Java Implementation Digital Signature

1. Generate public and private key pairs

Public class keygenerater { private byte[] prikey; private byte[]  pubkey; public void generater ()  {  try {    java.security.keypairgenerator keygen = java.security.keypairgenerator      .getinstance ("RSA");    securerandom secrand = new securerandom ();    secrand.setseed ("Syj". GetBytes ()); //  Initializes a random generator    keygen.initialize ( 1024, secrand);    keypair keys = keygen.genkeypair ();    Publickey pubkey = keys.getpublic ();   privatekey prikey =  Keys.getprivate ();    pubkey = base64.encodetobyte (pubkey.getencoded ());    prikey = base64.encodetobyte (prikey.getencoded ());    system.out.println ("PubKey  =  " + new string (PubKey));    system.out.println ("prikey = "  + new string (PriKey));   } catch  (java.lang.exception e)  {   system.out.println ("Generate key pair failed ");    e.printstacktrace ();   } } public byte[] getprikey ()  {   return prikey; } public byte[] getpubkey ()  {  return  pubkey; }}

2. Encryption process (digital signature): Data encryption of transmitted data with private key

Public class signaturer { /**  *   * description: Digital Signature    *   *  @param  priKeyText  *  @param  plaintext  *   @return     */ public static byte[] sign (Byte[] prikeytext,  string plaintext)  {  try {   pkcs8encodedkeyspec pripkcs8  = new pkcs8encodedkeyspec (Base64     .decode (priKeyText));    keyfactory keyf = keyfactory.getinstance ("RSA");   privatekey  Prikey = keyf.generateprivate (priPKCS8);   //  generate digital signatures for information with private key     java.security.signature signet = java.security.signature     . getinstance ("Md5withrsa");    signet.initsign (Prikey);    signet.update ( Plaintext.getbytes ());    byte[] signed = base64.encodetobyte (Signet.sign ());   return signed;   } catch  (java.lang.exception e)  {   system.out.println ("Signature failed");    e.printstacktrace ();   }  return null; }}

3. Verify the digital signature by using the public key and the data plaintext to encode the data check of the "Data word signature".

Public class signprovider { private signprovider ()  { } /**   *   * description: Verifying the digital signature, this method does not throw a task exception, returns true successfully, fails to return false, requires that all parameters cannot be empty   *    *  @param  pubKeyText  *              public Key, base64 encoding   *  @param  plainText  *              Clear   *  @param  signTest  *              digitally signed ciphertext, base64 encoding   *  @return   Verify successful return true  failure return false    */ public static boolean verify ( Byte[] pubkeytext, string plaintext,   byte[] signtext)  {   try {   //  decrypts the public key encoded by Base64 and constructs X509encodedkeyspec objects     Java.security.spec.x509encodedkeyspec bobpUbkeyspec = new java.security.spec.x509encodedkeyspec (      Base64.decode (Pubkeytext));    // rsa symmetric encryption Algorithm    java.security.KeyFactory  Keyfactory = java.security.keyfactory     .getinstance ("RSA");    //  access to public key objects    java.security.PublicKey pubKey = keyFactory      .generatepublic (Bobpubkeyspec);   //  decryption of digital signatures encoded by Base64     Byte[] signed = base64.decode (Signtext);   java.security.signature  Signaturechecker = java.security.signature     .getinstance ("MD5withRSA");    signaturechecker.initverify (PubKey);    signaturechecker.update ( Plaintext.getbytes ());   //  Verify that the signature is normal    if  (signaturechecker.verify ( Signed))     RETURN TRUE;&Nbsp;  else    return false;  } catch  (Throwable e)  {   system.out.println ("Verify signature Failed");    e.printstacktrace ();    return false;  } }}

Java Implementation Digital Signature