libsecurity_smime/lib/smimeutil.c

   1 /*
   2  * The contents of this file are subject to the Mozilla Public
   3  * License Version 1.1 (the "License"); you may not use this file
   4  * except in compliance with the License. You may obtain a copy of
   5  * the License at http://www.mozilla.org/MPL/
   6  *
   7  * Software distributed under the License is distributed on an "AS
   8  * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
   9  * implied. See the License for the specific language governing
  10  * rights and limitations under the License.
  11  *
  12  * The Original Code is the Netscape security libraries.
  13  *
  14  * The Initial Developer of the Original Code is Netscape
  15  * Communications Corporation.  Portions created by Netscape are
  16  * Copyright (C) 1994-2000 Netscape Communications Corporation.  All
  17  * Rights Reserved.
  18  *
  19  * Contributor(s):
  20  *
  21  * Alternatively, the contents of this file may be used under the
  22  * terms of the GNU General Public License Version 2 or later (the
  23  * "GPL"), in which case the provisions of the GPL are applicable
  24  * instead of those above.  If you wish to allow use of your
  25  * version of this file only under the terms of the GPL and not to
  26  * allow others to use your version of this file under the MPL,
  27  * indicate your decision by deleting the provisions above and
  28  * replace them with the notice and other provisions required by
  29  * the GPL.  If you do not delete the provisions above, a recipient
  30  * may use your version of this file under either the MPL or the
  31  * GPL.
  32  */
  33
  34 /*
  35  * Stuff specific to S/MIME policy and interoperability.
  36  */
  37
  38 #include "cmslocal.h"
  39
  40 #include "secoid.h"
  41 #include "secitem.h"
  42 #include "cert.h"
  43 #include "SecSMIMEPriv.h"
  44
  45 #include <security_asn1/secasn1.h>
  46 #include <security_asn1/secerr.h>
  47 #include <Security/SecSMIME.h>
  48 #include <Security/SecKeyPriv.h>
  49
  50 SEC_ASN1_MKSUB(CERT_IssuerAndSNTemplate)
  51 SEC_ASN1_MKSUB(SEC_OctetStringTemplate)
  52 SEC_ASN1_CHOOSER_DECLARE(CERT_IssuerAndSNTemplate)
  53
  54 /* various integer's ASN.1 encoding */
  55 static unsigned char asn1_int40[] = { SEC_ASN1_INTEGER, 0x01, 0x28 };
  56 static unsigned char asn1_int64[] = { SEC_ASN1_INTEGER, 0x01, 0x40 };
  57 static unsigned char asn1_int128[] = { SEC_ASN1_INTEGER, 0x02, 0x00, 0x80 };
  58
  59 /* RC2 algorithm parameters (used in smime_cipher_map) */
  60 static CSSM_DATA param_int40 = { sizeof(asn1_int40), asn1_int40 };
  61 static CSSM_DATA param_int64 = { sizeof(asn1_int64), asn1_int64 };
  62 static CSSM_DATA param_int128 = { sizeof(asn1_int128), asn1_int128 };
  63
  64 /*
  65  * XXX Would like the "parameters" field to be a CSSM_DATA_PTR , but the
  66  * encoder is having trouble with optional pointers to an ANY.  Maybe
  67  * once that is fixed, can change this back...
  68  */
  69 typedef struct {
  70     CSSM_DATA capabilityID;
  71     CSSM_DATA parameters;
  72     long cipher;                /* optimization */
  73 } NSSSMIMECapability;
  74
  75 static const SecAsn1Template NSSSMIMECapabilityTemplate[] = {
  76     { SEC_ASN1_SEQUENCE,
  77           0, NULL, sizeof(NSSSMIMECapability) },
  78     { SEC_ASN1_OBJECT_ID,
  79           offsetof(NSSSMIMECapability,capabilityID), },
  80     { SEC_ASN1_OPTIONAL | SEC_ASN1_ANY,
  81           offsetof(NSSSMIMECapability,parameters), },
  82     { 0, }
  83 };
  84
  85 static const SecAsn1Template NSSSMIMECapabilitiesTemplate[] = {
  86     { SEC_ASN1_SEQUENCE_OF, 0, NSSSMIMECapabilityTemplate }
  87 };
  88
  89 /*
  90  * NSSSMIMEEncryptionKeyPreference - if we find one of these, it needs to prompt us
  91  *  to store this and only this certificate permanently for the sender email address.
  92  */
  93 typedef enum {
  94     NSSSMIMEEncryptionKeyPref_IssuerSN,
  95     NSSSMIMEEncryptionKeyPref_RKeyID,
  96     NSSSMIMEEncryptionKeyPref_SubjectKeyID
  97 } NSSSMIMEEncryptionKeyPrefSelector;
  98
  99 typedef struct {
 100     NSSSMIMEEncryptionKeyPrefSelector selector;
 101     union {
 102         SecCmsIssuerAndSN               *issuerAndSN;
 103         SecCmsRecipientKeyIdentifier    *recipientKeyID;
 104         CSSM_DATA_PTR subjectKeyID;
 105     } id;
 106 } NSSSMIMEEncryptionKeyPreference;
 107
 108 extern const SecAsn1Template SecCmsRecipientKeyIdentifierTemplate[];
 109
 110 static const SecAsn1Template smime_encryptionkeypref_template[] = {
 111     { SEC_ASN1_CHOICE,
 112           offsetof(NSSSMIMEEncryptionKeyPreference,selector), NULL,
 113           sizeof(NSSSMIMEEncryptionKeyPreference) },
 114     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 0,
 115           offsetof(NSSSMIMEEncryptionKeyPreference,id.issuerAndSN),
 116           SEC_ASN1_SUB(SecCmsIssuerAndSNTemplate),
 117           NSSSMIMEEncryptionKeyPref_IssuerSN },
 118     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | 1,
 119           offsetof(NSSSMIMEEncryptionKeyPreference,id.recipientKeyID),
 120           SecCmsRecipientKeyIdentifierTemplate,
 121           NSSSMIMEEncryptionKeyPref_IssuerSN },
 122     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 2,
 123           offsetof(NSSSMIMEEncryptionKeyPreference,id.subjectKeyID),
 124           SEC_ASN1_SUB(kSecAsn1OctetStringTemplate),
 125           NSSSMIMEEncryptionKeyPref_SubjectKeyID },
 126     { 0, }
 127 };
 128
 129 /* smime_cipher_map - map of SMIME symmetric "ciphers" to algtag & parameters */
 130 typedef struct {
 131     unsigned long cipher;
 132     SECOidTag algtag;
 133     CSSM_DATA_PTR parms;
 134     Boolean enabled;    /* in the user's preferences */
 135     Boolean allowed;    /* per export policy */
 136 } smime_cipher_map_entry;
 137
 138 /* global: list of supported SMIME symmetric ciphers, ordered roughly by increasing strength */
 139 static smime_cipher_map_entry smime_cipher_map[] = {
 140 /*    cipher                    algtag                  parms           enabled  allowed */
 141 /*    ---------------------------------------------------------------------------------- */
 142     { SMIME_RC2_CBC_40,         SEC_OID_RC2_CBC,        &param_int40,   PR_TRUE, PR_TRUE },
 143     { SMIME_DES_CBC_56,         SEC_OID_DES_CBC,        NULL,           PR_TRUE, PR_TRUE },
 144     { SMIME_RC2_CBC_64,         SEC_OID_RC2_CBC,        &param_int64,   PR_TRUE, PR_TRUE },
 145     { SMIME_RC2_CBC_128,        SEC_OID_RC2_CBC,        &param_int128,  PR_TRUE, PR_TRUE },
 146     { SMIME_DES_EDE3_168,       SEC_OID_DES_EDE3_CBC,   NULL,           PR_TRUE, PR_TRUE },
 147     { SMIME_AES_CBC_128,        SEC_OID_AES_128_CBC,    NULL,           PR_TRUE, PR_TRUE },
 148     { SMIME_FORTEZZA,           SEC_OID_FORTEZZA_SKIPJACK, NULL,        PR_TRUE, PR_TRUE }
 149 };
 150 static const int smime_cipher_map_count = sizeof(smime_cipher_map) / sizeof(smime_cipher_map_entry);
 151
 152 /*
 153  * smime_mapi_by_cipher - find index into smime_cipher_map by cipher
 154  */
 155 static int
 156 smime_mapi_by_cipher(unsigned long cipher)
 157 {
 158     int i;
 159
 160     for (i = 0; i < smime_cipher_map_count; i++) {
 161         if (smime_cipher_map[i].cipher == cipher)
 162             return i;   /* bingo */
 163     }
 164     return -1;          /* should not happen if we're consistent, right? */
 165 }
 166
 167 /*
 168  * NSS_SMIME_EnableCipher - this function locally records the user's preference
 169  */
 170 OSStatus
 171 SecSMIMEEnableCipher(uint32 which, Boolean on)
 172 {
 173     unsigned long mask;
 174     int mapi;
 175
 176     mask = which & CIPHER_FAMILYID_MASK;
 177
 178     PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
 179     if (mask != CIPHER_FAMILYID_SMIME)
 180         /* XXX set an error! */
 181         return SECFailure;
 182
 183     mapi = smime_mapi_by_cipher(which);
 184     if (mapi < 0)
 185         /* XXX set an error */
 186         return SECFailure;
 187
 188     /* do we try to turn on a forbidden cipher? */
 189     if (!smime_cipher_map[mapi].allowed && on) {
 190         PORT_SetError (SEC_ERROR_BAD_EXPORT_ALGORITHM);
 191         return SECFailure;
 192     }
 193
 194     if (smime_cipher_map[mapi].enabled != on)
 195         smime_cipher_map[mapi].enabled = on;
 196
 197     return SECSuccess;
 198 }
 199
 200
 201 /*
 202  * this function locally records the export policy
 203  */
 204 OSStatus
 205 SecSMIMEAllowCipher(uint32 which, Boolean on)
 206 {
 207     unsigned long mask;
 208     int mapi;
 209
 210     mask = which & CIPHER_FAMILYID_MASK;
 211
 212     PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
 213     if (mask != CIPHER_FAMILYID_SMIME)
 214         /* XXX set an error! */
 215         return SECFailure;
 216
 217     mapi = smime_mapi_by_cipher(which);
 218     if (mapi < 0)
 219         /* XXX set an error */
 220         return SECFailure;
 221
 222     if (smime_cipher_map[mapi].allowed != on)
 223         smime_cipher_map[mapi].allowed = on;
 224
 225     return SECSuccess;
 226 }
 227
 228 /*
 229  * Based on the given algorithm (including its parameters, in some cases!)
 230  * and the given key (may or may not be inspected, depending on the
 231  * algorithm), find the appropriate policy algorithm specification
 232  * and return it.  If no match can be made, -1 is returned.
 233  */
 234 static OSStatus
 235 nss_smime_get_cipher_for_alg_and_key(SECAlgorithmID *algid, SecSymmetricKeyRef key, unsigned long *cipher)
 236 {
 237     SECOidTag algtag;
 238     unsigned int keylen_bits;
 239     unsigned long c;
 240
 241     algtag = SECOID_GetAlgorithmTag(algid);
 242     switch (algtag) {
 243     case SEC_OID_RC2_CBC:
 244         if (SecKeyGetStrengthInBits(key, algid, &keylen_bits))
 245             return SECFailure;
 246         switch (keylen_bits) {
 247         case 40:
 248             c = SMIME_RC2_CBC_40;
 249             break;
 250         case 64:
 251             c = SMIME_RC2_CBC_64;
 252             break;
 253         case 128:
 254             c = SMIME_RC2_CBC_128;
 255             break;
 256         default:
 257             return SECFailure;
 258         }
 259         break;
 260     case SEC_OID_DES_CBC:
 261         c = SMIME_DES_CBC_56;
 262         break;
 263     case SEC_OID_DES_EDE3_CBC:
 264         c = SMIME_DES_EDE3_168;
 265         break;
 266     case SEC_OID_AES_128_CBC:
 267         c = SMIME_AES_CBC_128;
 268         break;
 269     case SEC_OID_FORTEZZA_SKIPJACK:
 270         c = SMIME_FORTEZZA;
 271         break;
 272     default:
 273         return SECFailure;
 274     }
 275     *cipher = c;
 276     return SECSuccess;
 277 }
 278
 279 static Boolean
 280 nss_smime_cipher_allowed(unsigned long which)
 281 {
 282     int mapi;
 283
 284     mapi = smime_mapi_by_cipher(which);
 285     if (mapi < 0)
 286         return PR_FALSE;
 287     return smime_cipher_map[mapi].allowed;
 288 }
 289
 290 Boolean
 291 SecSMIMEDecryptionAllowed(SECAlgorithmID *algid, SecSymmetricKeyRef key)
 292 {
 293     unsigned long which;
 294
 295     if (nss_smime_get_cipher_for_alg_and_key(algid, key, &which) != SECSuccess)
 296         return PR_FALSE;
 297
 298     return nss_smime_cipher_allowed(which);
 299 }
 300
 301
 302 /*
 303  * NSS_SMIME_EncryptionPossible - check if any encryption is allowed
 304  *
 305  * This tells whether or not *any* S/MIME encryption can be done,
 306  * according to policy.  Callers may use this to do nicer user interface
 307  * (say, greying out a checkbox so a user does not even try to encrypt
 308  * a message when they are not allowed to) or for any reason they want
 309  * to check whether S/MIME encryption (or decryption, for that matter)
 310  * may be done.
 311  *
 312  * It takes no arguments.  The return value is a simple boolean:
 313  *   PR_TRUE means encryption (or decryption) is *possible*
 314  *      (but may still fail due to other reasons, like because we cannot
 315  *      find all the necessary certs, etc.; PR_TRUE is *not* a guarantee)
 316  *   PR_FALSE means encryption (or decryption) is not permitted
 317  *
 318  * There are no errors from this routine.
 319  */
 320 Boolean
 321 SecSMIMEEncryptionPossible(void)
 322 {
 323     int i;
 324
 325     for (i = 0; i < smime_cipher_map_count; i++) {
 326         if (smime_cipher_map[i].allowed)
 327             return PR_TRUE;
 328     }
 329     return PR_FALSE;
 330 }
 331
 332
 333 static int
 334 nss_SMIME_FindCipherForSMIMECap(NSSSMIMECapability *cap)
 335 {
 336     int i;
 337     SECOidTag capIDTag;
 338
 339     /* we need the OIDTag here */
 340     capIDTag = SECOID_FindOIDTag(&(cap->capabilityID));
 341
 342     /* go over all the SMIME ciphers we know and see if we find a match */
 343     for (i = 0; i < smime_cipher_map_count; i++) {
 344         if (smime_cipher_map[i].algtag != capIDTag)
 345             continue;
 346         /*
 347          * XXX If SECITEM_CompareItem allowed NULLs as arguments (comparing
 348          * 2 NULLs as equal and NULL and non-NULL as not equal), we could
 349          * use that here instead of all of the following comparison code.
 350          */
 351         if (cap->parameters.Data == NULL && smime_cipher_map[i].parms == NULL)
 352             break;      /* both empty: bingo */
 353
 354         if (cap->parameters.Data != NULL && smime_cipher_map[i].parms != NULL &&
 355             cap->parameters.Length == smime_cipher_map[i].parms->Length &&
 356             PORT_Memcmp (cap->parameters.Data, smime_cipher_map[i].parms->Data,
 357                              cap->parameters.Length) == 0)
 358         {
 359             break;      /* both not empty, same length & equal content: bingo */
 360         }
 361     }
 362
 363     if (i == smime_cipher_map_count)
 364         return 0;                               /* no match found */
 365     else
 366         return smime_cipher_map[i].cipher;      /* match found, point to cipher */
 367 }
 368
 369 /*
 370  * smime_choose_cipher - choose a cipher that works for all the recipients
 371  *
 372  * "scert"  - sender's certificate
 373  * "rcerts" - recipient's certificates
 374  */
 375 static long
 376 smime_choose_cipher(SecCertificateRef scert, SecCertificateRef *rcerts)
 377 {
 378     PRArenaPool *poolp;
 379     long cipher;
 380     long chosen_cipher;
 381     int *cipher_abilities;
 382     int *cipher_votes;
 383     int weak_mapi;
 384     int strong_mapi;
 385     int rcount, mapi, max, i;
 386 #if 1
 387     // @@@ We Don't support Fortezza yet.
 388     Boolean scert_is_fortezza  = PR_FALSE;
 389 #else
 390     Boolean scert_is_fortezza = (scert == NULL) ? PR_FALSE : PK11_FortezzaHasKEA(scert);
 391 #endif
 392
 393     chosen_cipher = SMIME_RC2_CBC_40;           /* the default, LCD */
 394     weak_mapi = smime_mapi_by_cipher(chosen_cipher);
 395
 396     poolp = PORT_NewArena (1024);               /* XXX what is right value? */
 397     if (poolp == NULL)
 398         goto done;
 399
 400     cipher_abilities = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));
 401     cipher_votes     = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));
 402     if (cipher_votes == NULL || cipher_abilities == NULL)
 403         goto done;
 404
 405     /* If the user has the Fortezza preference turned on, make
 406      *  that the strong cipher. Otherwise, use triple-DES. */
 407     strong_mapi = smime_mapi_by_cipher (SMIME_DES_EDE3_168);
 408     if (scert_is_fortezza) {
 409         mapi = smime_mapi_by_cipher(SMIME_FORTEZZA);
 410         if (mapi >= 0 && smime_cipher_map[mapi].enabled)
 411             strong_mapi = mapi;
 412     }
 413
 414     /* walk all the recipient's certs */
 415     for (rcount = 0; rcerts[rcount] != NULL; rcount++) {
 416         CSSM_DATA_PTR profile;
 417         NSSSMIMECapability **caps;
 418         int pref;
 419
 420         /* the first cipher that matches in the user's SMIME profile gets
 421          * "smime_cipher_map_count" votes; the next one gets "smime_cipher_map_count" - 1
 422          * and so on. If every cipher matches, the last one gets 1 (one) vote */
 423         pref = smime_cipher_map_count;
 424
 425         /* find recipient's SMIME profile */
 426         profile = CERT_FindSMimeProfile(rcerts[rcount]);
 427
 428         if (profile != NULL && profile->Data != NULL && profile->Length > 0) {
 429             /* we have a profile (still DER-encoded) */
 430             caps = NULL;
 431             /* decode it */
 432             if (SEC_ASN1DecodeItem(poolp, &caps, NSSSMIMECapabilitiesTemplate, profile) == SECSuccess &&
 433                     caps != NULL)
 434             {
 435                 /* walk the SMIME capabilities for this recipient */
 436                 for (i = 0; caps[i] != NULL; i++) {
 437                     cipher = nss_SMIME_FindCipherForSMIMECap(caps[i]);
 438                     mapi = smime_mapi_by_cipher(cipher);
 439                     if (mapi >= 0) {
 440                         /* found the cipher */
 441                         cipher_abilities[mapi]++;
 442                         cipher_votes[mapi] += pref;
 443                         --pref;
 444                     }
 445                 }
 446             }
 447         } else {
 448             /* no profile found - so we can only assume that the user can do
 449              * the mandatory algorithms which is RC2-40 (weak crypto) and 3DES (strong crypto) */
 450             SecPublicKeyRef key;
 451             unsigned int pklen_bits;
 452
 453             /*
 454              * if recipient's public key length is > 512, vote for a strong cipher
 455              * please not that the side effect of this is that if only one recipient
 456              * has an export-level public key, the strong cipher is disabled.
 457              *
 458              * XXX This is probably only good for RSA keys.  What I would
 459              * really like is a function to just say;  Is the public key in
 460              * this cert an export-length key?  Then I would not have to
 461              * know things like the value 512, or the kind of key, or what
 462              * a subjectPublicKeyInfo is, etc.
 463              */
 464             key = CERT_ExtractPublicKey(rcerts[rcount]);
 465             pklen_bits = 0;
 466             if (key != NULL) {
 467                 SecKeyGetStrengthInBits(key, NULL, &pklen_bits);
 468                 SECKEY_DestroyPublicKey (key);
 469             }
 470
 471             if (pklen_bits > 512) {
 472                 /* cast votes for the strong algorithm */
 473                 cipher_abilities[strong_mapi]++;
 474                 cipher_votes[strong_mapi] += pref;
 475                 pref--;
 476             }
 477
 478             /* always cast (possibly less) votes for the weak algorithm */
 479             cipher_abilities[weak_mapi]++;
 480             cipher_votes[weak_mapi] += pref;
 481         }
 482         if (profile != NULL)
 483             SECITEM_FreeItem(profile, PR_TRUE);
 484     }
 485
 486     /* find cipher that is agreeable by all recipients and that has the most votes */
 487     max = 0;
 488     for (mapi = 0; mapi < smime_cipher_map_count; mapi++) {
 489         /* if not all of the recipients can do this, forget it */
 490         if (cipher_abilities[mapi] != rcount)
 491             continue;
 492         /* if cipher is not enabled or not allowed by policy, forget it */
 493         if (!smime_cipher_map[mapi].enabled || !smime_cipher_map[mapi].allowed)
 494             continue;
 495         /* if we're not doing fortezza, but the cipher is fortezza, forget it */
 496         if (!scert_is_fortezza  && (smime_cipher_map[mapi].cipher == SMIME_FORTEZZA))
 497             continue;
 498         /* now see if this one has more votes than the last best one */
 499         if (cipher_votes[mapi] >= max) {
 500             /* if equal number of votes, prefer the ones further down in the list */
 501             /* with the expectation that these are higher rated ciphers */
 502             chosen_cipher = smime_cipher_map[mapi].cipher;
 503             max = cipher_votes[mapi];
 504         }
 505     }
 506     /* if no common cipher was found, chosen_cipher stays at the default */
 507
 508 done:
 509     if (poolp != NULL)
 510         PORT_FreeArena (poolp, PR_FALSE);
 511
 512     return chosen_cipher;
 513 }
 514
 515 /*
 516  * XXX This is a hack for now to satisfy our current interface.
 517  * Eventually, with more parameters needing to be specified, just
 518  * looking up the keysize is not going to be sufficient.
 519  */
 520 static int
 521 smime_keysize_by_cipher (unsigned long which)
 522 {
 523     int keysize;
 524
 525     switch (which) {
 526       case SMIME_RC2_CBC_40:
 527         keysize = 40;
 528         break;
 529       case SMIME_RC2_CBC_64:
 530         keysize = 64;
 531         break;
 532       case SMIME_RC2_CBC_128:
 533       case SMIME_AES_CBC_128:
 534         keysize = 128;
 535         break;
 536       case SMIME_DES_CBC_56:
 537         keysize = 64;
 538         break;
 539       case SMIME_DES_EDE3_168:
 540         keysize = 192;
 541         break;
 542       case SMIME_FORTEZZA:
 543         /*
 544          * This is special; since the key size is fixed, we actually
 545          * want to *avoid* specifying a key size.
 546          */
 547         keysize = 0;
 548         break;
 549       default:
 550         keysize = -1;
 551         break;
 552     }
 553
 554     return keysize;
 555 }
 556
 557 /*
 558  * SecSMIMEFindBulkAlgForRecipients - find bulk algorithm suitable for all recipients
 559  *
 560  * it would be great for UI purposes if there would be a way to find out which recipients
 561  * prevented a strong cipher from being used...
 562  */
 563 OSStatus
 564 SecSMIMEFindBulkAlgForRecipients(SecCertificateRef *rcerts, SECOidTag *bulkalgtag, int *keysize)
 565 {
 566     unsigned long cipher;
 567     int mapi;
 568
 569     cipher = smime_choose_cipher(NULL, rcerts);
 570     mapi = smime_mapi_by_cipher(cipher);
 571
 572     *bulkalgtag = smime_cipher_map[mapi].algtag;
 573     *keysize = smime_keysize_by_cipher(smime_cipher_map[mapi].cipher);
 574
 575     return SECSuccess;
 576 }
 577
 578 /*
 579  * SecSMIMECreateSMIMECapabilities - get S/MIME capabilities for this instance of NSS
 580  *
 581  * scans the list of allowed and enabled ciphers and construct a PKCS9-compliant
 582  * S/MIME capabilities attribute value.
 583  *
 584  * XXX Please note that, in contradiction to RFC2633 2.5.2, the capabilities only include
 585  * symmetric ciphers, NO signature algorithms or key encipherment algorithms.
 586  *
 587  * "poolp" - arena pool to create the S/MIME capabilities data on
 588  * "dest" - CSSM_DATA to put the data in
 589  * "includeFortezzaCiphers" - PR_TRUE if fortezza ciphers should be included
 590  */
 591 OSStatus
 592 SecSMIMECreateSMIMECapabilities(SecArenaPoolRef pool, CSSM_DATA_PTR dest, Boolean includeFortezzaCiphers)
 593 {
 594     PLArenaPool *poolp = (PLArenaPool *)pool;
 595     NSSSMIMECapability *cap;
 596     NSSSMIMECapability **smime_capabilities;
 597     smime_cipher_map_entry *map;
 598     SECOidData *oiddata;
 599     CSSM_DATA_PTR dummy;
 600     int i, capIndex;
 601
 602     /* if we have an old NSSSMIMECapability array, we'll reuse it (has the right size) */
 603     /* smime_cipher_map_count + 1 is an upper bound - we might end up with less */
 604     smime_capabilities = (NSSSMIMECapability **)PORT_ZAlloc((smime_cipher_map_count + 1)
 605                                       * sizeof(NSSSMIMECapability *));
 606     if (smime_capabilities == NULL)
 607         return SECFailure;
 608
 609     capIndex = 0;
 610
 611     /* Add all the symmetric ciphers
 612      * We walk the cipher list backwards, as it is ordered by increasing strength,
 613      * we prefer the stronger cipher over a weaker one, and we have to list the
 614      * preferred algorithm first */
 615     for (i = smime_cipher_map_count - 1; i >= 0; i--) {
 616         /* Find the corresponding entry in the cipher map. */
 617         map = &(smime_cipher_map[i]);
 618         if (!map->enabled)
 619             continue;
 620
 621         /* If we're using a non-Fortezza cert, only advertise non-Fortezza
 622            capabilities. (We advertise all capabilities if we have a
 623            Fortezza cert.) */
 624         if ((!includeFortezzaCiphers) && (map->cipher == SMIME_FORTEZZA))
 625             continue;
 626
 627         /* get next SMIME capability */
 628         cap = (NSSSMIMECapability *)PORT_ZAlloc(sizeof(NSSSMIMECapability));
 629         if (cap == NULL)
 630             break;
 631         smime_capabilities[capIndex++] = cap;
 632
 633         oiddata = SECOID_FindOIDByTag(map->algtag);
 634         if (oiddata == NULL)
 635             break;
 636
 637         cap->capabilityID.Data = oiddata->oid.Data;
 638         cap->capabilityID.Length = oiddata->oid.Length;
 639         cap->parameters.Data = map->parms ? map->parms->Data : NULL;
 640         cap->parameters.Length = map->parms ? map->parms->Length : 0;
 641         cap->cipher = smime_cipher_map[i].cipher;
 642     }
 643
 644     /* XXX add signature algorithms */
 645     /* XXX add key encipherment algorithms */
 646
 647     smime_capabilities[capIndex] = NULL;        /* last one - now encode */
 648     dummy = SEC_ASN1EncodeItem(poolp, dest, &smime_capabilities, NSSSMIMECapabilitiesTemplate);
 649
 650     /* now that we have the proper encoded SMIMECapabilities (or not),
 651      * free the work data */
 652     for (i = 0; smime_capabilities[i] != NULL; i++)
 653         PORT_Free(smime_capabilities[i]);
 654     PORT_Free(smime_capabilities);
 655
 656     return (dummy == NULL) ? SECFailure : SECSuccess;
 657 }
 658
 659 /*
 660  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value
 661  *
 662  * "poolp" - arena pool to create the attr value on
 663  * "dest" - CSSM_DATA to put the data in
 664  * "cert" - certificate that should be marked as preferred encryption key
 665  *          cert is expected to have been verified for EmailRecipient usage.
 666  */
 667 OSStatus
 668 SecSMIMECreateSMIMEEncKeyPrefs(SecArenaPoolRef pool, CSSM_DATA_PTR dest, SecCertificateRef cert)
 669 {
 670     PLArenaPool *poolp = (PLArenaPool *)pool;
 671     NSSSMIMEEncryptionKeyPreference ekp;
 672     CSSM_DATA_PTR dummy = NULL;
 673     PLArenaPool *tmppoolp = NULL;
 674
 675     if (cert == NULL)
 676         goto loser;
 677
 678     tmppoolp = PORT_NewArena(1024);
 679     if (tmppoolp == NULL)
 680         goto loser;
 681
 682     /* XXX hardcoded IssuerSN choice for now */
 683     ekp.selector = NSSSMIMEEncryptionKeyPref_IssuerSN;
 684     ekp.id.issuerAndSN = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 685     if (ekp.id.issuerAndSN == NULL)
 686         goto loser;
 687
 688     dummy = SEC_ASN1EncodeItem(poolp, dest, &ekp, smime_encryptionkeypref_template);
 689
 690 loser:
 691     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 692
 693     return (dummy == NULL) ? SECFailure : SECSuccess;
 694 }
 695
 696 /*
 697  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value using MS oid
 698  *
 699  * "poolp" - arena pool to create the attr value on
 700  * "dest" - CSSM_DATA to put the data in
 701  * "cert" - certificate that should be marked as preferred encryption key
 702  *          cert is expected to have been verified for EmailRecipient usage.
 703  */
 704 OSStatus
 705 SecSMIMECreateMSSMIMEEncKeyPrefs(SecArenaPoolRef pool, CSSM_DATA_PTR dest, SecCertificateRef cert)
 706 {
 707     PLArenaPool *poolp = (PLArenaPool *)pool;
 708     CSSM_DATA_PTR dummy = NULL;
 709     PLArenaPool *tmppoolp = NULL;
 710     SecCmsIssuerAndSN *isn;
 711
 712     if (cert == NULL)
 713         goto loser;
 714
 715     tmppoolp = PORT_NewArena(1024);
 716     if (tmppoolp == NULL)
 717         goto loser;
 718
 719     isn = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 720     if (isn == NULL)
 721         goto loser;
 722
 723     dummy = SEC_ASN1EncodeItem(poolp, dest, isn, SEC_ASN1_GET(SecCmsIssuerAndSNTemplate));
 724
 725 loser:
 726     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 727
 728     return (dummy == NULL) ? SECFailure : SECSuccess;
 729 }
 730
 731 /*
 732  * SecSMIMEGetCertFromEncryptionKeyPreference -
 733  *                              find cert marked by EncryptionKeyPreference attribute
 734  *
 735  * "keychainOrArray" - handle for the cert database to look in
 736  * "DERekp" - DER-encoded value of S/MIME Encryption Key Preference attribute
 737  *
 738  * if certificate is supposed to be found among the message's included certificates,
 739  * they are assumed to have been imported already.
 740  */
 741 SecCertificateRef
 742 SecSMIMEGetCertFromEncryptionKeyPreference(SecKeychainRef keychainOrArray, CSSM_DATA_PTR DERekp)
 743 {
 744     PLArenaPool *tmppoolp = NULL;
 745     SecCertificateRef cert = NULL;
 746     NSSSMIMEEncryptionKeyPreference ekp;
 747
 748     tmppoolp = PORT_NewArena(1024);
 749     if (tmppoolp == NULL)
 750         return NULL;
 751
 752     /* decode DERekp */
 753     if (SEC_ASN1DecodeItem(tmppoolp, &ekp, smime_encryptionkeypref_template, DERekp) != SECSuccess)
 754         goto loser;
 755
 756     /* find cert */
 757     switch (ekp.selector) {
 758     case NSSSMIMEEncryptionKeyPref_IssuerSN:
 759         cert = CERT_FindCertByIssuerAndSN(keychainOrArray, NULL, NULL, ekp.id.issuerAndSN);
 760         break;
 761     case NSSSMIMEEncryptionKeyPref_RKeyID:
 762     case NSSSMIMEEncryptionKeyPref_SubjectKeyID:
 763         /* XXX not supported yet - we need to be able to look up certs by SubjectKeyID */
 764         break;
 765     default:
 766         PORT_Assert(0);
 767     }
 768 loser:
 769     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 770
 771     return cert;
 772 }
 773
 774 #if 0
 775 extern const char __nss_smime_rcsid[];
 776 extern const char __nss_smime_sccsid[];
 777 #endif
 778
 779 Boolean
 780 NSSSMIME_VersionCheck(const char *importedVersion)
 781 {
 782 #if 1
 783     return PR_TRUE;
 784 #else
 785     /*
 786      * This is the secret handshake algorithm.
 787      *
 788      * This release has a simple version compatibility
 789      * check algorithm.  This release is not backward
 790      * compatible with previous major releases.  It is
 791      * not compatible with future major, minor, or
 792      * patch releases.
 793      */
 794     volatile char c; /* force a reference that won't get optimized away */
 795
 796     c = __nss_smime_rcsid[0] + __nss_smime_sccsid[0];
 797
 798     return NSS_VersionCheck(importedVersion);
 799 #endif
 800 }
 801