The Most Famous Unsolved Ciphers

In this video, explore the fascinating history of ciphers, from ancient Greek military communication to modern-day cryptography. Discover unsolved cases like Kryptos at CIA HQ, the Zodiac Killer ciphers, and the mysterious Dorabella Cipher. Plus, learn about the embarrassing unsolved D'Agapeyeff cipher.

More information on the images used in this video:

06:24 My Name is Cipher - Zodiac

09:01 Octaves-notes-ru

[martinstallard]

1:02 kryptos
3:46 zodiac killer ciphers
6:55 the dorabella cipher
9:41 d'agapeyeff cipher
13:17 rhe voynich manuscript

[blablah]

The sheer number of videos a week Simon puts out always amazes me

[crazyeyez]

"Be sure to drink your Ovaltine..." 😂😂😂😂
Loved that reference. Wonder if Simon caught it

[KhaoticDeterminism]

I’ve always figured the zodiac killer was trolling with the ciphers. Given them a few that have a solution and then after that just give them gibberish.

[josephteller]

In regards to the d'agapeyeff cipher it is sort of the proof of something I have often said, the way to throw off decryption is to use a language no one knows easily or has not thought to program into a computer (especially a dead language or an invented one). The bigger the alphabet that exists for the initial language the harder it is figure out.

That's why some ancient languages have not had their surviving texts decoded for a very long time. So much of what was written in Cuneiform (in languages of Sumerian, Akkadian, Eblaite, Elamite, Hittite, Hurrian, Luwian, Urartian, Palaic, Aramaic, Old Persian) but that you won't find too many modern translators able to take things written in such and work with them in a cryptographic manner if they are converted to modern numeric style forms.

[EAWanderer]

Unsolved Ciphers on Sideprojects?
Should be on Decoding the Unknown 😅 - Unravel so many enigmas!

[richardvandertulip]

Typing this without doing a deep dive, but has anyone considered that parts of the Voynich manuscript were written in either right to left and/or mirror script? 13:42 definitely looks like the author wrote left-handed like Da Vinci.
Probably still encrypted backwards, but just adding food for thought.

[TitanicTortise]

Simon's beautiful capitalist heart saw the perfect chance to end on a plug, gotta love it. DtU is the channel I started on btw, highly recommend.

[bendkok]

You thought you knew everything there is to know, but then you find out Simon has yet another channel you hadn't heard about.

[jorgelotr]

2:37 could they be all of those misspellings (iqlusion, undergruund, desparatly)?

[beautifulsmall]

The simple ones are a wonderful teaching game for kids treasure hunts.

[dstinnettmusic]

I like how Simon has different areas of his basement for filming.

[julianmhall]

A problem I've only just noticed. When deciphering text the assumption is that the plain text original was spelled correctly, for example at 2:31, in paragraph K3 'desperately' is wrongly spelled 'desparatly' so if the decryption process looks for proper words it will skip errors like this.

[HorusDeathtouch]

It is totally possible that some ciphers, especially the one supposedly giving the Zodiac Killer's name, could just complete nonsense symbols meant to mislead with no intended solution whatsoever.

[crackedmagnet]

For Z13 if you use the same key as z340 and the letter "D" for the symbol that doesn't appear in z340 you get DREADADOLEDO, which could be "Dread-a-doodle-doo" with the double letters changed to single ones to prevent a vulnerability in the cipher. Given its using a known key with only one symbol guessed, I think thats what the message probably said and he was just "needling police" again. But as Simon said, with such a short message it's basically impossible to prove any answer is correct.

[elfinthekitchen]

Them: yes we have a team of 5, 000 geniuses and 800 supercomputers working on this cypher 24/7

Me: cool, i dropped out of college and haven't slept in 72 hours...let me grab paper and pencil to try and solve this code that's eluded you for 19 years.

[laurenmp]

Funny enough for Zodiac's Z13 cypher if you use the key from the 408 cipher it says Weed Shrewh, which is interesting in that you wouldn't expect the key from one cipher to produce anything close to actual words in a cipher with a different key. And yet, Weed Shrew h, two actual words. Granted together they make no sense and don't seem to be any sort of clue, plus the h at the end. And the Z32 has an omega in it, which is used in physics for ohms, and thus used by electrical engineers as well. And a few of Zodiac's symbols are used in Boolean algebra, which is what electrical engineers use to design logic circuits. Seems Zodiac left clues, within his clues, about who he is.

[viciousvictortee]

Way to fulfill the void! Good Show Boyz!

[AngeliqueStP]

That first entry... did I hear that right? Is that CIA guy's last name 'shite'?
That poor dude ...ouch.

[elfinthekitchen]

If i could read/play music, i would crack the dorabella cypher in next to no time.