Cipher with random alphanumeric characters. What kind of cipher is this?

Question

My friend sent me a cipher with 3 parts (without telling me how to separate the parts. He encrypted each part in a different way, then the whole thing was encrypted again. He says that part 2 is longer than part 3, which in turn is longer than part 1, so 2>3>1. It is in base 10 and it doesn't make sense in any other bases anyway. It should mostly be in English but the last part is a poem, perhaps in German. Weirdly, he also provided this poem from Ready Player One by Ernest Cline:

"Three hidden keys open three secret gates
Wherein the errant will be tested for worthy traits
And those with the skill to survive these straits
Will reach The End where the prize awaits"
-Ernest Cline, Ready Player One

I don't know how to solve it because the text has seemingly random jumbles of alphanumeric characters. Here it is:

W3CWLI186N66NE6G9E6E76LLA31R7WRH5F1A7WR3WTETDO3B36T6RA3606RR6O6I9V86NW6F7W1A1FOH9TADUVIDUOIV7VME66DWE6AMWSSODDPSUBHADU2EAIE8WLDV7BWPVIEVMWVIW9WD9SW7LDYPWYVDJDY2E2DYW9WYJWBVUL7DLW6VERS76I5U6V7BW7L6UYWPD2W6V7BVYELCU7S7VA9YD2DVWBD22DLPWJWLBWELP6WBUYWBD22DL9YD69WY7VAJDYVIW6EHWDJDUYJUVUYW6ELPJDYW8WY67OLWPOWDYOWME6I7LOVDLONIRFWAN6W12NAGFRCTOTOPAN6S1A156OU6GU6G2FFPH3SLAN6RW6OSNW6DFH3A1FOTOPTHHANTAAN6W61GOFG3SNW1PPH6H1L6LWUBAFGTAAN6S1TGFUF3PFOAFTD6AF4N3WO6UAFAN66OPPFRAN6IFWHPFW2FPRFWX1PAN63GTAFR1OPGNC6AN1O21RUF3I6OAAN1GRTWTOPTW6G661O2AN1GC6GGT26AN6OSFO2WTA3HTA1FOGUF3NTD6GFHD6PAN6XW6OB13GS1BN66G12O6PX66OB13G

I managed to find some patterns in letter location, such as V only appearing in the first half, X only appearing at the end, Y only appearing in the middle, no Z in the entire text etc. I believe this may be some sort of computer encryption, yet I cannot think of any method in base 10 that could have random alphanumeric characters. What kind of cipher is this, and how can I solve it?

The poem is probably not that related. I'm not quite sure what kind of cipher was used, but I believe it is similar to something that already exists. I believe my friend used some sort of cipher similar to computer encryption, but still human-solvable (possibly with the help of online tools, but not requiring an actual program to be written)

Answer 1

Plaintext

Split the ciphertext into three parts:

W3CWLI186N66NE6G9E6E76LLA31R7WRH5F1A7WR3WTETDO3B36T6RA3606RR
6O6I9V86NW6F7W1A1FOH9T

ADUVIDUOIV7VME66DWE6AMWSSODDPSUBHADU2EAIE8WLDV7BWPVIEVMWVIW9
WD9SW7LDYPWYVDJDY2E2DYW9WYJWBVUL7DLW6VERS76I5U6V7BW7L6UYWPD2
W6V7BVYELCU7S7VA9YD2DVWBD22DLPWJWLBWELP6WBUYWBD22DL9YD69WY7V
AJDYVIW6EHWDJDUYJUVUYW6ELPJDYW8WY67OLWPOWDYOWME6I7LOVDL

ONIRFWAN6W12NAGFRCTOTOPAN6S1A156OU6GU6G2FFPH3SLAN6RW6OSNW6DF
H3A1FOTOPTHHANTAAN6W61GOFG3SNW1PPH6H1L6LWUBAFGTAAN6S1TGFUF3P
FOAFTD6AF4N3WO6UAFAN66OPPFRAN6IFWHPFW2FPRFWX1PAN63GTAFR1OPGN
C6AN1O21RUF3I6OAAN1GRTWTOPTW6G661O2AN1GC6GGT26AN6OSFO2WTA3HT
A1FOGUF3NTD6GFHD6PAN6XW6OB13GS1BN66G12O6PX66OB13G

Solve each part as a simple substitution. I could not find a method to the substitution that explains all of the apparent enciphering mistakes: a nonsense word at the beginning, occasional cases of a plaintext letter having two cipher equivalents, and cases of a cipher letter having two plain equivalents. It seems to be calling itself the "Brenpius Cipher", could that be your friend's name?

W3CWLI186N66NE6G9E6E76LLA31R7WRH5F1A7WR3WTETDO3B36T6RA3606RR
ah?alyivebeebdecodedwellthiswasfunitwashardrightheresthemess

6O6I9V86NW6F7W1A1FOH9T
egeyouvebaenwaitingfor


ADUVIDUOIV7VME66DWE6AMWSSODDPSUBHADU2EAIE8WLDV7BWPVIEVMWVIW9
youthoughtitwassoeasywellgoodluckyoumayhavenoticedthatwethep

WD9SW7LDYPWYVDJDY2E2DYW9WYJWBVUL7DLW6VERS76I5U6V7BW7L6UYWPD2
eopleinordertoformamoreperfectunionestablishjusticeinsuredom

W6V7BVYELCU7S7VA9YD2DVWBD22DLPWJWLBWELP6WBUYWBD22DL9YD69WY7V
estictranquilitypromotecommondefenceandsecurecommonprosperit

AJDYVIW6EHWDJDUYJUVUYW6ELPJDYW8WY67OLWPOWDYOWME6I7LOVDL
yforthesakeofourfuturesandforeversignedgeorgewashington


ONIRFWAN6W12NAGFRCTOTOPAN6S1A156OU6GU6G2FFPH3SLAN6RW6OSNW6DF
nhwfortherightsofmanandthecitizenyesyesgoodluckthefrenchrevo

H3A1FOTOPTHHANTAAN6W61GOFG3SNW1PPH6H1L6LWUBAFGTAAN6S1TGFUF3P
lutionandallthatthereisnosuchriddlelikekryptosattheciasoyoud

FOAFTD6AF4N3WO6UAFAN66OPPFRAN6IFWHPFW2FPRFWX1PAN63GTAFR1OPGN
ontoavetojhurneytotheenddoftheworldorgodforbidtheusatofindsh

C6AN1O21RUF3I6OAAN1GRTWTOPTW6G661O2AN1GC6GGT26AN6OSFO2WTA3HT
methingifyouwentthisfarandareseeingthismessagethencongratula

A1FOGUF3NTD6GFHD6PAN6XW6OB13GS1BN66G12O6PX66OB13G
tionsyouhavesolvedthebrenpiuscipheesignedbeenpius

Here are the substitution keys, as best as I can figure:

Plain:     abcdefghiijklmnopqrsttuuvwxyz
Cipher 1:  WNGE6HO31D..L0F9..TRAB5V87.I.
Cipher 2:  ERBPWJOI7.5HS2LD9CY6V.U.8M.A.
Cipher 3:  TXSP6R2N1.4LHCOFB.WGA.3.DI.U5

Solve path

I put the entire cipher into AZDecrypt, a robust program for solving substitution ciphers. It gave me a hundred nonsense words, but near the end I saw phrases SEEING THIS YESSAGE THEN CONGRATULATIONS and THE FRENCH RESOLUTION AND ALL THAT. These cribs allowed me to complete the solution by hand and identify where each of the three different substitutions began and ended.