如何使用'crypto/rand”包生成安全随机整数？

Generating Secure Random Integers with the "crypto/rand" Package

To securely generate a random integer between 0 and 27 using the "crypto/rand" package, you can utilize the following function:

func Int(rand io.Reader, max *big.Int) (n *big.Int, err error)

This function returns a pointer to a big.Int that represents the randomly generated integer, and it takes an io.Reader (in this case rand.Reader) and a big.Int that specifies the maximum value.

Here's how you can use this function to generate a random integer between 0 and 27:

package main

import (
    "fmt"
    "crypto/rand"
    "math/big"
)

func main() {
    nBig, err := rand.Int(rand.Reader, big.NewInt(27))
    if err != nil {
        panic(err)
    }
    n := nBig.Int64()
    fmt.Printf("Here is a random int in [0,27): %d\n", n)
}

You don't directly receive a go integer because the "crypto/rand" package uses a big.Int type to represent arbitrary-precision integers, which is more flexible for various scenarios.

For generating secure tokens, you can use a similar approach by generating a random array of bytes and encoding it using a suitable encoding scheme (such as Base64 or Base32) to translate the bytes to a string of tokens.

For instance, the provided code snippet you gave (getToken) demonstrates how to generate a secure token using this approach.

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