使用JavaScript解密C# AES加密字符串的技术问询

First, let's recap the key details from your C# encryption implementation and map them to a compatible JavaScript solution:

C# Encryption Code (Recap) #

public class AesCrypt { 
    public static string IV = @"!QAZ2WSX#EDC4RFV"; 
    public static string Key = @"5TGB&YHN7UJM(IK<5TGB&YHN7UJM(IK<"; 
    public static string Encrypt(string decrypted) { 
        byte[] textbytes = ASCIIEncoding.ASCII.GetBytes(decrypted); 
        AesCryptoServiceProvider encdec = new AesCryptoServiceProvider(); 
        encdec.BlockSize = 128; 
        encdec.KeySize = 256; 
        encdec.Key = ASCIIEncoding.ASCII.GetBytes(Key);
        encdec.IV = ASCIIEncoding.ASCII.GetBytes(IV);
        // Default settings: CBC mode, PKCS7 padding
        // (Rest of encryption logic would convert ciphertext to Base64 string)
    }
}

Critical Parameters to Match in JavaScript #

• Algorithm: AES-CBC (default for AesCryptoServiceProvider)
• Key Size: 256 bits (32 bytes, matches your ASCII-encoded Key string)
• IV: 128 bits (16 bytes, matches your ASCII-encoded IV string)
• Padding: PKCS7 (default padding scheme for C#'s AES implementation)
• Encoding: ASCII (used for all string-to-byte conversions in your C# code)
• Encrypted Format: Base64 (standard way to return ciphertext as a string in C#)

JavaScript Decryption Implementation #

We'll use the browser's Web Crypto API (secure, standard, and widely supported) to mirror the C# behavior:

async function decryptAesCbc(encryptedBase64) {
    // Convert Base64 ciphertext to ArrayBuffer
    const encryptedBuffer = base64ToArrayBuffer(encryptedBase64);
    
    // Convert ASCII key and IV to ArrayBuffers
    const keyBuffer = stringToArrayBuffer('5TGB&YHN7UJM(IK<5TGB&YHN7UJM(IK<', 'ascii');
    const ivBuffer = stringToArrayBuffer('!QAZ2WSX#EDC4RFV', 'ascii');
    
    // Import the AES key for decryption
    const key = await crypto.subtle.importKey(
        'raw',
        keyBuffer,
        { name: 'AES-CBC', length: 256 },
        false,
        ['decrypt']
    );
    
    // Perform decryption
    const decryptedBuffer = await crypto.subtle.decrypt(
        { name: 'AES-CBC', iv: ivBuffer },
        key,
        encryptedBuffer
    );
    
    // Convert decrypted buffer back to ASCII string
    return arrayBufferToString(decryptedBuffer, 'ascii');
}

// Helper conversion functions
function base64ToArrayBuffer(base64) {
    const binary = atob(base64);
    const bytes = new Uint8Array(binary.length);
    for (let i = 0; i < binary.length; i++) {
        bytes[i] = binary.charCodeAt(i);
    }
    return bytes.buffer;
}

function stringToArrayBuffer(str, encoding = 'utf8') {
    const encoder = new TextEncoder(encoding);
    return encoder.encode(str).buffer;
}

function arrayBufferToString(buffer, encoding = 'utf8') {
    const decoder = new TextDecoder(encoding);
    return decoder.decode(buffer);
}

How to Use #

// Replace with your actual encrypted Base64 string
const encryptedString = 'YOUR_ENCRYPTED_VALUE_HERE';

decryptAesCbc(encryptedString)
    .then(decryptedText => console.log('Decrypted result:', decryptedText))
    .catch(err => console.error('Decryption failed:', err));

Important Notes #

• For Node.js environments, use crypto.webcrypto (modern versions) instead of the browser's crypto object.
• Your C# code uses a static IV, which is not secure for production. In real-world scenarios, generate a random IV per encryption and prepend it to the ciphertext (then extract it before decryption in JS).
• Double-check that your C# encryption code actually converts the ciphertext to Base64 (this is the standard approach, but confirm if it's what you're doing).

内容的提问来源于stack exchange，提问作者riv