https://github.com/moreati/fsverity-hash
fs-verity digest implementation for Python
https://github.com/moreati/fsverity-hash
file-integrity fs-verity fsverity hashing-algorithm hashlib
Last synced: about 1 month ago
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fs-verity digest implementation for Python
- Host: GitHub
- URL: https://github.com/moreati/fsverity-hash
- Owner: moreati
- License: mit
- Created: 2023-02-03T20:33:27.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2023-02-27T20:37:18.000Z (about 2 years ago)
- Last Synced: 2025-03-18T07:47:39.657Z (about 1 month ago)
- Topics: file-integrity, fs-verity, fsverity, hashing-algorithm, hashlib
- Language: Python
- Homepage: https://pypi.org/project/fsverity-hash/
- Size: 15.6 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 13
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# fsverity-hash
Python implementation of [fs-verity] hash scheme.
## Installation
```
python -mpip install fsverity-hash
```
## Usage
`FSVerityHash` exposes a [hashlib] like interface
```python
>>> import fsverity_hash
>>> m = fsverity_hash.FSVerityHash()
>>> m.update(b"Nobody inspects the spammish repetition")
>>> m.digest()
b'>\xd6s\xd52<\x9e\x1c`\x82\x0f td\xb0\xb8X\xa9\x0b\xa4\xff\x94\x0b\x12=\xd1kBV\x99\xce\xbe'
>>> m.hexdigest()
'3ed673d5323c9e1c60820f207464b0b858a90ba4ff940b123dd16b425699cebe'
```
the `fsverity digest` command produces the same digest
```
$ echo -n "Nobody inspects the spammish repetition" > file.txt
$ fsverity digest file.txt
sha256:3ed673d5323c9e1c60820f207464b0b858a90ba4ff940b123dd16b425699cebe file.txt
```
The module exposes the same command line interface as `fsverity digest`
```
$ echo -n "Nobody inspects the spammish repetition" > spam.txt
$ fsverity digest spam.txt
sha256:3ed673d5323c9e1c60820f207464b0b858a90ba4ff940b123dd16b425699cebe spam.txt
$ python3 -m fsverity_hash spam.txt
sha256:3ed673d5323c9e1c60820f207464b0b858a90ba4ff940b123dd16b425699cebe spam.txt
$ python3 -m fsverity_hash --help
usage: fsverity_hash.py [-h] [--hash-alg {sha256,sha512}] [--block-size BYTES]
[--compact]
[FILE ...]
Compute fs-verity hashes
positional arguments:
FILE Input file(s) to process (default: stdin)
optional arguments:
-h, --help show this help message and exit
--hash-alg {sha256,sha512}
Merkle tree block hashing algorithm (default: sha256)
--block-size BYTES Merkle tree block size in bytes (default: 4096)
--compact Omit the hash algorithm name when printing digests
```
## Limitations
- Upto 8 GiB can be hashed. This is an implementation limit, not a limitation of fs-verity hashes in general.
- Salted hashes aren't implemented.
- No automated tests.
- No testing of custom block sizes.
- `FSVerityHash` objects cannot be copied.
## Other implementations
- https://git.kernel.org/pub/scm/fs/fsverity/fsverity-utils.git
reference libfsverity implementation and `fsverity` command
- https://github.com/rvolgers/fs-verity-rs Rust crate
## Further reading
- https://manpages.debian.org/testing/fsverity/fsverity.1.en.html
- https://www.kernel.org/doc/html/v6.1/filesystems/fsverity.html
[fs-verity]: https://www.kernel.org/doc/html/v6.1/filesystems/fsverity.html#file-digest-computation
[hashlib]: https://docs.python.org/3/library/hashlib.html