| crypto/hmac | Package hmac implements the Keyed-Hash Message Authentication Code (HMAC) as defined in U.S. |
| crypto/sha1 | Package sha1 implements the SHA1 hash algorithm as defined in RFC 3174. |
| crypto/subtle | Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly. |
| encoding/base64 | Package base64 implements base64 encoding as specified by RFC 4648. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| time | Package time provides functionality for measuring and displaying time. |