Hello, sending files and other informations in DingTalk that it will not leak, based on the SSL/TLS protocol to provide data confidentiality and integrity for applications, build a complete private secure communication protocol, which adopts TLS1.3 encryption, the key negotiation uses the elliptic curve algorithm ECDH (Curve25519), and the symmetric encryption algorithm uses: AES-256-GCM/Chacha20. Through this private secure communication protocol, the end-to-end communication link encryption of the nail industry is realized to prevent eavesdropping to ensure the transmission of sensitive information.