Module: CcipherFactory::SymKeyCipher::SymKeyDecrypt

Includes:
Common, Compression::CompressionHelper, TR::CondUtils
Defined in:
lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb

Defined Under Namespace

Classes: SymKeyDecryptError

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Compression::CompressionHelper

#compress_data_if_active, #compression_off, #compression_on, #compressor, #decompress_data_if_active, #decompressor, #decompressor_from_encoded, #encode_null_compressor, #is_compression_on?

Methods included from Common

#attach_mode, #cleanup_intOutputBuf, #cleanup_intOutputFile, #detach_mode, #disposeOutput, #intOutputBuf, #intOutputFile, #is_attach_mode?, #is_output_given?, #output, #output_obj, #sanitize_symbol, #write_to_output

Instance Attribute Details

#key ⇒ Object

Returns the value of attribute key.



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 13

def key
  @key
end

Instance Method Details

#decrypt_final ⇒ Object 



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 112

def decrypt_final

  begin
    dec = @cipher.final 
    logger.debug "Final length : #{dec.length}"
    res = decompress_data_if_active(dec)
    write_to_output(res)
  rescue Ccrypto::CipherEngineException => ex
    raise SymKeyDecryptionError, ex
  end

  @cipher = nil

  @key = nil
  # this is to clear up the cipher object from memory 
  # including key and IV value
  # Tested with aes-finder utility on ruby 3.0.2
  # https://github.com/mmozeiko/aes-finder
  GC.start

end

#decrypt_init(*args, &block) ⇒ Object

Raises:



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 19

def decrypt_init(*args, &block)

  #@decKey = args.first
  raise SymKeyDecryptError, "Decryption key is required" if is_empty?(@key)

  if block
    instance_eval(&block)
    decrypt_final
  else
    self
  end

end

#decrypt_update_cipher(val) ⇒ Object

Raises:



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 78

def decrypt_update_cipher(val)

  raise SymKeyCipherError, "Please call update_meta() first before update_cipher()" if @cipher.nil?
  
  logger.debug "Given cipher data : #{val.length}"

  dec = @cipher.update(val)


  if not_empty?(dec) and dec.length > 0

    logger.debug "After cipher before compression check : #{dec.length}"
    res = decompress_data_if_active(dec)
    write_to_output(res)

    #if @decompressor.nil?
    #  dc = dec
    #else
    #  begin
    #    dc = @decompressor.decompress_update(dec)
    #  rescue Zlib::Error => ex
    #    raise SymKeyDecryptionError, "Data decompression failed: #{ex.message}"
    #  end
    #end

    #write_to_output(dc)

  else

    logger.debug "Cipher update returns nothing"
  end

end

#decrypt_update_meta(val) ⇒ Object 



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 33

def decrypt_update_meta(val)

  intOutputBuf.write(val)
  begin
    Encoding.extract_meta(intOutputBuf) do |meta, bal|

      ts = BinStruct.instance.struct_from_bin(meta)
      @mode = BTag.value_constant(ts.mode)
      iv = ts.iv
      comp = ts.compression

      cts = BinStruct.instance.struct_from_bin(comp)
      if cts.oid == BTag.constant_value(:compression_zlib)
        @decompressor = CcipherFactory::Compression::Compressor.new
        @decompressor.decompress
        @decompressor.decompress_init
        @decompressor.decompress_update_meta(comp)

        compression_on
        logger.tdebug :symkey_dec, "Compression is active"
      else
        compression_off
        logger.tdebug :symkey_dec, "Compression is NOT active"
      end

      authTag = ts.auth_tag

      algoDef = SymKeyCipher.algo_default(@key.keytype)

      cconf = Ccrypto::DirectCipherConfig.new({ algo: @key.keytype, keysize: @key.keysize, mode: @mode, padding: :pkcs5 })
      cconf.cipherOps = :decrypt
      cconf.key = @key.key
      cconf.iv = iv if not_empty?(iv)
      cconf.auth_tag = authTag if cconf.respond_to?(:auth_tag=)
      @cipher = Ccrypto::AlgoFactory.engine(cconf)

      @cipher

    end
  rescue Encoding::InsufficientData => e
  end


end

#init ⇒ Object 



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 15

def init

end

#logger ⇒ Object 



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# File 'lib/ccipher_factory/symkey_cipher/symkey_decrypt.rb', line 134

def logger
  if @logger.nil?
    @logger = Tlogger.new
    @logger.tag = :symkey_dec
  end
  @logger
end