Chiasmus (cipher)
Chiasmus is an offline encryption software for computers with Windows operating system (95, 98, 2000, ME, NT from 3.5.2, XP, Vista, 7, 8 ) as well as Linux. With chiasm, it is possible to encrypt individual files or entire directories.
Use
Chiasmus may in principle be used only where the public interest for the use of there. The program can be used free of charge by departments of public administration. Other bodies which comply with the Terms of Service, obtain the tool by BSI. Chiasmus in version 1.7 is used for encryption of classified information classified up - admitted " VS ONLY FOR OFFICIAL USE ".
When using the software, you can create even key (leave ), but it can also be used as keys of communication partners that were exchanged before. This key exchange is done either by importing from a file or by typing on the keyboard.
During the installation neither entries in the start menu, registry, or made to any other system directories, nor are system drivers or DLLs installed. Through this type of installation, however, no integration into third-party applications, such as office products, Explorer or mail clients is possible. The encryption and decryption process must be carried out separately for each requirement by the user.
The Chiasmus encryption was integrated into the BSI software GSTOOL. The GSTOOL also provided so that the possibility of Chiasmus encryption including a tool-based key generation, but no compatibility was added to the chiasm for Windows. However, the implementation of chiasmus in GSTOOL is considered unsafe because it was used as the ECB encryption mode and key size are effectively met by error when creating the key only less than 31 bits. This enabled encrypted with GSTOOL files are decrypted by an attacker within minutes. The BSI does not recommend the use of the encryption function and has this disabled in the current version. The cipher itself as well as other implementations such as chiasmus for Windows are not affected by these problems.
Properties
According to BSI, the software uses a proprietary, undisclosed symmetric encryption algorithm that is encrypted using 128 -bit keys each 64 -bit blocks in CBC mode. About the type of padding used no statement is made.
The output is an ASCII text -compatible output format. Depending on how the file name of the file to be encrypted is maintained, the ending xia replaced or supplemented by the extension.. From Jahresbericht_2010.doc is so Jahresbericht_2010.doc, Jahresbericht_2010.xia or Jahresbericht_2010.doc.xia.
When you decrypt is maintained depending on the setting of the name of the encrypted file, the ending. Xia removed (if present) or replaced by an arbitrary extension.