Frequently Asked Questions

No. As of 2026, K4 remains unsolved after over 35 years. Reports in 2025 suggested that the full plaintext may exist in Smithsonian archival materials sealed until 2075, but this has not been publicly confirmed. The encryption method remains unknown to the public.

Over 475 experiments covering 671.0B++ configurations have been run, testing every major classical cipher family: Vigenère, Beaufort, columnar transposition, Playfair, Bifid, running keys, and more. All single-layer classical ciphers have been eliminated under direct positional correspondence (where ciphertext position N maps directly to plaintext position N). These eliminations do not rule out the same families as one layer of a multi-layer construction. Browse the full database to see what has been tested.

Yes. This is one of the most common suggestions we receive, and we’ve tested it extensively. We combined 14 different letter-rearrangement methods (columnar grids at all widths, rail fence, spiral, zigzag, double columnar, and more) with keyed substitution (Vigenère, Beaufort, and Variant Beaufort with every possible key length). Over 1.2 billion combinations were tested. None produced a solution.

We also mathematically proved that for 17 out of 25 possible key lengths, no rearrangement of any kind — not just the structured ones — can produce a valid solution with a repeating-key cipher. This proof holds for all 97! possible letter orderings (a number with 152 digits).

However, some combinations remain open: if the substitution uses a non-repeating key (like a passage from a book), the rearrangement + substitution model is still possible. This is one of the leading hypotheses. See the multi-layer category for full details.

K4 has 97 characters. The number of possible rearrangements of 97 characters is 97! (97 factorial), which equals approximately 10¹⁵². For comparison, there are roughly 10⁸⁰ atoms in the observable universe. Even if every atom in the universe were a computer testing one billion rearrangements per second, running for the entire age of the universe, you’d barely scratch the surface.

This is why we test structured rearrangement methods — methods a human could describe with a rule (like “write into 8 columns, read them in this order”). A human encryptor like Sanborn would have used a describable method, not a random shuffling.

We’ve tested hundreds of thematic keywords including KRYPTOS, PALIMPSEST, ABSCISSA, BERLIN, TUTANKHAMUN, SANBORN, SCHEIDT, COMPASS, SHADOW, SPHINX, and many more. But more importantly: the specific keyword doesn’t matter for most cipher types we’ve tested, because we tested every possible key of every possible length, which includes any keyword you could name.

The exception is running keys (where a long passage of text is the key). For those, the specific source text matters, and we’ve only tested texts that are publicly available. If Sanborn used a private or unpublished text, we wouldn’t have tested it.

All standard single-layer cipher families have been eliminated under direct positional correspondence and additive-key assumptions, including all repeating-key ciphers (proven impossible at every key length), all autokey ciphers (proven structurally impossible), and running keys from 60,000+ publicly available English texts (106 billion position-checks). These eliminations do not rule out the same families as one layer of a multi-layer construction, nor do they apply if K4 uses a non-additive cipher mechanism. The main surviving possibilities are: (1) a running key from a non-public source text; (2) a bespoke procedural cipher using Sanborn’s encoding charts (the original K4 chart was sold at auction in 2025 for $962,500); (3) a genuinely novel mechanism not yet conceived. See the Research Questions page for the full list of open problems.

Yes. Use the Submit a Theory page. Describe your idea in plain English and the theory classifier will check whether it matches anything in the elimination database. If your theory is genuinely novel, it will be queued for evaluation.

Every elimination includes a reproduction command you can run yourself. The codebase is fully open source. We also classify results by confidence tier and list explicit scope limitations for each elimination. If you find an error, report it and we will investigate.

kryptosbot.com is built by Colin Patrick (human lead) and Claude (AI computational partner, by Anthropic). The project began as a systematic attempt to solve K4 using computational cryptanalysis and evolved into a public elimination database so the community can build on our work rather than re-testing approaches already proven fruitless. This site does not know the solution and is not affiliated with the official Kryptos Keepers or their verification site.

K4 has only 97 characters, too short for most statistical attacks to distinguish signal from noise. Exhaustive testing has eliminated all standard periodic keys. Sanborn stated K4 uses two systems of encipherment, and pure transposition is independently impossible (the ciphertext has 2 E’s but the cribs require 3). The exact two-layer structure is unknown. There are an astronomically large number of possible methods that could produce the known letters, far too many to test one by one. Solving K4 requires identifying the specific method, not just trying all keys.