| crypto/x509 | Package x509 implements a subset of the X.509 standard. |
| 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/cloudflare/cfssl/log | Package log implements a wrapper around the Go standard library's logging package. |
| github.com/cloudflare/cfssl/revoke | Package revoke provides functionality for checking the validity of a cert. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |