https://github.com/woodruffw/baseperm
A small tool for generating valid permutations of strings in baseN alphabets.
https://github.com/woodruffw/baseperm
base32 base64 permutation rust
Last synced: 11 months ago
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A small tool for generating valid permutations of strings in baseN alphabets.
- Host: GitHub
- URL: https://github.com/woodruffw/baseperm
- Owner: woodruffw
- License: other
- Created: 2020-01-28T01:50:35.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2023-03-05T22:04:34.000Z (about 3 years ago)
- Last Synced: 2025-04-16T03:15:33.961Z (11 months ago)
- Topics: base32, base64, permutation, rust
- Language: Rust
- Homepage: https://crates.io/crates/baseperm
- Size: 85.9 KB
- Stars: 4
- Watchers: 2
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
baseperm
========
[](https://github.com/woodruffw/baseperm/actions/workflows/ci.yml)
A small tool for generating valid permutations of strings in base*N* alphabets.
## Theory of Operation
Many popular binary-to-printable serialization/encoding schemes use
alphabets whose bitnesses do not allow 8-bit bytes to fit evenly inside a symbol
(or multiple symbols):
* [base32](https://en.wikipedia.org/wiki/Base32): 5 bits
* [base64](https://en.wikipedia.org/wiki/Base64): 6 bits
* [base58](https://en.wikipedia.org/wiki/Base58): \~5.86 bits
Consequently, these encodings employ padding schemes to round their outputs to 8-bit multiples.
`baseperm` manipulates the padding bits in these encodings to produce distinct, valid encoded
forms that decode to the same input.
## Why?
Programmers frequently make the mistake of assuming that encoded representations have a 1-1
correspondence with their inputs. This results in all kinds of interesting, potentially exploitable
errors:
* Ratelimiting bypasses due to keying on the serialized form
* Dedeuplication and reuse bypasses
* Forced dictionary collisions
## Installation
`baseperm` is a single command-line program. You can install it using `cargo`:
```bash
cargo install baseperm
```
Or by building it locally:
```bash
git clone https://github.com/woodruffw/baseperm && cd baseperm
cargo build
```
## Usage
`baseperm` takes a permutation candidate on `stdin` and writes all permuted equivalent forms
to `stdout`, separated by newlines. The original input is also included in the output, and (RFC4648)
base64 is the default.
```bash
echo "hello!" | base64 | baseperm
```
Alternative encodings can be specified with `-e`, `--encoding`:
```bash
echo "hello!" | base32 | baseperm -e base32
```
See `baseperm -h` for a full list of supported encodings.