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

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Save/Load or.. Write/Read or.. Store/Retrieve Private Key/Public Key to/from disk/file :D

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  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. }

URL: http://java.sun.com/docs/books/tutorial/security/apisign/vstep2.html

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