Hello,
Please begin at the Bold Text if you're already familiar with The Giant Cipher.
Recently, with the increase in discussion around BO3 The Impossible Easter Egg, I've stumbled across The Giant Cipher. While the two are likely unrelated, I thought I'd give a crack at The Giant given my background. I have extensive experience with base-change numbering systems (binary, hexadecimal, etc.) and minor experience in cryptography.
I've read up on where were common knowledge is at and attempted a large number of different solving techniques personally (to no avail.) I just wanted to summarize my thoughts and see if anyone wanted to weigh in or look to extend beyond my ideas…
First, and I think most importantly, as we all know, the piece of paper is upside down. This seems like a simple fix, flip the paper, right? Once we've done that, we're given 5 lines of text
The Giant Cipher (180 degree rotation)
This text is alphanumeric WITH backslashes. This indicates a Base64 system as seen below:
Noteworthy observation, there isn't a "SPACE" in this table, which is likely why we see the first line (the key) read as "TheGiant" and not "The Giant". Another (I think) noteworthy part of the first line is that it's 8 characters long, which, coincidentally, the plaintext ("kCm… Fo1") happens to be divisible by 8. This can be easily verified with a simple code. Continuing on, it seems very convenient that the plaintext is perfectly divisible by the key. It's likely that the key needs to be iterated across the plaintext in some manner or another…
There are many approaches, including but not limited to a binary transformation with an XOR operation, a Vigenère cipher, and other, more obscure ciphers and methods. There is also discussion of a layered cipher, which would be significantly harder to decipher as it requires multiple operations. I think this is unlikely unless it is a commonplace cipher that is well documented. This leads me into my next point…
Security through obscurity. This is a common phrase in cryptography which effectively means "anything can be unsolvable if it's so over-done and complex that it can't be undone." This most certainly isn't the case here. No one who truly enjoys ciphers would make one that is a random operation guessing game. Given the other ciphers that have been solved, I think it stands to reason that the creator enjoys ciphers and would not do this. As such, I will assume that The Giant cipher only has 1, at most 2 (though unlikely), layers and the operations are well documented.
My Ideas
I'm presenting these as my ideas because I haven't seen them in other places. If others have posted them, I would be happy to give them credit and consider my time wasted. Moving on…
The Giant Cipher is NOT upside down. The Giant Cipher is right-side up. The initial assumption is the paper should be rotated 180 degrees prior to transcribing, but I propose that we keep it in it's original formatting.
⇂oℲ/ƐXq5ㄥᘔᗺ⇂xㄥZʞᗡƎnb/߈o߈ɯᴚMɓsqNIʇᒋ⇂ʍɔΛ5WℲbHoƐℲᴚʍʍɥ/ᗡ⅁ʇɓᗡMʎb⊥oɹ5Ɛ69⊥ᘔʇɐᘔ8W⇂ɔpƐ0ʌ0Wxᒋpuʍ0uᴉ߈ɓㄥZᒋ⅁Ɐɥ0Ⅎ8ǝlxƐʍ0ʌ߈Ɐ5ɔzMΛᴉꓘʇԀɐᗺᴚNტu⅄ɾq0⅂ɯɯꓘdɟᗺԀɟ∩߈Ǝᗺ⇂ʎn⇂∩⇂ԀzⱯXⱯlꓘ0lᴉZʞblʌƆ⊥ℲƆo⅂ʎɟqɟ⇂߈ტ⇂lNʞɓNᒋ∩⅁9ᴉℲɓlɯƆʞ
I encourage you to verify this on your own if you wish to proceed with this process. Also, if you believe it's line sensitive you should manually space it. This is the website I used to flip the text: https://cryptii.com/pipes/upside-down
Now, instead of a Base64 system, we have a MUCH more complicated one, but a system nonetheless. You may or may not be familiar, but Unicode (utf-8) is a character set that covers a HUGE range of characters, abstract, foreign, and much more. A simple code can output all the respective utf-8 hexadecimal values, which can then be manually verified. I will show the first character for proof of concept
As you can see above, the first character's hexadecimal value was properly calculated in the python code and corresponds to the utf-8 table. This process should be repeated for every character in both the key and plaintext. After this is done, there is now a completely new, unexplored cipher to be approached. I believe this is the proper route to solving the cipher and where I have been and will continue to place my efforts.
Looking Forward
As mentioned, my efforts will be placed in this "upside down" cipher. I've attempted some of the previously mentioned ciphers on the binary (converted from hexadecimal) plaintext and key with no luck. I think it should also be mentioned that modulus operations will likely be required to return post-operation characters to English characters. I would think mod 64 (Base64), 128 (standard ascii), or maybe 256 (extended ascii) are the most likely candidates for the correct mod. Also, also, I expect that all hexadecimal values (each equaling 4 binary characters (bits)) will maintain the integrity of the divisibility between the plaintext and the key. That's to say, although the greatest common factor won't be 8 anymore, I expect it will still be the exact length of the plaintext.