Eureka is a simple tool to encrypt and decrypt files.
If you have Go installed and
/usr/local/go/bin is in your PATH, you should be able to simply get the binary by doing
go get github.com/mimoo/eureka
If you are on MacOS, just use Homebrew:
brew tap mimoo/eureka && brew install eureka
You are trying to send Bob the file
myfile.txt. Start by encrypting the file via:
eureka -encrypt -file myfile.txt
which will return a one-time 256-bit AES key and create a new
File encrypted at myfile.txt.encrypted In a different secure channel, pass the following one-time key to your recipient. 613800fc6cf88f09aa6aeafab3eedd627503e6c5de28040c549efc2c6f80178d
Now. Find a channel to send the encrypted file to Bob. It could be via email, or via dropbox, or via google drive, etc.
You then need to transmit the one-time key (
613800fc6cf88f09aa6aeafab3eedd627503e6c5de28040c549efc2c6f80178d) to Bob in a different channel. For example, if you exchanged the file (or a link to the file) via email, then send this key to Bob via WhatsApp.
Once Bob receives the file and the one-time key from two different channels, he can decrypt the file via this command:
eureka -decrypt -file myfile.txt.encrypted -key 613800fc6cf88f09aa6aeafab3eedd627503e6c5de28040c549efc2c6f80178d
which will create a new file
myfile.txt containing the decrypted content.