java加密算法之RSA篇
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加密
/**
* 私钥加密
*
* @param data 源数据
* @param privateKey 私钥
* @return
* @throws Exception
*/
public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
try
byte[] keyBytes = MyBase64Utils.decodeStringForByte(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateK);
int inputLen = data.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 对数据分段加密
while (inputLen - offSet > 0)
if (inputLen - offSet > MAX_ENCRYPT_BLOCK)
cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
else
cache = cipher.doFinal(data, offSet, inputLen - offSet);
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
catch (Exception e)
return null;
解密
/**
* 公钥解密
*
* @param encryptedData 已加密数据
* @param publicKey 公钥
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
try
byte[] keyBytes = MyBase64Utils.decodeStringForByte(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicK);
int inputLen = encryptedData.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 对数据分段解密
while (inputLen - offSet > 0)
if (inputLen - offSet > MAX_DECRYPT_BLOCK)
cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
else
cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
catch (Exception ex)
return null;
常量
/**
* 加密算法RSA
*/
public static final String RSA_KEY_ALGORITHM = "RSA";
/**
* 签名算法
*/
public static final String SIGNATURE_ALGORITHM = "SHA1WithRSA";
/**
* RSA最大加密明文大小,依据需求自定义
*/
private static final int MAX_ENCRYPT_BLOCK = 117;
/**
* RSA最大解密密文大小,依据需求自定义
*/
private static final int MAX_DECRYPT_BLOCK = 128;
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