To decrypt it, even without an MDC, open the command line (see below for additional hints) and decrypt your file like: gpg -ignore-mdc-error -decrypt "path_to_your_file"Īdditionally to decrypting this will list the keyids of the recipients of that message, which you can then use in the command to re-encrypt the message. Afterwards it can be used as usual in Kleopatra and will be integrity protected. You can fix the error by re-encrypting it.
Such new algo, no MDC, messages are supposed to be rare and might be an indication of broken / insecure software or configuration. For messages that were encrypted using modern algorithms but still don't use MDC there is a hard failure that will be shown in diagnostics. In that case you only need to click on the decrypt anyway button. Since Gpg4win-3.1.3 Kleopatra offers to decrypt such messages anyway if they were done using an old encryption algorithm. The reason for this was the public attention to attacks possible against messages without MDC with the publication of " EFail". Starting with Gpg4win-3.1.2 the MDC message integrity mechanism, which has been well established for over 15 years, is now enforced by GnuPG.
Things like a full harddrive or wrong filesystem permissions.
Gpg4win is an installer for Windows and contains several Free Software components: Gpg4win and the software included with Gpg4win are Free Software (Open Source among other things free of charge for all commercial and non-commercial purposes). It is maintained by the developers of GnuPG. Gpg4win supports both relevant cryptography standards, OpenPGP and S/MIME (X.509), and is the official GnuPG distribution for Windows. Digital signatures make sure that it was not modified and comes from a specific sender. Encryption protects the contents against an unwanted party reading it. Gpg4win enables users to securely transport emails and files with the help of encryption and digital signatures.