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Rasn1

Rasn1 is a ruby ASN.1 library to encode, parse and decode ASN.1 data in DER format.

Installation

Add this line to your application's Gemfile:

gem 'rasn1'

And then execute:

bundle install

Or install it yourself as:

gem install rasn1

Simple usage

To decode a DER/BER string without checking a model, do:

decoded_der = RASN1.parse(der_string)
decoded_ber = RASN1.parse(ber_string, ber: true)

Advanced usage

All examples below will be based on:

Record ::= SEQUENCE {
 id INTEGER,
 room [0] INTEGER OPTIONAL,
 house [1] INTEGER DEFAULT 0
}
ComplexRecord ::= SEQUENCE {
 bool BOOLEAN,
 data [0] EXPLICIT OCTET STRING,
 a_record Record
}

Create a ASN.1 model

class Record < RASN1::Model
 sequence :record,
 content: [integer(:id),
 integer(:room, implicit: 0, optional: true),
 integer(:house, implicit: 1, default: 0)]
end

More comple classes may be designed by nesting simple classes. For example:

class ComplexRecord < RASN1::Model
 sequence :cplx_record,
 content: [boolean(:bool),
 octet_string(:data, explicit: 0),
 model(:a_record, Record)]
end

Parse a DER-encoded string

record = Record.parse(der_string)
record[:id] # => RASN1::Types::Integer
record[:id].value # => Integer
record[:id].to_i # => Integer
record[:id].asn1_class # => Symbol
record[:id].optional? # => false
record[:id].default # => nil
record[:room].optional # => true
record[:house].default # => 0
record[:id].to_der # => String
cplx_record = ComplexRecord.parse(der_string)
cplx_record[:bool] # => RASN1::Types::Boolean
cplx_record[:bool].value # => TrueClass/FalseClass
cplx_record[:data].value # => String
cplx_record[:data].explicit? # => true
cplx_record[:a_record] # => Record

Generate a DER-encoded string

record = Record.new(id: 12)
record[:id].to_i # => 12
record[:room] # => nil
record[:house] # => 0
# Set one value
record[:room] = 43
record[:room] # => 43
# Set mulitple values
record.set id: 124, house: 155
record.to_der # => String

More information

see https://github.com/sdaubert/rasn1/wiki

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/sdaubert/rasn1.