--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nss/lib/pkcs7/secmime.c	Mon Jul 28 10:47:06 2014 +0200
@@ -0,0 +1,822 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Stuff specific to S/MIME policy and interoperability.
+ * Depends on PKCS7, but there should be no dependency the other way around.
+ */
+
+#include "secmime.h"
+#include "secoid.h"
+#include "pk11func.h"
+#include "ciferfam.h"	/* for CIPHER_FAMILY symbols */
+#include "secasn1.h"
+#include "secitem.h"
+#include "cert.h"
+#include "key.h"
+#include "secerr.h"
+
+typedef struct smime_cipher_map_struct {
+    unsigned long cipher;
+    SECOidTag algtag;
+    SECItem *parms;
+} smime_cipher_map;
+
+/*
+ * These are macros because I think some subsequent parameters,
+ * like those for RC5, will want to use them, too, separately.
+ */
+#define SMIME_DER_INTVAL_16	SEC_ASN1_INTEGER, 0x01, 0x10
+#define SMIME_DER_INTVAL_40	SEC_ASN1_INTEGER, 0x01, 0x28
+#define SMIME_DER_INTVAL_64	SEC_ASN1_INTEGER, 0x01, 0x40
+#define SMIME_DER_INTVAL_128	SEC_ASN1_INTEGER, 0x02, 0x00, 0x80
+
+#ifdef SMIME_DOES_RC5	/* will be needed; quiet unused warning for now */
+static unsigned char smime_int16[] = { SMIME_DER_INTVAL_16 };
+#endif
+static unsigned char smime_int40[] = { SMIME_DER_INTVAL_40 };
+static unsigned char smime_int64[] = { SMIME_DER_INTVAL_64 };
+static unsigned char smime_int128[] = { SMIME_DER_INTVAL_128 };
+
+static SECItem smime_rc2p40 = { siBuffer, smime_int40, sizeof(smime_int40) };
+static SECItem smime_rc2p64 = { siBuffer, smime_int64, sizeof(smime_int64) };
+static SECItem smime_rc2p128 = { siBuffer, smime_int128, sizeof(smime_int128) };
+
+static smime_cipher_map smime_cipher_maps[] = {
+    { SMIME_RC2_CBC_40,		SEC_OID_RC2_CBC,	&smime_rc2p40 },
+    { SMIME_RC2_CBC_64,		SEC_OID_RC2_CBC,	&smime_rc2p64 },
+    { SMIME_RC2_CBC_128,	SEC_OID_RC2_CBC,	&smime_rc2p128 },
+#ifdef SMIME_DOES_RC5
+    { SMIME_RC5PAD_64_16_40,	SEC_OID_RC5_CBC_PAD,	&smime_rc5p40 },
+    { SMIME_RC5PAD_64_16_64,	SEC_OID_RC5_CBC_PAD,	&smime_rc5p64 },
+    { SMIME_RC5PAD_64_16_128,	SEC_OID_RC5_CBC_PAD,	&smime_rc5p128 },
+#endif
+    { SMIME_DES_CBC_56,		SEC_OID_DES_CBC,	NULL },
+    { SMIME_DES_EDE3_168,	SEC_OID_DES_EDE3_CBC,	NULL }
+};
+
+/*
+ * Note, the following value really just needs to be an upper bound
+ * on the ciphers.
+ */
+static const int smime_symmetric_count = sizeof(smime_cipher_maps)
+					 / sizeof(smime_cipher_map);
+
+static unsigned long *smime_prefs, *smime_newprefs;
+static int smime_current_pref_index = 0;
+static PRBool smime_prefs_complete = PR_FALSE;
+static PRBool smime_prefs_changed = PR_TRUE;
+
+static unsigned long smime_policy_bits = 0;
+
+
+static int
+smime_mapi_by_cipher (unsigned long cipher)
+{
+    int i;
+
+    for (i = 0; i < smime_symmetric_count; i++) {
+	if (smime_cipher_maps[i].cipher == cipher)
+	    break;
+    }
+
+    if (i == smime_symmetric_count)
+	return -1;
+
+    return i;
+}
+
+
+/*
+ * this function locally records the user's preference
+ */
+SECStatus 
+SECMIME_EnableCipher(long which, int on)
+{
+    unsigned long mask;
+
+    if (smime_newprefs == NULL || smime_prefs_complete) {
+	/*
+	 * This is either the very first time, or we are starting over.
+	 */
+	smime_newprefs = (unsigned long*)PORT_ZAlloc (smime_symmetric_count
+				      * sizeof(*smime_newprefs));
+	if (smime_newprefs == NULL)
+	    return SECFailure;
+	smime_current_pref_index = 0;
+	smime_prefs_complete = PR_FALSE;
+    }
+
+    mask = which & CIPHER_FAMILYID_MASK;
+    if (mask == CIPHER_FAMILYID_MASK) {
+    	/*
+	 * This call signifies that all preferences have been set.
+	 * Move "newprefs" over, after checking first whether or
+	 * not the new ones are different from the old ones.
+	 */
+	if (smime_prefs != NULL) {
+	    if (PORT_Memcmp (smime_prefs, smime_newprefs,
+			     smime_symmetric_count * sizeof(*smime_prefs)) == 0)
+		smime_prefs_changed = PR_FALSE;
+	    else
+		smime_prefs_changed = PR_TRUE;
+	    PORT_Free (smime_prefs);
+	}
+
+	smime_prefs = smime_newprefs;
+	smime_prefs_complete = PR_TRUE;
+	return SECSuccess;
+    }
+
+    PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
+    if (mask != CIPHER_FAMILYID_SMIME) {
+	/* XXX set an error! */
+    	return SECFailure;
+    }
+
+    if (on) {
+	PORT_Assert (smime_current_pref_index < smime_symmetric_count);
+	if (smime_current_pref_index >= smime_symmetric_count) {
+	    /* XXX set an error! */
+	    return SECFailure;
+	}
+
+	smime_newprefs[smime_current_pref_index++] = which;
+    }
+
+    return SECSuccess;
+}
+
+
+/*
+ * this function locally records the export policy
+ */
+SECStatus 
+SECMIME_SetPolicy(long which, int on)
+{
+    unsigned long mask;
+
+    PORT_Assert ((which & CIPHER_FAMILYID_MASK) == CIPHER_FAMILYID_SMIME);
+    if ((which & CIPHER_FAMILYID_MASK) != CIPHER_FAMILYID_SMIME) {
+	/* XXX set an error! */
+    	return SECFailure;
+    }
+
+    which &= ~CIPHER_FAMILYID_MASK;
+
+    PORT_Assert (which < 32);	/* bits in the long */
+    if (which >= 32) {
+	/* XXX set an error! */
+    	return SECFailure;
+    }
+
+    mask = 1UL << which;
+
+    if (on) {
+    	smime_policy_bits |= mask;
+    } else {
+    	smime_policy_bits &= ~mask;
+    }
+
+    return SECSuccess;
+}
+
+
+/*
+ * Based on the given algorithm (including its parameters, in some cases!)
+ * and the given key (may or may not be inspected, depending on the
+ * algorithm), find the appropriate policy algorithm specification
+ * and return it.  If no match can be made, -1 is returned.
+ */
+static long
+smime_policy_algorithm (SECAlgorithmID *algid, PK11SymKey *key)
+{
+    SECOidTag algtag;
+
+    algtag = SECOID_GetAlgorithmTag (algid);
+    switch (algtag) {
+      case SEC_OID_RC2_CBC:
+	{
+	    unsigned int keylen_bits;
+
+	    keylen_bits = PK11_GetKeyStrength (key, algid);
+	    switch (keylen_bits) {
+	      case 40:
+		return SMIME_RC2_CBC_40;
+	      case 64:
+		return SMIME_RC2_CBC_64;
+	      case 128:
+		return SMIME_RC2_CBC_128;
+	      default:
+		break;
+	    }
+	}
+	break;
+      case SEC_OID_DES_CBC:
+	return SMIME_DES_CBC_56;
+      case SEC_OID_DES_EDE3_CBC:
+	return SMIME_DES_EDE3_168;
+#ifdef SMIME_DOES_RC5
+      case SEC_OID_RC5_CBC_PAD:
+	PORT_Assert (0);	/* XXX need to pull out parameters and match */
+	break;
+#endif
+      default:
+	break;
+    }
+
+    return -1;
+}
+
+
+static PRBool
+smime_cipher_allowed (unsigned long which)
+{
+    unsigned long mask;
+
+    which &= ~CIPHER_FAMILYID_MASK;
+    PORT_Assert (which < 32);	/* bits per long (min) */
+    if (which >= 32)
+	return PR_FALSE;
+
+    mask = 1UL << which;
+    if ((mask & smime_policy_bits) == 0)
+	return PR_FALSE;
+
+    return PR_TRUE;
+}
+
+
+PRBool
+SECMIME_DecryptionAllowed(SECAlgorithmID *algid, PK11SymKey *key)
+{
+    long which;
+
+    which = smime_policy_algorithm (algid, key);
+    if (which < 0)
+	return PR_FALSE;
+
+    return smime_cipher_allowed ((unsigned long)which);
+}
+
+
+/*
+ * Does the current policy allow *any* S/MIME encryption (or decryption)?
+ *
+ * This tells whether or not *any* S/MIME encryption can be done,
+ * according to policy.  Callers may use this to do nicer user interface
+ * (say, greying out a checkbox so a user does not even try to encrypt
+ * a message when they are not allowed to) or for any reason they want
+ * to check whether S/MIME encryption (or decryption, for that matter)
+ * may be done.
+ *
+ * It takes no arguments.  The return value is a simple boolean:
+ *   PR_TRUE means encryption (or decryption) is *possible*
+ *	(but may still fail due to other reasons, like because we cannot
+ *	find all the necessary certs, etc.; PR_TRUE is *not* a guarantee)
+ *   PR_FALSE means encryption (or decryption) is not permitted
+ *
+ * There are no errors from this routine.
+ */
+PRBool
+SECMIME_EncryptionPossible (void)
+{
+    if (smime_policy_bits != 0)
+	return PR_TRUE;
+
+    return PR_FALSE;
+}
+
+
+/*
+ * XXX Would like the "parameters" field to be a SECItem *, but the
+ * encoder is having trouble with optional pointers to an ANY.  Maybe
+ * once that is fixed, can change this back...
+ */
+typedef struct smime_capability_struct {
+    unsigned long cipher;	/* local; not part of encoding */
+    SECOidTag capIDTag;		/* local; not part of encoding */
+    SECItem capabilityID;
+    SECItem parameters;
+} smime_capability;
+
+static const SEC_ASN1Template smime_capability_template[] = {
+    { SEC_ASN1_SEQUENCE,
+	  0, NULL, sizeof(smime_capability) },
+    { SEC_ASN1_OBJECT_ID,
+	  offsetof(smime_capability,capabilityID), },
+    { SEC_ASN1_OPTIONAL | SEC_ASN1_ANY,
+	  offsetof(smime_capability,parameters), },
+    { 0, }
+};
+
+static const SEC_ASN1Template smime_capabilities_template[] = {
+    { SEC_ASN1_SEQUENCE_OF, 0, smime_capability_template }
+};
+
+
+
+static void
+smime_fill_capability (smime_capability *cap)
+{
+    unsigned long cipher;
+    SECOidTag algtag;
+    int i;
+
+    algtag = SECOID_FindOIDTag (&(cap->capabilityID));
+
+    for (i = 0; i < smime_symmetric_count; i++) {
+	if (smime_cipher_maps[i].algtag != algtag)
+	    continue;
+	/*
+	 * XXX If SECITEM_CompareItem allowed NULLs as arguments (comparing
+	 * 2 NULLs as equal and NULL and non-NULL as not equal), we could
+	 * use that here instead of all of the following comparison code.
+	 */
+	if (cap->parameters.data != NULL) {
+	    if (smime_cipher_maps[i].parms == NULL)
+		continue;
+	    if (cap->parameters.len != smime_cipher_maps[i].parms->len)
+		continue;
+	    if (PORT_Memcmp (cap->parameters.data,
+			     smime_cipher_maps[i].parms->data,
+			     cap->parameters.len) == 0)
+		break;
+	} else if (smime_cipher_maps[i].parms == NULL) {
+	    break;
+	}
+    }
+
+    if (i == smime_symmetric_count)
+	cipher = 0;
+    else
+	cipher = smime_cipher_maps[i].cipher;
+
+    cap->cipher = cipher;
+    cap->capIDTag = algtag;
+}
+
+
+static long
+smime_choose_cipher (CERTCertificate *scert, CERTCertificate **rcerts)
+{
+    PLArenaPool *poolp;
+    long chosen_cipher;
+    int *cipher_abilities;
+    int *cipher_votes;
+    int strong_mapi;
+    int rcount, mapi, max;
+
+    if (smime_policy_bits == 0) {
+	PORT_SetError (SEC_ERROR_BAD_EXPORT_ALGORITHM);
+	return -1;
+    }
+
+    chosen_cipher = SMIME_RC2_CBC_40;		/* the default, LCD */
+
+    poolp = PORT_NewArena (1024);		/* XXX what is right value? */
+    if (poolp == NULL)
+	goto done;
+
+    cipher_abilities = (int*)PORT_ArenaZAlloc (poolp,
+					 smime_symmetric_count * sizeof(int));
+    if (cipher_abilities == NULL)
+	goto done;
+
+    cipher_votes = (int*)PORT_ArenaZAlloc (poolp,
+				     smime_symmetric_count * sizeof(int));
+    if (cipher_votes == NULL)
+	goto done;
+
+    /*
+     * XXX Should have a #define somewhere which specifies default
+     * strong cipher.  (Or better, a way to configure.)
+     */
+
+    /* Make triple-DES the strong cipher. */
+    strong_mapi = smime_mapi_by_cipher (SMIME_DES_EDE3_168);
+
+    PORT_Assert (strong_mapi >= 0);
+
+    for (rcount = 0; rcerts[rcount] != NULL; rcount++) {
+	SECItem *profile;
+	smime_capability **caps;
+	int capi, pref;
+	SECStatus dstat;
+
+	pref = smime_symmetric_count;
+	profile = CERT_FindSMimeProfile (rcerts[rcount]);
+	if (profile != NULL && profile->data != NULL && profile->len > 0) {
+	    caps = NULL;
+	    dstat = SEC_QuickDERDecodeItem (poolp, &caps,
+					smime_capabilities_template,
+					profile);
+	    if (dstat == SECSuccess && caps != NULL) {
+		for (capi = 0; caps[capi] != NULL; capi++) {
+		    smime_fill_capability (caps[capi]);
+		    mapi = smime_mapi_by_cipher (caps[capi]->cipher);
+		    if (mapi >= 0) {
+			cipher_abilities[mapi]++;
+			cipher_votes[mapi] += pref;
+			--pref;
+		    }
+		}
+	    }
+	} else {
+	    SECKEYPublicKey *key;
+	    unsigned int pklen_bits;
+
+	    /*
+	     * XXX This is probably only good for RSA keys.  What I would
+	     * really like is a function to just say;  Is the public key in
+	     * this cert an export-length key?  Then I would not have to
+	     * know things like the value 512, or the kind of key, or what
+	     * a subjectPublicKeyInfo is, etc.
+	     */
+	    key = CERT_ExtractPublicKey (rcerts[rcount]);
+	    if (key != NULL) {
+		pklen_bits = SECKEY_PublicKeyStrength (key) * 8;
+		SECKEY_DestroyPublicKey (key);
+
+		if (pklen_bits > 512) {
+		    cipher_abilities[strong_mapi]++;
+		    cipher_votes[strong_mapi] += pref;
+		}
+	    }
+	}
+	if (profile != NULL)
+	    SECITEM_FreeItem (profile, PR_TRUE);
+    }
+
+    max = 0;
+    for (mapi = 0; mapi < smime_symmetric_count; mapi++) {
+	if (cipher_abilities[mapi] != rcount)
+	    continue;
+	if (! smime_cipher_allowed (smime_cipher_maps[mapi].cipher))
+	    continue;
+	if (cipher_votes[mapi] > max) {
+	    chosen_cipher = smime_cipher_maps[mapi].cipher;
+	    max = cipher_votes[mapi];
+	} /* XXX else if a tie, let scert break it? */
+    }
+
+done:
+    if (poolp != NULL)
+	PORT_FreeArena (poolp, PR_FALSE);
+
+    return chosen_cipher;
+}
+
+
+/*
+ * XXX This is a hack for now to satisfy our current interface.
+ * Eventually, with more parameters needing to be specified, just
+ * looking up the keysize is not going to be sufficient.
+ */
+static int
+smime_keysize_by_cipher (unsigned long which)
+{
+    int keysize;
+
+    switch (which) {
+      case SMIME_RC2_CBC_40:
+	keysize = 40;
+	break;
+      case SMIME_RC2_CBC_64:
+	keysize = 64;
+	break;
+      case SMIME_RC2_CBC_128:
+	keysize = 128;
+	break;
+#ifdef SMIME_DOES_RC5
+      case SMIME_RC5PAD_64_16_40:
+      case SMIME_RC5PAD_64_16_64:
+      case SMIME_RC5PAD_64_16_128:
+	/* XXX See comment above; keysize is not enough... */
+	PORT_Assert (0);
+	PORT_SetError (SEC_ERROR_INVALID_ALGORITHM);
+	keysize = -1;
+	break;
+#endif
+      case SMIME_DES_CBC_56:
+      case SMIME_DES_EDE3_168:
+	/*
+	 * These are special; since the key size is fixed, we actually
+	 * want to *avoid* specifying a key size.
+	 */
+	keysize = 0;
+	break;
+      default:
+	keysize = -1;
+	break;
+    }
+
+    return keysize;
+}
+
+
+/*
+ * Start an S/MIME encrypting context.
+ *
+ * "scert" is the cert for the sender.  It will be checked for validity.
+ * "rcerts" are the certs for the recipients.  They will also be checked.
+ *
+ * "certdb" is the cert database to use for verifying the certs.
+ * It can be NULL if a default database is available (like in the client).
+ *
+ * This function already does all of the stuff specific to S/MIME protocol
+ * and local policy; the return value just needs to be passed to
+ * SEC_PKCS7Encode() or to SEC_PKCS7EncoderStart() to create the encoded data,
+ * and finally to SEC_PKCS7DestroyContentInfo().
+ *
+ * An error results in a return value of NULL and an error set.
+ * (Retrieve specific errors via PORT_GetError()/XP_GetError().)
+ */
+SEC_PKCS7ContentInfo *
+SECMIME_CreateEncrypted(CERTCertificate *scert,
+			CERTCertificate **rcerts,
+			CERTCertDBHandle *certdb,
+			SECKEYGetPasswordKey pwfn,
+			void *pwfn_arg)
+{
+    SEC_PKCS7ContentInfo *cinfo;
+    long cipher;
+    SECOidTag encalg;
+    int keysize;
+    int mapi, rci;
+
+    cipher = smime_choose_cipher (scert, rcerts);
+    if (cipher < 0)
+	return NULL;
+
+    mapi = smime_mapi_by_cipher (cipher);
+    if (mapi < 0)
+	return NULL;
+
+    /*
+     * XXX This is stretching it -- CreateEnvelopedData should probably
+     * take a cipher itself of some sort, because we cannot know what the
+     * future will bring in terms of parameters for each type of algorithm.
+     * For example, just an algorithm and keysize is *not* sufficient to
+     * fully specify the usage of RC5 (which also needs to know rounds and
+     * block size).  Work this out into a better API!
+     */
+    encalg = smime_cipher_maps[mapi].algtag;
+    keysize = smime_keysize_by_cipher (cipher);
+    if (keysize < 0)
+	return NULL;
+
+    cinfo = SEC_PKCS7CreateEnvelopedData (scert, certUsageEmailRecipient,
+					  certdb, encalg, keysize,
+					  pwfn, pwfn_arg);
+    if (cinfo == NULL)
+	return NULL;
+
+    for (rci = 0; rcerts[rci] != NULL; rci++) {
+	if (rcerts[rci] == scert)
+	    continue;
+	if (SEC_PKCS7AddRecipient (cinfo, rcerts[rci], certUsageEmailRecipient,
+				   NULL) != SECSuccess) {
+	    SEC_PKCS7DestroyContentInfo (cinfo);
+	    return NULL;
+	}
+    }
+
+    return cinfo;
+}
+
+
+static smime_capability **smime_capabilities;
+static SECItem *smime_encoded_caps;
+
+
+static SECStatus
+smime_init_caps (void)
+{
+    smime_capability *cap;
+    smime_cipher_map *map;
+    SECOidData *oiddata;
+    SECStatus rv;
+    int i;
+
+    if (smime_encoded_caps != NULL && (! smime_prefs_changed))
+	return SECSuccess;
+
+    if (smime_encoded_caps != NULL) {
+	SECITEM_FreeItem (smime_encoded_caps, PR_TRUE);
+	smime_encoded_caps = NULL;
+    }
+
+    if (smime_capabilities == NULL) {
+	smime_capabilities = (smime_capability**)PORT_ZAlloc (
+					  (smime_symmetric_count + 1)
+					  * sizeof(smime_capability *));
+	if (smime_capabilities == NULL)
+	    return SECFailure;
+    }
+
+    rv = SECFailure;
+
+    /* 
+       The process of creating the encoded PKCS7 cipher capability list
+       involves two basic steps: 
+
+       (a) Convert our internal representation of cipher preferences 
+           (smime_prefs) into an array containing cipher OIDs and 
+	   parameter data (smime_capabilities). This step is
+	   performed here.
+
+       (b) Encode, using ASN.1, the cipher information in 
+           smime_capabilities, leaving the encoded result in 
+	   smime_encoded_caps.
+
+       (In the process of performing (a), Lisa put in some optimizations
+       which allow us to avoid needlessly re-populating elements in 
+       smime_capabilities as we walk through smime_prefs.)
+    */
+    for (i = 0; i < smime_current_pref_index; i++) {
+	int mapi;
+
+	/* Get the next cipher preference in smime_prefs. */
+	mapi = smime_mapi_by_cipher (smime_prefs[i]);
+	if (mapi < 0)
+	    break;
+
+	/* Find the corresponding entry in the cipher map. */
+	PORT_Assert (mapi < smime_symmetric_count);
+	map = &(smime_cipher_maps[mapi]);
+
+	/*
+	 * Convert the next preference found in smime_prefs into an
+	 * smime_capability.
+	 */
+
+	cap = smime_capabilities[i];
+	if (cap == NULL) {
+	    cap = (smime_capability*)PORT_ZAlloc (sizeof(smime_capability));
+	    if (cap == NULL)
+		break;
+	    smime_capabilities[i] = cap;
+	} else if (cap->cipher == smime_prefs[i]) {
+	    continue;		/* no change to this one */
+	}
+
+	cap->capIDTag = map->algtag;
+	oiddata = SECOID_FindOIDByTag (map->algtag);
+	if (oiddata == NULL)
+	    break;
+
+	if (cap->capabilityID.data != NULL) {
+	    SECITEM_FreeItem (&(cap->capabilityID), PR_FALSE);
+	    cap->capabilityID.data = NULL;
+	    cap->capabilityID.len = 0;
+	}
+
+	rv = SECITEM_CopyItem (NULL, &(cap->capabilityID), &(oiddata->oid));
+	if (rv != SECSuccess)
+	    break;
+
+	if (map->parms == NULL) {
+	    cap->parameters.data = NULL;
+	    cap->parameters.len = 0;
+	} else {
+	    cap->parameters.data = map->parms->data;
+	    cap->parameters.len = map->parms->len;
+	}
+
+	cap->cipher = smime_prefs[i];
+    }
+
+    if (i != smime_current_pref_index)
+	return rv;
+
+    while (i < smime_symmetric_count) {
+	cap = smime_capabilities[i];
+	if (cap != NULL) {
+	    SECITEM_FreeItem (&(cap->capabilityID), PR_FALSE);
+	    PORT_Free (cap);
+	}
+	smime_capabilities[i] = NULL;
+	i++;
+    }
+    smime_capabilities[i] = NULL;
+
+    smime_encoded_caps = SEC_ASN1EncodeItem (NULL, NULL, &smime_capabilities,
+					     smime_capabilities_template);
+    if (smime_encoded_caps == NULL)
+	return SECFailure;
+
+    return SECSuccess;
+}
+
+
+static SECStatus
+smime_add_profile (CERTCertificate *cert, SEC_PKCS7ContentInfo *cinfo)
+{
+    PORT_Assert (smime_prefs_complete);
+    if (! smime_prefs_complete)
+	return SECFailure;
+
+    /* For that matter, if capabilities haven't been initialized yet,
+       do so now. */
+    if (smime_encoded_caps == NULL || smime_prefs_changed) {
+	SECStatus rv;
+
+	rv = smime_init_caps();
+	if (rv != SECSuccess)
+	    return rv;
+
+	PORT_Assert (smime_encoded_caps != NULL);
+    }
+
+    return SEC_PKCS7AddSignedAttribute (cinfo, SEC_OID_PKCS9_SMIME_CAPABILITIES,
+					smime_encoded_caps);
+}
+
+
+/*
+ * Start an S/MIME signing context.
+ *
+ * "scert" is the cert that will be used to sign the data.  It will be
+ * checked for validity.
+ *
+ * "ecert" is the signer's encryption cert.  If it is different from
+ * scert, then it will be included in the signed message so that the
+ * recipient can save it for future encryptions.
+ *
+ * "certdb" is the cert database to use for verifying the cert.
+ * It can be NULL if a default database is available (like in the client).
+ * 
+ * "digestalg" names the digest algorithm (e.g. SEC_OID_SHA1).
+ * XXX There should be SECMIME functions for hashing, or the hashing should
+ * be built into this interface, which we would like because we would
+ * support more smartcards that way, and then this argument should go away.)
+ *
+ * "digest" is the actual digest of the data.  It must be provided in
+ * the case of detached data or NULL if the content will be included.
+ *
+ * This function already does all of the stuff specific to S/MIME protocol
+ * and local policy; the return value just needs to be passed to
+ * SEC_PKCS7Encode() or to SEC_PKCS7EncoderStart() to create the encoded data,
+ * and finally to SEC_PKCS7DestroyContentInfo().
+ *
+ * An error results in a return value of NULL and an error set.
+ * (Retrieve specific errors via PORT_GetError()/XP_GetError().)
+ */
+
+SEC_PKCS7ContentInfo *
+SECMIME_CreateSigned (CERTCertificate *scert,
+		      CERTCertificate *ecert,
+		      CERTCertDBHandle *certdb,
+		      SECOidTag digestalg,
+		      SECItem *digest,
+		      SECKEYGetPasswordKey pwfn,
+		      void *pwfn_arg)
+{
+    SEC_PKCS7ContentInfo *cinfo;
+    SECStatus rv;
+
+    /* See note in header comment above about digestalg. */
+    /* Doesn't explain this. PORT_Assert (digestalg == SEC_OID_SHA1); */
+
+    cinfo = SEC_PKCS7CreateSignedData (scert, certUsageEmailSigner,
+				       certdb, digestalg, digest,
+				       pwfn, pwfn_arg);
+    if (cinfo == NULL)
+	return NULL;
+
+    if (SEC_PKCS7IncludeCertChain (cinfo, NULL) != SECSuccess) {
+	SEC_PKCS7DestroyContentInfo (cinfo);
+	return NULL;
+    }
+
+    /* if the encryption cert and the signing cert differ, then include
+     * the encryption cert too.
+     */
+    /* it is ok to compare the pointers since we ref count, and the same
+     * cert will always have the same pointer
+     */
+    if ( ( ecert != NULL ) && ( ecert != scert ) ) {
+	rv = SEC_PKCS7AddCertificate(cinfo, ecert);
+	if ( rv != SECSuccess ) {
+	    SEC_PKCS7DestroyContentInfo (cinfo);
+	    return NULL;
+	}
+    }
+    /*
+     * Add the signing time.  But if it fails for some reason,
+     * may as well not give up altogether -- just assert.
+     */
+    rv = SEC_PKCS7AddSigningTime (cinfo);
+    PORT_Assert (rv == SECSuccess);
+
+    /*
+     * Add the email profile.  Again, if it fails for some reason,
+     * may as well not give up altogether -- just assert.
+     */
+    rv = smime_add_profile (ecert, cinfo);
+    PORT_Assert (rv == SECSuccess);
+
+    return cinfo;
+}