Web Crypto API实现安全大文件上传：RSA与AES混合加密教程

async function importRSAPublicKey(jwkString) {
    try {
        const jwk = JSON.parse(atob(jwkString)); // 服务器可能将JWK进行Base64编码
        const importedKey = await window.crypto.subtle.importKey(
            "jwk",
            jwk,
            {
                name: "RSA-OAEP",
                hash: "SHA-256",
            },
            true, // extractable: true if you need to export it later, otherwise false
            ["encrypt"]
        );
        return importedKey;
    } catch (error) {
        console.error("Failed to import RSA public key:", error);
        throw error;
    }
}

async function generateAESKey() {
    return await window.crypto.subtle.generateKey(
        {
            name: "AES-GCM",
            length: 256, // 256-bit AES key
        },
        true, // extractable
        ["encrypt", "decrypt"]
    );
}

function generateIV() {
    return window.crypto.getRandomValues(new Uint8Array(12)); // AES-GCM recommended IV length is 12 bytes
}

async function encryptFileWithAES(fileBuffer, aesKey, iv) {
    try {
        const encryptedContent = await window.crypto.subtle.encrypt(
            {
                name: "AES-GCM",
                iv: iv,
            },
            aesKey,
            fileBuffer
        );
        return new Uint8Array(encryptedContent);
    } catch (error) {
        console.error("Failed to encrypt file with AES:", error);
        throw error;
    }
}

async function encryptAESKeyWithRSA(aesKey, rsaPublicKey) {
    try {
        const exportedAesKey = await window.crypto.subtle.exportKey("jwk", aesKey);
        const aesKeyBuffer = new TextEncoder().encode(JSON.stringify(exportedAesKey));

        const encryptedAesKey = await window.crypto.subtle.encrypt(
            { name: "RSA-OAEP" },
            rsaPublicKey,
            aesKeyBuffer
        );
        return new Uint8Array(encryptedAesKey);
    } catch (error) {
        console.error("Failed to encrypt AES key with RSA:", error);
        throw error;
    }
}

document.getElementById("input").addEventListener('change', async event => {
    if (event.target.files[0]) {
        const file = event.target.files[0];

        try {
            // 1. 读取文件内容
            const fileBuffer = await file.arrayBuffer();

            // 2. 获取RSA公钥
            const res = await fetch("/key");
            const exportedRsaJwk = await res.text(); // 假设服务器返回Base64编码的JWK
            const rsaPublicKey = await importRSAPublicKey(exportedRsaJwk);

            // 3. 生成AES密钥和IV
            const aesKey = await generateAESKey();
            const iv = generateIV();

            // 4. 使用AES加密文件内容
            const encryptedFileContent = await encryptFileWithAES(fileBuffer, aesKey, iv);

            // 5. 使用RSA加密AES密钥
            const encryptedAesKey = await encryptAESKeyWithRSA(aesKey, rsaPublicKey);

            // 6. 准备上传数据
            // 将二进制数据转换为Base64字符串以便传输
            const ivBase64 = btoa(String.fromCharCode.apply(null, iv));
            const encryptedAesKeyBase64 = btoa(String.fromCharCode.apply(null, encryptedAesKey));
            const encryptedFileContentBase64 = btoa(String.fromCharCode.apply(null, encryptedFileContent));

            const uploadPayload = {
                encryptedAesKey: encryptedAesKeyBase64,
                iv: ivBase64,
                encryptedFileContent: encryptedFileContentBase64,
                fileName: file.name,
                fileType: file.type
            };

            // 7. 上传到服务器
            await fetch(`/upload`, {
                method: "POST",
                headers: {
                    "Content-Type": "application/json"
                },
                body: JSON.stringify(uploadPayload)
            });

            console.log("File uploaded successfully with hybrid encryption!");

        } catch (error) {
            console.error("File upload failed:", error);
            alert("文件上传失败：" + error.message);
        }
    }
});