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 "SecAsn1Item.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 #include <Security/SecCertificatePriv.h>
  50
  51 SEC_ASN1_MKSUB(CERT_IssuerAndSNTemplate)
  52 SEC_ASN1_MKSUB(SEC_OctetStringTemplate)
  53 SEC_ASN1_CHOOSER_DECLARE(CERT_IssuerAndSNTemplate)
  54
  55 /* various integer's ASN.1 encoding */
  56 static unsigned char asn1_int40[] = { SEC_ASN1_INTEGER, 0x01, 0x28 };
  57 static unsigned char asn1_int64[] = { SEC_ASN1_INTEGER, 0x01, 0x40 };
  58 static unsigned char asn1_int128[] = { SEC_ASN1_INTEGER, 0x02, 0x00, 0x80 };
  59
  60 /* RC2 algorithm parameters (used in smime_cipher_map) */
  61 static SecAsn1Item param_int40 = { sizeof(asn1_int40), asn1_int40 };
  62 static SecAsn1Item param_int64 = { sizeof(asn1_int64), asn1_int64 };
  63 static SecAsn1Item param_int128 = { sizeof(asn1_int128), asn1_int128 };
  64
  65 /*
  66  * XXX Would like the "parameters" field to be a SecAsn1Item * , but the
  67  * encoder is having trouble with optional pointers to an ANY.  Maybe
  68  * once that is fixed, can change this back...
  69  */
  70 typedef struct {
  71     SecAsn1Item capabilityID;
  72     SecAsn1Item parameters;
  73     long cipher;                /* optimization */
  74 } NSSSMIMECapability;
  75
  76 static const SecAsn1Template NSSSMIMECapabilityTemplate[] = {
  77     { SEC_ASN1_SEQUENCE,
  78           0, NULL, sizeof(NSSSMIMECapability) },
  79     { SEC_ASN1_OBJECT_ID,
  80           offsetof(NSSSMIMECapability,capabilityID), },
  81     { SEC_ASN1_OPTIONAL | SEC_ASN1_ANY,
  82           offsetof(NSSSMIMECapability,parameters), },
  83     { 0, }
  84 };
  85
  86 static const SecAsn1Template NSSSMIMECapabilitiesTemplate[] = {
  87     { SEC_ASN1_SEQUENCE_OF, 0, NSSSMIMECapabilityTemplate }
  88 };
  89
  90 /*
  91  * NSSSMIMEEncryptionKeyPreference - if we find one of these, it needs to prompt us
  92  *  to store this and only this certificate permanently for the sender email address.
  93  */
  94 typedef enum {
  95     NSSSMIMEEncryptionKeyPref_IssuerSN,
  96     NSSSMIMEEncryptionKeyPref_RKeyID,
  97     NSSSMIMEEncryptionKeyPref_SubjectKeyID
  98 } NSSSMIMEEncryptionKeyPrefSelector;
  99
 100 typedef struct {
 101     NSSSMIMEEncryptionKeyPrefSelector selector;
 102     union {
 103         SecCmsIssuerAndSN               *issuerAndSN;
 104         SecCmsRecipientKeyIdentifier    *recipientKeyID;
 105         SecAsn1Item *subjectKeyID;
 106     } id;
 107 } NSSSMIMEEncryptionKeyPreference;
 108
 109 extern const SecAsn1Template SecCmsRecipientKeyIdentifierTemplate[];
 110
 111 static const SecAsn1Template smime_encryptionkeypref_template[] = {
 112     { SEC_ASN1_CHOICE,
 113           offsetof(NSSSMIMEEncryptionKeyPreference,selector), NULL,
 114           sizeof(NSSSMIMEEncryptionKeyPreference) },
 115     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 0,
 116           offsetof(NSSSMIMEEncryptionKeyPreference,id.issuerAndSN),
 117           SEC_ASN1_SUB(SecCmsIssuerAndSNTemplate),
 118           NSSSMIMEEncryptionKeyPref_IssuerSN },
 119     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | 1,
 120           offsetof(NSSSMIMEEncryptionKeyPreference,id.recipientKeyID),
 121           SEC_ASN1_SUB(SecCmsRecipientKeyIdentifierTemplate),
 122           NSSSMIMEEncryptionKeyPref_RKeyID },
 123     { SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | SEC_ASN1_XTRN | 2,
 124           offsetof(NSSSMIMEEncryptionKeyPreference,id.subjectKeyID),
 125           SEC_ASN1_SUB(kSecAsn1OctetStringTemplate),
 126           NSSSMIMEEncryptionKeyPref_SubjectKeyID },
 127     { 0, }
 128 };
 129
 130 /* smime_cipher_map - map of SMIME symmetric "ciphers" to algtag & parameters */
 131 typedef struct {
 132     unsigned long cipher;
 133     SECOidTag algtag;
 134     SecAsn1Item *parms;
 135     Boolean enabled;    /* in the user's preferences */
 136     Boolean allowed;    /* per export policy */
 137 } smime_cipher_map_entry;
 138
 139 /* global: list of supported SMIME symmetric ciphers, ordered roughly by increasing strength */
 140 static smime_cipher_map_entry smime_cipher_map[] = {
 141 /*    cipher                    algtag                  parms           enabled  allowed */
 142 /*    ---------------------------------------------------------------------------------- */
 143     { SMIME_RC2_CBC_40,         SEC_OID_RC2_CBC,        &param_int40,   PR_FALSE, PR_FALSE },
 144     { SMIME_DES_CBC_56,         SEC_OID_DES_CBC,        NULL,                   PR_TRUE, PR_FALSE },
 145     { SMIME_RC2_CBC_64,         SEC_OID_RC2_CBC,        &param_int64,   PR_FALSE, PR_FALSE },
 146     { SMIME_RC2_CBC_128,        SEC_OID_RC2_CBC,        &param_int128,  PR_FALSE, PR_FALSE },
 147     { SMIME_DES_EDE3_168,       SEC_OID_DES_EDE3_CBC,   NULL,           PR_TRUE, PR_TRUE },
 148     { SMIME_AES_CBC_128,        SEC_OID_AES_128_CBC,    NULL,           PR_TRUE, PR_TRUE },
 149     { SMIME_AES_CBC_192,        SEC_OID_AES_192_CBC,    NULL,           PR_TRUE, PR_TRUE },
 150     { SMIME_AES_CBC_256,        SEC_OID_AES_256_CBC,    NULL,           PR_TRUE, PR_TRUE },
 151     { SMIME_FORTEZZA,           SEC_OID_FORTEZZA_SKIPJACK, NULL,        PR_TRUE, PR_TRUE }
 152 };
 153 static const int smime_cipher_map_count = sizeof(smime_cipher_map) / sizeof(smime_cipher_map_entry);
 154
 155 /*
 156  * smime_mapi_by_cipher - find index into smime_cipher_map by cipher
 157  */
 158 static int
 159 smime_mapi_by_cipher(unsigned long cipher)
 160 {
 161     int i;
 162
 163     for (i = 0; i < smime_cipher_map_count; i++) {
 164         if (smime_cipher_map[i].cipher == cipher)
 165             return i;   /* bingo */
 166     }
 167     return -1;          /* should not happen if we're consistent, right? */
 168 }
 169
 170 /*
 171  * NSS_SMIME_EnableCipher - this function locally records the user's preference
 172  */
 173 OSStatus
 174 SecSMIMEEnableCipher(unsigned long which, Boolean on)
 175 {
 176     unsigned long mask;
 177     int mapi;
 178
 179     mask = which & CIPHER_FAMILYID_MASK;
 180
 181     PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
 182     if (mask != CIPHER_FAMILYID_SMIME)
 183         /* XXX set an error! */
 184         return SECFailure;
 185
 186     mapi = smime_mapi_by_cipher(which);
 187     if (mapi < 0)
 188         /* XXX set an error */
 189         return SECFailure;
 190
 191     /* do we try to turn on a forbidden cipher? */
 192     if (!smime_cipher_map[mapi].allowed && on) {
 193         PORT_SetError (SEC_ERROR_BAD_EXPORT_ALGORITHM);
 194         return SECFailure;
 195     }
 196
 197     smime_cipher_map[mapi].enabled = on;
 198
 199     return SECSuccess;
 200 }
 201
 202
 203 /*
 204  * this function locally records the export policy
 205  */
 206 OSStatus
 207 SecSMIMEAllowCipher(unsigned long which, Boolean on)
 208 {
 209     unsigned long mask;
 210     int mapi;
 211
 212     mask = which & CIPHER_FAMILYID_MASK;
 213
 214     PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
 215     if (mask != CIPHER_FAMILYID_SMIME)
 216         /* XXX set an error! */
 217         return SECFailure;
 218
 219     mapi = smime_mapi_by_cipher(which);
 220     if (mapi < 0)
 221         /* XXX set an error */
 222         return SECFailure;
 223
 224     smime_cipher_map[mapi].allowed = on;
 225
 226     return SECSuccess;
 227 }
 228
 229 /*
 230  * Based on the given algorithm (including its parameters, in some cases!)
 231  * and the given key (may or may not be inspected, depending on the
 232  * algorithm), find the appropriate policy algorithm specification
 233  * and return it.  If no match can be made, -1 is returned.
 234  */
 235 static OSStatus
 236 nss_smime_get_cipher_for_alg_and_key(SECAlgorithmID *algid, SecSymmetricKeyRef key, unsigned long *cipher)
 237 {
 238     SECOidTag algtag;
 239     CFIndex keylen_bits;
 240     unsigned long c;
 241
 242     algtag = SECOID_GetAlgorithmTag(algid);
 243     switch (algtag) {
 244     case SEC_OID_RC2_CBC:
 245 #if USE_CDSA_CRYPTO
 246         if (SecKeyGetStrengthInBits(key, algid, &keylen_bits))
 247             return SECFailure;
 248 #else
 249         keylen_bits = CFDataGetLength((CFDataRef)key) * 8;
 250 #endif
 251         switch (keylen_bits) {
 252         case 40:
 253             c = SMIME_RC2_CBC_40;
 254             break;
 255         case 64:
 256             c = SMIME_RC2_CBC_64;
 257             break;
 258         case 128:
 259             c = SMIME_RC2_CBC_128;
 260             break;
 261         default:
 262             return SECFailure;
 263         }
 264         break;
 265     case SEC_OID_DES_CBC:
 266         c = SMIME_DES_CBC_56;
 267         break;
 268     case SEC_OID_FORTEZZA_SKIPJACK:
 269         c = SMIME_FORTEZZA;
 270         break;
 271     case SEC_OID_DES_EDE3_CBC:
 272         c = SMIME_DES_EDE3_168;
 273         break;
 274     case SEC_OID_AES_128_CBC:
 275         c = SMIME_AES_CBC_128;
 276         break;
 277     case SEC_OID_AES_192_CBC:
 278         c = SMIME_AES_CBC_192;
 279         break;
 280     case SEC_OID_AES_256_CBC:
 281         c = SMIME_AES_CBC_256;
 282         break;
 283     default:
 284         return SECFailure;
 285     }
 286     *cipher = c;
 287     return SECSuccess;
 288 }
 289
 290 static Boolean
 291 nss_smime_cipher_allowed(unsigned long which)
 292 {
 293     int mapi;
 294
 295     mapi = smime_mapi_by_cipher(which);
 296     if (mapi < 0)
 297         return PR_FALSE;
 298     return smime_cipher_map[mapi].allowed;
 299 }
 300
 301 Boolean
 302 SecSMIMEDecryptionAllowed(SECAlgorithmID *algid, SecSymmetricKeyRef key)
 303 {
 304     unsigned long which;
 305
 306     if (nss_smime_get_cipher_for_alg_and_key(algid, key, &which) != SECSuccess)
 307         return PR_FALSE;
 308
 309     return nss_smime_cipher_allowed(which);
 310 }
 311
 312
 313 /*
 314  * NSS_SMIME_EncryptionPossible - check if any encryption is allowed
 315  *
 316  * This tells whether or not *any* S/MIME encryption can be done,
 317  * according to policy.  Callers may use this to do nicer user interface
 318  * (say, greying out a checkbox so a user does not even try to encrypt
 319  * a message when they are not allowed to) or for any reason they want
 320  * to check whether S/MIME encryption (or decryption, for that matter)
 321  * may be done.
 322  *
 323  * It takes no arguments.  The return value is a simple boolean:
 324  *   PR_TRUE means encryption (or decryption) is *possible*
 325  *      (but may still fail due to other reasons, like because we cannot
 326  *      find all the necessary certs, etc.; PR_TRUE is *not* a guarantee)
 327  *   PR_FALSE means encryption (or decryption) is not permitted
 328  *
 329  * There are no errors from this routine.
 330  */
 331 Boolean
 332 SecSMIMEEncryptionPossible(void)
 333 {
 334     int i;
 335
 336     for (i = 0; i < smime_cipher_map_count; i++) {
 337         if (smime_cipher_map[i].allowed)
 338             return PR_TRUE;
 339     }
 340     return PR_FALSE;
 341 }
 342
 343
 344 static unsigned long
 345 nss_SMIME_FindCipherForSMIMECap(NSSSMIMECapability *cap)
 346 {
 347     int i;
 348     SECOidTag capIDTag;
 349
 350     /* we need the OIDTag here */
 351     capIDTag = SECOID_FindOIDTag(&(cap->capabilityID));
 352
 353     /* go over all the SMIME ciphers we know and see if we find a match */
 354     for (i = 0; i < smime_cipher_map_count; i++) {
 355         if (smime_cipher_map[i].algtag != capIDTag)
 356             continue;
 357         /*
 358          * XXX If SECITEM_CompareItem allowed NULLs as arguments (comparing
 359          * 2 NULLs as equal and NULL and non-NULL as not equal), we could
 360          * use that here instead of all of the following comparison code.
 361          */
 362         if (cap->parameters.Data == NULL && smime_cipher_map[i].parms == NULL)
 363             break;      /* both empty: bingo */
 364
 365         if (cap->parameters.Data != NULL && smime_cipher_map[i].parms != NULL &&
 366             cap->parameters.Length == smime_cipher_map[i].parms->Length &&
 367             PORT_Memcmp (cap->parameters.Data, smime_cipher_map[i].parms->Data,
 368                              cap->parameters.Length) == 0)
 369         {
 370             break;      /* both not empty, same length & equal content: bingo */
 371         }
 372     }
 373
 374     if (i == smime_cipher_map_count)
 375         return 0;                               /* no match found */
 376     else
 377         return smime_cipher_map[i].cipher;      /* match found, point to cipher */
 378 }
 379
 380 static int smime_keysize_by_cipher (unsigned long which);
 381
 382 /*
 383  * smime_choose_cipher - choose a cipher that works for all the recipients
 384  *
 385  * "scert"  - sender's certificate
 386  * "rcerts" - recipient's certificates
 387  */
 388 static long
 389 smime_choose_cipher(SecCertificateRef scert, SecCertificateRef *rcerts)
 390 {
 391     PRArenaPool *poolp;
 392     long cipher;
 393     long chosen_cipher;
 394     int *cipher_abilities;
 395     int *cipher_votes;
 396     int weak_mapi;
 397     int strong_mapi;
 398     int rcount, mapi, max, i;
 399 #if 1
 400     // @@@ We Don't support Fortezza yet.
 401     Boolean scert_is_fortezza  = PR_FALSE;
 402 #else
 403     Boolean scert_is_fortezza = (scert == NULL) ? PR_FALSE : PK11_FortezzaHasKEA(scert);
 404 #endif
 405
 406     chosen_cipher = SMIME_DES_CBC_56;           /* the default, LCD */
 407     weak_mapi = smime_mapi_by_cipher(chosen_cipher);
 408
 409     poolp = PORT_NewArena (1024);               /* XXX what is right value? */
 410     if (poolp == NULL)
 411         goto done;
 412
 413     cipher_abilities = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));
 414     cipher_votes     = (int *)PORT_ArenaZAlloc(poolp, smime_cipher_map_count * sizeof(int));
 415     if (cipher_votes == NULL || cipher_abilities == NULL)
 416         goto done;
 417
 418     /* If the user has the Fortezza preference turned on, make
 419      *  that the strong cipher. Otherwise, use triple-DES. */
 420     strong_mapi = smime_mapi_by_cipher (SMIME_DES_EDE3_168);
 421     if (scert_is_fortezza) {
 422         mapi = smime_mapi_by_cipher(SMIME_FORTEZZA);
 423         if (mapi >= 0 && smime_cipher_map[mapi].enabled)
 424             strong_mapi = mapi;
 425     }
 426
 427     /* walk all the recipient's certs */
 428     for (rcount = 0; rcerts[rcount] != NULL; rcount++) {
 429         SecAsn1Item *profile;
 430         NSSSMIMECapability **caps;
 431         int pref;
 432
 433         /* the first cipher that matches in the user's SMIME profile gets
 434          * "smime_cipher_map_count" votes; the next one gets "smime_cipher_map_count" - 1
 435          * and so on. If every cipher matches, the last one gets 1 (one) vote */
 436         pref = smime_cipher_map_count;
 437
 438         /* find recipient's SMIME profile */
 439         profile = CERT_FindSMimeProfile(rcerts[rcount]);
 440
 441         if (profile != NULL && profile->Data != NULL && profile->Length > 0) {
 442             /* we have a profile (still DER-encoded) */
 443             caps = NULL;
 444             /* decode it */
 445             if (SEC_ASN1DecodeItem(poolp, &caps, NSSSMIMECapabilitiesTemplate, profile) == SECSuccess &&
 446                     caps != NULL)
 447             {
 448                 /* walk the SMIME capabilities for this recipient */
 449                 for (i = 0; caps[i] != NULL; i++) {
 450                     cipher = nss_SMIME_FindCipherForSMIMECap(caps[i]);
 451                     mapi = smime_mapi_by_cipher(cipher);
 452                     if (mapi >= 0) {
 453                         /* found the cipher */
 454                         cipher_abilities[mapi]++;
 455                         cipher_votes[mapi] += pref;
 456                         --pref;
 457                     }
 458                 }
 459             }
 460         } else {
 461             /* no profile found - so we can only assume that the user can do
 462              * the mandatory algorithms which is RC2-40 (weak crypto) and 3DES (strong crypto) */
 463             SecPublicKeyRef key;
 464             size_t pklen_bits;
 465
 466             /*
 467              * if recipient's public key length is > 512, vote for a strong cipher
 468              * please not that the side effect of this is that if only one recipient
 469              * has an export-level public key, the strong cipher is disabled.
 470              *
 471              * XXX This is probably only good for RSA keys.  What I would
 472              * really like is a function to just say;  Is the public key in
 473              * this cert an export-length key?  Then I would not have to
 474              * know things like the value 512, or the kind of key, or what
 475              * a subjectPublicKeyInfo is, etc.
 476              */
 477             key = CERT_ExtractPublicKey(rcerts[rcount]);
 478             pklen_bits = 0;
 479             if (key != NULL) {
 480 #if USE_CDSA_CRYPTO
 481                 SecKeyGetStrengthInBits(key, NULL, &pklen_bits);
 482 #else
 483                 pklen_bits = SecKeyGetSize(key, kSecKeyKeySizeInBits);
 484 #endif
 485                 SECKEY_DestroyPublicKey (key);
 486             }
 487
 488             if (pklen_bits > 512) {
 489                 /* cast votes for the strong algorithm */
 490                 cipher_abilities[strong_mapi]++;
 491                 cipher_votes[strong_mapi] += pref;
 492                 pref--;
 493             }
 494
 495             /* always cast (possibly less) votes for the weak algorithm */
 496             cipher_abilities[weak_mapi]++;
 497             cipher_votes[weak_mapi] += pref;
 498         }
 499         if (profile != NULL)
 500             SECITEM_FreeItem(profile, PR_TRUE);
 501     }
 502
 503     /* find cipher that is agreeable by all recipients and that has the most votes */
 504     max = 0;
 505     for (mapi = 0; mapi < smime_cipher_map_count; mapi++) {
 506         /* if not all of the recipients can do this, forget it */
 507         if (cipher_abilities[mapi] != rcount)
 508             continue;
 509         /* if cipher is not enabled or not allowed by policy, forget it */
 510         if (!smime_cipher_map[mapi].enabled || !smime_cipher_map[mapi].allowed)
 511             continue;
 512         /* if we're not doing fortezza, but the cipher is fortezza, forget it */
 513         if (!scert_is_fortezza  && (smime_cipher_map[mapi].cipher == SMIME_FORTEZZA))
 514             continue;
 515         /* now see if this one has more votes than the last best one */
 516         if (cipher_votes[mapi] >= max) {
 517             /* if equal number of votes, prefer the ones further down in the list */
 518             /* with the expectation that these are higher rated ciphers */
 519             chosen_cipher = smime_cipher_map[mapi].cipher;
 520             max = cipher_votes[mapi];
 521         }
 522     }
 523     /* if no common cipher was found, chosen_cipher stays at the default */
 524
 525 done:
 526     if (poolp != NULL)
 527         PORT_FreeArena (poolp, PR_FALSE);
 528
 529     if (smime_keysize_by_cipher(chosen_cipher) < 128) {
 530         /* you're going to use strong(er) crypto whether you like it or not */
 531         chosen_cipher = SMIME_DES_EDE3_168;
 532     }
 533     return chosen_cipher;
 534 }
 535
 536 /*
 537  * XXX This is a hack for now to satisfy our current interface.
 538  * Eventually, with more parameters needing to be specified, just
 539  * looking up the keysize is not going to be sufficient.
 540  */
 541 static int
 542 smime_keysize_by_cipher (unsigned long which)
 543 {
 544     int keysize;
 545
 546     switch (which) {
 547       case SMIME_RC2_CBC_40:
 548         keysize = 40;
 549         break;
 550       case SMIME_RC2_CBC_64:
 551         keysize = 64;
 552         break;
 553       case SMIME_RC2_CBC_128:
 554         keysize = 128;
 555         break;
 556       case SMIME_DES_CBC_56:
 557         keysize = 64;
 558         break;
 559       case SMIME_DES_EDE3_168:
 560         keysize = 192;
 561         break;
 562       case SMIME_FORTEZZA:
 563         /*
 564          * This is special; since the key size is fixed, we actually
 565          * want to *avoid* specifying a key size.
 566          */
 567         keysize = 0;
 568         break;
 569       default:
 570         keysize = -1;
 571         break;
 572     }
 573
 574     return keysize;
 575 }
 576
 577 /*
 578  * SecSMIMEFindBulkAlgForRecipients - find bulk algorithm suitable for all recipients
 579  *
 580  * it would be great for UI purposes if there would be a way to find out which recipients
 581  * prevented a strong cipher from being used...
 582  */
 583 OSStatus
 584 SecSMIMEFindBulkAlgForRecipients(SecCertificateRef *rcerts, SECOidTag *bulkalgtag, int *keysize)
 585 {
 586     unsigned long cipher;
 587     int mapi;
 588
 589     cipher = smime_choose_cipher(NULL, rcerts);
 590     mapi = smime_mapi_by_cipher(cipher);
 591     if (mapi < 0) {
 592         return SECFailure;
 593     }
 594
 595     *bulkalgtag = smime_cipher_map[mapi].algtag;
 596     *keysize = smime_keysize_by_cipher(smime_cipher_map[mapi].cipher);
 597
 598     return SECSuccess;
 599 }
 600
 601 /*
 602  * SecSMIMECreateSMIMECapabilities - get S/MIME capabilities for this instance of NSS
 603  *
 604  * scans the list of allowed and enabled ciphers and construct a PKCS9-compliant
 605  * S/MIME capabilities attribute value.
 606  *
 607  * XXX Please note that, in contradiction to RFC2633 2.5.2, the capabilities only include
 608  * symmetric ciphers, NO signature algorithms or key encipherment algorithms.
 609  *
 610  * "poolp" - arena pool to create the S/MIME capabilities data on
 611  * "dest" - SecAsn1Item to put the data in
 612  * "includeFortezzaCiphers" - PR_TRUE if fortezza ciphers should be included
 613  */
 614 OSStatus
 615 SecSMIMECreateSMIMECapabilities(PLArenaPool *poolp, SecAsn1Item *dest, Boolean includeFortezzaCiphers)
 616 {
 617     NSSSMIMECapability *cap;
 618     NSSSMIMECapability **smime_capabilities;
 619     smime_cipher_map_entry *map;
 620     SECOidData *oiddata;
 621     SecAsn1Item *dummy;
 622     int i, capIndex;
 623
 624     /* if we have an old NSSSMIMECapability array, we'll reuse it (has the right size) */
 625     /* smime_cipher_map_count + 1 is an upper bound - we might end up with less */
 626     smime_capabilities = (NSSSMIMECapability **)PORT_ZAlloc((smime_cipher_map_count + 1)
 627                                       * sizeof(NSSSMIMECapability *));
 628     if (smime_capabilities == NULL)
 629         return SECFailure;
 630
 631     capIndex = 0;
 632
 633     /* Add all the symmetric ciphers
 634      * We walk the cipher list backwards, as it is ordered by increasing strength,
 635      * we prefer the stronger cipher over a weaker one, and we have to list the
 636      * preferred algorithm first */
 637     for (i = smime_cipher_map_count - 1; i >= 0; i--) {
 638         /* Find the corresponding entry in the cipher map. */
 639         map = &(smime_cipher_map[i]);
 640         if (!map->enabled)
 641             continue;
 642
 643         /* If we're using a non-Fortezza cert, only advertise non-Fortezza
 644            capabilities. (We advertise all capabilities if we have a
 645            Fortezza cert.) */
 646         if ((!includeFortezzaCiphers) && (map->cipher == SMIME_FORTEZZA))
 647             continue;
 648
 649         /* get next SMIME capability */
 650         cap = (NSSSMIMECapability *)PORT_ZAlloc(sizeof(NSSSMIMECapability));
 651         if (cap == NULL)
 652             break;
 653         smime_capabilities[capIndex++] = cap;
 654
 655         oiddata = SECOID_FindOIDByTag(map->algtag);
 656         if (oiddata == NULL)
 657             break;
 658
 659         cap->capabilityID.Data = oiddata->oid.Data;
 660         cap->capabilityID.Length = oiddata->oid.Length;
 661         cap->parameters.Data = map->parms ? map->parms->Data : NULL;
 662         cap->parameters.Length = map->parms ? map->parms->Length : 0;
 663         cap->cipher = smime_cipher_map[i].cipher;
 664     }
 665
 666     /* XXX add signature algorithms */
 667     /* XXX add key encipherment algorithms */
 668
 669     smime_capabilities[capIndex] = NULL;        /* last one - now encode */
 670     dummy = SEC_ASN1EncodeItem(poolp, dest, &smime_capabilities, NSSSMIMECapabilitiesTemplate);
 671
 672     /* now that we have the proper encoded SMIMECapabilities (or not),
 673      * free the work data */
 674     for (i = 0; smime_capabilities[i] != NULL; i++)
 675         PORT_Free(smime_capabilities[i]);
 676     PORT_Free(smime_capabilities);
 677
 678     return (dummy == NULL) ? SECFailure : SECSuccess;
 679 }
 680
 681 /*
 682  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value
 683  *
 684  * "poolp" - arena pool to create the attr value on
 685  * "dest" - SecAsn1Item to put the data in
 686  * "cert" - certificate that should be marked as preferred encryption key
 687  *          cert is expected to have been verified for EmailRecipient usage.
 688  */
 689 OSStatus
 690 SecSMIMECreateSMIMEEncKeyPrefs(PLArenaPool *poolp, SecAsn1Item *dest, SecCertificateRef cert)
 691 {
 692     NSSSMIMEEncryptionKeyPreference ekp;
 693     SecAsn1Item *dummy = NULL;
 694     PLArenaPool *tmppoolp = NULL;
 695
 696     if (cert == NULL)
 697         goto loser;
 698
 699     tmppoolp = PORT_NewArena(1024);
 700     if (tmppoolp == NULL)
 701         goto loser;
 702
 703     /* XXX hardcoded IssuerSN choice for now */
 704     ekp.selector = NSSSMIMEEncryptionKeyPref_IssuerSN;
 705     ekp.id.issuerAndSN = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 706     if (ekp.id.issuerAndSN == NULL)
 707         goto loser;
 708
 709     dummy = SEC_ASN1EncodeItem(poolp, dest, &ekp, smime_encryptionkeypref_template);
 710
 711 loser:
 712     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 713
 714     return (dummy == NULL) ? SECFailure : SECSuccess;
 715 }
 716
 717 /*
 718  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value using MS oid
 719  *
 720  * "poolp" - arena pool to create the attr value on
 721  * "dest" - SecAsn1Item to put the data in
 722  * "cert" - certificate that should be marked as preferred encryption key
 723  *          cert is expected to have been verified for EmailRecipient usage.
 724  */
 725 OSStatus
 726 SecSMIMECreateMSSMIMEEncKeyPrefs(PLArenaPool *poolp, SecAsn1Item *dest, SecCertificateRef cert)
 727 {
 728     SecAsn1Item *dummy = NULL;
 729     PLArenaPool *tmppoolp = NULL;
 730     SecCmsIssuerAndSN *isn;
 731
 732     if (cert == NULL)
 733         goto loser;
 734
 735     tmppoolp = PORT_NewArena(1024);
 736     if (tmppoolp == NULL)
 737         goto loser;
 738
 739     isn = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 740     if (isn == NULL)
 741         goto loser;
 742
 743     dummy = SEC_ASN1EncodeItem(poolp, dest, isn, SEC_ASN1_GET(SecCmsIssuerAndSNTemplate));
 744
 745 loser:
 746     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 747
 748     return (dummy == NULL) ? SECFailure : SECSuccess;
 749 }
 750
 751 static CFArrayRef CF_RETURNS_RETAINED copyCertsFromRawCerts(SecAsn1Item **rawCerts) {
 752     CFMutableArrayRef certs = NULL;
 753     SecCertificateRef certificate = NULL;
 754     int numRawCerts = SecCmsArrayCount((void **)rawCerts);
 755     int dex;
 756
 757     certs = CFArrayCreateMutable(NULL, numRawCerts, &kCFTypeArrayCallBacks);
 758
 759     for(dex=0; dex<numRawCerts; dex++) {
 760         certificate = SecCertificateCreateWithBytes(NULL, rawCerts[dex]->Data, rawCerts[dex]->Length);
 761         if (certificate) {
 762             CFArrayAppendValue(certs, certificate);
 763             CFRelease(certificate);
 764         }
 765         certificate = NULL;
 766     }
 767
 768     if (CFArrayGetCount(certs) == 0) {
 769         CFRelease(certs);
 770         return NULL;
 771     }
 772     return certs;
 773 }
 774
 775 /*
 776  * SecSMIMEGetCertFromEncryptionKeyPreference -
 777  *                              find cert marked by EncryptionKeyPreference attribute
 778  *
 779  * "keychainOrArray" - handle for the cert database to look in
 780  * "DERekp" - DER-encoded value of S/MIME Encryption Key Preference attribute
 781  *
 782  * if certificate is supposed to be found among the message's included certificates,
 783  * they are assumed to have been imported already.
 784  */
 785 SecCertificateRef
 786 SecSMIMEGetCertFromEncryptionKeyPreference(SecAsn1Item **rawCerts, SecAsn1Item *DERekp)
 787 {
 788     PLArenaPool *tmppoolp = NULL;
 789     SecCertificateRef cert = NULL;
 790     NSSSMIMEEncryptionKeyPreference ekp;
 791     CFArrayRef certs = NULL;
 792
 793     tmppoolp = PORT_NewArena(1024);
 794     if (tmppoolp == NULL)
 795         return NULL;
 796
 797     /* decode DERekp */
 798     if (SEC_ASN1DecodeItem(tmppoolp, &ekp, smime_encryptionkeypref_template, DERekp) != SECSuccess)
 799         goto loser;
 800
 801     certs = copyCertsFromRawCerts(rawCerts);
 802
 803     /* find cert */
 804     switch (ekp.selector) {
 805     case NSSSMIMEEncryptionKeyPref_IssuerSN:
 806         cert = CERT_FindCertificateByIssuerAndSN(certs, ekp.id.issuerAndSN);
 807         break;
 808     case NSSSMIMEEncryptionKeyPref_RKeyID:
 809         cert = CERT_FindCertificateBySubjectKeyID(certs, &ekp.id.recipientKeyID->subjectKeyIdentifier);
 810         break;
 811     case NSSSMIMEEncryptionKeyPref_SubjectKeyID:
 812         cert = CERT_FindCertificateBySubjectKeyID(certs, ekp.id.subjectKeyID);
 813         break;
 814     default:
 815         PORT_Assert(0);
 816     }
 817 loser:
 818     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 819     if (certs) CFRelease(certs);
 820     return cert;
 821 }
 822
 823 #if 0
 824 extern const char __nss_smime_rcsid[];
 825 extern const char __nss_smime_sccsid[];
 826
 827 Boolean
 828 NSSSMIME_VersionCheck(const char *importedVersion)
 829 {
 830 #if 1
 831     return PR_TRUE;
 832 #else
 833     /*
 834      * This is the secret handshake algorithm.
 835      *
 836      * This release has a simple version compatibility
 837      * check algorithm.  This release is not backward
 838      * compatible with previous major releases.  It is
 839      * not compatible with future major, minor, or
 840      * patch releases.
 841      */
 842     volatile char c; /* force a reference that won't get optimized away */
 843
 844     c = __nss_smime_rcsid[0] + __nss_smime_sccsid[0];
 845
 846     return NSS_VersionCheck(importedVersion);
 847 #endif
 848 }
 849 #endif /* 0 */
 850