I need to utilize the encryptsymmetric ampscript function to pass an email through to Commerce Cloud that is encrypted. 

The guys on commerce cloud have generated a private and public key. I cannot import the cert. file associated to the public key so, I just copied the txt string and attempted to encrypt the email value but it doesn't appear to be working. 

We're also utilizing a SALT and an initial vector with this encrption string.

`https://www.sample.com?e=%%=EncryptSymmetric(emailaddr, "AES;mode=ecb;padding=none", 'CC_Public2', @null, 'Sample Salt2', @null, 'initVector', @null)=%%`

I can't find this specific process documented anywhere especially when it comes to what type of cert files can be uploaded to asymmetric keys or whether or not a plain text key can be copied into the symmetric key field without being truncated.