Person A want to send important excel files to Person B using plain FTP (no encryption). Person A says the "issue with private key encryption is that its tough to maintain across the company. Sharing private keys is not safe." Person B suggests to encrypt the excel file before sending but Person A says its not possible.

Are there any other ways to make this transfer safe or encrypted in transit? All I can think of is SFTP but it may affect the speed of the file transfer.

  • 5
    SFTP might affect transfer speeds? Are you using dial-up connections?
    – schroeder
    Feb 3, 2016 at 0:29
  • 2
    Yes, just use SFTP. It's the simplest and most logical solution here. Feb 3, 2016 at 0:34
  • 1
    yeah scp/sftp FTW! there are UI tools you can use or plain CLI :) Feb 3, 2016 at 7:59
  • may affect the speed of the file transfer - would it be so hard to test? Most ssh servers/clients can compress data - not true of FTP.
    – symcbean
    Feb 3, 2016 at 10:47

2 Answers 2


Sharing private keys - where all parties who have the one, single key can both decrypt as well as encrypt - is certainly not safe the way it's done at most companies (i.e. with a weak password, used over and over for different files, vendors, and clients, and usually sent via unencrypted email).

The two major other ways are: Encrypted transport, i.e. data in motion encryption - HTTPS, FTPS, and SFTP all fit into this model.

Public key encryption, in this context data at rest encryption, i.e. GPG - or an easily installable package including a GUI, such as GPG4Win, which has two keys for each file recipient, be it a company or Person B themselves.

The public key, which can be shared with the entire world(!) perfectly safely.

The private key, which is held by the recipient only, protected by a passphrase only that recipient (or their automated software) knows.

Anyone and everyone encrypting and sending TO Person B needs only Person B's public key.

Person B only needs Person B's private key to decrypt, no matter how many people are sending them files.

Now, if Person A is sending files to Persons B, C, D, and E, then Person A needs four public keys - one for each recipient.

There are a variety of other options, some required in regulated contexts in the United States, but those aren't critical to most users.

Note that the ideal case is to use both, plus GPG signatures (a way of validating that Person A's private key was in the hands of who really sent it, presumed to be Person A themselves)

Note also that a plain FTP username/password is 100% visible to anyone and everyone between Person A's computer and Person B's computer, since it's sent in cleartext over the wire.


SFTP is an FTP-like solution that utilizes the SFTP protocol (NOT the same thing as FTP tunneled over SSH Wikipedia:SFTP). You would need sftp-server installed on the server. That would be a secure way to transfer files. It supports compression too, I believe, so possibly it would be faster than FTP?

With the size of Excel files and the speed of modern internet it would likely not be noticeable either way.

Otherwise, if you have SSH enabled I would use scp to copy the files over SSH.


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