Hi! Thx your reply. I tried the following: gpg -u 4096R/626D791C --detach-sign t.txt The error is the same: gpg: skipped "4096R/626D791C": secret key not available gpg: signing failed: secret key not available I tried it with the public key's key ID too but the result was the same. What am i doing wrong? Best regards, Csabi