使用openssl生成密钥对：
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>openssl genrsa -out private.key >openssl rsa -in private.key -pubout -outform PEM -out public.key // 因为java里面不识别x509格式的私钥，所以必须转换为 pkcs8格式方可使用 // java异常描述为： java.security.spec.InvalidKeySpecException: Only RSAPrivate(Crt)KeySpec and PKCS8EncodedKeySpec supported for RSA private keys // 虽然RSAPrivate(Crt)KeySpec 也支持，但是目前还不知道怎么用 >openssl pkcs8 -topk8 -inform PEM -outform PEM -in private.key -out pkcs8_priv.pem -nocrypt |
java代码：
1. 注意： java 语言本身没有实现base64编码，而openssl生成的密钥对一般做base64编码，便于维护，所以这里引用了 org.apache.commons.codec.binary.Base64;
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import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.PrivateKey; import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Arrays; import javax.crypto.Cipher; import org.apache.commons.codec.binary.Base64; //下载地址： http://commons.apache.org/codec/download_codec.cgi public static class MyRsa { /** * String to hold name of the encryption algorithm. */ public static final String ALGORITHM = "RSA"; /** * String to hold the name of the private key file. */ public static final String PRIVATE_KEY_FILE = "D:/rsa/pkcs8_priv.pem"; /** * String to hold name of the public key file. */ public static final String PUBLIC_KEY_FILE = "D:/rsa/public.key"; /** * Encrypt the plain text using public key. * * @param text * : original plain text * @param key * :The public key * @return Encrypted text * @throws java.lang.Exception */ public static byte[] encrypt(String text, PublicKey key) { byte[] cipherText = null; try { // get an RSA cipher object and print the provider final Cipher cipher = Cipher.getInstance(ALGORITHM); // encrypt the plain text using the public key cipher.init(Cipher.ENCRYPT_MODE, key); cipherText = cipher.doFinal(text.getBytes()); } catch (Exception e) { e.printStackTrace(); } return cipherText; } /** * Decrypt text using private key. * * @param text * :encrypted text * @param key * :The private key * @return plain text * @throws java.lang.Exception */ public static String decrypt(byte[] text, PrivateKey key) { byte[] dectyptedText = null; try { // get an RSA cipher object and print the provider final Cipher cipher = Cipher.getInstance(ALGORITHM); // decrypt the text using the private key cipher.init(Cipher.DECRYPT_MODE, key); dectyptedText = cipher.doFinal(text); } catch (Exception ex) { ex.printStackTrace(); } return new String(dectyptedText); } public static void test() { String s = "Hello world"; try { BufferedReader privateKey = new BufferedReader(new FileReader( PRIVATE_KEY_FILE)); BufferedReader publicKey = new BufferedReader(new FileReader( PUBLIC_KEY_FILE)); String strPrivateKey = ""; String strPublicKey = ""; String line = ""; while((line = privateKey.readLine()) != null){ strPrivateKey += line; } while((line = publicKey.readLine()) != null){ strPublicKey += line; } privateKey.close(); publicKey.close(); // 私钥需要使用pkcs8格式的，公钥使用x509格式的 String strPrivKey = strPrivateKey.replace("-----BEGIN PRIVATE KEY-----", "") .replace("-----END PRIVATE KEY-----", ""); String strPubKey = strPublicKey.replace("-----BEGIN PUBLIC KEY-----", "") .replace("-----END PUBLIC KEY-----", ""); //System.out.print(strPrivKey); //System.out.println(strPubKey); byte [] privKeyByte = Base64.decodeBase64(strPrivKey); byte [] pubKeyByte = Base64.decodeBase64(strPubKey); PKCS8EncodedKeySpec privKeySpec = new PKCS8EncodedKeySpec(privKeyByte); //PKCS8EncodedKeySpec pubKeySpec = new PKCS8EncodedKeySpec(pubKeyByte); //X509EncodedKeySpec privKeySpec = new X509EncodedKeySpec(privKeyByte); X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(pubKeyByte); KeyFactory kf = KeyFactory.getInstance("RSA"); PrivateKey privKey = kf.generatePrivate(privKeySpec); PublicKey pubKey = kf.generatePublic(pubKeySpec); byte [] encryptByte = encrypt(s, pubKey); System.out.println(decrypt(encryptByte, privKey)); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvalidKeySpecException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } |
稍后提供一个PHP加密Java解密的实现
参考资料：
http://stackoverflow.com/questions/11787571/how-to-read-pem-file-to-get-private-and-public-key
http://stackoverflow.com/questions/8647165/how-to-sign-a-generic-text-with-rsa-key-and-encode-with-base64-in-java
http://www.javamex.com/tutorials/cryptography/rsa_encryption.shtml
http://snowolf.iteye.com/blog/381767
密钥结构及格式： https://polarssl.org/kb/cryptography/asn1-key-structures-in-der-and-pem