| crypto | Package crypto collects common cryptographic constants. |
| crypto/tls | Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446. |
| crypto/x509 | Package x509 implements a subset of the X.509 standard. |
| io | Package io provides basic interfaces to I/O primitives. |
| log | Package log implements a simple logging package. |
| net/rpc | Package rpc provides access to the exported methods of an object across a network or other I/O connection. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| time | Package time provides functionality for measuring and displaying time. |