如何使用Web Crypto API解密使用OpenSSL创建的文件？

Question

我试图解密使用OpenSSL命令行界面创建的文件.此文件创建于:

openssl aes-256-cbc -a -in file.txt -out file_encrypted.txt

并可以解密:

openssl aes-256-cbc -d -a -in file_encrypted.txt

通过使用-p标志,我可以检索WebCrypto API所需的实际值salt和IV:

> openssl aes-256-cbc -d -a -p -in file_encrypted.txt
salt=F57F1CC0CD384326
key=0E971326890959386F1CFB91F185CFE109203DCEBC81DCAD4EE642F34C538E5B
iv=A884549B66400EB198879F8A09148D4E
secret text

我目前的尝试看起来像这样:

function getKey (password) {
    return crypto.subtle.digest({name: "SHA-256"}, convertStringToArrayBufferView(password)).then(function(result){
        return crypto.subtle.importKey("raw", result, {name: "AES-CBC"}, false, ["encrypt", "decrypt"]);
    });
}

function decrypt(key, data, iv) {
    return crypto.subtle.decrypt({ name: "AES-CBC", iv: iv }, key, data).then(function(result){
        var decrypted_data = new Uint8Array(result);
        return convertArrayBufferViewtoString(decrypted_data);
    }, fail);
}

var encrypted = Uint8Array.from('0E971326890959386F1CFB91F185CFE109203DCEBC81DCAD4EE642F34C538E5B'.match(/\w\w/g));
var IV = Uint8Array.from('A884549B66400EB198879F8A09148D4E'.match(/\w\w/g));

getKey(prompt('Enter decryption password:')).then(function (key) {
    decrypt(key, encrypted, IV).then(result => {
        console.log(`password: ${result}`)
    });
}, fail);

(为简洁起见,省略了数组到缓冲区的方法 - 取自http://qnimate.com/passphrase-based-encryption-using-web-cryptography-api/)

这失败了,DOMException虽然没有说明,但我不知道接下来该做什么.

Answer 1

OpenSSL使用加密时生成的一些随机字节将加密密钥派生算法应用于密码,并存储在加密文件的标头中.

在这篇文章中有很好的解释

OpenSSL使用盐渍密钥派生算法.salt是一段随机字节,在加密时生成,并存储在文件头中; 在解密时,从头部检索盐,并从提供的密码和盐值重新计算密钥和IV.

OpenSSL使用的加密格式是非标准的:它是"OpenSSL的作用",如果OpenSSL的所有版本都倾向于彼此一致,那么除了OpenSSL源代码之外,仍然没有描述此格式的参考文档.

因此,一个固定的16字节头,从字符串"Salted__"的ASCII编码开始,然后是盐本身.

要使代码工作是必需的:

• 加载OpenSSL生成的密钥(或者使用提供的salt和openssl算法从密码中导出密钥.派生算法在openssl加密页面中没有记录,但是在这篇文章中说它是propietary,所以它在webcrypto中不可用)

• 使用hex2a和从HEX解码到ArrayBufferconvertStringToArrayBufferView

  var IV = convertStringToArrayBufferView (hex2a ('A884549B66400EB198879F8A09148D4E'));

• 加载加密文件:从base64解码(您使用-a选项)并删除盐的前16个字节

这是一个简化的javascript示例,使用相同的openssl命令生成数据

openssl aes-256-cbc -d -a -p -in file_encrypted.txt
enter aes-256-cbc decryption password:
salt=886DBE2C626D6112
key=0DA435C43BE722BB5BF09912E11E3E25BE826C35A674EC4284CD1C49AFBCC78E
iv =7F9608BF748309A2C7DAA63600AB3825
this is the secret value of the fiile

Javascript代码

//The content of file_encrypted.txt. It is encoded in base64
var opensslEncryptedData = atob('U2FsdGVkX1+Ibb4sYm1hEp/MYnmmcteeebZ1jdQ8GhzaYlrgDfHFfirVmaR3Yor5C9th02S2wLptpJC6IYKiCg==');
//Encrypted data removing salt and converted to arraybuffer
var encryptedData = convertStringToArrayBufferView(opensslEncryptedData.substr(16,opensslEncryptedData.length););

//key and IV. salt would be needed to derive key from password
var IV = convertStringToArrayBufferView (hex2a ('7F9608BF748309A2C7DAA63600AB3825'));
var key = convertStringToArrayBufferView (hex2a ('0DA435C43BE722BB5BF09912E11E3E25BE826C35A674EC4284CD1C49AFBCC78E'));
//var salt = convertStringToArrayBufferView (hex2a ('886DBE2C626D6112'));

crypto.subtle.importKey("raw", key, {name: "AES-CBC"}, false, ["encrypt", "decrypt"]). then (function (cryptokey){

    return crypto.subtle.decrypt({ name: "AES-CBC", iv: IV }, cryptokey, encryptedData).then(function(result){
        var decrypted_data = new Uint8Array(result);
        var res =  convertArrayBufferViewtoString(decrypted_data);
        console.log(res);
    }).catch (function (err){
        console.log(err);
    }); 

}).catch (function (err){
    console.log(err);
});    

实用功能

function hex2a(hexx) {
    var hex = hexx.toString();//force conversion
    var str = '';
    for (var i = 0; i < hex.length; i += 2)
        str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
    return str;
}

function convertStringToArrayBufferView(str){
    var bytes = new Uint8Array(str.length);
    for (var iii = 0; iii < str.length; iii++) {
        bytes[iii] = str.charCodeAt(iii);
    }

    return bytes;
}

function convertArrayBufferViewtoString(buffer){
    var str = "";
    for (var iii = 0; iii < buffer.byteLength; iii++) {
        str += String.fromCharCode(buffer[iii]);
    }

    return str;
}