The timeline of cryptography

Cryptography is a very old subject and a very recent one: the Roman cipher still taught in schools is two thousand years old, the algorithm that protects this page was chosen in the year 2000, and the standards meant to replace the public-key half of it were published in 2024. This is the whole story on one page, from a Mesopotamian potter's secret to post-quantum standards, with the date, the event and the page on this site that tells it properly. Every line links to the article, cipher or tool that covers it, and those pages carry the sources. Choose an era to narrow the list, or follow a link to a single event with its own address.

Ancient world To AD 500

1. c. 1900 BCUnusual hieroglyphs in an Egyptian tomb: play with writing rather than serious secret communication. A short history of cryptography
2. c. 1500 BCA Mesopotamian clay tablet records a pottery-glaze recipe in a disguised script, presumably a valuable trade secret. A short history of cryptography
3. 7th century BCThe poet Archilochus mentions the Spartan skytale, though only indirectly. The scytale cipher
4. 6th century BCThe Hebrew scriptures contain Atbash substitutions (Jeremiah 25:26 and 51:41), reversing the alphabet. The Atbash cipher
5. c. 150 BCPolybius describes the 5 by 5 square, credited to Cleoxenus and Democleitus. The Polybius square
6. 1st century BCJulius Caesar writes private letters with a shift of three, the cipher that carries his name. The Caesar cipher
7. c. AD 100Plutarch gives the first description of how the scytale worked. The scytale cipher
8. 2nd century ADSuetonius, Cassius Dio and Aulus Gellius all describe Caesar's cipher; Suetonius adds that Augustus used a shift of one. The Caesar cipher

Middle Ages and Renaissance 500 to 1599

1. c. 850Al-Kindi writes the oldest known description of breaking a cipher by counting letter frequencies. Al-Kindi and the invention of frequency analysis
2. Early 1400sA homophonic cipher, with several symbols for common letters, is in use at the court of the Duke of Mantua. Al-Kindi and the invention of frequency analysis
3. c. 1467Leon Battista Alberti proposes polyalphabetic substitution, changing the alphabet during a message. Al-Kindi and the invention of frequency analysis
4. 1474Cicco Simonetta writes a manual on deciphering Latin and Italian text. Al-Kindi and the invention of frequency analysis
5. 1553Giovan Battista Bellaso describes the repeating-key cipher later misattributed to Vigenère. The Vigenère cipher
6. 1586Blaise de Vigenère publishes his Traicté des chiffres, including the autokey cipher. The autokey cipher
7. 1586The Babington plot: Thomas Phelippes deciphers Mary, Queen of Scots' letters; she is tried in October and executed on 8 February 1587. The cipher that convicted Mary, Queen of Scots

Early modern and the telegraph age 1600 to 1899

1. 1605Francis Bacon describes a binary cipher in The Advancement of Learning. Bacon's (Baconian) cipher
2. 1626Antoine Rossignol becomes famous by breaking a Huguenot message intercepted near Réalmont. The Great Cipher
3. 17th centuryThe Rossignols design the Great Cipher for the French crown. The Great Cipher
4. 1685Falconer describes keyed columnar transposition in Cryptomenysis Patefacta. The columnar transposition cipher
5. Early 1700sFreemasons use the pigpen cipher. The pigpen cipher
6. 1786The Swedish baron Fredrik Gripenstierna builds a 57-disk cipher prototype. The Jefferson wheel cypher
7. 1790sThomas Jefferson describes his wheel cypher; he gives up the idea in 1803. The Jefferson wheel cypher
8. 1811The French army is still using a modified Great Cipher in the Peninsular War. The Great Cipher
9. 26 March 1854Charles Wheatstone describes the Playfair cipher; Lord Playfair promotes it. The Playfair cipher
10. 1857A card published after Sir Francis Beaufort's death describes the cipher that bears his name. The Beaufort cipher
11. 1863Friedrich Kasiski publishes a general method for breaking repeating-key ciphers. The Vigenère cipher
12. 1882Frank Miller, a banker, describes a one-time key system for telegrams; it is rediscovered in 2011. The one-time pad
13. Jan and Feb 1883Auguste Kerckhoffs publishes La cryptographie militaire: a cipher must survive the enemy knowing everything but the key. Kerckhoffs's principle
14. 1885The Beale ciphers appear in a pamphlet. The book cipher
15. c. 1890Étienne Bazeries, after about three years, breaks the Great Cipher. The Great Cipher
16. 1891Bazeries reinvents the wheel cipher that Jefferson had described a century earlier. The Jefferson wheel cypher

Machines and world wars 1900 to 1945

1. 1901 to 1902Félix Delastelle devises the bifid, two-square and four-square ciphers, published in 1902. The bifid cipher
2. 1917Gilbert Vernam of AT&T devises a teleprinter cipher that adds a key tape character by character. The one-time pad
3. February 1918Arthur Scherbius applies for a patent on a rotor cipher machine: the Enigma. The Enigma machine
4. March to June 1918The German Army introduces ADFGX in March and ADFGVX in June; Georges Painvin breaks it in June. The ADFGVX cipher
5. 1919Vernam's patent is issued. The one-time pad
6. 1922The US Army adopts the M-94, a pocket version of Jefferson's wheel. The Jefferson wheel cypher
7. 1929Lester Hill publishes the first cipher built on matrix algebra. The Hill cipher
8. 1930Enigma I enters military service in Germany. The Enigma machine
9. December 1932Marian Rejewski reconstructs the wiring of the German Army Enigma from permutation theory and documents obtained by French intelligence. How Enigma was broken: Warsaw, then Bletchley Park
10. 1935 to 1937Britain builds Typex: a prototype in April 1935, the Mark I in service in early 1937. The Typex cipher machine
11. 1937 to 1939Japan completes the Type B cipher machine (Purple); it is in service from February 1939. The Purple cipher machine
12. July 1939The Poles reveal their Enigma methods to French and British representatives near Warsaw. How Enigma was broken: Warsaw, then Bletchley Park
13. 4 September 1939Alan Turing and Gordon Welchman report to Bletchley Park. How Enigma was broken: Warsaw, then Bletchley Park
14. 18 March 1940The first British bombe, Victory, is installed at Bletchley Park. How Enigma was broken: Warsaw, then Bletchley Park
15. 1941The US Army and Navy adopt SIGABA, designed by William Friedman and Frank Rowlett; Lorenz SZ40 enters service the same year. The SIGABA cipher machine
16. 1942Lorenz SZ42 appears; the British call the machine Tunny. The M-209 starts rolling off Smith Corona's lines. The Lorenz cipher
17. 1 February 1942The German Navy adds a fourth rotor; Bletchley loses U-boat traffic until 13 December 1942. How Enigma was broken: Warsaw, then Bletchley Park
18. 1 February 1943The US Army begins Venona, which reads Soviet one-time-pad traffic made with reused key pages. Shannon and perfect secrecy
19. 1 May 1945The Dönitz message, sent on Enigma, is the real example decrypted in our simulator. The Enigma machine
20. 1 September 1945Claude Shannon writes the classified report proving what perfect secrecy requires; it is published in 1949. Shannon and perfect secrecy

The computer age 1946 to 1999

1. 20 December 1946Meredith Gardner makes the first break into Venona traffic; the project ends on 1 October 1980. Shannon and perfect secrecy
2. 1949Communication Theory of Secrecy Systems appears in the Bell System Technical Journal. Shannon and perfect secrecy
3. January 1970At GCHQ, James Ellis argues that "non-secret" encryption is possible; the work is classified until 1997. Public-key cryptography was invented twice
4. 15 May 1973The National Bureau of Standards asks for proposals for an encryption standard; none is suitable. The history of AES
5. 20 November 1973Clifford Cocks writes the GCHQ document that is, in essence, RSA. Public-key cryptography was invented twice
6. 21 January 1974Malcolm Williamson writes the GCHQ report on non-secret encryption using a finite field: the Diffie-Hellman exchange. Public-key cryptography was invented twice
7. 1974Ralph Merkle conceives Merkle's puzzles; they are published in 1978. Public-key cryptography was invented twice
8. 27 August 1974A second request brings IBM's candidate, based on Horst Feistel's Lucifer. The history of AES
9. 17 March 1975The proposed Data Encryption Standard is published in the Federal Register. The history of AES
10. November 1976Diffie and Hellman publish New Directions in Cryptography. Diffie-Hellman key exchange
11. 15 January 1977DES is published as FIPS 46. The Data Encryption Standard (DES)
12. 1977Rivest, Shamir and Adleman devise RSA; Martin Gardner describes it in Scientific American in August. RSA encryption, step by step
13. 1978Walter Tuchman proposes two-key Triple DES; the three-key form follows from Merkle and Hellman in 1981. Triple DES
14. 1982James Massey and Jim Omura propose the three-pass protocol with exponentiation. The Massey-Omura cryptosystem
15. 20 September 1983MIT is granted US patent 4,405,829 on RSA. RSA encryption, step by step
16. 1985Taher Elgamal publishes ElGamal encryption; Neal Koblitz and Victor Miller independently propose elliptic-curve cryptography. ElGamal encryption
17. 1987Ron Rivest designs RC4. The RC4 cipher
18. Late 1980s and 1991Biham and Shamir publicly discover differential cryptanalysis and find DES resists it; Coppersmith writes in 1994 that IBM knew in 1974. The history of AES
19. 3 November 1990Jim Sanborn's sculpture Kryptos, with four enciphered passages, is dedicated at the CIA. Kryptos
20. 1991Phil Zimmermann releases PGP; a criminal investigation under export law follows and is dropped in early 1996. The Crypto Wars
21. 1993The NSA-designed Clipper chip, with escrowed keys, is introduced; it is defunct by 1996. The Crypto Wars
22. 1993Bruce Schneier designs Blowfish and places it in the public domain. The Blowfish cipher
23. 20 August 1994Matt Blaze shows the Clipper access field can be defeated. The Crypto Wars
24. September 1994RC4, until then a trade secret, is posted anonymously on the Cypherpunks mailing list. The RC4 cipher
25. 1995NIST publishes SHA-1, a revision of the 1993 SHA. SHA-1 hash generator
26. 1995Paul Kocher shows that the time an RSA operation takes can reveal the private key. RSA encryption, step by step
27. 1996Hans Dobbertin finds a collision in MD5's compression function. MD5 hash generator
28. 12 September 1997NIST issues its call for an Advanced Encryption Standard. The history of AES
29. 18 December 1997Clifford Cocks gives a public talk on GCHQ's earlier invention of public-key cryptography. Public-key cryptography was invented twice
30. 1998Daniel Bleichenbacher shows that RSA with PKCS#1 v1.5 padding can be attacked through error messages. RSA encryption, step by step
31. July 1998The EFF's Deep Crack, built for under $250,000, finds a DES key in 56 hours. The history of AES
32. 20 August 1998NIST announces fifteen AES candidates. The history of AES
33. 1998The Twofish and Serpent designs are published. The Twofish cipher
34. August 1999NIST names five AES finalists: MARS, RC6, Rijndael, Serpent and Twofish. The history of AES
35. 25 October 1999FIPS 46-3 makes Triple DES the preferred form of DES. Triple DES

Today 2000 onwards

1. January 2000US export rules for software containing cryptography are greatly simplified. The Crypto Wars
2. 6 September 2000RSA Security places the RSA algorithm in the public domain, two weeks before the patent expires. RSA encryption, step by step
3. 2 October 2000NIST announces that Rijndael is its choice for AES. The history of AES
4. 26 November 2001FIPS 197 publishes the Advanced Encryption Standard. AES, the Advanced Encryption Standard
5. June 2003The US government announces that AES can protect classified information. The history of AES
6. August 2004Xiaoyun Wang and colleagues announce collisions for the full MD5. MD5 hash generator
7. 2005Daniel Bernstein publishes Salsa20, from which ChaCha20 follows in 2008. The ChaCha20 stream cipher
8. 19 May 2005NIST withdraws the DES standard. The Data Encryption Standard (DES)
9. August 2007Shumow and Ferguson show that the Dual_EC_DRBG constants could hide a back door. Dual_EC_DRBG: a standard with a possible back door
10. March 2008Intel proposes the AES instruction set (AES-NI). The history of AES
11. December 2008Researchers use MD5 collisions to forge a certificate-authority certificate. MD5 hash generator
12. 2009Colin Percival introduces scrypt, a memory-hard password hash. Password hashing: bcrypt, scrypt, Argon2 and PBKDF2
13. 2012The Flame malware forges a code-signing certificate with an MD5 collision; Keccak wins the SHA-3 contest. MD5 hash generator
14. 5 September 2013Leaked documents describe the NSA's Bullrun programme; NIST advises against Dual_EC_DRBG. Dual_EC_DRBG: a standard with a possible back door
15. 2014The POODLE attack exploits CBC padding in SSL 3.0; Google and Apple redesign phone encryption. Block cipher modes of operation: ECB, CBC, CTR, OFB and GCM
16. 2015The Logjam attack exposes servers that still accept export-grade 512-bit Diffie-Hellman. Diffie-Hellman key exchange
17. 20 July 2015Argon2 wins the Password Hashing Competition. Password hashing: bcrypt, scrypt, Argon2 and PBKDF2
18. 2015NIST publishes SHA-3 as FIPS 202. SHA-3 hash generator
19. February 2016The FBI obtains a court order for Apple to help unlock an iPhone; the case ends when the FBI finds another way in. The Crypto Wars
20. December 2016cipher.ink is built: AES-256 in OFB mode in the browser. The history of cipher.ink
21. 23 February 2017SHAttered: the first collision for full SHA-1. SHA-1 hash generator
22. October 2017The ROCA flaw is disclosed: RSA keys from one library had a structure that made them factorable. RSA encryption, step by step
23. 2018RFC 8439 standardizes ChaCha20-Poly1305. The ChaCha20 stream cipher
24. January 2020Leurent and Peyrin show a chosen-prefix collision for SHA-1. SHA-1 hash generator
25. 2020RSA-250, a 829-bit number, is factored. RSA encryption, step by step
26. 5 December 2020David Oranchak, Sam Blake and Jarl Van Eycke solve the Zodiac Killer's 340-character cipher. How the Zodiac 340 cipher was solved
27. 5 July 2022NIST announces its first post-quantum choices: Kyber, Dilithium, FALCON and SPHINCS+. Post-quantum cryptography
28. 2022The isogeny scheme SIKE is broken on an ordinary computer. Post-quantum cryptography
29. 15 December 2022NIST retires SHA-1, with a deadline of the end of 2030 for phasing it out. SHA-1 hash generator
30. 8 February 2023Lasry, Biermann and Tomokiyo announce 57 deciphered letters of Mary, Queen of Scots. The cipher that convicted Mary, Queen of Scots
31. 9 May 2023NIST publishes an editorial update of FIPS 197, with no change to AES. The history of AES
32. 2023Signal adds the Kyber-based PQXDH key agreement. The ML-KEM key-encapsulation mechanism
33. 21 February 2024Apple announces PQ3, post-quantum protection for iMessage. Post-quantum cryptography
34. 13 August 2024NIST publishes FIPS 203 (ML-KEM), 204 (ML-DSA) and 205 (SLH-DSA). The ML-KEM key-encapsulation mechanism
35. 11 March 2025NIST selects HQC, a code-based key-establishment scheme, as a backup to ML-KEM. Post-quantum cryptography
36. 9 April 2025OpenSSH 10.0 makes a hybrid ML-KEM and X25519 key exchange its default. Post-quantum cryptography
37. 6 August 2026cipher.ink stops working: an updated aes-js library renames a function the page calls. The history of cipher.ink
38. 22 October 2026cipher.ink is rebuilt in a day with Web Crypto, AES-256-GCM, secret links and burn after reading. The history of cipher.ink

How to read it

Dates are given as precisely as the sources allow, and where the sources disagree or only give a century, the entry says so. Where an event is known only from one account, the page it links to says whose account it is. If you know of a date here that is wrong, please tell us through the contact form. For the people and the principles behind the dates, start with Kerckhoffs's principle and Shannon and perfect secrecy.