A short unique ID generation method based on the ID generation used in Hashicorp Boundary and Vault

shortid.go

package shortid

import (
	"crypto/rand"
	"fmt"
	"io"
)

// Base58 contains the encoding charset for base58 encoding.
//
// Base58 was invented by Satoshi Nakamoto while creating
// Bitcoin. Base58 is ideal for encoding ID's that people will
// read or need to type out because the character set excludes
// characters the look similar and could be commonly mistaken.
const Base58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

// Base58Len contains the length of the base58 encoding charset.
const Base58Len = byte(len(Base58))

// NewWithLength returns a new short id
func NewWithLength (length int) string {
	output := make([]byte, 0, length)

	// Request a bit more than length to reduce the chance
	// of needing more than one batch of random bytes
	batchSize := length + length/4

	for {
		buf := make([]byte, batchSize)
		if _, err := io.ReadFull(rand.Reader, buf); err != nil {
			panic(fmt.Errorf("failed to read random bytes: %v", err))
		}

		for _, b := range buf {
			// Avoid bias by using a value range that's a multiple of 62
			if b < (Base58Len * 4) {
				output = append(output, Base58[b%Base58Len])

				if len(output) == length {
					return string(output)
				}
			}
		}
	}

	return ""
}

// New returns a new short id that's 10 characters long
func New () string {
	return NewWithLength(10)
}