# How to prove that ECB mode is not CPA secure?

I am new to cryptography and I do not know how to prove the ECB mode is not chosen plaintext attack (CPA) secure.

• Hint: request $m_1$ and $m_2$ from oracle? That is why we need probabilistic encryption. – kelalaka Oct 2 at 14:43
• Which definition(s) of chosen plaintext attack security do you know? – SEJPM Oct 2 at 15:03