接下來我們介紹典型的非對稱加密算法——RSA
RSA 這種算法1978年就出現(xiàn)了,,它是第一個既能用于數(shù)據(jù)加密也能用于數(shù)字簽名的算法,。它易于理解和操作,也很流行,。算法的名字以發(fā)明者的名字命名:Ron Rivest, AdiShamir 和Leonard Adleman。 這種加密算法的特點主要是密鑰的變化,,上文我們看到DES只有一個密鑰,。相當(dāng)于只有一把鑰匙,如果這把鑰匙丟了,,數(shù)據(jù)也就不安全了,。RSA同時有兩把鑰匙,公鑰與私鑰,。同時支持?jǐn)?shù)字簽名,。數(shù)字簽名的意義在于,對傳輸過來的數(shù)據(jù)進(jìn)行校驗,。確保數(shù)據(jù)在傳輸工程中不被修改,。
流程分析:
- 甲方構(gòu)建密鑰對兒,將公鑰公布給乙方,,將私鑰保留,。
- 甲方使用私鑰加密數(shù)據(jù),然后用私鑰對加密后的數(shù)據(jù)簽名,,發(fā)送給乙方簽名以及加密后的數(shù)據(jù),;乙方使用公鑰、簽名來驗證待解密數(shù)據(jù)是否有效,,如果有效使用公鑰對數(shù)據(jù)解密,。
- 乙方使用公鑰加密數(shù)據(jù),向甲方發(fā)送經(jīng)過加密后的數(shù)據(jù),;甲方獲得加密數(shù)據(jù),,通過私鑰解密。
按如上步驟給出序列圖,,如下:
通過java代碼實現(xiàn)如下:Coder類見 Java加密技術(shù)(一)
- import java.security.Key;
- import java.security.KeyFactory;
- import java.security.KeyPair;
- import java.security.KeyPairGenerator;
- import java.security.PrivateKey;
- import java.security.PublicKey;
- import java.security.Signature;
- import java.security.interfaces.RSAPrivateKey;
- import java.security.interfaces.RSAPublicKey;
- import java.security.spec.PKCS8EncodedKeySpec;
- import java.security.spec.X509EncodedKeySpec;
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- import java.util.HashMap;
- import java.util.Map;
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- import javax.crypto.Cipher;
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- public abstract class RSACoder extends Coder {
- public static final String KEY_ALGORITHM = "RSA";
- public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
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- private static final String PUBLIC_KEY = "RSAPublicKey";
- private static final String PRIVATE_KEY = "RSAPrivateKey";
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- public static String sign(byte[] data, String privateKey) throws Exception {
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- byte[] keyBytes = decryptBASE64(privateKey);
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- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
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- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
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- PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
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- Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
- signature.initSign(priKey);
- signature.update(data);
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- return encryptBASE64(signature.sign());
- }
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- public static boolean verify(byte[] data, String publicKey, String sign)
- throws Exception {
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- byte[] keyBytes = decryptBASE64(publicKey);
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- X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
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- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
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- PublicKey pubKey = keyFactory.generatePublic(keySpec);
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- Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
- signature.initVerify(pubKey);
- signature.update(data);
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- return signature.verify(decryptBASE64(sign));
- }
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- public static byte[] decryptByPrivateKey(byte[] data, String key)
- throws Exception {
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- byte[] keyBytes = decryptBASE64(key);
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- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
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- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.DECRYPT_MODE, privateKey);
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- return cipher.doFinal(data);
- }
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- public static byte[] decryptByPublicKey(byte[] data, String key)
- throws Exception {
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- byte[] keyBytes = decryptBASE64(key);
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- X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key publicKey = keyFactory.generatePublic(x509KeySpec);
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- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.DECRYPT_MODE, publicKey);
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- return cipher.doFinal(data);
- }
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- public static byte[] encryptByPublicKey(byte[] data, String key)
- throws Exception {
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- byte[] keyBytes = decryptBASE64(key);
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- X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key publicKey = keyFactory.generatePublic(x509KeySpec);
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- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.ENCRYPT_MODE, publicKey);
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- return cipher.doFinal(data);
- }
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- public static byte[] encryptByPrivateKey(byte[] data, String key)
- throws Exception {
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- byte[] keyBytes = decryptBASE64(key);
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- PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
- KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
- Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
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- Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
- cipher.init(Cipher.ENCRYPT_MODE, privateKey);
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- return cipher.doFinal(data);
- }
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- public static String getPrivateKey(Map<String, Object> keyMap)
- throws Exception {
- Key key = (Key) keyMap.get(PRIVATE_KEY);
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- return encryptBASE64(key.getEncoded());
- }
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- public static String getPublicKey(Map<String, Object> keyMap)
- throws Exception {
- Key key = (Key) keyMap.get(PUBLIC_KEY);
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- return encryptBASE64(key.getEncoded());
- }
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- public static Map<String, Object> initKey() throws Exception {
- KeyPairGenerator keyPairGen = KeyPairGenerator
- .getInstance(KEY_ALGORITHM);
- keyPairGen.initialize(1024);
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- KeyPair keyPair = keyPairGen.generateKeyPair();
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- RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
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- RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
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- Map<String, Object> keyMap = new HashMap<String, Object>(2);
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- keyMap.put(PUBLIC_KEY, publicKey);
- keyMap.put(PRIVATE_KEY, privateKey);
- return keyMap;
- }
- }
再給出一個測試類:
- import static org.junit.Assert.*;
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- import org.junit.Before;
- import org.junit.Test;
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- import java.util.Map;
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- public class RSACoderTest {
- private String publicKey;
- private String privateKey;
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- @Before
- public void setUp() throws Exception {
- Map<String, Object> keyMap = RSACoder.initKey();
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- publicKey = RSACoder.getPublicKey(keyMap);
- privateKey = RSACoder.getPrivateKey(keyMap);
- System.err.println("公鑰: \n\r" + publicKey);
- System.err.println("私鑰: \n\r" + privateKey);
- }
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- @Test
- public void test() throws Exception {
- System.err.println("公鑰加密——私鑰解密");
- String inputStr = "abc";
- byte[] data = inputStr.getBytes();
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- byte[] encodedData = RSACoder.encryptByPublicKey(data, publicKey);
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- byte[] decodedData = RSACoder.decryptByPrivateKey(encodedData,
- privateKey);
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- String outputStr = new String(decodedData);
- System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
- assertEquals(inputStr, outputStr);
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- }
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- @Test
- public void testSign() throws Exception {
- System.err.println("私鑰加密——公鑰解密");
- String inputStr = "sign";
- byte[] data = inputStr.getBytes();
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- byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
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- byte[] decodedData = RSACoder
- .decryptByPublicKey(encodedData, publicKey);
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- String outputStr = new String(decodedData);
- System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
- assertEquals(inputStr, outputStr);
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- System.err.println("私鑰簽名——公鑰驗證簽名");
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- String sign = RSACoder.sign(encodedData, privateKey);
- System.err.println("簽名:\r" + sign);
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- boolean status = RSACoder.verify(encodedData, publicKey, sign);
- System.err.println("狀態(tài):\r" + status);
- assertTrue(status);
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- }
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- }
控制臺輸出:
- 公鑰:
-
- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCYU/+I0+z1aBl5X6DUUOHQ7FZpmBSDbKTtx89J
- EcB64jFCkunELT8qiKly7fzEqD03g8ALlu5XvX+bBqHFy7YPJJP0ekE2X3wjUnh2NxlqpH3/B/xm
- 1ZdSlCwDIkbijhBVDjA/bu5BObhZqQmDwIxlQInL9oVz+o6FbAZCyHBd7wIDAQAB
-
- 私鑰:
-
- MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAJhT/4jT7PVoGXlfoNRQ4dDsVmmY
- FINspO3Hz0kRwHriMUKS6cQtPyqIqXLt/MSoPTeDwAuW7le9f5sGocXLtg8kk/R6QTZffCNSeHY3
- GWqkff8H/GbVl1KULAMiRuKOEFUOMD9u7kE5uFmpCYPAjGVAicv2hXP6joVsBkLIcF3vAgMBAAEC
- gYBvZHWoZHmS2EZQqKqeuGr58eobG9hcZzWQoJ4nq/CarBAjw/VovUHE490uK3S9ht4FW7Yzg3LV
- /MB06Huifh6qf/X9NQA7SeZRRC8gnCQk6JuDIEVJOud5jU+9tyumJakDKodQ3Jf2zQtNr+5ZdEPl
- uwWgv9c4kmpjhAdyMuQmYQJBANn6pcgvyYaia52dnu+yBUsGkaFfwXkzFSExIbi0MXTkhEb/ER/D
- rLytukkUu5S5ecz/KBa8U4xIslZDYQbLz5ECQQCy5dutt7RsxN4+dxCWn0/1FrkWl2G329Ucewm3
- QU9CKu4D+7Kqdj+Ha3lXP8F0Etaaapi7+EfkRUpukn2ItZV/AkEAlk+I0iphxT1rCB0Q5CjWDY5S
- Df2B5JmdEG5Y2o0nLXwG2w44OLct/k2uD4cEcuITY5Dvi/4BftMCZwm/dnhEgQJACIktJSnJwxLV
- o9dchENPtlsCM9C/Sd2EWpqISSUlmfugZbJBwR5pQ5XeMUqKeXZYpP+HEBj1nS+tMH9u2/IGEwJA
- fL8mZiZXan/oBKrblAbplNcKWGRVD/3y65042PAEeghahlJMiYquV5DzZajuuT0wbJ5xQuZB01+X
- nfpFpBJ2dw==
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- 公鑰加密——私鑰解密
- 加密前: abc
-
- 解密后: abc
- 公鑰:
-
- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDdOj40yEB48XqWxmPILmJAc7UecIN7F32etSHF
- 9rwbuEh3+iTPOGSxhoSQpOED0vOb0ZIMkBXZSgsxLaBSin2RZ09YKWRjtpCA0kDkiD11gj4tzTiM
- l9qq1kwSK7ZkGAgodEn3yIILVmQDuEImHOXFtulvJ71ka07u3LuwUNdB/wIDAQAB
-
- 私鑰:
-
- MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAN06PjTIQHjxepbGY8guYkBztR5w
- g3sXfZ61IcX2vBu4SHf6JM84ZLGGhJCk4QPS85vRkgyQFdlKCzEtoFKKfZFnT1gpZGO2kIDSQOSI
- PXWCPi3NOIyX2qrWTBIrtmQYCCh0SffIggtWZAO4QiYc5cW26W8nvWRrTu7cu7BQ10H/AgMBAAEC
- gYEAz2JWBizjI31bqhP4XiP9PuY5F3vqBW4T+L9cFbQiyumKJc58yzTWUAUGKIIn3enXLG7dNqGr
- mbJro4JeFIJ3CiVDpXR9+FluIgI4SXm7ioGKF2NOMA9LR5Fu82W+pLfpTN2y2SaLYWEDZyp53BxY
- j9gUxaxi1MQs+C1ZgDF2xmECQQDy70bQntbRfysP+ppCtd56YRnES1Tyekw0wryS2tr+ivQJl7JF
- gp5rPAOXpgrq36xHDwUspQ0sJ0vj0O7ywxr1AkEA6SAaLhrJJrYucC0jxwAhUYyaPN+aOsWymaRh
- 9jA/Wc0wp29SbGTh5CcMuGpXm1g0M+FKW3dGiHgS3rVUKim4owJAbnxgapUzAgiiHxxMeDaavnHW
- 9C2GrtjsO7qtZOTgYI/1uT8itvZW8lJTF+9OW8/qXE76fXl7ai9dFnl5kzMk2QJBALfHz/vCsArt
- mkRiwY6zApE4Z6tPl1V33ymSVovvUzHnOdD1SKQdD5t+UV/crb3QVi8ED0t2B0u0ZSPfDT/D7kMC
- QDpwdj9k2F5aokLHBHUNJPFDAp7a5QMaT64gv/d48ITJ68Co+v5WzLMpzJBYXK6PAtqIhxbuPEc2
- I2k1Afmrwyw=
-
- 私鑰加密——公鑰解密
- 加密前: sign
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- 解密后: sign
- 私鑰簽名——公鑰驗證簽名
- 簽名:
- ud1RsIwmSC1pN22I4IXteg1VD2FbiehKUfNxgVSHzvQNIK+d20FCkHCqh9djP3h94iWnIUY0ifU+
- mbJkhAl/i5krExOE0hknOnPMcEP+lZV1RbJI2zG2YooSp2XDleqrQk5e/QF2Mx0Zxt8Xsg7ucVpn
- i3wwbYWs9wSzIf0UjlM=
-
- 狀態(tài):
- true
簡要總結(jié)一下,,使用公鑰加密、私鑰解密,,完成了乙方到甲方的一次數(shù)據(jù)傳遞,,通過私鑰加密,、公鑰解密,同時通過私鑰簽名,、公鑰驗證簽名,,完成了一次甲方到乙方的數(shù)據(jù)傳遞與驗證,兩次數(shù)據(jù)傳遞完成一整套的數(shù)據(jù)交互,!
類似數(shù)字簽名,,數(shù)字信封是這樣描述的:
數(shù)字信封 數(shù)字信封用加密技術(shù)來保證只有特定的收信人才能閱讀信的內(nèi)容。 流程: 信息發(fā)送方采用對稱密鑰來加密信息,,然后再用接收方的公鑰來加密此對稱密鑰(這部分稱為數(shù)字信封),,再將它和信息一起發(fā)送給接收方;接收方先用相應(yīng)的私鑰打開數(shù)字信封,,得到對稱密鑰,,然后使用對稱密鑰再解開信息。
相關(guān)鏈接: Java加密技術(shù)(一)——BASE64與單向加密算法MD5&SHA&MAC Java加密技術(shù)(二)——對稱加密DES&AES Java加密技術(shù)(三)——PBE算法 Java加密技術(shù)(四)——非對稱加密算法RSA Java加密技術(shù)(五)——非對稱加密算法的由來DH Java加密技術(shù)(六)——數(shù)字簽名算法DSA Java加密技術(shù)(七)——非對稱加密算法最高ECC Java加密技術(shù)(八)——數(shù)字證書 Java加密技術(shù)(九)——初探SSL Java加密技術(shù)(十)——單向認(rèn)證 Java加密技術(shù)(十一)——雙向認(rèn)證 Java加密技術(shù)(十二)——*.PFX(*.p12)&個人信息交換文件
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