# rust-asn1
[![Dependency Status][deps-rs-image]][deps-rs-link]
[![Documentation][docs-rs-image]][docs-rs-link]
This is a Rust library for parsing and generating ASN.1 data (DER only).
## Installation
Add `asn1` to your `Cargo.toml`:
```console
$ cargo add asn1
```
Builds on Rust 1.65.0 and newer.
`rust-asn1` is compatible with `#![no_std]` environments:
```console
$ cargo add asn1 --no-default-features
```
## Changelog
### [0.21.3]
#### Added
- `BitString::new` is now `const fn`.
### [0.21.2]
#### Added
- `BigInt::new`, `BigUint::new`, and `DateTime::new` are now `const fn`.
### [0.21.1]
#### Added
- `Parser` now exposes a `peek_tag` method that returns the tag of the next
element in the parse, without consuming that element.
([#532](https://github.com/alex/rust-asn1/pull/532))
- `Parser` now exposes `read_explicit_element` and `read_implicit_element`
methods that allow parsing EXPLICIT/IMPLICIT elements when the tag number
is not known at compile time.
- `PrintableString`, `Utf8String`, `BMPString`, and `UniversalString` now
`#[derive(Hash)]`. ([#536](https://github.com/alex/rust-asn1/pull/536))
### [0.21.0]
#### Changes
- Updated MSRV to 1.65.0.
#### Fixes
- Fixed ["perfect derives"](https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive/)
in conjunction with `#[derive(Asn1DefinedByRead)]` and
`#[derive(Asn1DefinedByWrite)]`.
([#506](https://github.com/alex/rust-asn1/pull/506))
### [0.20.0]
#### :rotating_light: Breaking changes
- Removed `Writer::{write_explicit_element, write_optional_explicit_element, write_implicit_element, write_optional_implicit_element}`.
These can all be better accomplished with the `asn1::Explicit` and
`asn1::Implicit` types.
#### Fixes
- Fixed ["perfect derives"](https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive/)
in conjunction with `#[implicit]` and `#[explicit]`.
([#502](https://github.com/alex/rust-asn1/pull/502))
### [0.19.0]
#### :rotating_light: Breaking changes
- `GeneralizedTime` has been renamed to `X509GeneralizedTime`. The type does
not allow fractional seconds, however this restriction is not actually a DER
rule, it is specific to X.509.
([#494](https://github.com/alex/rust-asn1/pull/494))
- `GeneralizedTime` is a new type that accepts fractional seconds
replacing the old `GeneralizedTime`.
([#492](https://github.com/alex/rust-asn1/pull/492))
- `#[derive(asn1::Asn1Read)]` and `#[derive(asn1::Asn1Write)]` now implement
["perfect derives"](https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive/).
([#496](https://github.com/alex/rust-asn1/pull/496))
[deps-rs-image]: https://deps.rs/repo/github/alex/rust-asn1/status.svg
[deps-rs-link]: https://deps.rs/repo/github/alex/rust-asn1
[docs-rs-image]: https://docs.rs/asn1/badge.svg
[docs-rs-link]: https://docs.rs/asn1/