Zoom has been found to have significant weaknesses in its encryption scheme, including the use of a custom encryption protocol and the transmission of meeting encryption keys through servers in China. The company's documentation claims to use AES-256 encryption, but in reality, it uses AES-128 in ECB mode, which is not recommended due to its preservation of patterns in the plaintext. This has raised concerns about the security and privacy of Zoom meetings, particularly given the company's ties to China. The use of Chinese servers to distribute encryption keys has also sparked worries about potential pressure from Chinese authorities.