代碼如下，需要依賴壹個jar包commons-codec-1.9.jar，用於Base64轉換，請自行下載。
import?org.apache.commons.codec.binary.Base64;import?javax.crypto.BadPaddingException;
import?javax.crypto.Cipher;
import?javax.crypto.IllegalBlockSizeException;
import?java.io.ByteArrayOutputStream;
import?java.io.UnsupportedEncodingException;
import?java.security.*;
import?java.security.interfaces.RSAPrivateKey;
import?java.security.interfaces.RSAPublicKey;
import?java.security.spec.PKCS8EncodedKeySpec;
import?java.security.spec.X509EncodedKeySpec;
public?class?RSAUtils?{
//?加密方式
public?static?final?String?ALGORITHM?=?"RSA";
//?簽名算法
private?static?final?String?SIGNATURE_ALGORITHM?=?"SHA1WithRSA";
//?創建密鑰對初始長度
private?static?final?int?KEY_SIZE?=?512;
//?字符編碼格式
private?static?final?String?CHARSET?=?"UTF-8";
//?RSA最大加密明文大小
private?static?final?int?MAX_ENCRYPT_BLOCK?=?117;
//?RSA最大解密密文大小
private?static?final?int?MAX_DECRYPT_BLOCK?=?128;
private?KeyFactory?keyFactory;
public?RSAUtils()?throws?NoSuchAlgorithmException?{
keyFactory?=?KeyFactory.getInstance(ALGORITHM);
}
/**
*?私鑰加密 * *?@param?content待加密字符串 *?@param?privateKey?私鑰 *?@return?加密後字符串（BASE64編碼） */public?String?encryptByPrivateKey(String?content,?String?privateKey)?throws?Exception?{
String?result;
try?(ByteArrayOutputStream?out?=?new?ByteArrayOutputStream())?{
byte[]?keyBytes?=?new?Base64().decode(privateKey);
PKCS8EncodedKeySpec?pkcs8KeySpec?=?new?PKCS8EncodedKeySpec(keyBytes);
PrivateKey?pKey?=?keyFactory.generatePrivate(pkcs8KeySpec);
Cipher?cipher?=?Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE,?pKey);
byte[]?data?=?content.getBytes(CHARSET);
write2Stream(cipher,?data,?out);
byte[]?resultBytes?=?out.toByteArray();
result?=?Base64.encodeBase64String(resultBytes);
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?公鑰解密 * *?@param?content已加密字符串（BASE64加密） *?@param?publicKey?公鑰 *?@return */public?String?decryptByPublicKey(String?content,?String?publicKey)?throws?Exception?{
String?result?=?"";
try?(ByteArrayOutputStream?out?=?new?ByteArrayOutputStream())?{
byte[]?keyBytes?=?new?Base64().decode(publicKey);
X509EncodedKeySpec?x509KeySpec?=?new?X509EncodedKeySpec(keyBytes);
PublicKey?pKey?=?keyFactory.generatePublic(x509KeySpec);
Cipher?cipher?=?Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE,?pKey);
byte[]?data?=?Base64.decodeBase64(content);
write2Stream(cipher,?data,?out);
byte[]?resultBytes?=?out.toByteArray();
result?=?new?String(resultBytes);
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?公鑰加密 * *?@param?content待加密字符串 *?@param?publicKey?公鑰 *?@return?加密後字符串（BASE64編碼） */public?String?encryptByPublicKey(String?content,?String?publicKey)?throws?Exception?{
String?result?=?"";
try?(ByteArrayOutputStream?out?=?new?ByteArrayOutputStream())?{
byte[]?keyBytes?=?new?Base64().decode(publicKey);
X509EncodedKeySpec?x509KeySpec?=?new?X509EncodedKeySpec(keyBytes);
PublicKey?pKey?=?keyFactory.generatePublic(x509KeySpec);
Cipher?cipher?=?Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE,?pKey);
byte[]?data?=?content.getBytes(CHARSET);
write2Stream(cipher,
data,?out);
byte[]?resultBytes?=?out.toByteArray();
result?=?Base64.encodeBase64String(resultBytes);
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?私鑰解密 * *?@param?content已加密字符串 *?@param?privateKey?私鑰 *?@return?解密後字符串 */public?String?decryptByPrivateKey(String?content,?String?privateKey)?throws?Exception?{
String?result?=?"";
try?(ByteArrayOutputStream?out?=?new?ByteArrayOutputStream())?{
byte[]?keyBytes?=?new?Base64().decode(privateKey);
PKCS8EncodedKeySpec?pkcs8KeySpec?=?new?PKCS8EncodedKeySpec(keyBytes);
PrivateKey?pKey?=?keyFactory.generatePrivate(pkcs8KeySpec);
Cipher?cipher?=?Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE,?pKey);
byte[]?data?=?Base64.decodeBase64(content);
write2Stream(cipher,?data,?out);
byte[]?resultBytes?=?out.toByteArray();
result?=?new?String(resultBytes);
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
private?static?void?write2Stream(Cipher?cipher,?byte[]?data,?ByteArrayOutputStream?out)?throws
BadPaddingException,?IllegalBlockSizeException?{
int?dataLen?=?data.length;
int?offSet?=?0;
byte[]?cache;
int?i?=?0;
//?對數據分段解密
while?(dataLen?-?offSet?>?0)?{
if?(dataLen?-?offSet?>?MAX_DECRYPT_BLOCK)?{
cache?=?cipher.doFinal(data,?offSet,?MAX_DECRYPT_BLOCK);
}?else?{
cache?=?cipher.doFinal(data,?offSet,?dataLen?-?offSet);
}
out.write(cache,?0,?cache.length);
i++;
offSet?=?i?*?MAX_DECRYPT_BLOCK;
}
}
/**
*?用私鑰對信息生成數字簽名 * *?@param?data已加密數據 *?@param?privateKey?私鑰(BASE64編碼) *?@return?sign */public?String?sign(String?data,?String?privateKey)?throws?Exception?{
String?result?=?"";
try?{
byte[]?keyBytes?=?new?Base64().decode(privateKey);
PKCS8EncodedKeySpec?pkcs8KeySpec?=?new?PKCS8EncodedKeySpec(keyBytes);
PrivateKey?privateK?=?keyFactory.generatePrivate(pkcs8KeySpec);
Signature?signature?=?Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(privateK);
signature.update(parse2HexStr(data).getBytes(CHARSET));
result?=?new?Base64().encodeToString(signature.sign());
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?校驗數字簽名 * *?@param?data?已加密數據 *?@param?publicKey?公鑰(BASE64編碼) *?@param?sign?數字簽名 *?@return *?@throws?Exception */public?boolean?verify(String?data,?String?publicKey,?String?sign)?throws?Exception?{
boolean?result;
try?{
byte[]?keyBytes?=?new?Base64().decode(publicKey);
X509EncodedKeySpec?keySpec?=?new?X509EncodedKeySpec(keyBytes);
PublicKey?publicK?=?keyFactory.generatePublic(keySpec);
Signature?signature?=?Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(publicK);
signature.update(parse2HexStr(data).getBytes(CHARSET));
result?=?signature.verify(new?Base64().decode(sign));
}?catch?(Exception?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?將二進制轉換成16進制 * *?@param?data *?@return */public?static?String?parse2HexStr(String?data)?throws?Exception?{
String?result?=?"";
try?{
byte[]?buf?=?data.getBytes(CHARSET);
StringBuffer?sb?=?new?StringBuffer();
for?(int?i?=?0;?i?<?buf.length;?i++)?{
String?hex?=?Integer.toHexString(buf[i]?&?0xFF);
if?(hex.length()?==?1)?{
hex?=?'0'?+?hex;
}
sb.append(hex.toUpperCase());
}
result?=?sb.toString();
}?catch?(UnsupportedEncodingException?e)?{
throw?new?Exception(e);
}
return?result;
}
/**
*?生成公鑰與私鑰 */public?static?void?createKey()?throws?Exception?{
try?{
KeyPairGenerator?keyPairGenerator?=?KeyPairGenerator.getInstance(ALGORITHM);
keyPairGenerator.initialize(KEY_SIZE);
KeyPair?keyPair?=?keyPairGenerator.generateKeyPair();
RSAPublicKey?rsaPublicKey?=?(RSAPublicKey)?keyPair.getPublic();
RSAPrivateKey?rsaPrivateKey?=?(RSAPrivateKey)?keyPair.getPrivate();
String?publicKey?=?Base64.encodeBase64String(rsaPublicKey.getEncoded());
String?privateKey?=?Base64.encodeBase64String(rsaPrivateKey.getEncoded());
System.out.println("publicKey="?+?publicKey?+?"\nprivateKey="?+?privateKey);
}?catch?(NoSuchAlgorithmException?e)?{
throw?new?Exception(e);
}
}
public?static?void?main(String[]?args)?throws?Exception?{
String?PRIVATE_KEY?=?"MIICeAIBADANBgkqhkiG9w0BAQEFAASCAmIwggJeAgEAAoGBAKeYGXH6Vz+m+KuL11RDRaNdHB4YQeZgqpJGPRSwBelgvEoHu2/fNs1bmgfJhI8lhr/o/Hy8EFB/I/DDyLcCcU4bCLtxpki8edC+KJR2WvyYfnVmWEe/3q2jSVKRf81868q9Cd3MMfrQPMsY4x0TQ0GtOf/nMSMbAltV2W8J86IfAgMBAAECgYEApYu4lr2SMW3ddJZNvQ42W4g9nfyYG9igpJx8+VJmhIDpfLbmjzsOBwvUupx0NHH9CNQ7k3qxItJzzf+W5C+lesEOAqdO5nahRZsL8BIDoxTEn2j+1GXkzQw3vqPY50xqRnZsoP5TyNNsOM7KYaOoz4VFMdVIFwoT3OKM5z7mxgECQQD51r17WZDSa/kucaH7gCOePxJPS6Ust0eVd5tBOMpFzD/VtziogSIWyhGKkLH0SyTJEe91CCpdpxufLSZgIiN5AkEAq7ojtvU4twak1N1/1qX+t8f5wD8i/8GU702PeCwkGI5ymrARq+W2yCuvU1bouXBhjKHV4KhafKYixdHUMg00VwJAYVUjpLaUESY3gbyLWqvlNHVl8LaLtwwAO17JgXNaei7Ef8JNtHf6i95VTyJn8cCEqEDwhSuVNb8wp6azWKh0IQJBAJHrcT2d0bt0IcvfCynRk0eG3WnGPG8mhu9w8GAk4ecb47YdtmZio5YjyK8AQnCQVdOyEJL9eyY/5XxCeBSvs7ECQQCKQ2f5HLDkkHvc6rlaHCJmqNRCS+CxhoaiaSPYLAac7WXmb614ACLECc86C/nkefTq0SNpUDVbGxVpJi9/FOUf";
String?PUBLIC_KEY?=?"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCnmBlx+lc/pviri9dUQ0WjXRweGEHmYKqSRj0UsAXpYLxKB7tv3zbNW5oHyYSPJYa/6Px8vBBQfyPww8i3AnFOGwi7caZIvHnQviiUdlr8mH51ZlhHv96to0lSkX/NfOvKvQndzDH60DzLGOMdE0NBrTn/5zEjGwJbVdlvCfOiHwIDAQAB";
RSAUtils?rsaUtil?=?new?RSAUtils();
String?encryptByPublicKey?=?rsaUtil.encryptByPublicKey("妳好！",?PUBLIC_KEY);
System.out.println(encryptByPublicKey);
String?decryptByPrivateKey?=?rsaUtil.decryptByPrivateKey(encryptByPublicKey,?PRIVATE_KEY);
System.out.println(decryptByPrivateKey);
String?encryptByPrivateKey?=?rsaUtil.encryptByPrivateKey("妳好！",?PRIVATE_KEY);
System.out.println(encryptByPrivateKey);
String?decryptByPublicKey?=?rsaUtil.decryptByPublicKey(encryptByPrivateKey,?PUBLIC_KEY);
System.out.println(decryptByPublicKey);
String?sign?=?rsaUtil.sign("1234",?PRIVATE_KEY);
System.out.println("sign:"?+?sign);
System.out.println(rsaUtil.verify("1234",?PUBLIC_KEY,?sign));
}
}