Class: McAPI::Encryption::JweCrypto

Inherits:
Object
  • Object
show all
Defined in:
lib/mcapi/encryption/crypto/jwe-crypto.rb

Overview

JWE Crypto class provide RSA/AES encrypt/decrypt methods

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ JweCrypto

Create a new instance with the provided config

Parameters:

  • config (Hash) —

    configuration object



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# File 'lib/mcapi/encryption/crypto/jwe-crypto.rb', line 21

def initialize(config)
  @encoding = config['dataEncoding']
  @cert = OpenSSL::X509::Certificate.new(IO.binread(config['encryptionCertificate']))
  if config['privateKey']
    @private_key = OpenSSL::PKey.read(IO.binread(config['privateKey']))
  end
  @encrypted_value_field_name = config['encryptedValueFieldName'] || 'encryptedData'
  @public_key_fingerprint = compute_public_fingerprint
end

Instance Method Details

#decrypt_data(encrypted_data:) ⇒ String

Perform data decryption

Parameters:

  • encrypted_data (String) —

    encrypted data to decrypt

Returns:

  • (String) —

    Decrypted JSON object



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# File 'lib/mcapi/encryption/crypto/jwe-crypto.rb', line 70

def decrypt_data(encrypted_data:)
  parts = encrypted_data.split('.')
  encrypted_header, encrypted_key, initialization_vector, cipher_text, authentication_tag = parts

  jwe_header = jwe_decode(encrypted_header)
  encrypted_key = jwe_decode(encrypted_key)
  iv = jwe_decode(initialization_vector)
  cipher_text = jwe_decode(cipher_text)
  cipher_tag = jwe_decode(authentication_tag)

  md = OpenSSL::Digest::SHA256
  cek = @private_key.private_decrypt_oaep(encrypted_key, '', md, md)

  enc_method = JSON.parse(jwe_header)['enc']

  if enc_method == "A256GCM"
    enc_string = "aes-256-gcm"
  elsif enc_method == "A128GCM"
    enc_string = "aes-128-gcm"
  elsif enc_method == "A192GCM"
    enc_string = "aes-192-gcm"
  elsif enc_method == "A128CBC-HS256"
    cek = cek.byteslice(16, cek.length)
    enc_string = "aes-128-cbc"
  else
    raise Exception, "Encryption method '#{enc_method}' not supported."
  end

  cipher = OpenSSL::Cipher.new(enc_string)
  cipher.decrypt
  cipher.key = cek
  cipher.iv = iv
  if enc_method == "A256GCM" || enc_method == "A128GCM" || enc_method == "A192GCM"
    cipher.auth_data = encrypted_header
    cipher.auth_tag = cipher_tag
  end

  cipher.update(cipher_text) + cipher.final
end

#encrypt_data(data:) ⇒ Hash

Perform data encryption:

Parameters:

  • data (String) —

    json string to encrypt

Returns:

  • (Hash) —

    encrypted data



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# File 'lib/mcapi/encryption/crypto/jwe-crypto.rb', line 38

def encrypt_data(data:)
  cek = SecureRandom.random_bytes(32)
  iv = SecureRandom.random_bytes(12)

  md = OpenSSL::Digest::SHA256
  encrypted_key = @cert.public_key.public_encrypt_oaep(cek, '', md, md)

  header = generate_header('RSA-OAEP-256', 'A256GCM')
  json_hdr = header.to_json
  auth_data = jwe_encode(json_hdr)

  cipher = OpenSSL::Cipher.new('aes-256-gcm')
  cipher.encrypt
  cipher.key = cek
  cipher.iv = iv
  cipher.padding = 0
  cipher.auth_data = auth_data
  cipher_text = cipher.update(data) + cipher.final

  payload = generate_serialization(json_hdr, encrypted_key, cipher_text, iv, cipher.auth_tag)
  {
    @encrypted_value_field_name => payload
  }
end