# [RustCrypto]: Object Identifiers (OIDs)
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Const-friendly implementation of the ISO/IEC Object Identifier (OID) standard
as defined in ITU [X.660], with support for BER/DER encoding/decoding as well
as heapless `no_std` (i.e. embedded) environments.
[Documentation][docs-link]
## About OIDs
Object Identifiers, a.k.a. OIDs, are an International Telecommunications
Union (ITU) and ISO/IEC standard for naming any object, concept, or "thing"
with a globally unambiguous persistent name.
The ITU's [X.660] standard provides the OID specification. Every OID is part of
a hierarchical namespace which begins with a *root OID*, which is either the
ITU's root OID (0), the ISO's root OID (1), or the joint ISO/ITU root OID (2).
The following is an example of an OID, in this case identifying the
`rsaEncryption` algorithm:
```text
1.2.840.113549.1.1.1
```
For more information, see: <https://en.wikipedia.org/wiki/Object_identifier>
## Implementation
This library supports parsing OIDs in const contexts, e.g.:
```rust
use const_oid::ObjectIdentifier;
pub const MY_OID: ObjectIdentifier = ObjectIdentifier::new("1.2.840.113549.1.1.1");
```
The OID parser is implemented entirely in terms of `const fn` and without the
use of proc macros.
Additionally, it also includes a `const fn` OID serializer, and stores the OIDs
parsed from const contexts encoded using the BER/DER serialization
(sans header).
This allows `ObjectIdentifier` to impl `AsRef<[u8]>` which can be used to
obtain the BER/DER serialization of an OID, even one declared `const`.
Additionally, it impls `FromStr` and `TryFrom<&[u8]>` and functions just as
well as a runtime OID library.
## License
Licensed under either of:
* [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
* [MIT license](http://opensource.org/licenses/MIT)
at your option.
### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.
[//]: # (badges)
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[docs-link]: https://docs.rs/const-oid/
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[//]: # (links)
[RustCrypto]: https://github.com/rustcrypto
[X.660]: https://www.itu.int/rec/T-REC-X.660