OSX/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     smime_cipher_map[mapi].enabled = on;
 195
 196     return SECSuccess;
 197 }
 198
 199
 200 /*
 201  * this function locally records the export policy
 202  */
 203 OSStatus
 204 SecSMIMEAllowCipher(uint32 which, Boolean on)
 205 {
 206     unsigned long mask;
 207     int mapi;
 208
 209     mask = which & CIPHER_FAMILYID_MASK;
 210
 211     PORT_Assert (mask == CIPHER_FAMILYID_SMIME);
 212     if (mask != CIPHER_FAMILYID_SMIME)
 213         /* XXX set an error! */
 214         return SECFailure;
 215
 216     mapi = smime_mapi_by_cipher(which);
 217     if (mapi < 0)
 218         /* XXX set an error */
 219         return SECFailure;
 220
 221     smime_cipher_map[mapi].allowed = on;
 222
 223     return SECSuccess;
 224 }
 225
 226 /*
 227  * Based on the given algorithm (including its parameters, in some cases!)
 228  * and the given key (may or may not be inspected, depending on the
 229  * algorithm), find the appropriate policy algorithm specification
 230  * and return it.  If no match can be made, -1 is returned.
 231  */
 232 static OSStatus
 233 nss_smime_get_cipher_for_alg_and_key(SECAlgorithmID *algid, SecSymmetricKeyRef key, unsigned long *cipher)
 234 {
 235     SECOidTag algtag;
 236     unsigned int keylen_bits;
 237     unsigned long c;
 238
 239     algtag = SECOID_GetAlgorithmTag(algid);
 240     switch (algtag) {
 241     case SEC_OID_RC2_CBC:
 242         if (SecKeyGetStrengthInBits(key, algid, &keylen_bits))
 243             return SECFailure;
 244         switch (keylen_bits) {
 245         case 40:
 246             c = SMIME_RC2_CBC_40;
 247             break;
 248         case 64:
 249             c = SMIME_RC2_CBC_64;
 250             break;
 251         case 128:
 252             c = SMIME_RC2_CBC_128;
 253             break;
 254         default:
 255             return SECFailure;
 256         }
 257         break;
 258     case SEC_OID_DES_CBC:
 259         c = SMIME_DES_CBC_56;
 260         break;
 261     case SEC_OID_DES_EDE3_CBC:
 262         c = SMIME_DES_EDE3_168;
 263         break;
 264     case SEC_OID_AES_128_CBC:
 265         c = SMIME_AES_CBC_128;
 266         break;
 267     case SEC_OID_FORTEZZA_SKIPJACK:
 268         c = SMIME_FORTEZZA;
 269         break;
 270     default:
 271         return SECFailure;
 272     }
 273     *cipher = c;
 274     return SECSuccess;
 275 }
 276
 277 static Boolean
 278 nss_smime_cipher_allowed(unsigned long which)
 279 {
 280     int mapi;
 281
 282     mapi = smime_mapi_by_cipher(which);
 283     if (mapi < 0)
 284         return PR_FALSE;
 285     return smime_cipher_map[mapi].allowed;
 286 }
 287
 288 Boolean
 289 SecSMIMEDecryptionAllowed(SECAlgorithmID *algid, SecSymmetricKeyRef key)
 290 {
 291     unsigned long which;
 292
 293     if (nss_smime_get_cipher_for_alg_and_key(algid, key, &which) != SECSuccess)
 294         return PR_FALSE;
 295
 296     return nss_smime_cipher_allowed(which);
 297 }
 298
 299
 300 /*
 301  * NSS_SMIME_EncryptionPossible - check if any encryption is allowed
 302  *
 303  * This tells whether or not *any* S/MIME encryption can be done,
 304  * according to policy.  Callers may use this to do nicer user interface
 305  * (say, greying out a checkbox so a user does not even try to encrypt
 306  * a message when they are not allowed to) or for any reason they want
 307  * to check whether S/MIME encryption (or decryption, for that matter)
 308  * may be done.
 309  *
 310  * It takes no arguments.  The return value is a simple boolean:
 311  *   PR_TRUE means encryption (or decryption) is *possible*
 312  *      (but may still fail due to other reasons, like because we cannot
 313  *      find all the necessary certs, etc.; PR_TRUE is *not* a guarantee)
 314  *   PR_FALSE means encryption (or decryption) is not permitted
 315  *
 316  * There are no errors from this routine.
 317  */
 318 Boolean
 319 SecSMIMEEncryptionPossible(void)
 320 {
 321     int i;
 322
 323     for (i = 0; i < smime_cipher_map_count; i++) {
 324         if (smime_cipher_map[i].allowed)
 325             return PR_TRUE;
 326     }
 327     return PR_FALSE;
 328 }
 329
 330
 331 static unsigned long
 332 nss_SMIME_FindCipherForSMIMECap(NSSSMIMECapability *cap)
 333 {
 334     int i;
 335     SECOidTag capIDTag;
 336
 337     /* we need the OIDTag here */
 338     capIDTag = SECOID_FindOIDTag(&(cap->capabilityID));
 339
 340     /* go over all the SMIME ciphers we know and see if we find a match */
 341     for (i = 0; i < smime_cipher_map_count; i++) {
 342         if (smime_cipher_map[i].algtag != capIDTag)
 343             continue;
 344         /*
 345          * XXX If SECITEM_CompareItem allowed NULLs as arguments (comparing
 346          * 2 NULLs as equal and NULL and non-NULL as not equal), we could
 347          * use that here instead of all of the following comparison code.
 348          */
 349         if (cap->parameters.Data == NULL && smime_cipher_map[i].parms == NULL)
 350             break;      /* both empty: bingo */
 351
 352         if (cap->parameters.Data != NULL && smime_cipher_map[i].parms != NULL &&
 353             cap->parameters.Length == smime_cipher_map[i].parms->Length &&
 354             PORT_Memcmp (cap->parameters.Data, smime_cipher_map[i].parms->Data,
 355                              cap->parameters.Length) == 0)
 356         {
 357             break;      /* both not empty, same length & equal content: bingo */
 358         }
 359     }
 360
 361     if (i == smime_cipher_map_count)
 362         return 0;                               /* no match found */
 363     else
 364         return smime_cipher_map[i].cipher;      /* match found, point to cipher */
 365 }
 366
 367 static int smime_keysize_by_cipher (unsigned long which);
 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     if (smime_keysize_by_cipher(chosen_cipher) < 128) {
 513         /* you're going to use strong(er) crypto whether you like it or not */
 514         chosen_cipher = SMIME_DES_EDE3_168;
 515     }
 516     return chosen_cipher;
 517 }
 518
 519 /*
 520  * XXX This is a hack for now to satisfy our current interface.
 521  * Eventually, with more parameters needing to be specified, just
 522  * looking up the keysize is not going to be sufficient.
 523  */
 524 static int
 525 smime_keysize_by_cipher (unsigned long which)
 526 {
 527     int keysize;
 528
 529     switch (which) {
 530       case SMIME_RC2_CBC_40:
 531         keysize = 40;
 532         break;
 533       case SMIME_RC2_CBC_64:
 534         keysize = 64;
 535         break;
 536       case SMIME_RC2_CBC_128:
 537       case SMIME_AES_CBC_128:
 538         keysize = 128;
 539         break;
 540       case SMIME_DES_CBC_56:
 541         keysize = 64;
 542         break;
 543       case SMIME_DES_EDE3_168:
 544         keysize = 192;
 545         break;
 546       case SMIME_FORTEZZA:
 547         /*
 548          * This is special; since the key size is fixed, we actually
 549          * want to *avoid* specifying a key size.
 550          */
 551         keysize = 0;
 552         break;
 553       default:
 554         keysize = -1;
 555         break;
 556     }
 557
 558     return keysize;
 559 }
 560
 561 /*
 562  * SecSMIMEFindBulkAlgForRecipients - find bulk algorithm suitable for all recipients
 563  *
 564  * it would be great for UI purposes if there would be a way to find out which recipients
 565  * prevented a strong cipher from being used...
 566  */
 567 OSStatus
 568 SecSMIMEFindBulkAlgForRecipients(SecCertificateRef *rcerts, SECOidTag *bulkalgtag, int *keysize)
 569 {
 570     unsigned long cipher;
 571     int mapi;
 572
 573     cipher = smime_choose_cipher(NULL, rcerts);
 574     mapi = smime_mapi_by_cipher(cipher);
 575     if (mapi < 0) {
 576         return SECFailure;
 577     }
 578
 579     *bulkalgtag = smime_cipher_map[mapi].algtag;
 580     *keysize = smime_keysize_by_cipher(smime_cipher_map[mapi].cipher);
 581
 582     return SECSuccess;
 583 }
 584
 585 /*
 586  * SecSMIMECreateSMIMECapabilities - get S/MIME capabilities for this instance of NSS
 587  *
 588  * scans the list of allowed and enabled ciphers and construct a PKCS9-compliant
 589  * S/MIME capabilities attribute value.
 590  *
 591  * XXX Please note that, in contradiction to RFC2633 2.5.2, the capabilities only include
 592  * symmetric ciphers, NO signature algorithms or key encipherment algorithms.
 593  *
 594  * "poolp" - arena pool to create the S/MIME capabilities data on
 595  * "dest" - CSSM_DATA to put the data in
 596  * "includeFortezzaCiphers" - PR_TRUE if fortezza ciphers should be included
 597  */
 598 OSStatus
 599 SecSMIMECreateSMIMECapabilities(SecArenaPoolRef pool, CSSM_DATA_PTR dest, Boolean includeFortezzaCiphers)
 600 {
 601     PLArenaPool *poolp = (PLArenaPool *)pool;
 602     NSSSMIMECapability *cap;
 603     NSSSMIMECapability **smime_capabilities;
 604     smime_cipher_map_entry *map;
 605     SECOidData *oiddata;
 606     CSSM_DATA_PTR dummy;
 607     int i, capIndex;
 608
 609     /* if we have an old NSSSMIMECapability array, we'll reuse it (has the right size) */
 610     /* smime_cipher_map_count + 1 is an upper bound - we might end up with less */
 611     smime_capabilities = (NSSSMIMECapability **)PORT_ZAlloc((smime_cipher_map_count + 1)
 612                                       * sizeof(NSSSMIMECapability *));
 613     if (smime_capabilities == NULL)
 614         return SECFailure;
 615
 616     capIndex = 0;
 617
 618     /* Add all the symmetric ciphers
 619      * We walk the cipher list backwards, as it is ordered by increasing strength,
 620      * we prefer the stronger cipher over a weaker one, and we have to list the
 621      * preferred algorithm first */
 622     for (i = smime_cipher_map_count - 1; i >= 0; i--) {
 623         /* Find the corresponding entry in the cipher map. */
 624         map = &(smime_cipher_map[i]);
 625         if (!map->enabled)
 626             continue;
 627
 628         /* If we're using a non-Fortezza cert, only advertise non-Fortezza
 629            capabilities. (We advertise all capabilities if we have a
 630            Fortezza cert.) */
 631         if ((!includeFortezzaCiphers) && (map->cipher == SMIME_FORTEZZA))
 632             continue;
 633
 634         /* get next SMIME capability */
 635         cap = (NSSSMIMECapability *)PORT_ZAlloc(sizeof(NSSSMIMECapability));
 636         if (cap == NULL)
 637             break;
 638         smime_capabilities[capIndex++] = cap;
 639
 640         oiddata = SECOID_FindOIDByTag(map->algtag);
 641         if (oiddata == NULL)
 642             break;
 643
 644         cap->capabilityID.Data = oiddata->oid.Data;
 645         cap->capabilityID.Length = oiddata->oid.Length;
 646         cap->parameters.Data = map->parms ? map->parms->Data : NULL;
 647         cap->parameters.Length = map->parms ? map->parms->Length : 0;
 648         cap->cipher = smime_cipher_map[i].cipher;
 649     }
 650
 651     /* XXX add signature algorithms */
 652     /* XXX add key encipherment algorithms */
 653
 654     smime_capabilities[capIndex] = NULL;        /* last one - now encode */
 655     dummy = SEC_ASN1EncodeItem(poolp, dest, &smime_capabilities, NSSSMIMECapabilitiesTemplate);
 656
 657     /* now that we have the proper encoded SMIMECapabilities (or not),
 658      * free the work data */
 659     for (i = 0; smime_capabilities[i] != NULL; i++)
 660         PORT_Free(smime_capabilities[i]);
 661     PORT_Free(smime_capabilities);
 662
 663     return (dummy == NULL) ? SECFailure : SECSuccess;
 664 }
 665
 666 /*
 667  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value
 668  *
 669  * "poolp" - arena pool to create the attr value on
 670  * "dest" - CSSM_DATA to put the data in
 671  * "cert" - certificate that should be marked as preferred encryption key
 672  *          cert is expected to have been verified for EmailRecipient usage.
 673  */
 674 OSStatus
 675 SecSMIMECreateSMIMEEncKeyPrefs(SecArenaPoolRef pool, CSSM_DATA_PTR dest, SecCertificateRef cert)
 676 {
 677     PLArenaPool *poolp = (PLArenaPool *)pool;
 678     NSSSMIMEEncryptionKeyPreference ekp;
 679     CSSM_DATA_PTR dummy = NULL;
 680     PLArenaPool *tmppoolp = NULL;
 681
 682     if (cert == NULL)
 683         goto loser;
 684
 685     tmppoolp = PORT_NewArena(1024);
 686     if (tmppoolp == NULL)
 687         goto loser;
 688
 689     /* XXX hardcoded IssuerSN choice for now */
 690     ekp.selector = NSSSMIMEEncryptionKeyPref_IssuerSN;
 691     ekp.id.issuerAndSN = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 692     if (ekp.id.issuerAndSN == NULL)
 693         goto loser;
 694
 695     dummy = SEC_ASN1EncodeItem(poolp, dest, &ekp, smime_encryptionkeypref_template);
 696
 697 loser:
 698     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 699
 700     return (dummy == NULL) ? SECFailure : SECSuccess;
 701 }
 702
 703 /*
 704  * SecSMIMECreateSMIMEEncKeyPrefs - create S/MIME encryption key preferences attr value using MS oid
 705  *
 706  * "poolp" - arena pool to create the attr value on
 707  * "dest" - CSSM_DATA to put the data in
 708  * "cert" - certificate that should be marked as preferred encryption key
 709  *          cert is expected to have been verified for EmailRecipient usage.
 710  */
 711 OSStatus
 712 SecSMIMECreateMSSMIMEEncKeyPrefs(SecArenaPoolRef pool, CSSM_DATA_PTR dest, SecCertificateRef cert)
 713 {
 714     PLArenaPool *poolp = (PLArenaPool *)pool;
 715     CSSM_DATA_PTR dummy = NULL;
 716     PLArenaPool *tmppoolp = NULL;
 717     SecCmsIssuerAndSN *isn;
 718
 719     if (cert == NULL)
 720         goto loser;
 721
 722     tmppoolp = PORT_NewArena(1024);
 723     if (tmppoolp == NULL)
 724         goto loser;
 725
 726     isn = CERT_GetCertIssuerAndSN(tmppoolp, cert);
 727     if (isn == NULL)
 728         goto loser;
 729
 730     dummy = SEC_ASN1EncodeItem(poolp, dest, isn, SEC_ASN1_GET(SecCmsIssuerAndSNTemplate));
 731
 732 loser:
 733     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 734
 735     return (dummy == NULL) ? SECFailure : SECSuccess;
 736 }
 737
 738 /*
 739  * SecSMIMEGetCertFromEncryptionKeyPreference -
 740  *                              find cert marked by EncryptionKeyPreference attribute
 741  *
 742  * "keychainOrArray" - handle for the cert database to look in
 743  * "DERekp" - DER-encoded value of S/MIME Encryption Key Preference attribute
 744  *
 745  * if certificate is supposed to be found among the message's included certificates,
 746  * they are assumed to have been imported already.
 747  */
 748 SecCertificateRef
 749 SecSMIMEGetCertFromEncryptionKeyPreference(SecKeychainRef keychainOrArray, CSSM_DATA_PTR DERekp)
 750 {
 751     PLArenaPool *tmppoolp = NULL;
 752     SecCertificateRef cert = NULL;
 753     NSSSMIMEEncryptionKeyPreference ekp;
 754
 755     tmppoolp = PORT_NewArena(1024);
 756     if (tmppoolp == NULL)
 757         return NULL;
 758
 759     /* decode DERekp */
 760     if (SEC_ASN1DecodeItem(tmppoolp, &ekp, smime_encryptionkeypref_template, DERekp) != SECSuccess)
 761         goto loser;
 762
 763     /* find cert */
 764     switch (ekp.selector) {
 765     case NSSSMIMEEncryptionKeyPref_IssuerSN:
 766         cert = CERT_FindCertByIssuerAndSN(keychainOrArray, NULL, NULL, ekp.id.issuerAndSN);
 767         break;
 768     case NSSSMIMEEncryptionKeyPref_RKeyID:
 769     case NSSSMIMEEncryptionKeyPref_SubjectKeyID:
 770         /* XXX not supported yet - we need to be able to look up certs by SubjectKeyID */
 771         break;
 772     default:
 773         PORT_Assert(0);
 774     }
 775 loser:
 776     if (tmppoolp) PORT_FreeArena(tmppoolp, PR_FALSE);
 777
 778     return cert;
 779 }
 780
 781 #if 0
 782 extern const char __nss_smime_rcsid[];
 783 extern const char __nss_smime_sccsid[];
 784 #endif
 785
 786 #if 0 /* -- unused */
 787 Boolean
 788 NSSSMIME_VersionCheck(const char *importedVersion)
 789 {
 790 #if 1
 791     return PR_TRUE;
 792 #else
 793     /*
 794      * This is the secret handshake algorithm.
 795      *
 796      * This release has a simple version compatibility
 797      * check algorithm.  This release is not backward
 798      * compatible with previous major releases.  It is
 799      * not compatible with future major, minor, or
 800      * patch releases.
 801      */
 802     volatile char c; /* force a reference that won't get optimized away */
 803
 804     c = __nss_smime_rcsid[0] + __nss_smime_sccsid[0];
 805
 806     return NSS_VersionCheck(importedVersion);
 807 #endif
 808 }
 809 #endif