如何使用 RSA 私钥解密加密的消息

Question

我正在点击一个需要我的公钥的 API，然后 API 将返回一个包含矢量和令牌的响应，但它们是加密形式的（我认为他们使用我的公钥来做到这一点）。 为了解密它，我需要使用我的私钥。 私钥和公钥都采用 DER 编码。 我基本上想实现这样的东西https://www.devglan.com/online-tools/rsa-encryption-decryption

Keys that Im using (again they are dummy:) Public: MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCbI1SofN/ZPsprBlPAW/c4GDKHo6Idv3J/P5LEEUpAsbVVpq6wY7Tf6lfBSTcirq48oMD34p3z5sX1jYy15OXNxNKBpoOdv8BYQdnK/LfFcZ5720yUNka0xiHUol/Zi0c0PWB6HkAAkT0sbeGLbCuX6yr6SbJBFaI2ofIKk/mGswIDAQAB

Private: 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

Encrypted message: BUy5nR/PuJNCFXeUxQd4oxkCvMo2JiLwH5VkzLz1UdM4M0VXDv4Ba1OaNHbttqETQENy1VfW2V4v9Pw5HmDIcS1sdGN69ceEHJbned46rK1EVtMVQZGP9ha54AXie5v/1TdKYWJ+AFt0FxVj4kfFXGXEzF19Q8LB2AOJCAEJK6s= Lets go to the coding part: I'm retrieving my private and public keys from the env file:

public := goDotEnvVariable("publicKey")
private := goDotEnvVariable("privateKey")

现在，在点击 API 并获得结果后，我尝试使用rsa.DecryptOAEP function 解密消息，但它一直给我[] crypto/rsa: decryption error 。 在 package 内部调试后，我在这里得到错误：

k := priv.Size() // private key size
if len(ciphertext) > k || //ciphertext is the encrypted text and hash.Size()*2+2 is the hash size that Im using
    k < hash.Size()*2+2 {
    return nil, ErrDecryption
}

if 语句的结果： k = 128 hash.Size()*2+2=66 cipher = 172 起初我在将私钥（在我的例子中是字符串，因为它来自 env 文件）转换为 rsa private 时遇到了问题钥匙。 这是我为解决问题所做的工作：

    sEnc, err := b64.StdEncoding.DecodeString(private) //using this package "encoding/base64"

然后我像这样转换它：

    block := &pem.Block{
    Type:  "RSA PRIVATE KEY",
    Bytes: sEnc,
    }
    parseResult, err := x509.ParsePKCS8PrivateKey(block.Bytes)

我究竟做错了什么？

Answer 1

如果在Select Cipher Type字段中选择了RSA ，devglan 网站将应用 PKCS#1 v1.5 作为填充，因此必须使用rsa.DecryptPKCS1v15() 。 私钥是一个 Base64 编码的 PKCS#8 DER 密钥，可以使用x509.ParsePKCS8PrivateKey()导入。

全部一起：

import (
    "crypto/rand"
    "crypto/rsa"
    "crypto/x509"
    b64 "encoding/base64"
    "fmt"
)

func main() {

    // Base64 decode ciphertext
    ciphertext, _ := b64.StdEncoding.DecodeString("BUy5nR/PuJNCFXeUxQd4oxkCvMo2JiLwH5VkzLz1UdM4M0VXDv4Ba1OaNHbttqETQENy1VfW2V4v9Pw5HmDIcS1sdGN69ceEHJbned46rK1EVtMVQZGP9ha54AXie5v/1TdKYWJ+AFt0FxVj4kfFXGXEzF19Q8LB2AOJCAEJK6s=")

    // Import PKCS#8 key
    pkcs8DerKey, _ := b64.StdEncoding.DecodeString("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")
    key, _ := x509.ParsePKCS8PrivateKey(pkcs8DerKey)
    var privateKey *rsa.PrivateKey
    privateKey, _ = key.(*rsa.PrivateKey)

    // Decrypt (using RSA with PKCS#1 v1.5 padding)
    rng := rand.Reader
    plaintext, _ := rsa.DecryptPKCS1v15(rng, privateKey, ciphertext)

    fmt.Println(string(plaintext)) // {"token":"312ade4b52e7bb4cadf59b4c7c83cb41","vector":"2b8db4fdb11f361d","id":"63876cf63ec7a641db8f1def"}
}