Java 中公钥密码体制 API

Java中公钥密码体制API • RSA中的密钥生成通过学习,我们已经知道要生成RSA的密钥，需要做如下工作: • 确定两个大素数p,q(至少512bit) • 此处涉及到素数的判定（该算法是比较费时的）． • 计算n=pq; • 计算 • 选定一个e,使 • 最后得到公钥: n,e • 最后得到私钥: d ( )

Java中公钥密码体制API • KeyPairGenerator • The KeyPairGenerator class is an engine class used to generate pairs of public and private keys • Creating the Key Pair Generator try{ //取得KeyPairGenerator实例 KeyPairGenerator keyGen=KeyPairGenerator.getInstance("RSA"); System.out.println("Key Test program is ok"); } catch(NoSuchAlgorithmException e){ System.out.println("Error: "+e.getMessage()); }

Java中公钥密码体制API • Initializing the Key Pair Generator SecureRandom random = SecureRandom.getInstance(“SHA1PRNG”, “SUN”); random.setSeed(userSeed); //这两条语句可省略,省略时系统采用 keyGen.initialize(1024, random); //默认值

Java中公钥密码体制API • The KeyPair Class KeyPair类是用于封装密钥对的类． KeyPair pair = keyGen.generateKeyPair();

Java中公钥密码体制API • The PublicKey Class 封装了公钥体制中的公钥(n,e)

Java中公钥密码体制API • The PrivateKey Class 封装了公钥体制中的私钥(n,d,p,q)

Java中公钥密码体制API • KeyFactory 用于实现密钥对象与密钥的标准表达方式之间的转换．

用于测试RSA密钥对的代码 // 取得KeyPairGenerator实例 KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA"); // 生成随机数对象 SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN"); // 初始化keyGen为产生一对1024位的密钥的对象 keyGen.initialize(1024, random); // 生成密钥对 KeyPair pair = keyGen.generateKeyPair(); // 读取公钥对象和私钥对象 PublicKey puKey = pair.getPublic(); PrivateKey prKey = pair.getPrivate(); //将公钥和私钥输出 System.out.println(puKey.toString()); System.out.println(prKey.toString());

Java中公钥密码体制API • Sun RSA public key, 1024 bits • modulus( n) : 145334580766753352968271624143227642903180026858070538178093842654655131896488508859021170467602039725331815700222176862989556902870844823932940664684208523041952356061062674190324733884210594543025749003442008772730874286810845100551163211606567048423518752061867186661617099735966587084128589872797083364747 • public exponent( e): 65537 • Sun RSA private CRT(中国剩余定理) key, 1024 bits • modulus(n ): 145334580766753352968271624143227642903180026858070538178093842654655131896488508859021170467602039725331815700222176862989556902870844823932940664684208523041952356061062674190324733884210594543025749003442008772730874286810845100551163211606567048423518752061867186661617099735966587084128589872797083364747 • public exponent( e ): 65537 • private exponent( d ) : 123650928314896931628818186529780584107273984429851154893759778027387819085650895913303346874330868563479816159248796247973430327100346926738740536218117730278249237671789995775819474273027581511787552426991635086254315333676872987600640893099168403376116367516517690236495972293965947291133168132306425021585 • prime p: 12836193223793558297927305428496631019420276059582307483685094836716895113592759865558860520415443996103674401559926195951777679843538568226126094329161913 • prime q: 11322249379773806480799329481584580801659487779713145666093610874564424578061919183694263286905364957495175786438352752223906032465534494985244811289566819 • prime exponent p: 9148115978816938941686233038570458596274819322137278722560991875406808674040267864575090381418803770786186738386857391005381389023790468073571745545755305 • prime exponent q: 6844970668111417772796286576893398781490616984604338685571432266675573587551937073365433353532774844453001508071379135387084866751864476949057550209865067 • crt coefficient: 12215131375839181768650789125852251387959893277517099645583985397510200970338820228475780242328195082955827984916897355413623358654311131059893783646946460

Java中公钥密码体制API • RSA用于加密和解密 RSA算法用于加密和解密时,用法同对称加密体制. 具体请参照Cipher类

用于测试RSA加密及解密方法的代码 Cipher rsaCipher; // Create the cipher rsaCipher = Cipher.getInstance("RSA"); // Initialize the cipher for encryption rsaCipher.init(Cipher.ENCRYPT_MODE, pair.getPublic()); // Our cleartext byte[] cleartext = "This is just an example,******************".getBytes(); // Encrypt the cleartext byte[] ciphertext = rsaCipher.doFinal(cleartext); System.out.println("ciphertext"); System.out.println(Tools.toHexString(ciphertext)); // Initialize the cipher for decryption rsaCipher.init(Cipher.DECRYPT_MODE, pair.getPrivate()); // Dncrypt the cleartext byte[] cleartext1 = rsaCipher.doFinal(ciphertext); System.out.println("****************** old clear text is *****************"); System.out.println(new String(cleartext)); System.out.println("************* new decryption cleartext **************"); System.out.println(new String(cleartext1));

Tools.java publicclass Tools { /* Converts a byte array to hex string-将字符串转换成16进制字符 System.out.println(Tools.toHexString(ciphertext));--具体用法 */ publicstatic String toHexString(byte[] block) { StringBuffer buf = new StringBuffer(); int len = block.length; for (int i = 0; i < len; i++) { byte2hex(block[i], buf); if (i < len-1) { buf.append(":"); } } return buf.toString(); }

privatestaticvoid byte2hex(byte b, StringBuffer buf) { char[] hexChars = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; int high = ((b & 0xf0) >> 4); int low = (b & 0x0f); buf.append(hexChars[high]); buf.append(hexChars[low]); }

/* * Convnvert a hex string to byte array */ publicstaticvoid hex2byte(String buf,byte[] block){ int len; int i; byte high,low; byte [] ch; len=buf.length(); ch=buf.getBytes(); for(i=0;i<len/2;i++){ high=(byte)(ch[i*2]<<4); low=(byte)(ch[i*2+1]& 0x0f); block[i]=(byte)(high+low); } } }

Java 中公钥密码体制 API