CertUtil: Add methods to export private keys

Unused so far, to be used for family key

core/java/src/net/i2p/crypto/CertUtil.java

@@ -8,6 +8,8 @@ import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.security.GeneralSecurityException;
+import java.security.InvalidKeyException;
+import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateFactory;
@@ -36,31 +38,16 @@ public class CertUtil {
     private static final int LINE_LENGTH = 64;
 
     /**
-     *  Modified from:
-     *  http://www.exampledepot.com/egs/java.security.cert/ExportCert.html
-     *
-     *  This method writes a certificate to a file in base64 format.
+     *  Write a certificate to a file in base64 format.
      *
      *  @return success
      *  @since 0.8.2, moved from SSLEepGet in 0.9.9
      */
     public static boolean saveCert(Certificate cert, File file) {
         OutputStream os = null;
-        PrintWriter wr = null;
         try {
-           // Get the encoded form which is suitable for exporting
-           byte[] buf = cert.getEncoded();
            os = new SecureFileOutputStream(file);
-           wr = new PrintWriter(new OutputStreamWriter(os, "UTF-8"));
-           wr.println("-----BEGIN CERTIFICATE-----");
-           String b64 = Base64.encode(buf, true);     // true = use standard alphabet
-           for (int i = 0; i < b64.length(); i += LINE_LENGTH) {
-               wr.println(b64.substring(i, Math.min(i + LINE_LENGTH, b64.length())));
-           }
-           wr.println("-----END CERTIFICATE-----");
-           wr.flush();
-           if (wr.checkError())
-               throw new IOException("Failed write to " + file);
+           exportCert(cert, os);
            return true;
         } catch (CertificateEncodingException cee) {
             error("Error writing X509 Certificate " + file.getAbsolutePath(), cee);
@@ -73,6 +60,79 @@ public class CertUtil {
         }
     }
 
+    /**
+     *  Writes the private key and all certs in base64 format.
+     *  Does NOT close the stream. Throws on all errors.
+     *
+     *  @param pk non-null
+     *  @param certs certificate chain, null or empty to export pk only
+     *  @throws InvalidKeyException if the key does not support encoding
+     *  @throws CertificateEncodingException if a cert does not support encoding
+     *  @since 0.9.24
+     */
+    public static void exportPrivateKey(PrivateKey pk, Certificate[] certs, OutputStream out)
+                                                throws IOException, GeneralSecurityException {
+        exportPrivateKey(pk, out);
+        if (certs == null)
+            return;
+        for (int i = 0; i < certs.length; i++) {
+            exportCert(certs[i], out);
+        }
+    }
+
+    /**
+     *  Modified from:
+     *  http://www.exampledepot.com/egs/java.security.cert/ExportCert.html
+     *
+     *  Writes a certificate in base64 format.
+     *  Does NOT close the stream. Throws on all errors.
+     *
+     *  @since 0.9.24, pulled out of saveCert()
+     */
+    private static void exportCert(Certificate cert, OutputStream out)
+                                                throws IOException, CertificateEncodingException {
+        // Get the encoded form which is suitable for exporting
+        byte[] buf = cert.getEncoded();
+        PrintWriter wr = new PrintWriter(new OutputStreamWriter(out, "UTF-8"));
+        wr.println("-----BEGIN CERTIFICATE-----");
+        String b64 = Base64.encode(buf, true);     // true = use standard alphabet
+        for (int i = 0; i < b64.length(); i += LINE_LENGTH) {
+            wr.println(b64.substring(i, Math.min(i + LINE_LENGTH, b64.length())));
+        }
+        wr.println("-----END CERTIFICATE-----");
+        wr.flush();
+        if (wr.checkError())
+            throw new IOException("Failed write to " + out);
+    }
+
+    /**
+     *  Modified from:
+     *  http://www.exampledepot.com/egs/java.security.cert/ExportCert.html
+     *
+     *  Writes a private key in base64 format.
+     *  Does NOT close the stream. Throws on all errors.
+     *
+     *  @throws InvalidKeyException if the key does not support encoding
+     *  @since 0.9.24
+     */
+    private static void exportPrivateKey(PrivateKey pk, OutputStream out)
+                                                throws IOException, InvalidKeyException {
+        // Get the encoded form which is suitable for exporting
+        byte[] buf = pk.getEncoded();
+        if (buf == null)
+            throw new InvalidKeyException("encoding unsupported for this key");
+        PrintWriter wr = new PrintWriter(new OutputStreamWriter(out, "UTF-8"));
+        wr.println("-----BEGIN PRIVATE KEY-----");
+        String b64 = Base64.encode(buf, true);     // true = use standard alphabet
+        for (int i = 0; i < b64.length(); i += LINE_LENGTH) {
+            wr.println(b64.substring(i, Math.min(i + LINE_LENGTH, b64.length())));
+        }
+        wr.println("-----END PRIVATE KEY-----");
+        wr.flush();
+        if (wr.checkError())
+            throw new IOException("Failed write to " + out);
+    }
+
     /**
      *  Get a value out of the subject distinguished name.
      *