| Path | Synopsis | 
|---|---|
| crypto/rand | Package rand implements a cryptographically secure pseudorandom number generator. | 
| crypto/subtle | Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly. | 
| errors | Package errors implements functions to manipulate errors. | 
| io | Package io provides basic interfaces to I/O primitives. | 
| math/big | Package big implements arbitrary-precision arithmetic (big numbers). |