Suppose a file (say, a text file source.txt) was encrypted into danger.gpg using GPG symmetric encryption on a compromised device. Since the device is compromised, danger.gpg could have been created by a modified program masquerading as GPG, or the encrypted file could have been modified after running GPG. The attacker knows the encryption key since it was entered on the compromised device in order to create danger.gpg.
If I try to decrypt danger.gpg on a clean device, do I risk infecting it by running the GPG symmetric decryption on the malicious file?