Our company needs to exchange data with a vendor using 128 bit AES encryption. Everything I've read suggests that AES can encrypt files using a passphrase not a pre-shared key.

Is there a way to create a shared key between us and the vendor to encrypt/decrypt AES encrypted files? I could use any tool but I'm partial to using openssl.

1 Answer 1


I'm not sure what do you mean by pass phrase vs PSK. A PSK key could be a pass phrase. If OpenSSL is not a requirement, a very good tool to perform file encryption in command line is mcrypt.

Mcrypt supports AES 128, 192 and 256 bits encryption and has all the options one would expect to find in a standard encryption system.

  • I guess you're right. What I expected was that there would be a key file stored on the vendor's side. When we sent them an encrypted file, the key file would be used to decrypt the file we send them. We could then update the key file once a year and use the new key to encrypt files, like when using a PSK for SSH connections.
    – Tensigh
    Sep 28, 2015 at 5:08
  • You might wanna take a look at asymmetric encryption, also known as Public Key Cryptography, although I'm not sure how you would manage the time constraints, key rotation, etc. Really depends on the specifics.
    – atmosx
    Sep 28, 2015 at 12:16

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