The higher classes seal their mail with wax seals. How could I make sure a design on the seal is uncopyable or at least make it very hard?

Magic exists, but it's primarily elemental manipulation. Signet rings can be made out of magic disrupting material to prevent arcane duplication with earth magic, but is there a way to prevent copying from the seal design?

Technology level: http://tvtropes.org/pmwiki/pmwiki.php/Main/SchizoTech Predominately "medieval" with higher technology with lightning powered railgun, but none that I think affects the question.

Edit for more details:

  1. For the sake of my story, it has to make duplication pointless or too difficult to be worth much.
  2. It should be relatively simple and achievable by the poorest of nobles, so it should not be too expensive.
  3. The wax seal is for the dual purpose of making sure the letter was secure in transit and possibly ensuring the legitimacy of the document.
  4. The original signet ring itself cannot be directly duplicated with magic so it has to be handcrafted. This leaves any unscrupulous people only the wax to work with.
  5. Magic wax is possible by imbuing energy.
  6. Everyone's magic has a signature. The closer by blood, the more similar. Twins have almost identical signatures. For example, a "barrier stone" activated for a descendant dozens of generations later but it's very general. A signet ring meant to be handed down would be slightly less general but it's the same idea.

Is that enough of a "criteria?"

  • $\begingroup$ People, if you vote to close, please take the time to write something about it! To Emily, there are many possibilities to answer your question.And it is not, currently, possible to distinguish what makes a better answer than another. You could improve your question by specifying the kind of answer you would like. $\endgroup$ Commented Jun 20, 2016 at 7:37
  • $\begingroup$ Welcome to the site Emily. To expand on what Bilbo is saying I would suggest adding criteria for what you believe would make a good answer. The trouble, as he suggests, is that 8 people could write 9 different answers and there is nothing in the question that would suggest what makes an answer better than any of the others. If you have questions check out the help center (particularly the portion on asking questions) and once you hit 20 rep feel free to visit Worldbuilding Chat its a good place to vet out questions and get ideas. $\endgroup$
    – James
    Commented Jun 20, 2016 at 15:04
  • $\begingroup$ I see! Let me think on it before I add a few more criteria. My question has been answered, so the criteria should be why I prefered one answer over the other? $\endgroup$ Commented Jun 21, 2016 at 20:51
  • $\begingroup$ Try posting on the "sandbox" on the Worldbuilding Meta, to help get it into good shape. Then you can ask again and get a solid reception with good results. $\endgroup$
    – JDługosz
    Commented Jun 22, 2016 at 7:15

4 Answers 4


Wax that changes color with time

A wax that changes color with time. It changes color according to an unpredictable pattern. This wax, from this particular sender, no matter which wax seal it is, always changes to the same color at the same time.

The sender has previously sent/handed over documents with these wax seals to all presumptive important receivers, and to the notary public in relevant cities. He has either done this in person, or through a courier that he and the receivers trust explicitly. These documents have then been archived.

When a new document arrives that need to be verified, the recipient brings out the old document and compares the wax seals. If they change to the same color at the same time enough times, the document is judged authentic. If the recipient has no own reference, he will go to the nearest notary public and have them verify the authenticity by comparing with the archived document.

If the sender has no magic wax of his own, he can go see the notary public, because notary public has — of course — their own magic wax, and has exchanged documents with wax seals with other notary public in other cities. The notary public will authenticate the sender and add their own wax to the document.

Oh, and this wax ceases to change color the very instant it is broken, removed from the document or the document is tampered with.

For added security, a closed document may be sealed with an outer wax seal that must be broken in order to open and read the document, and an inner wax seal that remains even after it is opened. That way it can be verified both that the document has not been opened in transit, and that it is unaltered and from the right sender.

Behind-the-scenes: this is a magic version of a security token. The sender gives out identical but un-cloneable, un-movable tokens to all relevant recipients. As long as two tokens are the same, they can be judge to come from the sender in question.


You could use similarity/contagion magic to verify that the seal you're checking was made by the same signet ring as your known good sample -

things once in contact (i.e. signet and wax) remain magically connected... so if wax seal 1 and wax seal 2 were made by the same signet, both are magically connected to the signet and thus to each other.

Or, you could have the signets magically rather than physically mark the wax seal - producing either something like a credit card hologram that can't be practically copied by mechanical means the way a normal seal impression could be. Or just a complex colour pattern in the wax that would be tricky to reproduce by non-magical means.

Or combine both - you have a recognisable pattern / hologram that's hard to reproduce - so works for casual checks - with the contagion check against the signet or known sample for legal verification.


You could recreate with magic something like we do today in asymmetric cryptography.

The idea is simple. Your signet has some secret magical properties (private key). It scans whatever will be signing and calculate some other magical property based on the document and the secret that will be applied to the seal (signature).

For every signet there is some known spell (public key) that can be cast to see if the signature was created with the signet and the content wasn't changed. You can't calculate the secret from the known spell and there would be so many possible spells that just guessing would take centuries to find the correct secret.

Depending on how your magic works you can base it on the same algorithm that it security uses today. Instead of knowing the design of the seal you would need to know the spell.

  • Use magical magic-detecting sealing wax. It will discolor if the signet has a magical signature, so it must be used with conventional signets. There are spells to judge the integrity of the wax without discoloration.
  • Use only magical signets, which will imprint a signature in the wax or the document. The court wizard of any noteworthy noble can analyze the wax.
  • The signet is only a symbol for easily impressed laypersons. Everybody who matters will understand that the document is worthless unless somebody can vouch for the provenance.

Follow-up: Imagine a poor peasant or a simple craftsman who shows up with the deed to a small manor, signed by a recently deceased lord. None of the heirs have heard of this guy. Everybody assumed that the manor would stay in the family. So what happens?

Will a cleric or clerk examine the seals on that document to decide if it is genuine?

Or will somebody examine the peasant and ask pointed questions where he got the deed? If the peasant is lucky, somebody might ask the scribe of the late lord if he remembers the deed. Otherwise they will go on to hot and pointed instruments for their questions if the peasant does not confess.

If it was a genuine deed, the person holding it would be known to the heirs of the lord, and also to the neighbors. Anything else is unthinkable.

  • $\begingroup$ I like your second point, and can you please elaborate on the third? Thanks, I'd like to wait for more answers before I accept. $\endgroup$ Commented Jun 19, 2016 at 16:16

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