RSA是1977年由罗纳德·李维斯特（Ron Rivest）、阿迪·萨莫尔（Adi Shamir）和伦纳德·阿德曼（Leonard Adleman）一起提出的。当时他们三人都在麻省理工学院工作。RSA就是他们三人姓氏开头字母拼在一起组成的
RSA公开密钥密码体制是一种使用不同的加密密钥与解密密钥，“由已知加密密钥推导出解密密钥在计算上是不可行的”密码体制” 。
- 在公开密钥密码体制中，加密密钥（即公开密钥）PK是公开信息，
- 解密密钥（即秘密密钥）SK是需要保密的。
- 加密算法E和解密算法D也都是公开的。
- 虽然解密密钥SK是由公开密钥PK决定的，但却不能根据PK计算出SK
详细原理参见RSA算法
RSA算法工具类 源码import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
/**
* @ClassName: RSAUtil
* @Description: RSA非对称加密算法工具类
*/
public class RSAUtil {
public static final String CHARSET = "UTF-8";
public static final String RSA_ALGORITHM = "RSA";
public static void main(String[] args) throws Exception {
Map<String, String> keyMap = RSAUtil.createKeys(1024);
String publicKey = keyMap.get("publicKey");
String privateKey = keyMap.get("privateKey");
printMsg("公钥: %s", publicKey);
printMsg("私钥： %s", privateKey);
String str = "不到长城非好汉";
printMsg("明文：%s, 长度:%d", str, str.getBytes().length);
printMsg("公钥加密----私钥解密");
String encodedData = RSAUtil.publicEncrypt(str, RSAUtil.getPublicKey(publicKey));
printMsg("密文：%s", encodedData);
String decodedData = RSAUtil.privateDecrypt(encodedData, RSAUtil.getPrivateKey(privateKey));
printMsg("解密后文字: %s", decodedData);
printMsg("私钥加密----公钥解密");
encodedData = RSAUtil.privateEncrypt(str, RSAUtil.getPrivateKey(privateKey));
printMsg("密文：%s", encodedData);
decodedData = RSAUtil.publicDecrypt(encodedData, RSAUtil.getPublicKey(publicKey));
printMsg("解密后文字: %s", decodedData);
}
public static void printMsg(String format, Object... args) {
System.out.println(String.format(format, args));
}
/**
* 为RSA算法创建一个KeyPairGenerator对象（KeyPairGenerator，密钥对生成器，用于生成公钥和私钥对）
*
* @param keySize
* @return
*/
public static Map<String, String> createKeys(int keySize) {
KeyPairGenerator kpg;
try {
kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
} catch (NoSuchAlgorithmException e) {
throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
}
//初始化KeyPairGenerator对象,密钥长度
kpg.initialize(keySize);
KeyPair keyPair = kpg.generateKeyPair();
Key publicKey = keyPair.getPublic();
String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());
Key privateKey = keyPair.getPrivate();
String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());
Map<String, String> keyPairMap = new HashMap<String, String>();
keyPairMap.put("publicKey", publicKeyStr);
keyPairMap.put("privateKey", privateKeyStr);
return keyPairMap;
}
/**
* 获取公钥
*
* @param publicKey 密钥字符串（经过base64编码）
* @throws Exception
*/
public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
//通过X509编码的Key指令获得公钥对象
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
return key;
}
/**
* 获取私钥
*
* @param privateKey 密钥字符串（经过base64编码）
* @throws Exception
*/
public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
//通过PKCS8编码的Key指令获得私钥对象
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
return key;
}
/**
* 公钥加密
*
* @param data
* @param publicKey
* @return
*/
public static String publicEncrypt(String data, RSAPublicKey publicKey) {
try {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));
} catch (Exception e) {
throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
}
}
/**
* 私钥解密
*
* @param data
* @param privateKey
* @return
*/
public static String privateDecrypt(String data, RSAPrivateKey privateKey) {
try {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);
} catch (Exception e) {
throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
}
}
/**
* 私钥加密
*
* @param data
* @param privateKey
* @return
*/
public static String privateEncrypt(String data, RSAPrivateKey privateKey) {
try {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
} catch (Exception e) {
throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
}
}
/**
* 公钥解密
*
* @param data
* @param publicKey
* @return
*/
public static String publicDecrypt(String data, RSAPublicKey publicKey) {
try {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, publicKey);
return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
} catch (Exception e) {
throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
}
}
private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize) {
int maxBlock = 0;
if (opmode == Cipher.DECRYPT_MODE) {
maxBlock = keySize / 8;
} else {
maxBlock = keySize / 8 - 11;
}
byte[] resultDatas = null;
int offSet = 0;
byte[] buff;
int i = 0;
try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
while (datas.length > offSet) {
if (datas.length - offSet > maxBlock) {
buff = cipher.doFinal(datas, offSet, maxBlock);
} else {
buff = cipher.doFinal(datas, offSet, datas.length - offSet);
}
out.write(buff, 0, buff.length);
i++;
offSet = i * maxBlock;
}
resultDatas = out.toByteArray();
} catch (Exception e) {
throw new RuntimeException("加解密阀值为[" + maxBlock + "]的数据时发生异常", e);
}
return resultDatas;
}
}
公钥: MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCgneHE8CBOH9YpBaNGF-hu-O6p_Ap9fM38q1uaCY5lDj4P3GHl3WuMjJztoM5gwHQS7va64tqw9soFdi7XI8SawEP4jz2435dHCwv_iwqnwFKFSc92DPkNsYZGw7iCkjiFN-_o7QMJ6hXyFWE3q4ua9QmpZWHoar--ngg34rZC9QIDAQAB
私钥： MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBAKCd4cTwIE4f1ikFo0YX6G747qn8Cn18zfyrW5oJjmUOPg_cYeXda4yMnO2gzmDAdBLu9rri2rD2ygV2LtcjxJrAQ_iPPbjfl0cLC_-LCqfAUoVJz3YM-Q2xhkbDuIKSOIU37-jtAwnqFfIVYTeri5r1CallYehqv76eCDfitkL1AgMBAAECgYEAn27ZEwJBLwuPLD06a3OD99QGJJnZV-MxHaSDUw41WL6ggGIEk4YNIgDaLU84TPX8wmaOZ8iTyKHQu0crC8eneVlQ95gaJJHAeTu5X_vsGB_fBIscjc8bT412UbTrKF3qGGlYJSx5woDXgIFCRe05F3ZhwMj93-_npsTtbaE7BoECQQDdTcaAcIZGEc_clZrZCqlTKfzJ2D3LLqazVxNgeb2PGx21f5FNoB9UXUM0--LZNRXnkpk1gbM6_IZLxBG-6pIxAkEAucxgaQFMBX21l8YQ_x0bMVrKtoDOYstsQVG7O8eZWdY5KbzHBIBdDKKR5RFZg61l8WsKYjROmdVXxOXH57XoBQJABW4LGMup_74gI4FoMzsXvHqjQTCVE48pd-0DBLL3-7Lmn7Vpk0YCfsdrBrnHbxzmVLA8Ihv0kdXwVZuR8-U9gQJAIO54qCPytYZyiVQx7wXZrAXLqE1sR1aG-YzjAtV9-M5fk2ZCYCngVDz8Xv2UQCKbzw6J6J4c0GdgByYzKH61gQI_Brbi7mGZ9FclisIcu2XLc5S9KdWqaOoYrwV36G5t5CfXjRtCPMz8V7Owa9O6lpaDm9Y8EkMiEnwbkd_VtKD8
明文：不到长城非好汉, 长度:21
公钥加密----私钥解密
密文：CcNsy-4dprsQoTD6q_64abzmypwAgT3UOdrur2ZLtbFIgRwNRwpt7GeqkbQs2Vj0h4x5ANsb17Pfiarl2Ajdlf8L-Ox_lOrp05tYicYypBMGDGbFTVqEGXcjzzVBWu-QPh0MWiTW6FdpIb1FW6KkkWi3ISzL7B3ZbW34tVBbsh0
解密后文字: 不到长城非好汉
私钥加密----公钥解密
密文：IiLm174Eg8aPDHUIU6s77EtfCF-I4kTD_ZuoWvR8ZTm4SW5PFjpzskY6I96tFxxWDsgm0WJD3g82LD3maLKs4LLDH8PpkyjNgfq_B7vyACSRf-BuiOHwFPJB8gUlxcwo436Nb7HirMbTzlpBBL3U5u3Ywiuh5gLNwahlzEIM6pE
解密后文字: 不到长城非好汉
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