How secure is this cipher?

Question

Encryption

Good day!
I recently came up with my own cipher.
It is a hybrid between the Par cipher and the Caesar cipher.
Algorithm of actions :
1. Mix the alphabet
2. Divide it into two equal parts
3. Look for a letter from the plaintext in the lists, then find the position in the second list by index
4. Use the Caesar cipher to look for a "false" index and insert a character under this "false" index into ciphertext (numbers for "Caesar Cipher" are also chosen randomly)
What do you think: how reliable is this algorithm?

Answer 1

Classical ciphers rely on no one guessing how to decipher them, and picking them by hand can be tricky. And then, in fact, some of them break very easily. For example, a simple substitution cipher is broken by frequency analysis, and a shift cipher is broken by simply enumeration of different shift options, the number of which does not exceed the length of the alphabet.
With the advent of computing technology, everything has changed. No matter how confusing a cipher is for a human, a machine can very effectively check even a million different "classic" variants with a wide variety of algorithms and keys. Here it is even useless to hide the algorithm if it can be guessed by selection and combination.
The basis of modern cryptography is computational complexity. You can even know everything about the encryption algorithm - but you won't be able to decrypt it in a reasonable time. But the old-fashioned character-for-character encryption methods are computationally very simple and in no way suitable in the modern world.

Answer 2

Yes, this is bullshit, not a cipher.
Zero security.

Answer 3

3 point more clearly describe.
If the alphabet is divided into two parts, then the first and second will have 16 letters each. How is your encryption going next? And why do we need the first part of the cipher?

Answer 4

Very bad cipher idea.
If you encrypt the same text with your cipher, you get the same result.
Thus, you use a complicated way to encrypt, while the result is the usual character substitution, which can be done on the table. The one who will decrypt will not even use your double conversion. If there is enough text (even a paragraph), you can check the frequency of use of characters. And on a modern computer, you can generally try to sort through all the substitution options with automatic dictionary checking.
If you want cryptographic strength, start with the Vigenere cipher to understand how cryptographic algorithms work.