BHL File

What are BHL files and how to open them

Are you having problems opening a BHL file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BHL files.

What is a BHL file?

A .BHL file is a BlockHashLoc Recovery Info file.

BlockHashLoc Recovery Info files are metadata files created by the BlockHashLoc project by Marco Pontello. Their purpose is to aid in recovering files after a total loss of filesystem structures (such as partition tables, directory data or a corrupted filesystem), even when the filesystem used by the storage medium is unknown. A BlockHashLoc recovery info file stores cryptographic hashes of fixed-size blocks of the file alongside metadata so that each block can later be located in a raw disk image or other media by recomputing hashes on candidate blocks.

Production of recovery info files is done via the BlockHashLoc tool "BHLMake," which reads one or more files and writes a parallel recovery file for each. Recovery is performed via "BHLReco," which scans a disk image, computes hashes of blocks, matches them against stored hashes in the recovery files, and reconstructs the original files from matching blocks. Typical workflows involve selecting a block size (such as 512 bytes or 4 kilobytes), generating the recovery info files, then later scanning raw media with those files to reconstruct lost data.

Internally, the file begins with a fixed header signature consisting of the ASCII string BlockHashLoc plus a specific byte (0x1A) and version byte, followed by fields for block-size and the original file size. After a metadata section, it contains a sequence of block hashes: one hash per block, using SHA-256, and also a final hash over all previous block hashes. If the file ends with a partial block (a "last block remainder"), that part is compressed using zlib in version 1.

Byte signature information begins with the ASCII signature "BlockHashLoc\x1A\x01" at offset zero identifying version 1 as written by the format vendor.

How to open BHL files

Important: Different programs may use files with the BHL file extension for different purposes, so unless you are sure which format your BHL file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 24, 2026

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