Cyber Security in the Ancient World

Cyber security in the Ancient World — Part 1

Ancient governments, like modern ones, realized that to keep their borders safe, control their populations and keep abreast of political developments abroad, they needed the means to collect the intelligence which enabled them to make informed decisions.

Martine Diepenbroek, Ph.D.
May 5, 2022
6 min read
Photo by ESR LAW / Unsplash

Cyber security in the Ancient World — Part 1

Communication security is of major importance to our modern world. Indeed, as Gerolymatos points out, the gathering of intelligence and spying on one’s enemies is essential for any government to determine the political and military direction of the state, especially in times of conflict when essential information on enemies can obviously facilitate the war effort.[1]  And as Starr argues, 'modern superpowers need to be able to assess swiftly the potentialities of other states within a framework of rapid technological change'.[2]

Yet, since antiquity, individuals in all civilizations have been trying to encipher confidential correspondence (mainly in a military context, according to our available sources[3]), while others have been trying to decipher these messages. In fact, in the 6th century, CE Procopius of Caesarea already described the practice of secretly communicating and spying as a very old one that went all the way back to the ancient Near Eastern kingdoms (Procopius of Caesarea, Secret History, 12-14). Sheldon accordingly argues that:

Ancient governments, like modern ones, realized that to keep their borders safe, control their populations and keep abreast of political developments abroad, they needed the means to collect the intelligence which enabled them to make informed decisions.[4]

And Van Tilborg claims that:

The protection of sensitive information against unauthorized access […] has been of prime concern throughout the centuries.[5]

Because of the fear of interception of valuable information by the enemy, some method of concealing messages was essential. This could be achieved by completely hiding a message so that it seemed that there was no message at all, or by writing a message that could not be (easily) understood by the enemy. This concealing of information is known as cryptography and steganography, and it was among the common practices of spies in antiquity – especially in times of war.[6] Steganography, from the Greek words στεγανός (steganos) meaning ‘covered’ or ‘concealed’ and γράφειν (graphein) meaning ‘to write’, is the practice of concealing a message within another message, an image, or an object, without giving the idea that a secret message is hidden in it. In other words, we can say that steganography is ‘the practice of undetectably altering a work to embed a secret message’.[7] Cryptography, from the Greek words κρυπτός (kryptos), meaning ‘hidden from’ or ‘secret’, and γράφειν (graphein), meaning ‘to write’, is the practice of techniques for securing communication by enciphering a text. [8]                                                    

Cryptography and steganography form part of contemporary studies of mathematics and computer science, but also play significant roles in studies of military history, both ancient and modern. Scholars working in these fields have written numerous works in which ancient methods of cryptography and steganography are referred to in passing as the early (which, in these studies, typically signifies ‘primitive’) precursors to modern cryptographic methods.[9] Examples from antiquity up to the Middle Ages are briefly mentioned as an embryonic or primitive phase in the evolution of secret communication technologies and are followed in each case by a more extensive discussion of secret communication from the early Renaissance until the modern day. The focus of the studies is typically the use of cryptography in the First and Second World Wars often presented as a technical apogee. This leads to the undervaluation, underappreciation, and misunderstanding of the relative sophistication of cryptographic devices described in ancient Greek and Roman sources if these sources are discussed or referred to at all.[10]

In my research, I show that the Greeks and Romans understood the importance of hiding confidential communication as opposed to the view of modern cryptographers that communication security in the ancient world had no value at all. On the contrary, the Greeks and Romans invented systems that formed the basis for modern cryptographic techniques!

Want to know more about the Spartan scytale, Aeneas Tacticus, the Caesar cipher, invisible ink, and much more? Then wait for my next post.

[1] Gerolymatos 1986, 13.

[2] Starr 1974, 1.

[3] Yet, evidence for the use of secret confidential information in other contexts in antiquity might be lost.

[4] Sheldon 2008, 8.

[5] Van Tilborg 2006, xiii.

[6] Besides its use in a military context, other ancient uses of cryptography and steganography include its use in love letters, its use to increase the level of mysticism in inscriptions, and its use in magical and religious texts (Ausonius, Epistles, 28.21-22; Ovid, Ars Amatoria, 3.627-630; Pliny the Elder, Natural History, 26.39 (62). See also: Pieprzyk; Hardjono, and Seberry 2013, 6; Waldstein & Wisse 1995; Wisse 1979; 1980; 1981; 1982; 1983; 1989; 1990.

[7] Cox, Miller et al. 2008, 2. See also Johnson, Duric et al. 2001, 1; Kahn 1996a, 1; Schaathun 2012, 15; Singh 1999, 5; Whitiak 2003, 1.

[8] Bauer 2013, xix; Hodges 1985, 146; Reba & Shier 2015, 479-480; Reinke 1962, 113; Seyfarth 1970, 181; Smith 1955, 16.

[9] Cox, Miller et al. 2008; D’Agapeyeff 1939; Kahn 1967; 1996a; 1996b; Sheldon 2008, 54-148; Singh 1999; Whitiak 2003, 1.

[10] Cox, Miller et al. 2008; D’Agapeyeff 1939; Kahn 1967; 1996a; 1996b; Mollin 2005; Sheldon 2008, 54-148; Singh 1999; Whitiak 2003, 1.


Cox, I., Miller, M., Bloom, J., Fridrich, J., & Kalker, T. (2008). Digital Watermarking and Steganography (2 ed.). Amsterdam/ Boston/ Heidelberg/ London/ New York/ Oxford/ Paris/ San Diego/ San Francisco/ Singapore/ Sydney/ Tokyo: Morgen Kaufman Publishers - An Imprint of Elsevier.

D'Agapeyeff, A. (1939). Codes and Ciphers - A History of Cryptography. Oxford / London / New York/ Toronto: Oxford University Press.

Gerolymatos, A. (1986). Espionage and Treason. Amsterdam: J. C. Gieben Publisher.

Johnson, N., Duric, Z., & Jajodia, S. (2001). Information Hiding: Steganography and Watermarking-Attacks and Countermeasures. Norwell: Kluwer Academic Publishers.

Kahn, D. (1967). The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet. London: Weidenfeld and Nicolson.

Kahn, D. (1996a). The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet (2nd edition, revised). London: Weidenfeld and Nicolson.

Kahn, D. (1996b). The History of Steganography. In R. Anderson, Information Hiding: First International Workshop, Cambridge, U.K., May 30 - June 1, 1996. Proceedings, Volume 1 (pp. 1-6). Cambridge: SpringerVerlag.

Mollin, R. A. (2005). Codes: The Guide to Secrecy From Ancient to Modern Times. Boca Raton/ London/ New York/ Singapore: Chapman & Hall/CRC - An imprint of Taylor and Francis Group.

Pieprzyk, J., Hardjono, T., & Seberry, J. (2013). Fundamentals of Computer Security. Berlin: Springer Science & Business Media.

Schaathun, H. G. (2012). Machine Learning in Image Steganalysis. Chichester: John Wiley & Sons Limited.

Sheldon, R. M. (2008). Espionage in the Ancient World: An Annotated Bibliography of Books and Articles in Western Languages. Jefferson/ London: McFarland and Company Incorporated Publishers.

Singh, S. (1999). The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography. London: Fourth Estate.

Smith, L. D. (1955). Cryptography: The Science of Secret Writing: History and Modern Use of Codes and Ciphers, together with 151 Problems and their Solutions. Mineola: Courier Corporation: Business and Economics/Dover Publications.

Starr, C. G. (1974). Political Intelligence in Classical Greece. Leiden: Brill.

Van Tilborg, H. C. (2006). Fundamentals of Cryptology: A Professional Reference and Interactive Tutorial by Henk C. A. van Tilborg, Eindhoven University of Technology, The Netherlands (2 ed.). Boston/ Dordrecht/ London: Kluwer Academic Publishers.

Waldstein, M., & Wisse, F. (1995). The Apocryphon of John: Synopsis of Nag Hammadi Codices II, 1, III, 1, and IV, 1, with BG 8502, 2. Leiden: Brill.

Whitiak, D. A. (2003). The Art of Steganography (Global Information Assurance Certification Paper, SANS Institute 2003 - Part of GIAC practical repository ed.). Retrieved from

Wisse, F. (1979). Language Mysticism in the Nag Hammadi Texts and in Early Coptic Monasticism I: Cryptography. Enchoria: Zeitschrift für Demotistik und Koptologie, 9, 101-120.

Wisse, F. (1980). Textual Restorations in On The Origin of the World. The Bulletin of the American Society of Papyrologists, 17 (1-2), 87-91.

Wisse, F. (1981). The Opponents in the New Testament in light of the Nag Hammadi Writing. In B. Barc (Ed.), Colloque international sur les textes de Nag Hammadi : Québec, 22-25 août 1978 (pp. 99-120). Québec/ Louvain: Presses de l'Université Laval/ Editions Peeters.

Wisse, F. (1982). The Profile Method for the Classification and Evaluation of Manuscript Evidence, as applied to the continuous Greek text of the Gospel of Luke. Grand Rapids: Eerdmans.

Wisse, F. (1983). Prolegomena to the study of the New Testament and Gnosis. In A. Logan, & A. Weddeburn, The New Testament and gnosis: essays in honor of Robert McL. Wilson (pp. 138-145). Edinburgh: T. & T. Clark.

Wisse, F. (1989). The Nature and Purpose of Redactional Changes in Early Christian Texts: The Canonical Gospels. In W. Petersen, Gospel Traditions in the Second Century: Origins, Recensions, Text, and Transmission (pp. 39-53). Notre Dame: University of Notre Dame Press.

Wisse, F. (1990). Pseudo-Liberius, Oratio Consolitaria de morte Athanasii. Le Muséon, 103 (1-2), 43-65.

Cyber security in the Ancient World — Part 2
This article relates to episode 2 in the series ‘Cyber Security in the Ancient World’. Since there will be two videos on Herodotus, this article provides background information on Herodotus’ life and work.

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