Certificates with RSA keys shorter than 2048 bits are also disallowed. In iOS 11 or later and macOS 10.13 or later, SHA-1 certificates are no longer allowed for TLS connections unless trusted by the user. CFNetwork disallows SSL 3, and apps that use WebKit (such as Safari) are prohibited from making an SSL 3 connection.
High-level APIs (such as CFNetwork) make it easy for developers to adopt TLS in their apps, while low-level APIs (such as amework) provide fine-grained control. Internet apps such as Safari, Calendar, and Mail automatically use this protocol to enable an encrypted communication channel between the device and network services. The TLS protocol supports both AES128 and AES256, and prefers cipher suites with forward secrecy. IOS, iPadOS, and macOS support Transport Layer Security (TLS 1.0, TLS 1.1, TLS 1.2, TLS 1.3) and Datagram Transport Layer Security (DTLS).
