asn1

asn1 is a pure V Language module for X.690 Abstract Syntax Notation One (ASN.1) Distinguished Encoding Rules (DER) encoding and decoding.

This module provides you with the ability to generate and parse ASN.1 encoded data. More precisely, it provides you with the ability to generate and parse data encoded with ASN.1’s DER (Distinguished Encoding Rules) encoding. It does not support other than DER.

Status

Warning

This module is under development, its changed rapidly, and even its functionality mostly and hardly tested, i'm sure there are buggy code uncovered recently, so feel free to report an isdue or submit a bug report, or give a feedback.

Supported ASN.1 Type

It's currently supports following basic ASN1 type:

• Boolean
• BitString
• Integer (through int, i64, and math.big.Integer)
• ObjectIdentifier
• NumericString
• Null
• Enumerated
• IA5String (ascii string)
• OctetString
• PrintableString
• UTF8String
• UTCTime
• GeneralizedTime
• VisibleString
• Sequence,
• SequenceOf
• Set
• SetOf

Features

---

• Support mostly basic ASN.1 tag type, except for a few types.
• Supports single and multibyte (high form) tag format for tag number > 31
• Serializing and deserializing of ASN.1 objcet to bytes and vice versa.

Code Examples

Here are some simple usage examples.

Encode

Encode a sequence containing a UTF-8 string, an integer and an explicitly tagged object identifier, conforming to the following ASN.1 specification:

Example ::= SEQUENCE {
    greeting    UTF8String,
    answer      INTEGER,
    type        [1] EXPLICIT OBJECT IDENTIFIER
}

mut seq := new_sequence()

seq.add(new_utf8string('Hello')!) 
seq.add(new_integer(i64(42))) 
seq.add(new_explicit_context(new_oid_from_string('1.3.6.1.3')!, 1))

out := seq.encode()!
assert out == [u8(0x30), 18, u8(12), 5, 72, 101, 108, 108, 111, u8(2), 1, 42, u8(0xA1), 6, 6, 4, 43, 6, 1, 3]

Decode

Decode DER encoding from above.

data := [u8(0x30), 18, u8(12), 5, 72, 101, 108, 108, 111, u8(2), 1, 42, u8(0xA1), 6, 6, 4, 43, 6, 1, 3]
//decode the data 
out := der_decode(data)!

// cast to Sequence 
seq := out.as_sequence()!

assert seq.elements[0] is UTF8String
assert seq.elements[1] is AsnInteger
assert seq.elements[2] is Tagged

Documentation

See the documentation for more detail information on how to use functionality in this module.

License

This project is licensed under the MIT License (see LICENSE file)