Save/Load Private and Public Key to/from a file

1. package net.java.edem;
2.  
3. import java.io.*;
4. import java.security.*;
5. import java.security.spec.*;
6.  
7. public class Adam {
8.  
9. public static void main(String args[]) {
10. Adam adam = new Adam();
11. try {
12. String path = "C:\\Documents and Settings\\george\\My Documents\\workspaces\\gsoc09\\playground\\tmp";
13.  
14. KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
15.  
16. keyGen.initialize(1024);
17. KeyPair generatedKeyPair = keyGen.genKeyPair();
18.  
19. System.out.println("Generated Key Pair");
20. adam.dumpKeyPair(generatedKeyPair);
21. adam.SaveKeyPair(path, generatedKeyPair);
22.  
23. KeyPair loadedKeyPair = adam.LoadKeyPair(path, "DSA");
24. System.out.println("Loaded Key Pair");
25. adam.dumpKeyPair(loadedKeyPair);
26. } catch (Exception e) {
27. e.printStackTrace();
28. return;
29. }
30. }
31.  
32. private void dumpKeyPair(KeyPair keyPair) {
33. PublicKey pub = keyPair.getPublic();
34. System.out.println("Public Key: " + getHexString(pub.getEncoded()));
35.  
36. PrivateKey priv = keyPair.getPrivate();
37. System.out.println("Private Key: " + getHexString(priv.getEncoded()));
38. }
39.  
40. private String getHexString(byte[] b) {
41. String result = "";
42. for (int i = 0; i < b.length; i++) {
43. result += Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1);
44. }
45. return result;
46. }
47.  
48. public void SaveKeyPair(String path, KeyPair keyPair) throws IOException {
49. PrivateKey privateKey = keyPair.getPrivate();
50. PublicKey publicKey = keyPair.getPublic();
51.  
52. // Store Public Key.
53. X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
54. publicKey.getEncoded());
55. FileOutputStream fos = new FileOutputStream(path + "/public.key");
56. fos.write(x509EncodedKeySpec.getEncoded());
57. fos.close();
58.  
59. // Store Private Key.
60. PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(
61. privateKey.getEncoded());
62. fos = new FileOutputStream(path + "/private.key");
63. fos.write(pkcs8EncodedKeySpec.getEncoded());
64. fos.close();
65. }
66.  
67. public KeyPair LoadKeyPair(String path, String algorithm)
68. throws IOException, NoSuchAlgorithmException,
69. InvalidKeySpecException {
70. // Read Public Key.
71. File filePublicKey = new File(path + "/public.key");
72. FileInputStream fis = new FileInputStream(path + "/public.key");
73. byte[] encodedPublicKey = new byte[(int) filePublicKey.length()];
74. fis.read(encodedPublicKey);
75. fis.close();
76.  
77. // Read Private Key.
78. File filePrivateKey = new File(path + "/private.key");
79. fis = new FileInputStream(path + "/private.key");
80. byte[] encodedPrivateKey = new byte[(int) filePrivateKey.length()];
81. fis.read(encodedPrivateKey);
82. fis.close();
83.  
84. // Generate KeyPair.
85. KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
86. X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(
87. encodedPublicKey);
88. PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
89.  
90. PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(
91. encodedPrivateKey);
92. PrivateKey privateKey = keyFactory.generatePrivate(privateKeySpec);
93.  
94. return new KeyPair(publicKey, privateKey);
95. }
96. }