Traditional encryption is weak and no longer be used. They can be easily broken

Question

Traditional encryption is weak and no longer be used. They can be easily broken by using frequency analysis is a well-known fact.

But, the frequency analysis often depends on the number of captured ciphertext, or the duplication of the text. What if the text was compressed by some types of algorithms (such as Huffman algorithm?zlib or lzma) before using traditional encrption? For better security, magic-number-like header or identifier is not added to the text.

How much difficulty increases for frequency analysis attack?

Explanation / Answer

Im no crypto expert, so I cannot answer the full of your question-- but this part is not correct. Encryption using algorithms such as 3DES, RC4, AES, etc is secure to the point where it is not possible to determine from looking at a block of data whether it is random or encrypted. Further, if properly designed there will be an avalanche effect: a very minor change in key or plaintext will have a drastic effect on the encrypted text.

If an algorithm's output is attackable by frequency analysis, it is not suitable for production. I will note that there are some historical computer crypto algorithms (such as AES ECB) which HAVE been susceptible to frequency analysis; and when they are, they are marked as "not safe" and they fall out of use.

Regarding compression, if changing the plaintext increases the difficulty of cracking your encryption, then your algorithm is not secure. I will leave explanations for why that is to others with more knowledge on the topic.

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