ASN.1 for Ruby

Currently early stage proof-of-concept.

Requires modified version of asn1c, available here: https://github.com/danielcode/asn1c

Works by wrapping C produced by asn1c.

Creates a separate class for each ASN.1 type.

Supports subset of primitive types and these structured types:

• SEQUENCE
• SEQUENCE OF
• CHOICE

Status

ASN.1 Type	Status	Ruby Class
ANY	Not Implemented
BIT_STRING	Implemented	Asn1::Type::BitString
BMPString	Implemented	Asn1::Type::BMPString
BOOLEAN	Implemented	Asn1::Type::Boolean
ENUMERATED	Implemented	N/A
GeneralString	Unsupported	N/A
GeneralizedTime	Implemented	Asn1::Type::GeneralizedTime
GraphicString	Unsupported	N/A
IA5String	Implemented	Asn1::Type::IA5String
INTEGER	Implemented	Asn1::Type::Integer
ISO646String	Implemented	Asn1::Type::ISO646String
NULL	Implemented	Asn1::Type::Null
NumericString	Implemented	Asn1::Type::NumericString
OBJECT_IDENTIFIER	Not Implemented
OCTET_STRING	Implemented	Asn1::Type::OctetString
ObjectDescriptor	Unsupported
PrintableString	Implemented	Asn1::Type::PrintableString
REAL	Not Implemented	Asn1::Type::Real
RELATIVE-OID	Not Implemented
T61String	Unsupported	N/A
TeletexString	Implemented	Asn1::Type::TeletexString
UTCTime	Not Implemented
UTF8String	Implemented	Asn1::Type::UTF8String
UniversalString	Implemented	Asn1::Type::UniversalString
VideotexString	Unsupported
VisibleString	Implemented	Asn1::Type::VisibleString
CHOICE	Implemented	N/A
SEQUENCE	Implemented	N/A
SEQUENCE_OF	Implemented	N/A
SET	Not Implemented	N/A
SET_OF	Not Implemented	N/A

Building

1. clone and install asn1c:
   • git clone https://github.com/danielcode/asn1c.git
   • cd asn1c
   • ./configure --prefix=
   • make; make check; make install
2. clone asn1:
   • git clone https://github.com/danielcode/asn1.git
3. cd asn1/ext/asn1
4. asn1c -fall-defs-global -fwide-types Test.asn1
   • rm Makefile.am.sample
   • rm converter-sample.c
5. cd ../..
6. rake compile
7. rake install_gem

Example Usage

Integer

$ irb
> require 'asn1/asn1'
=> true
> encoded = Asn1::Integer.encode :der, 1234567890
=> "\x02\x04I\x96\x02\xD2"
> Asn1::Integer.decode :der, encoded
=> 1234567890

IA5String

> encoded = Asn1::IA5String.encode :der, 'Hello, world!'
=> "\x16\rHello, world!"
> Asn1::IA5String.decode :der, encoded
=> "Hello, world!"

Sample Sequence

> x = Asn1::Type::SimpleSequence.new
=> #<Asn1::Type::SimpleSequence:0x00000801ca1b20>
> x.simpleString = "Hello, world!"
=> "Hello, world!"
> x.simpleInt = 1
=> 1
> y = Asn1::Schema::SimpleSequence.encode :der, x
=> "0\x12\x02\x01\x01\x16\rHello, world!"
> Asn1::Schema::SimpleSequence.decode :der, y
=> #<Asn1::Type::SimpleSequence:0x00000801c6b728 @simpleString="Hello, world!", @simpleInt=1>

> require 'base64'
=> true
> puts Base64.encode64(y)
MBICAQEWDUhlbGxvLCB3b3JsZCE=

Now, try decoding the base64 encoded string here: http://www.lapo.it/asn1js/

Type Classes

Types are held under Asn1::Type. They include all primitive types and types defined by the user.

Primitive Types

Primitive types currently include:

• Asn1::Type::Boolean
• Asn1::Type::IA5String
• Asn1::Type::Integer
• Asn1::Type::Null
• Asn1::Type::Real
• Asn1::Type::UTF8String

All primitive types have two class methods:

• encode(format, object)
• decode(format, object) where format is one of :xer, :der or :per. However, :per does not currently work.

Primitive Type Aliases

Each type alias in an ASN.1 module maps to a type under Asn1::Type.

E.g. MyInt ::= INTEGER => Asn1::Type::MyInt

Complex Types

Complex types have an associated schema, defined under Asn1::Schema

SEQUENCE

SEQUENCE_OF

ENUMERATED