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# -*- coding: binary -*-
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module Rex
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  module Proto
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    module Kerberos
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      module Model
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        # This class provides a representation of a Kerberos EncryptionKey data
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        # definition
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        class EncryptionKey < Element
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          # @!attribute key
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          #   @return [Integer] The type of encryption key
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          attr_accessor :type
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          # @!attribute value
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          #   @return [String] the key itself
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          attr_accessor :value
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          def ==(other)
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            type == other.type &&
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              value == other.value
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          end
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          # Decodes a Rex::Proto::Kerberos::Model::EncryptionKey
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          #
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          # @param input [String, OpenSSL::ASN1::Sequence] the input to decode from
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          # @return [self] if decoding succeeds
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          # @raise [Rex::Proto::Kerberos::Model::Error::KerberosDecodingError] if decoding doesn't succeed
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          def decode(input)
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            case input
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            when String
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              decode_string(input)
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            when OpenSSL::ASN1::Sequence
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              decode_asn1(input)
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            else
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              raise ::Rex::Proto::Kerberos::Model::Error::KerberosDecodingError, 'Failed to decode EncryptionKey, invalid input'
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            end
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            self
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          end
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          # Encodes a Rex::Proto::Kerberos::Model::EncryptionKey into an
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          # ASN.1 String
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          #
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          # @return [String]
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          def encode
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            elems = []
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            elems << OpenSSL::ASN1::ASN1Data.new([encode_type], 0, :CONTEXT_SPECIFIC)
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            elems << OpenSSL::ASN1::ASN1Data.new([encode_value], 1, :CONTEXT_SPECIFIC)
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            seq = OpenSSL::ASN1::Sequence.new(elems)
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            seq.to_der
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          end
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          private
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          # Decodes a Rex::Proto::Kerberos::Model::EncryptionKey from an String
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          #
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          # @param input [String] the input to decode from
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          def decode_string(input)
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            asn1 = OpenSSL::ASN1.decode(input)
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            decode_asn1(asn1)
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          end
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          # Decodes a Rex::Proto::Kerberos::Model::EncryptionKey from an
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          # OpenSSL::ASN1::Sequence
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          #
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          # @param input [OpenSSL::ASN1::Sequence] the input to decode from
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          def decode_asn1(input)
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            seq_values = input.value
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            self.type = decode_type(seq_values[0])
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            self.value = decode_value(seq_values[1])
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          end
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          # Decodes the type from an OpenSSL::ASN1::ASN1Data
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          #
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          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
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          # @return [Integer]
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          def decode_type(input)
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            input.value[0].value.to_i
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          end
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          # Decodes the value from an OpenSSL::ASN1::ASN1Data
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          #
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          # @param input [OpenSSL::ASN1::ASN1Data] the input to decode from
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          # @return [String]
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          def decode_value(input)
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            input.value[0].value
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          end
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          # Encodes the type field
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          #
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          # @return [OpenSSL::ASN1::Integer]
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          def encode_type
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            bn = OpenSSL::BN.new(type.to_s)
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            int = OpenSSL::ASN1::Integer.new(bn)
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            int
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          end
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          # Encodes the value field
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          #
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          # @return [OpenSSL::ASN1::OctetString]
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          def encode_value
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            OpenSSL::ASN1::OctetString.new(value)
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          end
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        end
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      end
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    end
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  end
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end
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