Crypted Private Message from Nepgear to Uni decyphered - I did it for you <3

[Drksun_Illys]

Screenshot : https://steamuserimages-a.akamaihd.net/ugc/921421499992890132/CDDB997D6397F5694327737BD64E6804DB327638/

If you wondered what was Nepgear saying to Uni, I decyphered it for you. Here is the process.


The original message says :
"Xril Hvc, gpuas sbc zbz uyeula jyisvva jqnu uy.
V'u nuihxnoy gih syrx oc ecgp uyt gl uyppuaqw
ppuga, ual C ppyeqmu woe nlvmhqabvx mb dyeg ghkb."


I could have isolated the lone capital letters "V'u" and "C" since the only one in the english language would be the first person subject capital "I", but since the two are differents we can't. But we can assume from that that the switching is different for each letter.

Thus I needed a serie of short words to find this order and the cyphering method.

As the second word of the message is "Hvc" made of 3 letters with the first being in capital, it wouldn't be surprising for it to be "Uni",
knowing the personnalité of Nepgear, we can also assume that her type of writing would be formal and it would make sense for her message to begin with "Dear Uni,".

From that I could find the cyphering method :
Have to go from Xril Hvc to Dear Uni, thus…

To go from X to D we need to change the letter with the 6th following it.
To go from r to e we need to change the letter with the 13th following/preceding it.
To go from i to a we need to change the letter with the 8th preceding it.
To go from l to r we need to change the letter with the 6th following it.
To go from H to U we need to change the letter with the 13th following/preceding it.
To go from v to n we need to change the letter with the 8th preceding it.
To go from c to i we need to change the letter with the 6th following it.

This gives us 6 13 -8 6 13 -8 6 from which we can see a recurring patern of 13 -8 6.

Now using simple handmades tables for switching letters:

13
ABCDEFGHIJKLMNOPQRSTUVWXYZ
NOPQRSTUVWXYZABCDEFGHIJKLM

-8
ABCDEFGHIJKLMNOPQRSTUVWXYZ
STUVWXYZABCDEFGHIJKLMNOPQR

6
ABCDEFGHIJKLMNOPQRSTUVWXYZ
GHIJKLMNOPQRSTUVWXYZABCDEF




I could decypher the crypted original message :

"Xril Hvc, gpuas sbc zbz uyeula jyisvva jqnu uy.
V'u nuihxnoy gih syrx oc ecgp uyt gl uyppuaqw
ppuga, ual C ppyeqmu woe nlvmhqabvx mb dyeg ghkb."


giving the proper version :

"Dear Uni, thank you for always playing with me.
I'm thankful you keep up with all my mechanic
chats, and I cherish our friendship so very much."



You're welcome, dear Neptunia community !
I had fun doing this little brain-teaser, am gonna have a lot more fun continuing to play the game, and hope I could help you getting the answer you were looking for ^^

— Drksun, 28th February 2018

[Ztarman]

Old news

[Drksun_Illys]

Come on, there is no topic on it in the Steam Community threads, and I legitimately found it by myself without looking it out.
It's fun having fun and sharing it ^^

[Ztarman]

Originally posted by Drksun:

Come on, there is no topic on it in the Steam Community threads, and I legitimately found it by myself without looking it out.
It's fun having fun and sharing it ^^

Yet.

Everyone's currently too busy roasting the game or IFI.

[Unyaa]

Damn...

[DanielCLFFF13]

Originally posted by Unyaa:

Damn...

[Tipomaniac]

Well congrats

[Galleta.]

good stuff op

[HyperAije]

Thank you for posting this. I doubt I would have ever found out what she was saying myself. Also the message itself is really cute

[Steins]

It's a method called "Vigenère cipher".
To decode the message, you have to use the key "UNI".

Good job, you almost found the right way to use this method.

"UNI" -> 13,20,8.
To encode, you add the key to the text modulo 26.
To decode, you sub the key to the cipher modulo 26.

With a little key, it's easy to crack the key by grouping letters.
You can do frequency analysis for each group.
If you are interested, you can follow this link : https://en.wikipedia.org/wiki/Letter_frequency

[Zanameth]

Otsukare. Naisu Desu.

[Drksun_Illys]

Originally posted by Steins:

It's a method called "Vigenère cipher".
To decode the message, you have to use the key "UNI".

Good job, you almost found the right way to use this method.

"UNI" -> 13,20,8.
To encode, you add the key to the text modulo 26.
To decode, you sub the key to the cipher modulo 26.

With a little key, it's easy to crack the key by grouping letters.
You can do frequency analysis for each group.
If you are interested, you can follow this link : https://en.wikipedia.org/wiki/Letter_frequency

Yeah I've always been the type of guy instinctively using the method "why make it easy when you can make it complicated" :p
And I have no background or knowledge in cyphering, so.
Still had fun ^^

But that makes more sense of course with Nepgear being a tech-nerd :3

[Mama Llama]

I was starting with a basic shift then I realized I should probably just check to see if anyone else posted a full message. Whew, glad I didn't bother because I would have worked on it for ages before considering moving to a keyed shift. The "UNI" key is an especially nice touch though

[DeltaBladeX]

I remember the GameFAQs topic all about translating this message

[Zergem]

Aw, nice. Thanks.

[Fahmi4869]

I've been wondering since the first time seeing this code in the game if I can decrypt it myself, but I was still confused. Glad you solved it. Nice job tho