X-IM Help

Memo Security Info

All components of the memo are separately encrypted, signed, hashed, and combined into the secure memo file. Besides the text and file(s) this also includes the subject line, recipient, and sender. If someone gets possession of a memo file that they are not a recipient or sender of, the only information they can derive from it is its size and the number (but nothing about the identities) of the recipient(s).

Therefore, when you use the "Send" function, besides the memo file, you are also sending to the X-IM Server a list of the memo's recipient(s) (encrypted specifically for the X-IM Server) so that the server knows who to forward the memo to.

As explained further in the Memo Inbox/Outbox Section, X-IM Memo files can be distributed through other means besides the "Send" function, such as email, diskettes, etc., and their security format makes them appropriate for conveying secure information over such insecure means.

Each element of the memo is signed by the sender, encrypted for each recipient, and protected against alteration by hash function.

Since the files and text are encrypted, hashed, and signed together, this is an appropriate mechanism to use for digital signatures. In other words, if you create a memo with attachments, which reads "I agree to the terms specified on the attached files," then it is provable by any of the recipients of the memo that those files contained what they contained when you attached them to that memo.

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