java RSA2加解密

以下是Java RSA2加解密的示例代码：

1.生成公钥和私钥

KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(2048);
KeyPair keyPair = keyPairGen.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();

2.使用公钥加密

Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encryptedData = cipher.doFinal(data.getBytes());

3.使用私钥解密

Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] decryptedData = cipher.doFinal(encryptedData);

需要注意的是，RSA加密算法只能加密比密钥长度小的数据，因此在实际使用中需要对数据进行分块加密。

相关问题

Java RSA 分段加解密

非常感谢您的提问。关于Java RSA分段加解密，我可以给您提供一些相关的信息和代码示例。RSA是一种非对称加密算法，可以实现安全的数据传输和数据存储。但是，RSA算法在处理大量数据时可能会出现性能问题。因此，我们需要将大块数据分成小块进行加密和解密。以下是Java RSA分段加解密的代码示例：

// RSA密钥长度，推荐使用2048位及以上
private static final int RSA_KEY_SIZE = 2048;
// 分段加密的块大小，推荐使用RSA密钥长度-11
private static final int BLOCK_SIZE = RSA_KEY_SIZE / 8 - 11;

// 生成RSA密钥对
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(RSA_KEY_SIZE);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();

// 分段加密
public static byte[] encrypt(byte[] data, PublicKey publicKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    int inputLen = data.length;
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int offSet = 0;
    byte[] block;
    int i = 0;
    while (inputLen - offSet > 0) {
        if (inputLen - offSet > BLOCK_SIZE) {
            block = cipher.doFinal(data, offSet, BLOCK_SIZE);
        } else {
            block = cipher.doFinal(data, offSet, inputLen - offSet);
        }
        out.write(block, 0, block.length);
        i++;
        offSet = i * BLOCK_SIZE;
    }
    byte[] encryptedData = out.toByteArray();
    out.close();
    return encryptedData;
}

// 分段解密
public static byte[] decrypt(byte[] encryptedData, PrivateKey privateKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    int inputLen = encryptedData.length;
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int offSet = 0;
    byte[] block;
    int i = 0;
    while (inputLen - offSet > 0) {
        if (inputLen - offSet > RSA_KEY_SIZE / 8) {
            block = cipher.doFinal(encryptedData, offSet, RSA_KEY_SIZE / 8);
        } else {
            block = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
        }
        out.write(block, 0, block.length);
        i++;
        offSet = i * (RSA_KEY_SIZE / 8);
    }
    byte[] decryptedData = out.toByteArray();
    out.close();
    return decryptedData;
}

通过以上代码示例，您可以实现Java RSA分段加解密。请注意，RSA算法只适合加密小块数据，不适合加密大块数据，否则可能会出现性能问题。如果您需要加密大块数据，可以考虑使用对称加密算法，如AES。

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。