Class: Ccrypto::Java::HKDFEngine

Inherits:
Object
  • Object
show all
Includes:
DataConversion, TR::CondUtils
Defined in:
lib/ccrypto/java/engines/hkdf_engine.rb

Defined Under Namespace

Classes: HKDFEngineError, HKDFSupportedDigest

Class Method Summary collapse

Instance Method Summary collapse

Methods included from DataConversion

#from_b64, #from_b64_mime, #from_hex, included, #to_b64, #to_b64_mime, #to_bin, #to_hex, #to_java_bytes, #to_str

Constructor Details

#initialize(*args, &block) ⇒ HKDFEngine

Returns a new instance of HKDFEngine.

Raises:

  • (KDFEngineException) 


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# File 'lib/ccrypto/java/engines/hkdf_engine.rb', line 54

def initialize(*args, &block)
  @config = args.first

  raise KDFEngineException, "HKDF config is expected. Given #{@config}" if not @config.is_a?(Ccrypto::HKDFConfig)
  raise KDFEngineException, "Output bit length (outBitLength) value is not given or not a positive value (#{@config.outBitLength})" if is_empty?(@config.outBitLength) or @config.outBitLength <= 0

end

Class Method Details

.find_hkdf_config_by_digest(algo) ⇒ Object 



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# File 'lib/ccrypto/java/engines/hkdf_engine.rb', line 44

def self.find_hkdf_config_by_digest(algo)
  supported_hkdf_configs.find({ calgo: algo })
end

.supported_hkdf_configs ⇒ Object 



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# File 'lib/ccrypto/java/engines/hkdf_engine.rb', line 19

def self.supported_hkdf_configs
  if ENV[Java::ENV_PROBE_DIGEST_KEY] == "true"
    @_supportedHkdf = HKDFSupportedDigest.new
  else
    @_supportedHkdf = HKDFSupportedDigest.load_from_storage("supported_hkdf")
  end

  if @_supportedHkdf.empty?
    @_supportedHkdf = HKDFSupportedDigest.new
    Ccrypto::Java::DigestEngine.supported.each do |dig|
      bcDig = Ccrypto::Java::DigestEngine.to_bc_digest_inst(dig)
      if not bcDig.nil?
        logger.debug "Digest #{dig.inspect} has BC instance #{bcDig}"
        conf = Ccrypto::HKDFConfig.new
        conf.digest = dig
        conf.provider_config = { bc_digest: bcDig }
        @_supportedHkdf.register(conf, { tag_under: :calgo, tag_value: dig.algo })
      end
    end
    @_supportedHkdf.save_to_storage("supported_hkdf")
  end

  @_supportedHkdf
end

Instance Method Details

#derive(input, output = :binary) ⇒ Object 



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# File 'lib/ccrypto/java/engines/hkdf_engine.rb', line 62

def derive(input, output = :binary)
  begin

    logger.debug "HKDF config : #{@config.inspect}"

    case @config.digest
    when Symbol, String
      hkdfConf = self.class.find_hkdf_config_by_digest(@config.digest)
      raise HKDFEngineError, "Unsupported digest '#{@config.digest}'" if is_empty?(hkdfConf)
      digest = hkdfConf.first.digest
    when Ccrypto::DigestConfig
      digest = @config.digest
    else
      raise HKDFEngineError, "Unsupported digest '#{@config.digest}'"
    end

    logger.debug "Digest for HKDF : #{digest.inspect}"

    begin
      dig = Ccrypto::Java::DigestEngine.instance(digest) 
    rescue Exception => ex
      raise KDFEngineException, "Failed to initialize digest engine. Error was : #{ex}"
    end

    #bcDigest = Ccrypto::Java::DigestEngine.to_bc_digest_inst(digest.provider_config[:algo_name])
    #raise KDFEngineException, "Digest '#{digest.algo}' not supported. Please report to library owner for further verification" if bcDigest.nil?

    bcDigest = eval(@config.provider_config[:bc_digest])

    # https://soatok.blog/2021/11/17/understanding-hkdf/
    # info field should be the randomness entrophy compare to salt
    # HKDf can have fix or null salt but better have additional info for each purposes
    @config.info = "" if @config.info.nil?

    logger.debug "Salt length : #{@config.salt.nil? ? "0" : @config.salt.length}"
    logger.debug "Info length : #{@config.info.nil? ? "0" : @config.info.length}"
    logger.debug "Digest : #{bcDigest}"

    logger.warn "Salt is empty!" if is_empty?(@config.salt)

    hkdf = org.bouncycastle.crypto.generators.HKDFBytesGenerator.new(bcDigest)
    hkdfParam = org.bouncycastle.crypto.params.HKDFParameters.new(to_java_bytes(input), to_java_bytes(@config.salt) ,to_java_bytes(@config.info))
    hkdf.init(hkdfParam)

    out = ::Java::byte[@config.outBitLength/8].new
    hkdf.generateBytes(out, 0, out.length)

    case output
    when :b64
      to_b64(out)
    when :hex
      to_hex(out)
    else
      out
    end

  rescue Exception => ex
    raise KDFEngineException, ex
  end
  
end