If you add up all the digits in the string you get 152. 152 can be divided by 8 which could mean binary. Use Run Length Encoding to get the following binary string

[hint]Haven’t seen this in a while but your hint is “A”[/hint]

After trying multiple cipher including morse, BiFid, Playfair I opted for one that hasn’t been used in a long time: Vigenere Autokey with A

xotninesevencryptotwosixfouruk

xot97crypto264uk

Yep, sometimes you just need to try stuff !!!

Code #3

Observations

36 letters… that a perfect square!

[hint]It’s a square but mixed up[/hint]

Make a 6×6 grid

e

e

d

p

n

b

e

e

c

s

i

l

n

i

y

t

n

a

i

g

t

h

e

c

n

h

h

r

b

k

e

t

r

e

g

o

We have some numbers in there but things are out of place. The BlackO columns sort of gives it away for the keyword which should be BlackOps. Let’s rearrange the columns in this way: 3, 1, 6, 4, 2, 5