5 releases
0.2.1 | Apr 27, 2023 |
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0.2.0 | Apr 12, 2023 |
0.1.2 | Apr 9, 2022 |
0.1.1 | Apr 1, 2022 |
0.1.0 | Apr 1, 2022 |
#4 in #distributed-id
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Used in 2 crates
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block-id
block-id
is a Rust library for generating opaque, unique, and short string values from (unsigned) integers.
tl;dr:
use block_id::{Alphabet, BlockId};
fn main() {
// Random seed.
let seed = 9876;
// Code length.
let length = 5;
let generator = BlockId::new(Alphabet::alphanumeric(), seed, length);
// Number to string.
assert_eq!(Some("wjweA".to_string()), generator.encode_string(0));
assert_eq!(Some("ZxJrE".to_string()), generator.encode_string(1));
assert_eq!(Some("3e0IT".to_string()), generator.encode_string(2));
// String to number.
assert_eq!(Some(2), generator.decode_string("3e0IT"));
}
Introduction
Random-looking alphanumeric strings are often used in place of sequential numeric IDs for user-facing purposes. This has several advantages:
- String identifiers are usually visually distinct, even if they were generated adjacently in sequence.
- The higher information density of a larger alphabet allows for shorter codes.
- Sequential identifiers reveal unnecessary information about ordering and object creation rate that you may not want to reveal.
block-id
is the successor to tiny_id
, which allows the creation of tightly-packed alphanumeric strings. tiny_id
turned out to be difficult to use in a distributed environment because its state needs to be synchronized across every node that needs to generate IDs. Rather than building distributed functionality into a short ID generator, block-id
provides a way of turning a sequential ID generator into a string ID generator by creating a one-to-one mapping between integers and random-looking short strings. That way, any system of generating sequential numeric IDs (for example, a database's sequence generator) can be turned into a system for generating random-looking string IDs.
use block_id::{Alphabet, BlockId};
fn main() {
// The alphabet determines the set of valid characters in an ID.
// For convenience, we include some common alphabets like `alphanumeric`.
let alphabet = Alphabet::alphanumeric();
// The generator takes a u128 as a seed.
let seed = 1234;
// The length of a generated code. This is really a _minimum_ length; larger numbers
// will be converted to longer codes since that's the only way to avoid collisions.
let length = 4;
// A small amount of pre-caching work happens when we create the BlockId instance,
// so it's good to re-use the same generator where possible.
let generator = BlockId::new(alphabet, seed, length);
// Now that we have a generator, we can turn numbers into short IDs.
assert_eq!(Some("In4R".to_string()), generator.encode_string(0));
assert_eq!(Some("4A7N".to_string()), generator.encode_string(440));
assert_eq!(Some("tSp9".to_string()), generator.encode_string(441));
assert_eq!(Some("6z6y".to_string()), generator.encode_string(442));
assert_eq!(Some("ft0M".to_string()), generator.encode_string(443));
// When we've exhausted all 4-digit codes, we simply move on to 5-digit codes.
assert_eq!(Some("YeyKs".to_string()), generator.encode_string(123456789));
// ...and so on.
assert_eq!(Some("pFbrRf".to_string()), generator.encode_string(1234567890));
// Codes are reversible, assuming we have the seed they were generated with.
assert_eq!(Some(1234567890), generator.decode_string("pFbrRf"));
}
How it works
block-id
applies a pipeline of reversible transformations on a data in order to turn it into a string.
- Base conversion turns the input integer into a base-N representation where N is the number of characters in the desired output alphabet.
- Rounds consisting of:
- Permutation applies an N-to-N map to every digit of the base-N representation. The permutation is generated from the random seed passed in the
BlockId
constructor. - Cascade applies a left-to-right cumulative sum, modulo N, to the base-N representation.
- Rotate takes the first digit of the base-N representation and moves it to the last digit, shifting all of the other digits left by one.
- Permutation applies an N-to-N map to every digit of the base-N representation. The permutation is generated from the random seed passed in the
- Alphabetization translates every digit of the base-N representation to a “letter” in the alphabet provided at construction.
The number of rounds is the same as the number of digits in the base-N representation. This gives every digit a chance to influence every other digit.
Security
block-id
is designed to make it easy for a human to distinguish between two sequential codes, not to make it impossible for an adversary to reverse. It should not be considered cryptographically secure.
Dependencies
~345KB