Bug 1240290

Tag #1273

14 files changed, 282 insertions, 215 deletions

diff --git a/mailnews/compose/src/nsMsgAttachmentHandler.cpp b/mailnews/compose/src/nsMsgAttachmentHandler.cpp
index 9555de37fc..4994c3fe69 100644
--- a/mailnews/compose/src/nsMsgAttachmentHandler.cpp
+++ b/mailnews/compose/src/nsMsgAttachmentHandler.cpp
@@ -116,7 +116,6 @@ nsMsgAttachmentHandler::nsMsgAttachmentHandler() :
   m_bogus_attachment(false),
   m_done(false),
   m_already_encoded_p(false),
-  m_decrypted_p(false),
   mDeleteFile(false),
   mMHTMLPart(false),
   mPartUserOmissionOverride(false),
diff --git a/mailnews/compose/src/nsMsgAttachmentHandler.h b/mailnews/compose/src/nsMsgAttachmentHandler.h
index 79e526627d..2034cba032 100644
--- a/mailnews/compose/src/nsMsgAttachmentHandler.h
+++ b/mailnews/compose/src/nsMsgAttachmentHandler.h
@@ -140,16 +140,6 @@ public:
   bool                  m_already_encoded_p; // If we attach a document that is already
                                              // encoded, we just pass it through.
 
-  bool                  m_decrypted_p;  /* S/MIME -- when attaching a message that was
-                                           encrypted, it's necessary to decrypt it first
-                                           (since nobody but the original recipient can
-                                           read it -- if you forward it to someone in the
-                                           raw, it will be useless to them.)  This flag
-                                           indicates whether decryption occurred, so that
-                                           libmsg can issue appropriate warnings about
-                                           doing a cleartext forward of a message that was
-                                           originally encrypted. */
-
   bool                  mDeleteFile;      // If this is true, Delete the file...its 
                                           // NOT the original file!
 
diff --git a/mailnews/mime/src/mimecms.cpp b/mailnews/mime/src/mimecms.cpp
index 9289c0c33d..6f7455c0a0 100644
--- a/mailnews/mime/src/mimecms.cpp
+++ b/mailnews/mime/src/mimecms.cpp
@@ -8,6 +8,7 @@
 #include "nsICMSMessageErrors.h"
 #include "nsICMSDecoder.h"
 #include "mimecms.h"
+#include "mimemcms.h"
 #include "mimemsig.h"
 #include "nspr.h"
 #include "mimemsg.h"
@@ -28,6 +29,9 @@
 
 using namespace mozilla::mailnews;
 
+// The name "mime encrypted" is misleading, because this code is used
+// both for CMS messages that are encrypted, and also for messages that
+// aren't encrypted, but only contain a signature.
 
 #define MIME_SUPERCLASS mimeEncryptedClass
 MimeDefClass(MimeEncryptedCMS, MimeEncryptedCMSClass,
@@ -68,10 +72,11 @@ typedef struct MimeCMSdata
   bool ci_is_encrypted;
   char *sender_addr;
   bool decoding_failed;
+  bool skip_content;
   uint32_t decoded_bytes;
   MimeObject *self;
-  bool parent_is_encrypted_p;
-  bool parent_holds_stamp_p;
+  bool any_parent_is_encrypted_p;
+  bool any_parent_is_signed_p;
   nsCOMPtr<nsIMsgSMIMEHeaderSink> smimeHeaderSink;
   nsCString url;
 
@@ -81,12 +86,11 @@ typedef struct MimeCMSdata
   ci_is_encrypted(false),
   sender_addr(nullptr),
   decoding_failed(false),
+  skip_content(false),
   decoded_bytes(0),
   self(nullptr),
-  parent_is_encrypted_p(false),
-  parent_holds_stamp_p(false)
-  {
-  }
+  any_parent_is_encrypted_p(false),
+  any_parent_is_signed_p(false) {}
 
   ~MimeCMSdata()
   {
@@ -140,6 +144,46 @@ bool MimeEncryptedCMS_encrypted_p (MimeObject *obj)
   return false;
 }
 
+bool MimeEncOrMP_CMS_signed_p(MimeObject *obj) {
+  bool is_signed;
+
+  if (!obj) return false;
+  if (mime_typep(obj, (MimeObjectClass *)&mimeMultipartSignedCMSClass)) {
+    return true;
+  }
+  if (mime_typep(obj, (MimeObjectClass *)&mimeEncryptedCMSClass)) {
+    MimeEncrypted *enc = (MimeEncrypted *)obj;
+    MimeCMSdata *data = (MimeCMSdata *)enc->crypto_closure;
+    if (!data || !data->content_info) return false;
+    data->content_info->ContentIsSigned(&is_signed);
+    return is_signed;
+  }
+  return false;
+}
+
+bool MimeAnyParentCMSEncrypted(MimeObject *obj)
+{
+  MimeObject *o2 = obj;
+  while (o2 && o2->parent) {
+    if (MimeEncryptedCMS_encrypted_p(o2->parent)) {
+      return true;
+    }
+    o2 = o2->parent;
+  }
+  return false;
+}
+
+bool MimeAnyParentCMSSigned(MimeObject *obj)
+{
+  MimeObject *o2 = obj;
+  while (o2 && o2->parent) {
+    if (MimeEncOrMP_CMS_signed_p(o2->parent)) {
+      return true;
+    }
+    o2 = o2->parent;
+  }
+  return false;
+}
 
 bool MimeCMSHeadersAndCertsMatch(nsICMSMessage *content_info,
                                    nsIX509Cert *signerCert,
@@ -439,38 +483,37 @@ static void *MimeCMS_init(MimeObject *obj,
   data->output_fn = output_fn;
   data->output_closure = output_closure;
   PR_SetError(0, 0);
-  data->decoder_context = do_CreateInstance(NS_CMSDECODER_CONTRACTID, &rv);
-  if (NS_FAILED(rv))
-  {
-    delete data;
-    return 0;
-  }
 
-  rv = data->decoder_context->Start(MimeCMS_content_callback, data);
-  if (NS_FAILED(rv))
-  {
-    delete data;
-    return 0;
+  data->any_parent_is_signed_p = MimeAnyParentCMSSigned(obj);
+
+  if (data->any_parent_is_signed_p) {
+    // Parent is signed.
+    // We don't know yet if this child is signed or encrypted.
+    // (We'll know after decoding has completed and EOF is called.)
+    // We don't support "inner encrypt" with outer sign, because the
+    // inner encrypted part could have been produced by an attacker who
+    // stripped away a part containing the signature (S/MIME doesn't
+    // have integrity protection).
+    // A sign-then-sign encoding is confusing, too, because it could be
+    // an attempt to influence which signature is shown.
+    data->skip_content = true;
   }
 
-  // XXX Fix later XXX //
-  data->parent_holds_stamp_p =
-  (obj->parent &&
-   (mime_crypto_stamped_p(obj->parent) ||
-    mime_typep(obj->parent, (MimeObjectClass *) &mimeEncryptedClass)));
+  if (!data->skip_content) {
+    data->decoder_context = do_CreateInstance(NS_CMSDECODER_CONTRACTID, &rv);
+    if (NS_FAILED(rv)) {
+      delete data;
+      return 0;
+    }
 
-  data->parent_is_encrypted_p =
-  (obj->parent && MimeEncryptedCMS_encrypted_p (obj->parent));
+    rv = data->decoder_context->Start(MimeCMS_content_callback, data);
+    if (NS_FAILED(rv)) {
+      delete data;
+      return 0;
+    }
+  }
 
-  /* If the parent of this object is a crypto-blob, then it's the grandparent
-   who would have written out the headers and prepared for a stamp...
-   (This shit sucks.)
-   */
-  if (data->parent_is_encrypted_p &&
-    !data->parent_holds_stamp_p &&
-    obj->parent && obj->parent->parent)
-  data->parent_holds_stamp_p =
-    mime_crypto_stamped_p (obj->parent->parent);
+  data->any_parent_is_encrypted_p = MimeAnyParentCMSEncrypted(obj);
 
   mime_stream_data *msd = (mime_stream_data *) (data->self->options->stream_closure);
   if (msd)
@@ -530,9 +573,11 @@ MimeCMS_write (const char *buf, int32_t buf_size, void *closure)
 
   if (!data || !data->output_fn || !data->decoder_context) return -1;
 
-  PR_SetError(0, 0);
-  rv = data->decoder_context->Update(buf, buf_size);
-  data->decoding_failed = NS_FAILED(rv);
+  if (!data->decoding_failed && !data->skip_content) {
+    PR_SetError(0, 0);
+    rv = data->decoder_context->Update(buf, buf_size);
+    data->decoding_failed = NS_FAILED(rv);
+  }
 
   return 0;
 }
@@ -606,7 +651,12 @@ MimeCMS_eof (void *crypto_closure, bool abort_p)
   nsresult rv;
   int32_t status = nsICMSMessageErrors::SUCCESS;
 
-  if (!data || !data->output_fn || !data->decoder_context) {
+  if (!data || !data->output_fn) {
+    return -1;
+  }
+
+  if (!data->skip_content && !data->decoder_context) {
+    // If we don't skip, we should have a context.
     return -1;
   }
 
@@ -621,11 +671,12 @@ MimeCMS_eof (void *crypto_closure, bool abort_p)
    */
 
   PR_SetError(0, 0);
-  rv = data->decoder_context->Finish(getter_AddRefs(data->content_info));
-  if (NS_FAILED(rv))
-    status = nsICMSMessageErrors::GENERAL_ERROR;
+  if (!data->skip_content) {
+    rv = data->decoder_context->Finish(getter_AddRefs(data->content_info));
+    if (NS_FAILED(rv)) status = nsICMSMessageErrors::GENERAL_ERROR;
 
-  data->decoder_context = nullptr;
+    data->decoder_context = nullptr;
+  }
 
   nsCOMPtr<nsIX509Cert> certOfInterest;
 
@@ -644,6 +695,21 @@ MimeCMS_eof (void *crypto_closure, bool abort_p)
   if (data->decoding_failed)
     status = nsICMSMessageErrors::GENERAL_ERROR;
 
+  if (data->skip_content) {
+    // Skipping content means, we detected a forbidden combination
+    // of CMS objects, so let's make sure we replace the parent status
+    // with a bad status.
+    if (data->any_parent_is_signed_p) {
+      data->smimeHeaderSink->SignedStatus(aRelativeNestLevel,
+        nsICMSMessageErrors::GENERAL_ERROR, nullptr, data->url);
+    }
+    if (data->any_parent_is_encrypted_p) {
+      data->smimeHeaderSink->EncryptionStatus(aRelativeNestLevel,
+        nsICMSMessageErrors::GENERAL_ERROR, nullptr, data->url);
+    }
+    return 0;
+  }
+
   if (!data->content_info)
   {
     if (!data->decoded_bytes)
diff --git a/mailnews/mime/src/mimecryp.cpp b/mailnews/mime/src/mimecryp.cpp
index 9f6e3630f5..fd4f8f8ae7 100644
--- a/mailnews/mime/src/mimecryp.cpp
+++ b/mailnews/mime/src/mimecryp.cpp
@@ -418,18 +418,8 @@ MimeEncrypted_emit_buffered_child(MimeObject *obj)
     obj->options->headers != MimeHeadersCitation &&
     obj->options->write_html_p &&
     obj->options->output_fn)
-    // && !mime_crypto_object_p(enc->hdrs, true, obj->options)) // XXX fix later XXX //
   {
     char *html;
-#if 0 // XXX Fix this later XXX //
-    char *html = (((MimeEncryptedClass *) obj->clazz)->crypto_generate_html
-          (enc->crypto_closure));
-    if (!html) return -1; /* MK_OUT_OF_MEMORY? */
-
-    status = MimeObject_write(obj, html, strlen(html), false);
-    PR_FREEIF(html);
-    if (status < 0) return status;
-#endif
 
     /* Now that we have written out the crypto stamp, the outermost header
      block is well and truly closed.  If this is in fact the outermost
@@ -445,7 +435,8 @@ MimeEncrypted_emit_buffered_child(MimeObject *obj)
       for (p = obj; p->parent; p = p->parent)
         outer_headers = p->headers;
       NS_ASSERTION(obj->options->state->first_data_written_p, "1.2 <mscott@netscape.com> 01 Nov 2001 17:59");
-      html = obj->options->generate_post_header_html_fn(NULL,
+      char *html = obj->options->generate_post_header_html_fn(
+                          NULL,
                           obj->options->html_closure,
                               outer_headers);
       obj->options->state->post_header_html_run_p = true;
diff --git a/mailnews/mime/src/mimeeobj.cpp b/mailnews/mime/src/mimeeobj.cpp
index da59a9d623..7d8b2f8a66 100644
--- a/mailnews/mime/src/mimeeobj.cpp
+++ b/mailnews/mime/src/mimeeobj.cpp
@@ -234,3 +234,13 @@ MimeExternalObject_displayable_inline_p (MimeObjectClass *clazz,
 {
   return false;
 }
+
+#undef MIME_SUPERCLASS
+#define MIME_SUPERCLASS mimeExternalObjectClass
+MimeDefClass(MimeSuppressedCrypto, MimeSuppressedCryptoClass,
+             mimeSuppressedCryptoClass, &MIME_SUPERCLASS);
+
+static int MimeSuppressedCryptoClassInitialize(MimeSuppressedCryptoClass *clazz) {
+  MimeExternalObjectClass *lclass = (MimeExternalObjectClass *)clazz;
+  return MimeExternalObjectClassInitialize(lclass);
+}
diff --git a/mailnews/mime/src/mimeeobj.h b/mailnews/mime/src/mimeeobj.h
index 2b8ade5d54..076f8f9bf6 100644
--- a/mailnews/mime/src/mimeeobj.h
+++ b/mailnews/mime/src/mimeeobj.h
@@ -31,4 +31,20 @@ struct MimeExternalObject {
 #define MimeExternalObjectClassInitializer(ITYPE,CSUPER) \
   { MimeLeafClassInitializer(ITYPE,CSUPER) }
 
+typedef struct MimeSuppressedCryptoClass MimeSuppressedCryptoClass;
+typedef struct MimeSuppressedCrypto MimeSuppressedCrypto;
+
+struct MimeSuppressedCryptoClass {
+  MimeExternalObjectClass eobj;
+};
+
+extern "C" MimeSuppressedCryptoClass mimeSuppressedCryptoClass;
+
+struct MimeSuppressedCrypto {
+  MimeExternalObject eobj;
+};
+
+#define MimeSuppressedCryptoClassInitializer(ITYPE, CSUPER) \
+  { MimeExternalObjectClassInitializer(ITYPE, CSUPER) }
+
 #endif /* _MIMEEOBJ_H_ */
diff --git a/mailnews/mime/src/mimei.cpp b/mailnews/mime/src/mimei.cpp
index c0a134a627..015830a80a 100644
--- a/mailnews/mime/src/mimei.cpp
+++ b/mailnews/mime/src/mimei.cpp
@@ -731,7 +731,7 @@ mime_find_class (const char *content_type, MimeHeaders *hdrs,
           // Allowing them would leak the plain text in case the part is
           // cleverly hidden and the decrypted content gets included in
           // replies and forwards.
-          clazz = (MimeObjectClass *)&mimeExternalObjectClass;
+          clazz = (MimeObjectClass *)&mimeSuppressedCryptoClass;
           return clazz;
         }
 
@@ -951,9 +951,14 @@ mime_create (const char *content_type, MimeHeaders *hdrs,
           (clazz != (MimeObjectClass *)&mimeInlineTextRichtextClass) &&
           (clazz != (MimeObjectClass *)&mimeInlineTextEnrichedClass) &&
           (clazz != (MimeObjectClass *)&mimeMessageClass) &&
-          (clazz != (MimeObjectClass *)&mimeInlineImageClass) )
+          (clazz != (MimeObjectClass *)&mimeInlineImageClass) ) {
       // not a special inline type, so show as attachment
-      clazz = (MimeObjectClass *)&mimeExternalObjectClass;
+      // However, mimeSuppressedCryptoClass is treated identically as
+      // mimeExternalObjectClass, let's not lose that type information.
+      if (clazz != (MimeObjectClass *)&mimeSuppressedCryptoClass) {
+        clazz = (MimeObjectClass *)&mimeExternalObjectClass;
+      }
+    }
   }
 
   /* If the option `Show Attachments Inline' is off, now would be the time to change our mind... */
@@ -1221,21 +1226,6 @@ mime_crypto_object_p(MimeHeaders *hdrs, bool clearsigned_counts, MimeDisplayOpti
   return false;
 }
 
-/* Whether the given object has written out the HTML version of its headers
-   in such a way that it will have a "crypto stamp" next to the headers.  If
-   this is true, then the child must write out its HTML slightly differently
-   to take this into account...
- */
-bool
-mime_crypto_stamped_p(MimeObject *obj)
-{
-  if (!obj) return false;
-  if (mime_typep (obj, (MimeObjectClass *) &mimeMessageClass))
-  return ((MimeMessage *) obj)->crypto_stamped_p;
-  else
-  return false;
-}
-
 #endif // ENABLE_SMIME
 
 /* Puts a part-number into a URL.  If append_p is true, then the part number
diff --git a/mailnews/mime/src/mimei.h b/mailnews/mime/src/mimei.h
index a2d8332cdf..a024c45237 100644
--- a/mailnews/mime/src/mimei.h
+++ b/mailnews/mime/src/mimei.h
@@ -332,14 +332,6 @@ extern void mime_get_crypto_state (MimeObject *obj,
                    bool *signed_p, bool *encrypted_p,
                    bool *signed_ok, bool *encrypted_ok);
 
-
-/* Whether the given object has written out the HTML version of its headers
-   in such a way that it will have a "crypto stamp" next to the headers.  If
-   this is true, then the child must write out its HTML slightly differently
-   to take this into account...
- */
-extern bool mime_crypto_stamped_p(MimeObject *obj);
-
 /* How the crypto code tells the MimeMessage object what the crypto stamp
    on it says. */
 extern void mime_set_crypto_stamp(MimeObject *obj,
@@ -352,7 +344,7 @@ public:
   MimeParseStateObject()
       {root = 0; separator_queued_p = false; separator_suppressed_p = false;
         first_part_written_p = false; post_header_html_run_p = false; first_data_written_p = false;
-        decrypted_p = false; strippingPart = false;
+        strippingPart = false;
       }
   MimeObject *root;        /* The outermost parser object. */
 
@@ -376,10 +368,6 @@ public:
   bool first_data_written_p;  /* State used for Mozilla lazy-stream-
                    creation evilness. */
 
-  bool decrypted_p; /* If options->dexlate_p is true, then this
-                        will be set to indicate whether any
-                        dexlateion did in fact occur.
-                      */
   nsTArray<nsCString> partsToStrip; /* if we're stripping parts, what parts to strip */
   nsTArray<nsCString> detachToFiles; /* if we're detaching parts, where each part was detached to */
   bool strippingPart;
diff --git a/mailnews/mime/src/mimemcms.cpp b/mailnews/mime/src/mimemcms.cpp
index 1a281b1620..96aa5481f2 100644
--- a/mailnews/mime/src/mimemcms.cpp
+++ b/mailnews/mime/src/mimemcms.cpp
@@ -38,6 +38,7 @@ static int MimeMultCMS_sig_eof  (void *, bool);
 static int MimeMultCMS_sig_init (void *, MimeObject *, MimeHeaders *);
 static char * MimeMultCMS_generate (void *);
 static void MimeMultCMS_free (void *);
+static void MimeMultCMS_suppressed_child(void *crypto_closure);
 
 extern int SEC_ERROR_CERT_ADDR_MISMATCH;
 
@@ -56,6 +57,7 @@ MimeMultipartSignedCMSClassInitialize(MimeMultipartSignedCMSClass *clazz)
   sclass->crypto_signature_hash = MimeMultCMS_sig_hash;
   sclass->crypto_signature_eof  = MimeMultCMS_sig_eof;
   sclass->crypto_generate_html  = MimeMultCMS_generate;
+  sclass->crypto_notify_suppressed_child = MimeMultCMS_suppressed_child;
   sclass->crypto_free           = MimeMultCMS_free;
 
   PR_ASSERT(!oclass->class_initialized);
@@ -80,8 +82,6 @@ typedef struct MimeMultCMSdata
   unsigned char* item_data;
   uint32_t item_len;
   MimeObject *self;
-  bool parent_is_encrypted_p;
-  bool parent_holds_stamp_p;
   nsCOMPtr<nsIMsgSMIMEHeaderSink> smimeHeaderSink;
   nsCString url;
 
@@ -90,11 +90,7 @@ typedef struct MimeMultCMSdata
   sender_addr(nullptr),
   decoding_failed(false),
   item_data(nullptr),
-  self(nullptr),
-  parent_is_encrypted_p(false),
-  parent_holds_stamp_p(false)
-  {
-  }
+  self(nullptr) {}
 
   ~MimeMultCMSdata()
   {
@@ -113,7 +109,7 @@ typedef struct MimeMultCMSdata
 
 /* #### MimeEncryptedCMS and MimeMultipartSignedCMS have a sleazy,
         incestuous, dysfunctional relationship. */
-extern bool MimeEncryptedCMS_encrypted_p (MimeObject *obj);
+extern bool MimeAnyParentCMSSigned(MimeObject *obj);
 extern void MimeCMSGetFromSender(MimeObject *obj,
                                  nsCString &from_addr,
                                  nsCString &from_name,
@@ -142,82 +138,11 @@ MimeMultCMS_init (MimeObject *obj)
   int16_t hash_type;
   nsresult rv;
 
-  ct = MimeHeaders_get (hdrs, HEADER_CONTENT_TYPE, false, false);
-  if (!ct) return 0; /* #### bogus message?  out of memory? */
-  micalg = MimeHeaders_get_parameter (ct, PARAM_MICALG, NULL, NULL);
-  PR_Free(ct);
-  ct = 0;
-  if (!micalg) return 0; /* #### bogus message?  out of memory? */
-
-  if (!PL_strcasecmp(micalg, PARAM_MICALG_MD5) ||
-      !PL_strcasecmp(micalg, PARAM_MICALG_MD5_2))
-    hash_type = nsICryptoHash::MD5;
-  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA1) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_2) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_3) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_4) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_5))
-    hash_type = nsICryptoHash::SHA1;
-  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA256) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA256_2) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA256_3))
-    hash_type = nsICryptoHash::SHA256;
-  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA384) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA384_2) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA384_3))
-    hash_type = nsICryptoHash::SHA384;
-  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA512) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA512_2) ||
-       !PL_strcasecmp(micalg, PARAM_MICALG_SHA512_3))
-    hash_type = nsICryptoHash::SHA512;
-  else if (!PL_strcasecmp(micalg, PARAM_MICALG_MD2))
-    hash_type = nsICryptoHash::MD2;
-  else
-    hash_type = -1;
-
-  PR_Free(micalg);
-  micalg = 0;
-
-  if (hash_type == -1) return 0; /* #### bogus message? */
-
   data = new MimeMultCMSdata;
   if (!data)
     return 0;
 
   data->self = obj;
-  data->hash_type = hash_type;
-
-  data->data_hash_context = do_CreateInstance("@mozilla.org/security/hash;1", &rv);
-  if (NS_FAILED(rv))
-  {
-    delete data;
-    return 0;
-  }
-
-  rv = data->data_hash_context->Init(data->hash_type);
-  if (NS_FAILED(rv))
-  {
-    delete data;
-    return 0;
-  }
-
-  PR_SetError(0,0);
-
-  data->parent_holds_stamp_p =
-  (obj->parent && mime_crypto_stamped_p(obj->parent));
-
-  data->parent_is_encrypted_p =
-  (obj->parent && MimeEncryptedCMS_encrypted_p (obj->parent));
-
-  /* If the parent of this object is a crypto-blob, then it's the grandparent
-   who would have written out the headers and prepared for a stamp...
-   (This s##t s$%#s.)
-   */
-  if (data->parent_is_encrypted_p &&
-    !data->parent_holds_stamp_p &&
-    obj->parent && obj->parent->parent)
-  data->parent_holds_stamp_p =
-    mime_crypto_stamped_p (obj->parent->parent);
 
   mime_stream_data *msd = (mime_stream_data *) (data->self->options->stream_closure);
   if (msd)
@@ -266,6 +191,89 @@ MimeMultCMS_init (MimeObject *obj)
     } // if channel
   } // if msd
 
+  if (obj->parent && MimeAnyParentCMSSigned(obj)) {
+    // Parent is signed. We know this part is a signature, too, because
+    // multipart doesn't allow encryption.
+    // We don't support "inner sign" with outer sign, because the
+    // inner encrypted part could have been produced by an attacker who
+    // stripped away a part containing the signature (S/MIME doesn't
+    // have integrity protection).
+    // Also we don't want to support sign-then-sign, that's misleading,
+    // which part would be shown as having a signature?
+    // TODO: should we show all contents, without any signature info?
+
+    if (data->smimeHeaderSink) {
+      data->smimeHeaderSink->SignedStatus(
+          MIMEGetRelativeCryptoNestLevel(data->self),
+          nsICMSMessageErrors::GENERAL_ERROR, nullptr, data->url);
+    }
+    delete data;
+    PR_SetError(-1, 0);
+    return 0;
+  }
+
+  ct = MimeHeaders_get(hdrs, HEADER_CONTENT_TYPE, false, false);
+  if (!ct) {
+    delete data;
+    return 0; /* #### bogus message?  out of memory? */
+  }
+  micalg = MimeHeaders_get_parameter(ct, PARAM_MICALG, NULL, NULL);
+  PR_Free(ct);
+  ct = 0;
+  if (!micalg) {
+    delete data;
+    return 0; /* #### bogus message?  out of memory? */
+  }
+
+  if (!PL_strcasecmp(micalg, PARAM_MICALG_MD5) ||
+      !PL_strcasecmp(micalg, PARAM_MICALG_MD5_2))
+    hash_type = nsICryptoHash::MD5;
+  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA1) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_2) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_3) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_4) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA1_5))
+    hash_type = nsICryptoHash::SHA1;
+  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA256) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA256_2) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA256_3))
+    hash_type = nsICryptoHash::SHA256;
+  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA384) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA384_2) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA384_3))
+    hash_type = nsICryptoHash::SHA384;
+  else if (!PL_strcasecmp(micalg, PARAM_MICALG_SHA512) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA512_2) ||
+           !PL_strcasecmp(micalg, PARAM_MICALG_SHA512_3))
+    hash_type = nsICryptoHash::SHA512;
+  else
+    hash_type = -1;
+
+  PR_Free(micalg);
+  micalg = 0;
+
+  if (hash_type == -1) {
+    delete data;
+    return 0; /* #### bogus message? */
+  }
+
+  data->hash_type = hash_type;
+
+  data->data_hash_context =
+      do_CreateInstance("@mozilla.org/security/hash;1", &rv);
+  if (NS_FAILED(rv)) {
+    delete data;
+    return 0;
+  }
+
+  rv = data->data_hash_context->Init(data->hash_type);
+  if (NS_FAILED(rv)) {
+    delete data;
+    return 0;
+  }
+
+  PR_SetError(0, 0);
+
   return data;
 }
 
@@ -400,6 +408,17 @@ MimeMultCMS_free (void *crypto_closure)
   delete data;
 }
 
+static void MimeMultCMS_suppressed_child(void *crypto_closure) {
+  // I'm a multipart/signed. If one of my cryptographic child elements
+  // was suppressed, then I want my signature to be shown as invalid.
+  MimeMultCMSdata *data = (MimeMultCMSdata *)crypto_closure;
+  if (data && data->smimeHeaderSink) {
+    data->smimeHeaderSink->SignedStatus(
+        MIMEGetRelativeCryptoNestLevel(data->self),
+        nsICMSMessageErrors::GENERAL_ERROR, nullptr, data->url);
+  }
+}
+
 static char *
 MimeMultCMS_generate (void *crypto_closure)
 {
diff --git a/mailnews/mime/src/mimemsg.cpp b/mailnews/mime/src/mimemsg.cpp
index 2d69570690..d024a77258 100644
--- a/mailnews/mime/src/mimemsg.cpp
+++ b/mailnews/mime/src/mimemsg.cpp
@@ -786,34 +786,22 @@ MimeMessage_write_headers_html (MimeObject *obj)
     return status;
   }
 
-  if (!msg->crypto_stamped_p)
-  {
-  /* If we're not writing a xlation stamp, and this is the outermost
-  message, then now is the time to run the post_header_html_fn.
-  (Otherwise, it will be run when the xlation-stamp is finally
-  closed off, in MimeXlateed_emit_buffered_child() or
-  MimeMultipartSigned_emit_child().)
-     */
-    if (obj->options &&
-      obj->options->state &&
+  // If this is the outermost message, then now is the time to run the
+  // post_header_html_fn.
+  if (obj->options && obj->options->state &&
       obj->options->generate_post_header_html_fn &&
-      !obj->options->state->post_header_html_run_p)
-    {
-      char *html = 0;
-      PR_ASSERT(obj->options->state->first_data_written_p);
-      html = obj->options->generate_post_header_html_fn(NULL,
-                                          obj->options->html_closure,
-                                          msg->hdrs);
-      obj->options->state->post_header_html_run_p = true;
-      if (html)
-      {
-        status = MimeObject_write(obj, html, strlen(html), false);
-        PR_Free(html);
-        if (status < 0)
-        {
-          mimeEmitterEndHeader(obj->options, obj);
-          return status;
-        }
+      !obj->options->state->post_header_html_run_p) {
+    char *html = 0;
+    PR_ASSERT(obj->options->state->first_data_written_p);
+    html = obj->options->generate_post_header_html_fn(
+        NULL, obj->options->html_closure, msg->hdrs);
+    obj->options->state->post_header_html_run_p = true;
+    if (html) {
+      status = MimeObject_write(obj, html, strlen(html), false);
+      PR_Free(html);
+      if (status < 0) {
+        mimeEmitterEndHeader(obj->options, obj);
+        return status;
       }
     }
   }
diff --git a/mailnews/mime/src/mimemsg.h b/mailnews/mime/src/mimemsg.h
index c4023ccf09..9a38a6e719 100644
--- a/mailnews/mime/src/mimemsg.h
+++ b/mailnews/mime/src/mimemsg.h
@@ -25,12 +25,6 @@ struct MimeMessage {
   MimeContainer container;    /* superclass variables */
   MimeHeaders *hdrs;      /* headers of this message */
   bool newline_p;      /* whether the last line ended in a newline */
-  bool crypto_stamped_p;    /* whether the header of this message has been
-                   emitted expecting its child to emit HTML
-                   which says that it is xlated. */
-
-  bool crypto_msg_signed_p;  /* What the emitted xlation-stamp *says*. */
-  bool crypto_msg_encrypted_p;
   bool grabSubject;  /* Should we try to grab the subject of this message */
   int32_t bodyLength; /* Used for determining if the body has been truncated */
   int32_t sizeSoFar; /* The total size of the MIME message, once parsing is
diff --git a/mailnews/mime/src/mimemsig.cpp b/mailnews/mime/src/mimemsig.cpp
index d74cfb09ae..bb34607cba 100644
--- a/mailnews/mime/src/mimemsig.cpp
+++ b/mailnews/mime/src/mimemsig.cpp
@@ -14,6 +14,7 @@
 #include "msgCore.h"
 #include "nsMimeStringResources.h"
 #include "mimemoz2.h"
+#include "mimeeobj.h"
 #include "nsIMimeConverter.h" // for MimeConverterOutputCallback
 #include "mozilla/Attributes.h"
 
@@ -32,6 +33,8 @@ static void MimeMultipartSigned_finalize (MimeObject *);
 
 static int MimeMultipartSigned_emit_child (MimeObject *obj);
 
+extern "C" MimeSuppressedCryptoClass mimeSuppressedCryptoClass;
+
 static int
 MimeMultipartSignedClassInitialize(MimeMultipartSignedClass *clazz)
 {
@@ -582,6 +585,11 @@ MimeMultipartSigned_emit_child (MimeObject *obj)
   int status = 0;
   MimeObject *body;
 
+  if (!sig->crypto_closure) {
+    // We might have decided to skip processing this part.
+    return 0;
+  }
+
   NS_ASSERTION(sig->crypto_closure, "no crypto closure");
 
   /* Emit some HTML saying whether the signature was cool.
@@ -594,15 +602,11 @@ MimeMultipartSigned_emit_child (MimeObject *obj)
     obj->options->headers != MimeHeadersCitation &&
     sig->crypto_closure)
   {
+    // Calling crypto_generate_html may trigger wanted side effects,
+    // but we're no longer using its results.
     char *html = (((MimeMultipartSignedClass *) obj->clazz)
           ->crypto_generate_html (sig->crypto_closure));
-#if 0 // XXX For the moment, no HTML output. Fix this XXX //
-    if (!html) return -1; /* MIME_OUT_OF_MEMORY? */
-
-    status = MimeObject_write(obj, html, strlen(html), false);
-    PR_Free(html);
-    if (status < 0) return status;
-#endif
+    PR_FREEIF(html);
 
     /* Now that we have written out the crypto stamp, the outermost header
      block is well and truly closed.  If this is in fact the outermost
@@ -719,6 +723,11 @@ MimeMultipartSigned_emit_child (MimeObject *obj)
   if (!body)
     return -1;
 
+  if (mime_typep(body, (MimeObjectClass *)&mimeSuppressedCryptoClass)) {
+    ((MimeMultipartSignedClass *)obj->clazz)
+      ->crypto_notify_suppressed_child(sig->crypto_closure);
+  }
+
 #ifdef MIME_DRAFTS
   if (body->options->decompose_file_p) {
     body->options->signed_p = true;
diff --git a/mailnews/mime/src/mimemsig.h b/mailnews/mime/src/mimemsig.h
index f8581c3a36..2ec9d314d0 100644
--- a/mailnews/mime/src/mimemsig.h
+++ b/mailnews/mime/src/mimemsig.h
@@ -105,6 +105,8 @@ struct MimeMultipartSignedClass {
 
   char * (*crypto_generate_html) (void *crypto_closure);
 
+  void (*crypto_notify_suppressed_child)(void *crypto_closure);
+
   void (*crypto_free) (void *crypto_closure);
 };
 
diff --git a/mailnews/mime/src/mimemult.cpp b/mailnews/mime/src/mimemult.cpp
index 64f292ec0c..4695ba9910 100644
--- a/mailnews/mime/src/mimemult.cpp
+++ b/mailnews/mime/src/mimemult.cpp
@@ -43,6 +43,7 @@ extern "C" MimeObjectClass mimeMultipartRelatedClass;
 extern "C" MimeObjectClass mimeMultipartSignedClass;
 extern "C" MimeObjectClass mimeInlineTextVCardClass;
 extern "C" MimeExternalObjectClass mimeExternalObjectClass;
+extern "C" MimeSuppressedCryptoClass mimeSuppressedCryptoClass;
 
 #if defined(DEBUG) && defined(XP_UNIX)
 static int MimeMultipart_debug_print (MimeObject *, PRFileDesc *, int32_t);
@@ -471,7 +472,9 @@ MimeMultipart_create_child(MimeObject *obj)
               part functions set correctly */
            !mime_typep(body, (MimeObjectClass*) &mimeMultipartClass)
 #endif
-    &&        ! (mime_typep(body, (MimeObjectClass*)&mimeExternalObjectClass) && !strcmp(body->content_type, "text/x-vcard"))
+      &&   !((mime_typep(body, (MimeObjectClass *)&mimeExternalObjectClass) ||
+             mime_typep(body, (MimeObjectClass *)&mimeSuppressedCryptoClass)) &&
+           !strcmp(body->content_type, "text/x-vcard"))
        )
     {
     status = obj->options->decompose_file_init_fn ( obj->options->stream_closure, mult->hdrs );
@@ -575,7 +578,9 @@ MimeMultipart_close_child(MimeObject *object)
                       part functions set correctly */
                    !mime_typep(kid,(MimeObjectClass*) &mimeMultipartClass)
 #endif
-                                  && !(mime_typep(kid, (MimeObjectClass*)&mimeExternalObjectClass) && !strcmp(kid->content_type, "text/x-vcard"))
+           &&      !((mime_typep(kid, (MimeObjectClass *)&mimeExternalObjectClass) ||
+                       mime_typep(kid, (MimeObjectClass *)&mimeSuppressedCryptoClass)) &&
+                   !strcmp(kid->content_type, "text/x-vcard"))
            )
         {
           status = object->options->decompose_file_close_fn ( object->options->stream_closure );