Answer:
No, because substitution ciphers can be broken very easily by frequency analysis.
Step-by-step explanation:
No, because substitution ciphers can be broken very easily.
They are the oldest form of cipher, look at, for example, Caesar's Cipher.
In a substitution cipher each letter is assigned a ciphered letter. For example, a is assigned d, b assigned e and as follows. By frequency analysis, it is very easily to be broken. For example, in the english language, let's say a is the most frequent character. So in the ciphered text, d is going to be the most frequent character.