Consider a substitution cipher where the key is a transposition of the alphabet:

Plain Alphabet: ABCDEFGHIJKLMNOPQRSTUVWXYZ

Cipher Key: EKMFLGDQVZNTOWYHXUSPAIBRCJ

a$.$ Decrypt the following ciphertext: "UFJB XVXQ QEPQ IGRBV C$"$

b$.$ Provide a detailed explanation of the decryption process, including the substitution of each

letter and the final decrypted message.

c$.$ Analyze the security aspects of the given substitution cipher key and discuss potential

vulnerabilities or strengths.