What Is A858, Reddit's Unsolved Puzzle Mystery?

Background

In 2011, a Reddit account began posting to a newly created subreddit under an unusual name: r/A858DE45F56D9BC9, a string that looked like a hexadecimal code. The posts themselves were similarly opaque: long, seemingly random sequences of letters and numbers, posted with no title, explanation, or context attached. For nearly a year the subreddit attracted almost no attention, until a user asked publicly whether the strings "correlate to something" or were "some big joke I'm missing out on." No answer came from the original poster, but the question was enough to draw a small, then growing, community of people convinced the posts were an intentional code rather than noise.

That interest formalised into a dedicated sister community, r/Solving_A858, made up of, in the words of contemporary coverage, "a dedicated group of computer science students, amateur cryptographers, and motivated enthusiasts." More than a decade later, the original A858 account has continued posting intermittently, the Solving_A858 community continues attempting to decode the pattern, and neither the poster's identity nor a comprehensive explanation of the content has ever been confirmed.

Main Theories

An intentional, unsolved cipher

The dominant view among the puzzle's dedicated community is that the posts encode genuine information using a cipher or encoding scheme not yet identified, an approach consistent with some of the statistical regularities researchers have found in specific posts over the years. This theory treats A858 in the same broad category as other deliberately constructed internet ciphers, an anonymous creator communicating a real, if currently inaccessible, message.

Structured randomness or an evolving experiment

An alternative and more cautious reading holds that at least some A858 posts may be automatically or semi-automatically generated, an evolving technical experiment, a bot testing output patterns, or a long-running piece of generative art or performance rather than a message with a fixed, decodable meaning. Proponents of this view note that a decade of sustained cryptographic attention has failed to produce a stable, repeatable decoding method across the full body of posts, which is unusual for a genuinely single, static cipher of the kind human codemakers have historically used.

Common Misconceptions

A858 is sometimes assumed to be a hoax or a simple prank with no real content behind it at all, a stronger claim than the evidence supports. Genuine statistical regularities have been identified in specific posts by researchers within the Solving_A858 community, which is inconsistent with pure, meaningless randomness, even though no comprehensive decoding has followed from those findings.

It is also sometimes conflated directly with Cicada 3301, given their similar reputations as the internet's leading unsolved puzzles. The two differ in a specific way: Cicada 3301 presented an explicit, structured challenge with escalating stages that were, in fact, successfully solved as puzzles, even though the identity and ultimate purpose of its creators remain unconfirmed. A858 has never presented itself as a challenge with stages or an endpoint at all; whether it is a puzzle intended to be solved is itself part of what remains unknown.

Current Consensus

There is no expert or community consensus on what A858 actually is or means. Cryptographers and hobbyists within the Solving_A858 community agree that specific posts show genuine statistical structure inconsistent with pure randomness, but disagree on whether that structure reflects a genuinely decodable cipher, an automated generative process, or something else entirely. The identity of the original poster remains entirely unconfirmed.

Why This Mystery Endures

A858 endures precisely because it offers so little to work with beyond the challenge itself: no manifesto, no stated goal, no confirmed creator, and no resolution after more than a decade of sustained attention from a community built specifically to crack it. That absence of any narrative framing is unusual among internet mysteries, most of which eventually attract at least a claimed explanation, true or false, that gives the story a shape; A858 has never had one.

It also endures by comparison with the internet's other famous puzzles. Cicada 3301 rewarded solvers with a structured sequence of increasingly difficult stages, giving the mystery a satisfying shape even though its ultimate creators and purpose were never confirmed; Webdriver Torso turned out to be the opposite kind of case entirely, a mundane technical testing channel with no puzzle intended at all, eventually traced to its source by an ordinary blogger. A858 sits in a stranger position between those two: unlike Webdriver Torso, its content shows genuine cryptographic structure worth investigating; unlike Cicada 3301, it has never given investigators any confirmation that a solution exists to be found. This page is part of this site's internet mysteries coverage.