Were Ancient Seals Secure?
Johnston, Roger G., Martinez, Debbie D., Garcia, Anthony R. E., Antiquity
Stamp and cylinder seals were widely used in the ancient world. They were made by inscribing symbols or a design into wood, bone, clay or stone (Gibson & Biggs 1977; Collon 1987; 1990). The seal pattern could then be impressed into wet clay. The clay containing the seal impression, sometimes in conjunction with twine or rope, was used to seal the object or container of interest such as a jar, basket, bundle, sack, door, or document. The clay was allowed to harden by drying or by baking in the sun. Any attempt to gain unauthorized access would require either damaging the container or cutting the twine/rope, which would be noticeable, or else destroying the seal impression, which would supposedly be difficult to reproduce without possessing the original seal. Other security applications for seals probably included identifying people, authenticating documents, demonstrating signature and legal authority, marking ownership and trademarks, and assisting with customs, taxation and business contracts (Gibson & Biggs 1977; Collon 1987: 113-19; 1990: 11-30). Non-security applications may have included personalization, labelling, time and location stamping, counting, ceremony, magic and decoration (Gibson & Biggs 1977; Collon 1987: 113-19).
Stamp seals were first used at least 7000 years ago, becoming especially popular in Middle Eastern and Aegean civilizations of the 2nd and 3rd millennia BC (Gibson & Biggs 1977; Collon 1987: 13-93). Cylinder seals were invented around 3500 BC and were in widespread use from 3000 to 500 BC (Collon 1987; 1990: 11-20). Both types of seals were also found in the New World (Enciso 1953). Wax or resin eventually replaced clay as the preferred sealing material in the 1st millennium AD, with lead seals coming into use by the 4th century AD (Vikan & Nesbitt 1980: 23-8).
Given the importance of seals, the question of how secure they might have been is of interest. Forged ancient seals have been detected in modern times (Porada 1957; Porada 1978; Collon 1987: 94-6; Collon 1990: 56-7; Gorelick & Gwinnett 1978:40-43 & figures 7A-D). There appears, however, to be little previous analysis of ancient seal security.
The Vulnerability Assessment Team at Los Alamos National Laboratory (LANL) has extensively studied modern seals (Johnston 1997; forthcoming). The goal is to determine how the seals can be defeated, and then to devise countermeasures. To `defeat' a seal means to remove it, then reseal (using either the original seal or a counterfeit) without being detected. To `attack' a seal means to try to defeat it.
This paper discusses a vulnerability assessment conducted on clay seal impressions similar to those made by ancient stamp and cylinder seals. As a result of this work, ancient seals do indeed appear to have been vulnerable to fairly simple attacks using materials available several thousand years ago.
We experimented with four possible attacks. None require access to the original seal, only to an impression made by the seal.
1 Beeswax casting attack
We use liquid (heated) beeswax to cast a copy of the stamp seal impression. Olive or sesame oil is lightly brushed on the original clay impression prior to casting to serve as a mould release. The beeswax solidifies within 3 minutes and can then be used to create multiple counterfeit seal impressions.
2 Clay casting attack
We use wet clay to make a copy of the stamp seal impression. Oil is again used as a mould release. Once the clay is removed and allowed to dry and harden, it can be used to make counterfeit seal impressions.
3 Counterfeit carving attack
We make a free-hand counterfeit carving (forgery) of the cylinder seal based on the seal impression. The counterfeit cylinder seal can be used multiple times to create fake seal impressions.
4 Cut and paste (cookie-cutter) attack
We use water and a metal tool to cut the seal impression out of the clay. …