After installing the new Gpg4win 2.2.1 (2013-10-07) version, I imported my previously generated long (16383-bit) RSA secret key into Kleopatra. At first everything seemed to work fine, but after some hours of frustration I came to the conclusion that Kleopatra can't handle such large keys. It is possible to encrypt a file, but not to DECRYPT. Every time after pinentry, Kleopatra crashes with these details: APPCRASH gpg2.exe 2.0.22.8453 libgcrypt-11.dll (given by Windows 8 Pro - 64 Bit) Also, with Thunderbird 24.0 and the latest Enigmal v1.6, there is a similar problem. It is possible to send encrypted emails with the 16K key public key, but every try to decrypt the message with the private part crashes Enigmail. It would be a pity if these days only 4096-bit keys would work with Kleopatra. Any help appreciated. Reproducible: Always Steps to Reproduce: 1. Encrypt file/email with 16K key. 2. Try to decrypt it, make pinentry. 3. Crash. Actual Results: Kleopatra application crash: APPCRASH gpg2.exe 2.0.22.8453 libgcrypt-11.dll (given by Windows 8 Pro - 64 Bit) Expected Results: Accept pinentry, decrypt file/email. Why large RSA keys might be already necessary: Post-quantum threats to traditional cryptography and generating 16k RSA asymmetric key pairs with GnuPG http://randexec.wordpress.com/2013/07/15/modify-gnupg-to-generate-16k-asymmetric-rsa-key-pairs/
This is an upstream gnupg issue. Please refer to: https://www.gnupg.org/faq/gnupg-faq.html#default_rsa2048 Especially the part: I think I need larger key sizes.