src/org/cacert/gigi/crypto/SMIME.java

   1 package org.cacert.gigi.crypto;
   2
   3 import java.io.ByteArrayOutputStream;
   4 import java.io.IOException;
   5 import java.io.PrintWriter;
   6 import java.math.BigInteger;
   7 import java.security.GeneralSecurityException;
   8 import java.security.PrivateKey;
   9 import java.security.Signature;
  10 import java.security.cert.X509Certificate;
  11 import java.util.Base64;
  12 import java.util.Random;
  13
  14 import sun.security.pkcs.ContentInfo;
  15 import sun.security.pkcs.PKCS7;
  16 import sun.security.pkcs.SignerInfo;
  17 import sun.security.util.DerOutputStream;
  18 import sun.security.x509.AlgorithmId;
  19 import sun.security.x509.X500Name;
  20
  21 public class SMIME {
  22
  23     public static String doAlternatives(String plain, String html) {
  24
  25         plain = "Content-type: text/plain\r\n\r\n" + plain;
  26         html = "Content-type: text/html\r\n\r\n" + html;
  27         String boundary = generateBoundary(plain, html);
  28         StringBuffer content = new StringBuffer("Content-Type: multipart/alternative; boundary=\"");
  29         content.append(boundary);
  30         content.append("\"\r\n\r\n");
  31         content.append("--");
  32         content.append(boundary);
  33         content.append("\r\n");
  34         content.append(plain);
  35         content.append("\r\n--");
  36         content.append(boundary);
  37         content.append("\r\n");
  38         content.append(html);
  39         content.append("\r\n--");
  40         content.append(boundary);
  41         content.append("--\r\n");
  42         return content.toString();
  43
  44     }
  45
  46     public static void smime(String contents, PrivateKey pKey, X509Certificate c, PrintWriter to) throws IOException, GeneralSecurityException {
  47
  48         Signature signature = Signature.getInstance("SHA1WithRSA");
  49         signature.initSign(pKey);
  50         signature.update(contents.getBytes("UTF-8"));
  51         byte[] signedData = signature.sign();
  52
  53         // "IssuerAndSerialNumber"
  54         X500Name xName = X500Name.asX500Name(c.getIssuerX500Principal());
  55         BigInteger serial = c.getSerialNumber();
  56
  57         SignerInfo sInfo = new SignerInfo(xName, serial, new AlgorithmId(AlgorithmId.SHA_oid), null, new AlgorithmId(AlgorithmId.RSAEncryption_oid), signedData, null);
  58
  59         // Content is outside so content here is null.
  60         ContentInfo cInfo = new ContentInfo(ContentInfo.DATA_OID, null);
  61
  62         // Create PKCS7 Signed data
  63         PKCS7 p7 = new PKCS7(new AlgorithmId[] {
  64             new AlgorithmId(AlgorithmId.SHA_oid)
  65         }, cInfo, new java.security.cert.X509Certificate[] {
  66             c
  67         }, new SignerInfo[] {
  68             sInfo
  69         });
  70
  71         ByteArrayOutputStream bOut = new DerOutputStream();
  72         p7.encodeSignedData(bOut);
  73
  74         mimeEncode(contents, Base64.getEncoder().encodeToString(bOut.toByteArray()).replaceAll("(.{64})(?=.)", "$1\n"), to);
  75     }
  76
  77     static Random r = new Random();
  78
  79     private static void mimeEncode(String contents, String signature, PrintWriter to) {
  80         String boundary = generateBoundary(contents, null);
  81         to.println("MIME-Version: 1.0");
  82         to.println("Content-Type: multipart/signed; protocol=\"application/x-pkcs7-signature\"; micalg=\"sha1\"; boundary=\"" + boundary + "\"");
  83         to.println("");
  84         to.println("This is an S/MIME signed message");
  85         to.println("");
  86         to.println("--" + boundary);
  87         to.println(contents);
  88         to.println("--" + boundary);
  89         to.println("Content-Type: application/x-pkcs7-signature; name=\"smime.p7s\"");
  90         to.println("Content-Transfer-Encoding: base64");
  91         to.println("Content-Disposition: attachment; filename=\"smime.p7s\"");
  92         to.println("");
  93         to.println(signature);
  94         to.println();
  95         to.println("--" + boundary + "--");
  96     }
  97
  98     private static String generateBoundary(String contents, String contents2) {
  99         String boundary = "";
 100         while (contents.contains(boundary) || (contents2 != null && contents2.contains(boundary))) {
 101             boundary = "--" + new BigInteger(16 * 8, r).toString(16).toUpperCase();
 102         }
 103         return boundary;
 104     }
 105 }