A set of parsers/encoders for Basic Encoding Rules (BER [[X.690]]) and Distinguished Encoding Rules(DER [[X.690]]) formats, implemented with the nom parser combinator framework.
It is written in pure Rust, fast, and makes extensive use of zero-copy. A lot of care is taken to ensure security and safety of this crate, including design (recursion limit, defensive programming), tests, and fuzzing. It also aims to be panic-free.
This crate is a rewrite of der-parser to propose a more data-oriented API, and add generalized support for serialization.
Many ideas were borrowed from the crypto/utils/der crate (like
the Any
/TryFrom
/FromDer
mechanism), adapted and merged into a generalized BER/DER crate.
Credits (and many thanks) go to Tony Arcieri for writing the original crate.
BER stands for Basic Encoding Rules, and is defined in [[X.690]]. It defines a set of rules to encode and decode ASN.1 [[X.680]] objects in binary.
[[X.690]] also defines Distinguished Encoding Rules (DER), which is BER with added rules to ensure canonical and unequivocal binary representation of objects.
The choice of which one to use is usually guided by the speficication of the data format based on BER or DER: for example, X.509 uses DER as encoding representation.
The main traits for parsing are the [FromBer
] and [FromDer
] traits.
These traits provide methods to parse binary input, and return either the remaining (unparsed) bytes
and the parsed object, or an error.
The parsers follow the interface from nom, and the [ParseResult
] object is a specialized version
of nom::IResult
. This means that most nom
combinators (map
, many0
, etc.) can be used in
combination to objects and methods from this crate. Reading the nom documentation may
help understanding how to write and combine parsers and use the output.
Minimum Supported Rust Version: 1.63.0
See [doc::recipes] and [doc::derive] for more examples and recipes.
See [doc::debug] for advice and tools to debug parsers.
Parse 2 BER integers:
use asn1_rs::{Integer, FromBer};
let bytes = [ 0x02, 0x03, 0x01, 0x00, 0x01,
0x02, 0x03, 0x01, 0x00, 0x00,
];
let (rem, obj1) = Integer::from_ber(&bytes).expect("parsing failed");
let (rem, obj2) = Integer::from_ber(&bytes).expect("parsing failed");
assert_eq!(obj1, Integer::from_u32(65537));
In the above example, the generic [Integer
] type is used. This type can contain integers of any
size, but do not provide a simple API to manipulate the numbers.
In most cases, the integer either has a limit, or is expected to fit into a primitive type.
To get a simple value, just use the from_ber
/from_der
methods on the primitive types:
use asn1_rs::FromBer;
let bytes = [ 0x02, 0x03, 0x01, 0x00, 0x01,
0x02, 0x03, 0x01, 0x00, 0x00,
];
let (rem, obj1) = u32::from_ber(&bytes).expect("parsing failed");
let (rem, obj2) = u32::from_ber(&rem).expect("parsing failed");
assert_eq!(obj1, 65537);
assert_eq!(obj2, 65536);
If the parsing succeeds, but the integer cannot fit into the expected type, the method will return
an IntegerTooLarge
error.
BER/DER encoding is symmetrical to decoding, using the traits ToBer
and [ToDer
] traits.
These traits provide methods to write encoded content to objects with the io::Write
trait,
or return an allocated Vec<u8>
with the encoded data.
If the serialization fails, an error is returned.
Writing 2 BER integers:
use asn1_rs::{Integer, ToDer};
let mut writer = Vec::new();
let obj1 = Integer::from_u32(65537);
let obj2 = Integer::from_u32(65536);
let _ = obj1.write_der(&mut writer).expect("serialization failed");
let _ = obj2.write_der(&mut writer).expect("serialization failed");
let bytes = &[ 0x02, 0x03, 0x01, 0x00, 0x01,
0x02, 0x03, 0x01, 0x00, 0x00,
];
assert_eq!(&writer, bytes);
Similarly to FromBer
/FromDer
, serialization methods are also implemented for primitive types:
use asn1_rs::ToDer;
let mut writer = Vec::new();
let _ = 65537.write_der(&mut writer).expect("serialization failed");
let _ = 65536.write_der(&mut writer).expect("serialization failed");
let bytes = &[ 0x02, 0x03, 0x01, 0x00, 0x01,
0x02, 0x03, 0x01, 0x00, 0x00,
];
assert_eq!(&writer, bytes);
If the parsing succeeds, but the integer cannot fit into the expected type, the method will return
an IntegerTooLarge
error.
See CHANGELOG.md
.
[X.680]: http://www.itu.int/rec/T-REC-X.680/en "Abstract Syntax Notation One (ASN.1): Specification of basic notation." [X.690]: https://www.itu.int/rec/T-REC-X.690/en "ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)."
See CHANGELOG.md
, and UPGRADING.md
for instructions for upgrading major versions.
Licensed under either of
at your option.
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.