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.Random;
  12
  13 import org.cacert.gigi.util.PEM;
  14
  15 import sun.security.pkcs.ContentInfo;
  16 import sun.security.pkcs.PKCS7;
  17 import sun.security.pkcs.SignerInfo;
  18 import sun.security.util.DerOutputStream;
  19 import sun.security.x509.AlgorithmId;
  20 import sun.security.x509.X500Name;
  21
  22 public class SMIME {
  23
  24     public static String doAlternatives(String plain, String html) {
  25
  26         plain = "Content-type: text/plain\r\n\r\n" + plain;
  27         html = "Content-type: text/html\r\n\r\n" + html;
  28         String boundary = generateBoundary(plain, html);
  29         StringBuffer content = new StringBuffer("Content-Type: multipart/alternative; boundary=\"");
  30         content.append(boundary);
  31         content.append("\"\r\n\r\n");
  32         content.append("--");
  33         content.append(boundary);
  34         content.append("\r\n");
  35         content.append(plain);
  36         content.append("\r\n--");
  37         content.append(boundary);
  38         content.append("\r\n");
  39         content.append(html);
  40         content.append("\r\n--");
  41         content.append(boundary);
  42         content.append("--\r\n");
  43         return content.toString();
  44
  45     }
  46
  47     public static void smime(String contents, PrivateKey pKey, X509Certificate c, PrintWriter to) throws IOException, GeneralSecurityException {
  48         contents = normalizeNewlinesToCRLF(contents);
  49
  50         Signature signature = Signature.getInstance("SHA1WithRSA");
  51         signature.initSign(pKey);
  52         signature.update(contents.getBytes("UTF-8"));
  53         byte[] signedData = signature.sign();
  54
  55         // "IssuerAndSerialNumber"
  56         X500Name xName = X500Name.asX500Name(c.getIssuerX500Principal());
  57         BigInteger serial = c.getSerialNumber();
  58
  59         SignerInfo sInfo = new SignerInfo(xName, serial, new AlgorithmId(AlgorithmId.SHA_oid), null, new AlgorithmId(AlgorithmId.RSAEncryption_oid), signedData, null);
  60
  61         // Content is outside so content here is null.
  62         ContentInfo cInfo = new ContentInfo(ContentInfo.DATA_OID, null);
  63
  64         // Create PKCS7 Signed data
  65         PKCS7 p7 = new PKCS7(new AlgorithmId[] {
  66                 new AlgorithmId(AlgorithmId.SHA_oid)
  67         }, cInfo, new java.security.cert.X509Certificate[] {
  68                 c
  69         }, new SignerInfo[] {
  70                 sInfo
  71         });
  72
  73         ByteArrayOutputStream bOut = new DerOutputStream();
  74         p7.encodeSignedData(bOut);
  75
  76         mimeEncode(contents, PEM.formatBase64(bOut.toByteArray()), to);
  77     }
  78
  79     private static String normalizeNewlinesToCRLF(String contents) {
  80         return contents.replace("\r\n", "\r").replace("\r", "\n").replace("\n", "\r\n");
  81     }
  82
  83     private static Random r = new Random();
  84
  85     private static void mimeEncode(String contents, String signature, PrintWriter to) {
  86         String boundary = generateBoundary(contents, null);
  87         to.print("MIME-Version: 1.0\r\n");
  88         to.print("Content-Type: multipart/signed; protocol=\"application/x-pkcs7-signature\"; micalg=\"sha1\"; boundary=\"" + boundary + "\"\r\n");
  89         to.print("\r\n");
  90         to.print("This is an S/MIME signed message\r\n");
  91         to.print("\r\n");
  92         to.print("--" + boundary + "\r\n");
  93         to.print(contents + "\r\n");
  94         to.print("--" + boundary + "\r\n");
  95         to.print("Content-Type: application/x-pkcs7-signature; name=\"smime.p7s\"\r\n");
  96         to.print("Content-Transfer-Encoding: base64\r\n");
  97         to.print("Content-Disposition: attachment; filename=\"smime.p7s\"\r\n");
  98         to.print("\r\n");
  99         to.print(signature + "\r\n");
 100         to.print("\r\n");
 101         to.print("--" + boundary + "--\r\n");
 102     }
 103
 104     private static String generateBoundary(String contents, String contents2) {
 105         String boundary = "";
 106         while (contents.contains(boundary) || (contents2 != null && contents2.contains(boundary))) {
 107             boundary = "--" + new BigInteger(16 * 8, r).toString(16).toUpperCase();
 108         }
 109         return boundary;
 110     }
 111 }