js java rsa 分段 加解密

RSA加密和解密过程中需要对数据进行分段操作，以保证数据的安全性和加密效率。下面是JS和Java两种语言的RSA分段加解密示例代码：

JS代码：

// RSA加密
function rsaEncrypt(text, publicKey) {
  const buffer = Buffer.from(text);
  const blockSize = publicKey.keySize / 8 - 11; // 1024位密钥，每段最大长度为117
  let result = "";
  for (let i = 0; i < buffer.length; i += blockSize) {
    const chunk = buffer.slice(i, i + blockSize);
    const encrypted = publicKey.encrypt(chunk);
    result += encrypted.toString("base64");
  }
  return result;
}

// RSA解密
function rsaDecrypt(text, privateKey) {
  const buffer = Buffer.from(text, "base64");
  const blockSize = privateKey.keySize / 8; // 1024位密钥，每段最大长度为128
  let result = "";
  for (let i = 0; i < buffer.length; i += blockSize) {
    const chunk = buffer.slice(i, i + blockSize);
    const decrypted = privateKey.decrypt(chunk);
    result += decrypted.toString();
  }
  return result;
}

Java代码：

// RSA加密
public static String rsaEncrypt(String text, PublicKey publicKey) throws Exception {
    byte[] bytes = text.getBytes("UTF-8");
    int blockSize = publicKey.getModulus().bitLength() / 8 - 11; // 1024位密钥，每段最大长度为117
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int i = 0;
    while (i < bytes.length) {
        int length = Math.min(blockSize, bytes.length - i);
        byte[] chunk = Arrays.copyOfRange(bytes, i, i + length);
        byte[] encrypted = rsaEncrypt(chunk, publicKey);
        out.write(encrypted);
        i += blockSize;
    }
    return Base64.getEncoder().encodeToString(out.toByteArray());
}

private static byte[] rsaEncrypt(byte[] data, PublicKey publicKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    return cipher.doFinal(data);
}

// RSA解密
public static String rsaDecrypt(String text, PrivateKey privateKey) throws Exception {
    byte[] bytes = Base64.getDecoder().decode(text);
    int blockSize = privateKey.getModulus().bitLength() / 8; // 1024位密钥，每段最大长度为128
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int i = 0;
    while (i < bytes.length) {
        int length = Math.min(blockSize, bytes.length - i);
        byte[] chunk = Arrays.copyOfRange(bytes, i, i + length);
        byte[] decrypted = rsaDecrypt(chunk, privateKey);
        out.write(decrypted);
        i += blockSize;
    }
    return new String(out.toByteArray(), "UTF-8");
}

private static byte[] rsaDecrypt(byte[] data, PrivateKey privateKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    return cipher.doFinal(data);
}

以上代码均是用的是PKCS#1 v1.5填充方式，如果需要使用其他填充方式，需要相应地修改代码。