节点JS decipher.final()抛出“错误的最终块长度”错误

Question

我正试图加密/解密。加密工作正常，并将加密数据写入文件。在解密时，我得到了一个长度错误问题。我使用了"utf-8“格式，但错误仍在继续。

/ A decrypt function 
function decrypt(file) {

  let data = JSON.parse(fs.readFileSync(file));

  let iv = Buffer.from(data.iv, 'hex');
  let encryptedText =
    Buffer.from(data.encryptedData, 'hex');


  //  Creating Decipher 
  let decipher = crypto.createDecipheriv(
    algorithm, Buffer.from(key), iv);

  // Updating encrypted text 
  let decrypted = decipher.update(encryptedText);
  let decrypted = Buffer.concat([decrypted, decipher.final()]);

  //  // returns data after decryption 
  return decrypted.toString();
}

//run 
// Decrypts output 
console.log(decrypt('./file.json.enc'));

Error: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length
    at Decipheriv.final (internal/crypto/cipher.js:170:29)
    at decrypt (/Users/chandrasekarareddy/Documents/projects/encrypt/final.js:48:22)
    at Object.<anonymous> (/Users/chandrasekarareddy/Documents/projects/encrypt/final.js:64:13)
    at Module._compile (internal/modules/cjs/loader.js:959:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
    at Module.load (internal/modules/cjs/loader.js:815:32)
    at Function.Module._load (internal/modules/cjs/loader.js:727:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
    at internal/main/run_main_module.js:17:11 {
  library: 'digital envelope routines',
  function: 'EVP_DecryptFinal_ex',
  reason: 'wrong final block length',
  code: 'ERR_OSSL_EVP_WRONG_FINAL_BLOCK_LENGTH'
}

它在decipher.final()上抛出错误。而不是文件作为输入参数，如果我传递文本，这是错误的罚款。提前感谢

Answer 1

如果您收到此错误，很可能是您传入了错误的键。如果密钥被错误地编码到所讨论的文件中，则会发生这种情况。

我建议最好的方法是以十六进制格式编码(因为我们在这里使用JSON )。

下面是对.json.enc文件进行编码的完整示例，然后再进行解码。注意，我使用的是aes-256-cbc，所以如果您更改加密模式，密钥和iv长度可能必须更改。

const crypto = require("crypto");
const fs = require("fs");

function encrypt(buffer, algorithm, key, iv) {
    const cipher = crypto.createCipheriv(algorithm, key, iv);
    return Buffer.concat([cipher.update(buffer, null), cipher.final()]);
}

function decrypt(buffer, algorithm, key, iv) {
    const decipher = crypto.createDecipheriv(algorithm, key, iv);
    return Buffer.concat([decipher.update(buffer), decipher.final()]);
}

function encryptToJsonFile(buffer, filePath, algorithm, key, iv) {
    let encryptedData = encrypt(buffer, algorithm, key, iv);
    let fileData = { encryptedData: encryptedData.toString("hex"), iv: iv.toString("hex") };
    fs.writeFileSync(filePath, JSON.stringify(fileData), "utf8");
    return fileData;
}

function decryptJsonFile(filePath, algorithm, key) {
    let fileData = JSON.parse(fs.readFileSync(filePath, "utf8"));
    let encryptedData = Buffer.from(fileData.encryptedData, "hex");
    let iv = Buffer.from(fileData.iv, "hex");
    return decrypt(encryptedData, algorithm, key, iv);
}

const filePath = "./test.json.enc";
const EncryptionAlgorithm = "aes-256-cbc";

const key = Buffer.from("70ac30ae736068d90467beec0aedd75f3714cfe1e83b030c67911bb649316be0", "hex");
const iv = Buffer.from("3d4be42df33cc6a030aa54df2e144920", "hex");

const textToEncrypt = "My secrets are here";
const bufferToEncrypt = Buffer.from(textToEncrypt, "utf8");

console.log("Encrypted:", encryptToJsonFile(bufferToEncrypt, filePath, EncryptionAlgorithm, key, iv));
console.log("Decrypted:", decryptJsonFile(filePath, EncryptionAlgorithm, key).toString("utf8"));

Answer 2

我得到了同样的错误，所以我解释我的解决方案，因为它可能会帮助其他人。

在我的例子中，我对文件进行加密，并将缓冲区(由encrypt()返回)直接存储在s3中。将其转换为JSON。我通过在base64编码字符串(而不是缓冲区)中存储缓冲区来解决这个问题。

createDecipheriv.update()的酷之处在于它接收base64编码的字符串作为输入，并返回解密缓冲区，您可以将其转换为可查看的ascii格式。

让我们看看我的功能：

// this returns buffer, but a buffer can’t be saved in s3 or db (details lost). So always convert 
// it to base64 encoding (which reduces space) and simply give its base64 encoded string 
// output as input to decrypt function as it accepts base64 encoded STRING.
function encrypt(key, buffer) {
  try {
    const cipher = crypto.createCipheriv('aes256', key, resizedIV);
    return Buffer.concat([cipher.update(buffer), cipher.final()]).toString('base64');
  } catch (error) {
    console.log('crypto encrypt err - ', error);
  }
}

这是我的解密函数：

// here cipher text was saved in s3 in base64 format 
// and decipher.update expects an base64 encoded STRING (not buffer)
async function decrypt(key, ciphertext) {
  try {
    const decipher = crypto.createDecipheriv('aes256', key, resizedIV);

    return Buffer.concat([
      decipher.update(ciphertext, 'base64'), // Expect `text` to be a base64 string
      decipher.final(),
    ]).toString();
  } catch (err) {
    console.log('decrypt err - ', err);
  }
}

红利：如果您使用KMS的信封加密从lambda函数中保存dataKey或从lambda函数返回datakey，那么:因为它是一个缓冲区，

在发送/保存缓冲区时，始终将其转换为一个Buffer.from(dataKey).toString('base64')

• When字符串，例如：Buffer.from(dataKey).toString('base64')

• When访问/检索该dataKey，将其转换回ascii格式，例如：Buffer.from(base64EncodedData, 'base64').toString('ascii')

如果错误仍然存在，请按以下链接操作：https://mlink.in/qa/?qa=755282/

请让我知道它是否对任何人有帮助:)