Using Transport Layer Security

Z and I Emulator for Windows allows you to negotiate the Transport Layer Security 1.0 protocol. The TLS protocol is based on the SSL protocol. TLS differs from SSL mainly in the initial handshake protocol for establishing client/server authentication and encryption. TLS also allows you to use FIPS (Federal Information Processing Standard) mode. Although TLS and SSL do not operate with each other, TLS provides a mechanism by which a TLS 1.0 implementation can revert to SSLv3.

The TLS protocol uses public-key and symmetric-key cryptographic technology. Public-key cryptography uses a pair of keys, one public and one private. Information encrypted with one key can only be decrypted with the other key. For example, information encrypted with the public key can be decrypted only with the private key. Each server's public key is published, while the private key is confidential. To send a secure message to the server, the client encrypts the message by using the server's public key. When the server receives the message, it decrypts the message with its private key.

Symmetric-key cryptography uses the same key to encrypt and decrypt messages. The client randomly generates a symmetric key to be used for encrypting all session data. The key is then encrypted with the server's public key and sent to the server.