Autokey Cipher Solver

Autokey Cipher is a letter replacement password, which is an extension of the Virginia (Vigenere) password, but uses a different replacement method to generate the key, which is generally more secure than the Virginia (Vigenere) password .
The Autokey Cipher encryption process is:
1) The "key" of the automatic key password is a keyword, such as "FORMATATION";
2) Autokey password uses the following table to encrypt the plain text;
3) To encrypt the message, place the key above the plain text, and after writing all the key characters, start to write the plain text as the key:
Key: FORTIFICATIONILIKEAUTOM
Original: ILIKEAUTOMATICKEYCIPHER
4) The letter "I" to be coded is found in the first column of the table. Then, we move along the "I" row of the table until we reach the column with "F" at the top ("F" is the key letter of the first "D"), and the intersection is our ciphertext character "N" ; Therefore, the ciphertext of the above plaintext is:
Key: FORTIFICATIONILIKEAUTOM
Original: ILIKEAUTOMATICKEYCIPHER
Ciphertext: NZZDMFCVOFIHVKVMIGIJASD

Autokey password table:
 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
    ---------------------------------------------------
A   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B   B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
C   C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
D   D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
E    E F G H I J K L M N O P Q R S T U V W X Y Z A B C D
F    F G H I J K L M N O P Q R S T U V W X Y Z A B C D E
G   G H I J K L M N O P Q R S T U V W X Y Z A B C D E F
H   H I J K L M N O P Q R S T U V W X Y Z A B C D E F G
I     I J K L M N O P Q R S T U V W X Y Z A B C D E F G H
J    J K L M N O P Q R S T U V W X Y Z A B C D E F G H I
K   K L M N O P Q R S T U V W X Y Z A B C D E F G H I J
L    L M N O P Q R S T U V W X Y Z A B C D E F G H I J K
M   M N O P Q R S T U V W X Y Z A B C D E F G H I J K L
N   N O P Q R S T U V W X Y Z A B C D E F G H I J K L M
O   O P Q R S T U V W X Y Z A B C D E F G H I J K L M N
P    P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
Q   Q R S T U V W X Y Z A B C D E F G H I J K L M N O P
R   R S T U V W X Y Z A B C D E F G H I J K L M N O P Q
S   S T U V W X Y Z A B C D E F G H I J K L M N O P Q R
T   T U V W X Y Z A B C D E F G H I J K L M N O P Q R S
U   U V W X Y Z A B C D E F G H I J K L M N O P Q R S T
V   V W X Y Z A B C D E F G H I J K L M N O P Q R S T U
W   W X Y Z A B C D E F G H I J K L M N O P Q R S T U V
X   X Y Z A B C D E F G H I J K L M N O P Q R S T U V W
Y   Y Z A B C D E F G H I J K L M N O P Q R S T U V W X
Z   Z A B C D E F G H I J K L M N O P Q R S T U V W X Y