SpringBoot集成ECDH密钥交换的方法
简介
对称加解密算法都需要一把秘钥,但是很多情况下,互联网环境不适合传输这把对称密码,有密钥泄露的风险,为了解决这个问题ECDH密钥交换应运而生
EC:Elliptic Curve——椭圆曲线,生成密钥的方法
DH:Diffie-Hellman Key Exchange——交换密钥的方法
设计
数据传输的两方服务端(Server)和客户端(Client)
服务端生成密钥对Server-Public和Servier-Private
客户端生成密钥对Client-Public和Client-Private
客户端获取服务端的公钥和客户端的私钥进行计算CaculateKey(Server-Public,Client-Private)出共享密钥ShareKey1
服务端获取客户端的公钥和服务端的私钥进行计算CaculateKey(Client-Public,Server-Private)出共享密钥ShareKey2
ShareKey1和ShareKey2必定一致,ShareKey就是双方传输数据进行AES加密时的密钥
实现
生成密钥对
后端
public static ECDHKeyInfo generateKeyInfo(){ ECDHKeyInfo keyInfo = new ECDHKeyInfo(); try{ KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC"); ECGenParameterSpec ecSpec = new ECGenParameterSpec("secp256r1"); keyPairGenerator.initialize(ecSpec, new SecureRandom()); KeyPair kp = keyPairGenerator.generateKeyPair(); ECPublicKey ecPublicKey = (ECPublicKey) kp.getPublic(); ECPrivateKey ecPrivateKey = (ECPrivateKey) kp.getPrivate(); // 获取公钥点的x和y坐标 BigInteger x = ecPublicKey.getW().getAffineX(); BigInteger y = ecPublicKey.getW().getAffineY(); // 将x和y坐标转换为十六进制字符串 String xHex = x.toString(16); String yHex = y.toString(16); String publicKey = xHex + "|" + yHex; String privateKey = Base64.getEncoder().encodeToString(ecPrivateKey.getEncoded()); keyInfo.setPublicKey(publicKey); keyInfo.setPrivateKey(privateKey); }catch (Exception e){ e.printStackTrace(); } return keyInfo; } public static class ECDHKeyInfo{ private String publicKey; private String privateKey; public String getPublicKey() { return publicKey; } public void setPublicKey(String publicKey) { this.publicKey = publicKey; } public String getPrivateKey() { return privateKey; } public void setPrivateKey(String privateKey) { this.privateKey = privateKey; } }
前端
引入elliptic.js(https://cdn.bootcdn.net/ajax/libs/elliptic/6.5.6/elliptic.js)
const EC = elliptic.ec; const ec = new EC('p256'); // P-256曲线 // 生成密钥对 const keyPair = ec.genKeyPair(); const publicKey = keyPair.getPublic().getX().toString('hex') + "|" + keyPair.getPublic().getY().toString('hex');
共享密钥计算
后端
public static String caculateShareKey(String serverPrivateKey,String receivePublicKey){ String shareKey = ""; try{ // 1. 后端私钥 Base64 字符串 // 2. 从 Base64 恢复后端私钥 ECPrivateKey privKey = loadPrivateKeyFromBase64(serverPrivateKey); // 3. 前端传递的公钥坐标 (x 和 y 坐标,假设为十六进制字符串) // 假设这是从前端接收到的公钥的 x 和 y 坐标 String xHex = receivePublicKey.split("\\|")[0]; // 用前端传递的 x 坐标替换 String yHex = receivePublicKey.split("\\|")[1]; // 用前端传递的 y 坐标替换 // 4. 将 x 和 y 转换为 BigInteger BigInteger x = new BigInteger(xHex, 16); BigInteger y = new BigInteger(yHex, 16); // 5. 创建 ECPoint 对象 (公钥坐标) ECPoint ecPoint = new ECPoint(x, y); // 6. 获取 EC 参数(例如 secp256r1) ECParameterSpec ecSpec = getECParameterSpec(); // 7. 恢复公钥 ECPublicKey pubKey = recoverPublicKey(ecPoint, ecSpec); // 8. 使用 ECDH 计算共享密钥 byte[] sharedSecret = calculateSharedSecret(privKey, pubKey); // 9. 打印共享密钥 shareKey = bytesToHex(sharedSecret); }catch (Exception e){ e.printStackTrace(); } return shareKey; } // 从 Base64 加载 ECPrivateKey private static ECPrivateKey loadPrivateKeyFromBase64(String privateKeyBase64) throws Exception { byte[] decodedKey = Base64.getDecoder().decode(privateKeyBase64); PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey); KeyFactory keyFactory = KeyFactory.getInstance("EC"); return (ECPrivateKey) keyFactory.generatePrivate(keySpec); } // 获取 EC 参数(例如 secp256r1) private static ECParameterSpec getECParameterSpec() throws Exception { // 手动指定 EC 曲线(例如 secp256r1) AlgorithmParameters params = AlgorithmParameters.getInstance("EC"); params.init(new ECGenParameterSpec("secp256r1")); // 使用标准的 P-256 曲线 return params.getParameterSpec(ECParameterSpec.class); } // 恢复公钥 private static ECPublicKey recoverPublicKey(ECPoint ecPoint, ECParameterSpec ecSpec) throws Exception { ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(ecPoint, ecSpec); KeyFactory keyFactory = KeyFactory.getInstance("EC"); return (ECPublicKey) keyFactory.generatePublic(pubKeySpec); } // 使用 ECDH 计算共享密钥 private static byte[] calculateSharedSecret(ECPrivateKey privKey, ECPublicKey pubKey) throws Exception { KeyAgreement keyAgreement = KeyAgreement.getInstance("ECDH"); keyAgreement.init(privKey); keyAgreement.doPhase(pubKey, true); return keyAgreement.generateSecret(); } // 将字节数组转换为十六进制字符串 private static String bytesToHex(byte[] bytes) { StringBuilder hexString = new StringBuilder(); for (byte b : bytes) { hexString.append(String.format("%02x", b)); } return hexString.toString(); }
前端
var keyArray = serverPublicPointKey.split("|") const otherKey = ec.keyFromPublic({ x: keyArray[0], y: keyArray[1] }, 'hex'); const sharedSecret = keyPair.derive(otherKey.getPublic());
AES加密
后端
public static String encryptData(String data,String shareKey){ String result = ""; try{ MessageDigest digest = MessageDigest.getInstance("SHA-256"); byte[] aesKey = digest.digest(shareKey.getBytes()); // 获取 256 位密钥 SecretKey key = new SecretKeySpec(aesKey, "AES"); byte[] resultData = encrypt(data,key); result = Base64.getEncoder().encodeToString(resultData); }catch (Exception e){ e.printStackTrace(); } return result; } public static String decryptData(String data,String shareKey){ String result = ""; try{ MessageDigest digest = MessageDigest.getInstance("SHA-256"); byte[] aesKey = digest.digest(shareKey.getBytes()); // 获取 256 位密钥 SecretKey key = new SecretKeySpec(aesKey, "AES"); byte[] resultData = decrypt(Base64.getDecoder().decode(data),key); result = new String(resultData); }catch (Exception e){ e.printStackTrace(); } return result; } private static final String KEY_ALGORITHM = "AES"; private static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding"; private static final String IV = "0102030405060708"; // 16 bytes key // 使用AES密钥加密数据 private static byte[] encrypt(String plaintext, SecretKey aesKey) throws Exception { SecretKeySpec keySpec = new SecretKeySpec(aesKey.getEncoded(), KEY_ALGORITHM); IvParameterSpec iv = new IvParameterSpec(IV.getBytes()); Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM); cipher.init(Cipher.ENCRYPT_MODE, keySpec, iv); byte[] encrypted = cipher.doFinal(plaintext.getBytes()); return encrypted; } // 使用AES密钥解密数据 private static byte[] decrypt(byte[] encryptedData, SecretKey aesKey) throws Exception { SecretKeySpec keySpec = new SecretKeySpec(aesKey.getEncoded(), KEY_ALGORITHM); IvParameterSpec iv = new IvParameterSpec(IV.getBytes()); Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM); cipher.init(Cipher.DECRYPT_MODE, keySpec, iv); byte[] original = cipher.doFinal(encryptedData); return original; }
前端
引入crypto-js.min.js(https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.1.1/crypto-js.min.js)
function encryptByECDH(message, shareKey) { const aesKey = CryptoJS.SHA256(shareKey); const key = CryptoJS.enc.Base64.parse(aesKey.toString(CryptoJS.enc.Base64)); return encryptByAES(message,key) } function decryptByECDH(message, shareKey) { const aesKey = CryptoJS.SHA256(shareKey); const key = CryptoJS.enc.Base64.parse(aesKey.toString(CryptoJS.enc.Base64)); return decryptByAES(message,key) } function encryptByAES(message, key) { const iv = CryptoJS.enc.Utf8.parse("0102030405060708"); const encrypted = CryptoJS.AES.encrypt(message, key, { iv: iv , mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7 }); return encrypted.toString(); } function decryptByAES(message, key) { const iv = CryptoJS.enc.Utf8.parse("0102030405060708"); const bytes = CryptoJS.AES.decrypt(message, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7 }); const originalText = bytes.toString(CryptoJS.enc.Utf8); return originalText; }
注意
- 前端生成的密钥对和后端生成的密钥对形式不一致,需要将前端的公钥拆解成坐标点到后端进行公钥还原
- 同理后端的公钥也要拆分成坐标点传输到前端进行计算
- 生成的ShareKey共享密钥为了满足AES的密钥长度要求需要进行Share256计算
- 前后端AES互通需要保证IV向量为同一值
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