| crypto/rand | Package rand implements a cryptographically secure random number generator. |
| crypto/sha256 | Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4. |
| crypto/subtle | Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly. |
| encoding/hex | Package hex implements hexadecimal encoding and decoding. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| hash | Package hash provides interfaces for hash functions. |
| io | Package io provides basic interfaces to I/O primitives. |
| math/big | Package big implements arbitrary-precision arithmetic (big numbers). |
| os | Package os provides a platform-independent interface to operating system functionality. |
| 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. |