| crypto/rand | Package rand implements a cryptographically secure random number generator. |
| crypto/rsa | Package rsa implements RSA encryption as specified in PKCS #1 and RFC 8017. |
| crypto/tls | Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446. |
| encoding/pem | Package pem implements the PEM data encoding, which originated in Privacy Enhanced Mail. |
| flag | Package flag implements command-line flag parsing. |
| github.com/google/certificate-transparency-go/x509 | Package x509 parses X.509-encoded keys and certificates. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| math/big | Package big implements arbitrary-precision arithmetic (big numbers). |
| os | Package os provides a platform-independent interface to operating system functionality. |
| testing | Package testing provides support for automated testing of Go packages. |
| time | Package time provides functionality for measuring and displaying time. |