| encoding/base64 | Package base64 implements base64 encoding as specified by RFC 4648. |
| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/cloudflare/cfssl/cli/version | Package version implements the version command. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| os | Package os provides a platform-independent interface to operating system functionality. |