It seems impossible to use encrypt-file on multiple files.

One can run the command multiple times on different files, but the later invocation overwrites the secure environment variables, invalidating the earlier encryptions.

I suspect -K and -iv flags are meant to overcome this, but it fails as follows:

$ travis encrypt-file --skip-version-check -K 7b758bbf041361268b192d816d60ec84907106015402f31fdc5ae165fdce0979 -iv 7aaf728695ac967003d5345d9be63924 foo1                                                        
travis: version unknown