Dual-Hash Cryptographic Proof
The source drive and the forensic forensic image (E01 / raw DD) are simultaneously hashed with MD5 and SHA-256 algorithms. Identical hashes mathematically prove that evidence was not altered.
Supported Forensic Media & Enterprise Environments
| Device / Platform | Hardware Toolchain | Evidentiary Deliverables |
|---|---|---|
| NVMe / PCIe SSDs | Tableau T7u PCIe Bridge | Bit-stream E01 image, TRIM mitigation, dual MD5/SHA-256 hashes. |
| SATA & SAS Enterprise Drives | Atola TaskForce / Tableau T35u | High-speed multi-drive imaging, damaged sector recovery maps. |
| Server RAID Arrays (0, 1, 5, 6, 10) | Direct Controller Interrogation | Virtual RAID re-assembly, stripe size calculation, parity reconstruction. |
| Apple Mac Systems (T2 / M1-M4) | Target Disk Mode / Apple Diagnostics | APFS container extraction, FileVault volume decryption with custodial recovery keys. |
| Mobile Devices (iOS & Android) | Cellebrite UFED / Baylexx Engine | Full physical file system extractions, unallocated SQLite carving. |