Sony PCWA-C800S - Manual (Page 67)

I cannot input the encryption key
You must enter the correct encryption key (WEP key). Permissible encryption key characters and their maximum number are detailed below .
Ke y form at Ke y le ngth Num be r of characte rs
ASCII
(alphanumeric characters and symbols) 40 bits
5 characters
104 bits 13 characters
Hexadecimal
(0 to 9, A to F, a to f)
40 bits 10 characters
104 bits 26 characters
Hint
ASCII and hexadecimal formats are detected automatically.
Page 67