Assembly code for simple coding/decoding of string confusion?

Question

I am learning for my exam and I am so confused by this assembly code. It is a program in which first user enters a string, than that string gets coded and printed, than decoded

Answer 1

Explained:

INC bx   ; increment bx, skip this byte (why ?)
MOV cl, [bx]  ; get number of characters of the string
XOR ch, ch    ; quick way to set ch to zero, so cx == cl for the loop

coding:
    INC bx    ; next address
    MOV dl, [bx]  ; get character value
    XOR dl, ah    ; decode it with XOR key in ah
    MOV [bx], dl  ; store in the same memory value
LOOP coding       ; decrement cl and goto coding if cx > 0

Format of the string seems "custom", certainly not NULL terminated but rather containing size first (is it Pascal? Ada uses this kind of system)

• The first byte seems ignored there.
• The second byte contains the length of the following string
• The rest of the data is the string itself

Note that in that case encoding and decoding are the same since XOR masking is used.