#HashIds for Rust

A Rust port of the JavaScript hashids implementation. It generates YouTube-like hashes from one or many numbers. Use hashids when you do not want to expose your database ids to the user. Website: http://www.hashids.org/

What is it?

hashids (Hash ID's) creates short, unique, decodeable hashes from unsigned (long) integers.

It was designed for websites to use in URL shortening, tracking stuff, or making pages private (or at least unguessable).

This algorithm tries to satisfy the following requirements:

1. Hashes must be unique and decodable.
2. They should be able to contain more than one integer (so you can use them in complex or clustered systems).
3. You should be able to specify minimum hash length.
4. Hashes should not contain basic English curse words (since they are meant to appear in public places - like the URL).

Instead of showing items as 1, 2, or 3, you could show them as U6dc, u87U, and HMou. You don't have to store these hashes in the database, but can encode + decode on the fly.

All (long) integers need to be greater than or equal to zero.

Usage

Import the package

use hashids::HashIds;

Create the encoder/decoder HashidCodec

The builder allows you to customize the encoding process: salt, alphabet and length. You must pass a unique salt value so your hashes differ from everyone else's. I use "this is my salt" as an example.

You can pass it through code, but it is recommended to pass it through environnment variable. If it's not set through code, it will look for the HASHID_SALT environnment variable, or send a Error::MissingSalt

Encrypting one number

let id_builder = HashIdBuilder::new().with_salt("this is my salt").ok().unwrap();

let numbers: Vec<i64> = vec![12345];
let hash = id_builder.encode(&numbers);

hash is now going to be:

NkK9

Decrypting

Notice during decoding, the same builder is used, which will use the same salt.

let longs = id_builder.decode("NkK9".to_string());

longs is now going to be:

[ 12345 ]

Decrypting with different salt

Decryption will not work if salt is changed:

let wrong_id_builder = HashIdBuilder::new_with_salt(HashidSalt::from("not the same salt")).unwrap();

let numbers = wrong_id_builder.decode("NkK9");

numbers is now going to be:

[]

Encrypting several numbers

let id_builder = HashIdBuilder::new_with_salt(HashidSalt::from("this is my salt")).unwrap();

let numbers: Vec<i64> = vec![683, 94108, 123, 5];
let hash = ids.encode(&numbers);

hash is now going to be:

aBMswoO2UB3Sj

Decrypting is done the same way

let id_builder = HashIdBuilder::new_with_salt(HashidSalt::from("this is my salt")).unwrap();

let longs = ids.decode("aBMswoO2UB3Sj".to_string());

longs is now going to be:

[ 683, 94108, 123, 5 ]

Encrypting and specifying minimum hash length

Here we encode integer 1, and set the minimum hash length to 8 (by default it's 0 -- meaning hashes will be the shortest possible length).

let id_builder = HashIdBuilder::new_with_salt_and_min_length(HashidSalt::from("this is my salt"), 8).unwrap();

let numbers : Vec<i64> = vec![1];
let hash = ids.encode(&numbers);

hash is now going to be:

gB0NV05e

Decrypting

let ids_some = HashIds::new_with_salt_and_min_length("this is my salt".to_string(), 8);
let ids = match ids_some {
  Ok(v) => { v }
  Err(e) => {
    println!("error");
    return;
  }
};

let numbers = ids.decode("gB0NV05e")

numbers is now going to be:

[ 1 ]

Specifying custom hash alphabet

Here we set the alphabet to consist of only four letters: "0123456789abcdef"

let ids_some = HashIds::new("this is my salt".to_string(), 0, "0123456789abcdef".to_string());
let ids = match ids_some {
  Ok(v) => { v }
  Err(e) => {
    println!("error");
    return;
  }
};


let numbers : Vec<i64> = vec![1234567];
hashids.encode(&numbers);

hash is now going to be:

b332db5

Randomness

The primary purpose of hashids is to obfuscate ids. It's not meant or tested to be used for security purposes or compression. Having said that, this algorithm does try to make these hashes unguessable and unpredictable:

Repeating numbers

let ids_some = HashIds::new_with_salt("this is my salt".to_string());
let ids = match ids_some {
  Ok(v) => { v }
  Err(e) => {
    println!("error");
    return;
  }
};

let numbers: Vec<i64> = vec![5, 5, 5, 5];
let encode = ids.encode(&numbers);

You don't see any repeating patterns that might show there's 4 identical numbers in the hash:

1Wc8cwcE

Same with incremented numbers:

let ids_some = HashIds::new_with_salt("this is my salt".to_string());
let ids = match ids_some {
  Ok(v) => { v }
  Err(e) => {
    println!("error");
    return;
  }
};

let numbers: Vec<i64> = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let encode = ids.encode(&numbers);

hash will be :

kRHnurhptKcjIDTWC3sx

Incrementing number hashes:

let ids_some = HashIds::new_with_salt("this is my salt".to_string());
let ids = match ids_some {
  Ok(v) => { v }
  Err(e) => {
    println!("error");
    return;
  }
};

let numbers_1: Vec<i64> = vec![1];
let encode_1 = ids.encode(&numbers_1);

let numbers_2: Vec<i64> = vec![2];
let encode_2 = ids.encode(&numbers_2);

let numbers_3: Vec<i64> = vec![3];
let encode_3 = ids.encode(&numbers_3);

let numbers_4: Vec<i64> = vec![4];
let encode_4 = ids.encode(&numbers_4);

let numbers_5: Vec<i64> = vec![5];
let encode_5 = ids.encode(&numbers_5);

Bad hashes

I wrote this class with the intent of placing these hashes in visible places - like the URL. If I create a unique hash for each user, it would be unfortunate if the hash ended up accidentally being a bad word. Imagine auto-creating a URL with hash for your user that looks like this - http://example.com/user/a**hole

Therefore, this algorithm tries to avoid generating most common English curse words with the default alphabet. This is done by never placing the following letters next to each other:

c, C, s, S, f, F, h, H, u, U, i, I, t, T

Contact

Follow me @charsyam, @IvanAkimov

License

MIT License. See the LICENSE file.