61 lines
2.2 KiB
Markdown
61 lines
2.2 KiB
Markdown
# Mesozoa
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Why not Anubis? Because it provides no build instructions and only supports Docker.
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Why not using Realm completely? Because the hook system is useless and only allows filtering.
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## Install
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Must be used behind a reverse proxy providing `X-Forwarded-For`.
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## Challenge protocol
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### Challenge generation
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Sent by the server as a cookie.
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`secret <- chosen randomly, long term`
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`salt <- chosen randomly, not stored`
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`timestamp <- UNIX time in seconds, 64 bits, big endian`
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`ua <- User-Agent from request header`
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`ip <- X-Forwarded-For from request header (client's IP)`
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`set-cookie: mesozoa-challenge=BASE64(salt || timestamp || SHA3-256(secret || salt || timestamp || ip || "/" || ua))`
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Where `BASE64` is unpadded.
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### Challenge verification
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Request must contain both cookies `mesozoa-challenge` and `mesozoa-proof`.
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## Security
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### Network handling and HTTP parsing
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This implementation uses cheap tricks and regexes, is probably not fully compliant to HTTP specs, etc.
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You should probably not expose it directly to an open network.
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Please use it behind a safer reverse proxy like Apache or Nginx.
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### Length-extension attack
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SHA3 (used as a MAC in the challenge cookie) is not vulnerable. Values in the hash are either fixed-length, safe, or delimited.
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SHA2 (used for PoW) is vulnerable but nonce is at the beginning so this is not a problem.
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### PoW
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I would like a better PoW: memory-bound and ideally non-parallel. Cuckoo seems a good candidate.
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## License
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[Support me via LiberaPay](https://liberapay.com/tuxmain/donate)
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GNU AGPL v3, CopyLeft 2025 Pascal Engélibert [(why copyleft?)](https://txmn.tk/blog/why-copyleft/)
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This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, version 3 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.
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