The “cryptoTool” is an open source software for the encryption and decryption of large files transmitted per S/MIME e-mails, e.g. to a platform offering file uploads. A companion tool allows for additional end-to-end-encryption. Therefore, the “cryptoTool” is a secure transfer solution for the receipt of e-mail attachments exceeding 200 MB: it helps users to circumvent out-of-memory errors or time-consuming operations caused by ordinary decrypting applications such as e-mail clients that are not able to decrypt large files.


  • Comfortable installation via the open source-installer Izpack
  • Comfortable use per executable .exe-file
  • Swing GUI for decryption
  • Decryption of S/MIME- encrypted e-mails
  • Decryption per soft token key memory (PKCS#12)
  • Decryption per Smartcard key memory (PKCS#11)
  • Option to unpack the e-mail (outcome: text file with e-mail message, subfolder with e-mail attachments)
  • Option to automatically unpack the .zip-archives included in the attachments enclosed in the e-mail