While it’s probably not obvious when you first start out, by experience you’ll remembers that pattern as a Polybius square.
Here’s what it looks like
1
2
3
4
5
1
a
b
c
d
e
2
f
g
h
j
k
3
l
m
n
o
p
4
q
r
s
t
u
5
v
w
x
y
z
Each pairs correspond to a grid coordinate. 43 is S, get the corresponding letter for each pair.
seyxdseaurasdsiptwe
7yxd7aurasd6p2e
Code #3
Observations
24 characters, rings a bell right ?
[hint]What cipher usually start with a N[/hint]
When counting 24 characters, Base64 should come up to mind. Base64 passcodes usually start with a capital N. We have that n at the end of the string. Let’s reverse it.
nfnbnvzjsu5tudfsrvu5vdjw
Now let’s make those letters all caps.
NFNBNVZJSU5TUDFSRVU5VDJW
Convert Base64 to text
4SA5VIINSP1REU9T2V
That doesn’t work, need a but of tweaking. Roman numerals, the 5 should be a V and VI is 6.
