lib/rex/proto/kerberos/model/krb_cred.rb
# -*- coding: binary -*-
module Rex
module Proto
module Kerberos
module Model
# This class provides a representation of a Kerberos KRB-CRED
# message definition.
class KrbCred < Element
# @!attribute pvno
# @return [Integer] The protocol version number
attr_accessor :pvno
# @!attribute msg_type
# @return [Integer] The type of a protocol message
attr_accessor :msg_type
# @!attribute tickets
# @return [Array<Rex::Proto::Kerberos::Model::Ticket>] Tickets encapsulated in this message
attr_accessor :tickets
# @!attribute enc_part
# @return [Rex::Proto::Kerberos::Model::EncryptedData] Encrypted KRB-CRED blob
attr_accessor :enc_part
def ==(other)
pvno == other.pvno &&
msg_type == other.msg_type &&
tickets == other.tickets &&
enc_part == other.enc_part
end
# Decodes the Rex::Proto::Kerberos::Model::KrbCred from an input
#
# @param input [String, OpenSSL::ASN1::ASN1Data] the input to decode from
# @return [self] if decoding succeeds
# @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
def decode(input)
case input
when String
decode_string(input)
when OpenSSL::ASN1::Sequence
decode_asn1(input)
else
raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode KrbCred, invalid input'
end
self
end
# Rex::Proto::Kerberos::Model::KrbCred encoding isn't supported
#
# @raise [NotImplementedError]
def encode
elems = []
elems << OpenSSL::ASN1::ASN1Data.new([encode_pvno], 0, :CONTEXT_SPECIFIC)
elems << OpenSSL::ASN1::ASN1Data.new([encode_msg_type], 1, :CONTEXT_SPECIFIC)
elems << OpenSSL::ASN1::ASN1Data.new([encode_tickets], 2, :CONTEXT_SPECIFIC)
elems << OpenSSL::ASN1::ASN1Data.new([encode_enc_part], 3, :CONTEXT_SPECIFIC)
seq = OpenSSL::ASN1::Sequence.new(elems)
seq_asn1 = OpenSSL::ASN1::ASN1Data.new([seq], KRB_CRED, :APPLICATION)
seq_asn1.to_der
end
# Loads a KrbCred from a kirbi file
# @param [String] file_path the path to load the file from
# @return [Rex::Proto::Kerberos::Model::KrbCred]
def self.load_credential_from_file(file_path)
unless File.readable?(file_path.to_s)
raise ::ArgumentError, "Failed to load kirbi file '#{file_path}'"
end
decode(File.binread(file_path))
end
# Saves a KrbCred to a kirbi file
# @param [String] file_path the path to save the file to
# @return [Integer] The length written
def save_credential_to_file(file_path)
File.binwrite(file_path, encode)
end
private
# Encodes the pvno
#
# @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError]
def encode_pvno
bn = OpenSSL::BN.new(pvno.to_s)
int = OpenSSL::ASN1::Integer.new(bn)
int
rescue OpenSSL::ASN1::ASN1Error
raise Rex::Proto::Kerberos::Model::Error::KerberosDecodingError
end
# Encodes the msg_type field
#
# @return [OpenSSL::ASN1::Integer]
def encode_msg_type
bn = OpenSSL::BN.new(msg_type.to_s)
int = OpenSSL::ASN1::Integer.new(bn)
int
end
# Encodes the ticket field
#
# @return [OpenSSL::ASN1::Sequence]
def encode_tickets
encoded = tickets.map(&:encode)
seq = OpenSSL::ASN1::Sequence.new(encoded)
end
# Encodes the enc_part field
#
# @return [String]
def encode_enc_part
encoded = enc_part.encode
end
# Decodes a Rex::Proto::Kerberos::Model::KrbCred
#
# @param input [String] the input to decode from
def decode_string(input)
asn1 = OpenSSL::ASN1.decode(input)
decode_asn1(asn1)
end
# Decodes a Rex::Proto::Kerberos::Model::KrbCred from an
# OpenSSL::ASN1Data
#
# @param input [OpenSSL::ASN1Data] the input to decode from
def decode_asn1(input)
input.value[0].value.each do |val|
case val.tag
when 0
self.pvno = decode_pvno(val)
when 1
self.msg_type = decode_msg_type(val)
when 2
self.tickets = decode_tickets(val)
when 3
self.enc_part = decode_enc_part(val)
else
raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, "Failed to decode KrbCred (#{val.tag})"
end
end
end
# Decodes the pvno from an OpenSSL::ASN1::ASN1Data
#
# @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
# @return [Integer]
def decode_pvno(input)
input.value[0].value.to_i
end
# Decodes the msg_type from an OpenSSL::ASN1::ASN1Data
#
# @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
# @return [Integer]
def decode_msg_type(input)
input.value[0].value.to_i
end
# Decodes the tickets from an OpenSSL::ASN1::Sequence
#
# @param input [OpenSSL::ASN1::Sequence] the input to decode from
# @return [Array<Rex::Proto::Kerberos::Model::Tickets>]
def decode_tickets(input)
tickets = []
input.value[0].value.each do |val|
tickets << Rex::Proto::Kerberos::Model::Ticket.decode(val)
end
tickets
end
# Decodes the enc_part
#
# @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
# @return [Rex::Proto::Kerberos::Model::EncryptedData]
def decode_enc_part(input)
Rex::Proto::Kerberos::Model::EncryptedData.decode(input.value[0])
end
end
end
end
end
end