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BlockHashLoc (BHL) enable the recovery of files via previously made small files with a list of blocks hashes.
With adequately sized blocks (512 bytes, 4KB, etc. depending on the media and File System), this let one recover a file regardless of the FS used, or the FS integrity, or the fragmentation level.
Tech spec
Byte order: Big Endian
Hash: SHA-256
BHL file structure
| section
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desc
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note
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| Header
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Signature & version
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| Metadata
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Misc info
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| Hash
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Blocks hash list & final hash
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| Last block
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zlib compressed last block remainder
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if needed
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| pos
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to pos
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size
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desc
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| 0
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12
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13
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Signature = ‘BlockHashLoc’ + 0x1a
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| 13
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13
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1
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Version byte
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| 14
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16
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4
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Block size
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| 18
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24
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8
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File size
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Metadata
| pos
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to pos
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size
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desc
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| 26
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28
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4
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Metadata section size
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| 30
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var
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var
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Encoded metadata list
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Hash
| pos
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to pos
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size
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desc
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| var
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var
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32
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1st block hash
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| …
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…
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32
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…
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| var
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var
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32
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Last block hash
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| var
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var
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32
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Hash of all previous block hashes
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Versions
Currently the only version is 1.
Metadata encoding
| Bytes
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Field
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| 3
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ID
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| 1
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Len
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| n
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Data
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IDs
| ID
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Desc
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| FNM
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filename (utf-8)
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| FDT
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date & time (8 bytes, seconds since epoch)
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External Links
