如何自己产生熵？ - RSA Golang

Question

我正在使用 Golang 的 RSA 加密库。以下是加密消息的函数：

func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, label []byte) ([]byte, error)

随机参数用作熵的来源，以确保对同一消息进行两次加密不会产生相同的密文。此参数允许使用 linux 函数，如 getrandom(2)（如果可用）或 /dev/urandom，否则通过访问从设备和其他来源收集的环境噪声作为随机数生成器。我不希望 EncryptOAEP 函数使用操作系统的函数（getrandom(2) 或 /dev/urandom）来生成随机数。我需要自己生成一个随机数（即在EncryptOAEP函数之外），然后插入其中。这个库有可能吗？如果不是，我可以使用什么 Golang 的库来实现这种行为？我希望我足够清楚，任何帮助将不胜感激，谢谢！

Answer 1

按照设计，这是可能的，而且很容易做到。提供任何 io.Reader 作为 random 参数。

这是来自 Go crypto/rsa 包的示例。我将 crypto/rand io.Reader 替换为 math/rand io.Reader 。

package main

import (
    "crypto/rsa"
    "crypto/sha256"
    "fmt"
    "math/big"
    "math/rand"
    "os"
    "time"
)

func main() {
    secretMessage := []byte("send reinforcements, we're going to advance")
    label := []byte("orders")

    // crypto/rand.Reader is a good source of entropy for randomizing the
    // encryption function.
    // rng := rand.Reader
    // However, you can use any io.Reader.
    // For example, math/rand.Reader
    rng := rand.New(rand.NewSource(time.Now().UnixNano()))

    ciphertext, err := rsa.EncryptOAEP(sha256.New(), rng, &test2048Key.PublicKey, secretMessage, label)
    if err != nil {
        fmt.Fprintf(os.Stderr, "Error from encryption: %s\n", err)
        return
    }

    // Since encryption is a randomized function, ciphertext will be
    // different each time.
    fmt.Printf("Ciphertext: %x\n", ciphertext)
}

func fromBase10(base10 string) *big.Int {
    i, ok := new(big.Int).SetString(base10, 10)
    if !ok {
        panic("bad number: " + base10)
    }
    return i
}

var test2048Key *rsa.PrivateKey

func init() {
    test2048Key = &rsa.PrivateKey{
        PublicKey: rsa.PublicKey{
            N: fromBase10("14314132931241006650998084889274020608918049032671858325988396851334124245188214251956198731333464217832226406088020736932173064754214329009979944037640912127943488972644697423190955557435910767690712778463524983667852819010259499695177313115447116110358524558307947613422897787329221478860907963827160223559690523660574329011927531289655711860504630573766609239332569210831325633840174683944553667352219670930408593321661375473885147973879086994006440025257225431977751512374815915392249179976902953721486040787792801849818254465486633791826766873076617116727073077821584676715609985777563958286637185868165868520557"),
            E: 3,
        },
        D: fromBase10("9542755287494004433998723259516013739278699355114572217325597900889416163458809501304132487555642811888150937392013824621448709836142886006653296025093941418628992648429798282127303704957273845127141852309016655778568546006839666463451542076964744073572349705538631742281931858219480985907271975884773482372966847639853897890615456605598071088189838676728836833012254065983259638538107719766738032720239892094196108713378822882383694456030043492571063441943847195939549773271694647657549658603365629458610273821292232646334717612674519997533901052790334279661754176490593041941863932308687197618671528035670452762731"),
        Primes: []*big.Int{
            fromBase10("130903255182996722426771613606077755295583329135067340152947172868415809027537376306193179624298874215608270802054347609836776473930072411958753044562214537013874103802006369634761074377213995983876788718033850153719421695468704276694983032644416930879093914927146648402139231293035971427838068945045019075433"),
            fromBase10("109348945610485453577574767652527472924289229538286649661240938988020367005475727988253438647560958573506159449538793540472829815903949343191091817779240101054552748665267574271163617694640513549693841337820602726596756351006149518830932261246698766355347898158548465400674856021497190430791824869615170301029"),
        },
    }
    test2048Key.Precompute()
}

游乐场：https://play.golang.org/p/KtqUuDC2Tai

输出：

Ciphertext: 47516ff9863897f8f5344d07bca363515856ace56fed5451ede414eb6771eff357f09ca67f07d0d918b6e7107975f83afc4eebc932a7d9ba3f48c3f70399af88917c852e46a3d43eaa9bc563c7780bf7cf090c0b5e1690ac77af9e7c8cc6ec0d2fb729eed3fb45c824754bfd898e02eee8dae88b4fb3277f6970dbb0b929da7c14d245e51ed3a3e63127efc3e4c438adcfce78bbc1117a134f5a9dd62f9ebc14f125561c959ce6963a2b8605687ab568ec570295bb8f25477c7bbcb7303d96e888a0150e23ea0dd4880fefe40d86567518784d7f54c594f2c0e576a14c210201bf9d75fbd96b70fdd793c28ffecaa5c036b2949dba6e66004ec2f0e676095f1c