OSX/libsecurity_apple_csp/lib/wrapKey.cpp

   1 /*
   2  * Copyright (c) 2000-2001,2011-2012,2014 Apple Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // wrapKey.cpp - wrap/unwrap key functions for AppleCSPSession
  21 //
  22
  23 /*
  24  * Currently the Security Server wraps public keys when they're stored, so we have
  25  * to allow this. We might not want to do this in the real world.
  26  */
  27 #define ALLOW_PUB_KEY_WRAP              1
  28
  29 #include "AppleCSPSession.h"
  30 #include "AppleCSPUtils.h"
  31 #include "AppleCSPKeys.h"
  32 #include "pkcs8.h"
  33 #include "cspdebugging.h"
  34
  35 /*
  36  * Wrap key function. Used for two things:
  37  *
  38  *  -- Encrypt and encode a private or session key for export to
  39  *     a foreign system or program. Any type of keys may be used
  40  *     for the  unwrapped key and the wrapping (encrypting) key,
  41  *     as long as this CSP understands those keys. The context
  42  *     must be of  class ALGCLASS_SYMMETRIC or ALGCLASS_ASYMMETRIC,
  43  *     matching the wrapping key.
  44  *
  45  *         In the absence of an explicit CSSM_ATTRIBUTE_WRAPPED_KEY_FORMAT
  46  *     attribute, private keys will be PKCS8 wrapped; session keys will be
  47  *     PKCS7 wrapped. Both input keys may be in raw or reference
  48  *     format. Wrapped key will have BlobType CSSM_KEYBLOB_WRAPPED.
  49  *
  50  *  -- Convert a reference key to a RAW key (with no encrypting).
  51  *     This is called a NULL wrap; no wrapping key need be present in
  52  *     the context, but the context must be of class
  53  *         ALGCLASS_SYMMETRIC and algorithm ALGID_NONE.
  54  *
  55  * There are serious inconsistencies in the specification of wrap
  56  * algorithms to be used in the various CDSA specs (c914.pdf,
  57  * CSP Behavior spec) and between those specs and the PKCS standards
  58  * PKCS7, PKCS8, RFC2630). Here is what this module implements:
  59  *
  60  * On a wrap key op, the caller can add a CSSM_ATTRIBUTE_WRAPPED_KEY_FORMAT
  61  * attribute to the context to specify the wrapping algorithm to be used.
  62  * If it's there, that's what we use if appropriate for the incoming key
  63  * types. Otherwise we figure out a reasonable default from the incoming
  64  * key types. The wrapped key always has the appropriate KeyHeader.Format
  65  * field set indicating how it was wrapped. Defaults are shows below.
  66  *
  67  * The format CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM is used to indicate
  68  * a modified CMS-style wrapping which is similar to that specified in
  69  * RFC2630, with some modification.
  70  *
  71  * Default wrapping if none specified based on ther unwrapped key as
  72  * follows:
  73  *
  74  * UnwrappedKey                 Wrap format
  75  * ------------                 -----------
  76  * Symmetric                    PKCS7
  77  * Public                               APPLE_CUSTOM
  78  * FEE private                  APPLE_CUSTOM
  79  * Other private                PKCS8
  80  */
  81
  82 void AppleCSPSession::WrapKey(
  83                 CSSM_CC_HANDLE CCHandle,
  84                 const Context &Context,
  85         const AccessCredentials &AccessCred,
  86         const CssmKey &UnwrappedKey,
  87         const CssmData *DescriptiveData,
  88         CssmKey &WrappedKey,
  89                 CSSM_PRIVILEGE Privilege)
  90 {
  91         CssmKey::Header                 &wrappedHdr   = WrappedKey.header();
  92         bool                                    isNullWrap = false;
  93         CssmKey                                 *wrappingKey = NULL;
  94         CSSM_KEYBLOB_FORMAT             wrapFormat;
  95
  96         switch(UnwrappedKey.keyClass()) {
  97                 case CSSM_KEYCLASS_PUBLIC_KEY:
  98                 case CSSM_KEYCLASS_PRIVATE_KEY:
  99                 case CSSM_KEYCLASS_SESSION_KEY:
 100                         break;
 101                 default:
 102                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 103         }
 104
 105         /* wrapping key only required for non-NULL wrap */
 106         wrappingKey = Context.get<CssmKey>(CSSM_ATTRIBUTE_KEY);
 107         if(wrappingKey == NULL) {
 108                 if((Context.algorithm() == CSSM_ALGID_NONE) &&
 109                    (Context.type() == CSSM_ALGCLASS_SYMMETRIC)) {
 110                                 // NULL wrap, OK
 111                                 isNullWrap = true;
 112                 }
 113                 else {
 114                         errorLog0("WrapKey: missing wrapping key\n");
 115                         CssmError::throwMe(CSSMERR_CSP_MISSING_ATTR_KEY);
 116                 }
 117         }
 118
 119         /*
 120          * Validate misc. params as best we can
 121          */
 122         if(isNullWrap) {
 123                 wrapFormat = CSSM_KEYBLOB_WRAPPED_FORMAT_NONE;
 124         }
 125         else {
 126                 /*
 127                  * Can only wrap session and private keys.
 128                  */
 129                 #if             !ALLOW_PUB_KEY_WRAP
 130                 if(UnwrappedKey.keyClass() == CSSM_KEYCLASS_PUBLIC_KEY) {
 131                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 132                 }
 133                 #endif  /* ALLOW_PUB_KEY_WRAP */
 134                 cspValidateIntendedKeyUsage(&wrappingKey->KeyHeader, CSSM_KEYUSE_WRAP);
 135                 cspVerifyKeyTimes(wrappingKey->KeyHeader);
 136
 137                 /*
 138                  * make sure wrapping key type matches context
 139                  */
 140                 CSSM_CONTEXT_TYPE wrapType;
 141                 switch(wrappingKey->KeyHeader.KeyClass) {
 142                         case CSSM_KEYCLASS_PUBLIC_KEY:
 143                         case CSSM_KEYCLASS_PRIVATE_KEY:
 144                                 wrapType = CSSM_ALGCLASS_ASYMMETRIC;
 145                                 break;
 146                         case CSSM_KEYCLASS_SESSION_KEY:
 147                                 wrapType = CSSM_ALGCLASS_SYMMETRIC;
 148                                 break;
 149                         default:
 150                                 errorLog0("WrapKey: bad class of wrappingKey\n");
 151                                 CssmError::throwMe(CSSMERR_CSP_INVALID_ATTR_KEY);
 152                 }
 153                 if(wrapType != Context.type()) {
 154                         errorLog0("WrapKey: mismatch wrappingKey/contextType\n");
 155                         CssmError::throwMe(CSSMERR_CSP_INVALID_CONTEXT);
 156                 }
 157                 if(Context.algorithm() == CSSM_ALGID_NONE) {
 158                         errorLog0("WrapKey: null wrap alg, non-null key\n");
 159                         CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 160                 }
 161
 162                 /*
 163                  * Get optional wrap format, set default per incoming keys
 164                  * Note: no such atrribute ==> 0 ==> FORMAT_NONE, which we
 165                  * take to mean "use the default".
 166                  */
 167                 wrapFormat = Context.getInt(CSSM_ATTRIBUTE_WRAPPED_KEY_FORMAT);
 168                 if(wrapFormat == CSSM_KEYBLOB_WRAPPED_FORMAT_NONE) {
 169                         /* figure out a default based on unwrapped key */
 170                         switch(UnwrappedKey.keyClass()) {
 171                                 case CSSM_KEYCLASS_SESSION_KEY:
 172                                         wrapFormat = CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS7;
 173                                         break;
 174                                 case CSSM_KEYCLASS_PUBLIC_KEY:
 175                                         wrapFormat = CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM;
 176                                         break;
 177                                 case CSSM_KEYCLASS_PRIVATE_KEY:
 178                                         switch(UnwrappedKey.algorithm()) {
 179                                                 case CSSM_ALGID_FEE:
 180                                                         wrapFormat = CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM;
 181                                                         break;
 182                                                 default:
 183                                                         wrapFormat = CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS8;
 184                                                         break;
 185                                         }
 186                                         break;
 187                                 default:
 188                                         /* NOT REACHED - checked above */
 189                                         break;
 190                         }
 191                 }               /* no format present or FORMAT_NONE */
 192         }
 193
 194         /* make sure we have a valid format here */
 195         switch(wrapFormat) {
 196                 case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS7:
 197                         if(UnwrappedKey.keyClass() != CSSM_KEYCLASS_SESSION_KEY) {
 198                                 /* this wrapping style only for symmetric keys */
 199                                 CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 200                         }
 201                         break;
 202                 case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS8:
 203                 case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSL:
 204                         if(UnwrappedKey.keyClass() != CSSM_KEYCLASS_PRIVATE_KEY) {
 205                                 /* these wrapping styles only for private keys */
 206                                 CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 207                         }
 208                         break;
 209                 case CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM:
 210                         /* no restrictions (well AES can't be the wrap alg but that will
 211                          * be caught later */
 212                         break;
 213                 case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1:
 214                         /* RSA private key, reference format, only */
 215                         if(UnwrappedKey.keyClass() != CSSM_KEYCLASS_PRIVATE_KEY) {
 216                                 CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 217                         }
 218                         if(UnwrappedKey.algorithm() != CSSM_ALGID_RSA) {
 219                                 CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 220                         }
 221                         if(UnwrappedKey.blobType() != CSSM_KEYBLOB_REFERENCE) {
 222                                 CssmError::throwMe(CSSMERR_CSP_KEY_BLOB_TYPE_INCORRECT);
 223                         }
 224                         break;
 225                 case CSSM_KEYBLOB_WRAPPED_FORMAT_NONE:
 226                         if(isNullWrap) {
 227                                 /* only time this is OK */
 228                                 break;
 229                         }
 230                         /* else fall thru */
 231                 default:
 232                         dprintf1("KeyWrap: invalid wrapFormat (%d)\n", (int)wrapFormat);
 233                         CssmError::throwMe(CSSMERR_CSP_INVALID_ATTR_WRAPPED_KEY_FORMAT);
 234         }
 235         /* get the blob to be wrappped */
 236         CssmData rawBlob;
 237         bool allocdRawBlob = false;
 238         CSSM_KEYBLOB_FORMAT rawFormat = CSSM_KEYBLOB_RAW_FORMAT_NONE;
 239
 240         /*
 241          * Outgoing same as incoming unless a partial key is completed during
 242          * generateKeyBlob()
 243          */
 244         const CssmKey::Header &unwrappedHdr = UnwrappedKey.header();
 245         CSSM_KEYATTR_FLAGS unwrappedKeyAttrFlags = unwrappedHdr.KeyAttr;
 246
 247         switch(UnwrappedKey.blobType()) {
 248                 case CSSM_KEYBLOB_RAW:
 249                         /*
 250                          * Trivial case - we already have the blob.
 251                          * This op - wrapping a raw key - is not supported for the
 252                          * CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1 format since that doesn't
 253                          * operate on a key blob.
 254                          */
 255                         rawBlob = CssmData::overlay(UnwrappedKey.KeyData);
 256                         rawFormat = UnwrappedKey.blobFormat();
 257                         break;
 258                 case CSSM_KEYBLOB_REFERENCE:
 259                         /* get binary key, then get blob from it */
 260                         {
 261                                 BinaryKey &binKey = lookupRefKey(UnwrappedKey);
 262
 263                                 /*
 264                                  * Subsequent tests for extractability: don't trust the
 265                                  * caller's header; use the one in the BinaryKey.
 266                                  */
 267                                 CSSM_KEYATTR_FLAGS keyAttr = binKey.mKeyHeader.KeyAttr;
 268                                 if(!(keyAttr & CSSM_KEYATTR_EXTRACTABLE)) {
 269                                         /* this key not extractable in any form */
 270                                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEYATTR_MASK);
 271                                 }
 272
 273                                 /*
 274                                  * CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1: we're ready to roll;
 275                                  * all we need is the reference key.
 276                                  */
 277                                 if(wrapFormat == CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1) {
 278                                         break;
 279                                 }
 280
 281                                 /*
 282                                  * Null wrap - prevent caller from obtaining
 283                                  * clear bits if CSSM_KEYATTR_SENSITIVE
 284                                  */
 285                                 if(isNullWrap && (keyAttr & CSSM_KEYATTR_SENSITIVE)) {
 286                                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEYATTR_MASK);
 287                                 }
 288
 289                                 /*
 290                                  * Special case for PKCS8 and openssl: need to get blob of a specific
 291                                  * algorithm-dependent format. Caller can override our
 292                                  * preference with a
 293                                  * CSSM_ATTRIBUTE_{PRIVATE,PUBLIC,SESSION}_KEY_FORMAT
 294                                  * context attribute.
 295                                  */
 296                                 rawFormat = requestedKeyFormat(Context, UnwrappedKey);
 297                                 if(rawFormat == CSSM_KEYBLOB_RAW_FORMAT_NONE) {
 298                                         CSSM_ALGORITHMS keyAlg = binKey.mKeyHeader.AlgorithmId;
 299                                         switch(wrapFormat) {
 300                                                 case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS8:
 301                                                         rawFormat = pkcs8RawKeyFormat(keyAlg);
 302                                                         break;
 303                                                 case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSL:
 304                                                         rawFormat = opensslRawKeyFormat(keyAlg);
 305                                                         break;
 306                                                 default:
 307                                                         /* punt and take default for key type */
 308                                                         break;
 309                                         }
 310                                 }
 311
 312                                 /*
 313                                  * DescriptiveData for encoding, currently only used for
 314                                  * SSH1 keys.
 315                                  */
 316                                 if((DescriptiveData != NULL) && (DescriptiveData->Length != 0)) {
 317                                         binKey.descData(*DescriptiveData);
 318                                 }
 319
 320                                 /* optional parameter-bearing key */
 321                                 CssmKey *paramKey = Context.get<CssmKey>(CSSM_ATTRIBUTE_PARAM_KEY);
 322                                 binKey.generateKeyBlob(privAllocator,
 323                                         rawBlob,
 324                                         rawFormat,
 325                                         *this,
 326                                         paramKey,
 327                                         unwrappedKeyAttrFlags);
 328                         }
 329                         allocdRawBlob = true;           // remember - we need to free
 330                         break;
 331
 332                 default:
 333                         errorLog0("WrapKey: bad unwrappedKey BlobType\n");
 334                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY);
 335         }
 336
 337         /*
 338          * Prepare outgoing header.
 339          */
 340         setKeyHeader(wrappedHdr,
 341                 plugin.myGuid(),
 342                 unwrappedHdr.algorithm(),               // same as incoming
 343                 unwrappedHdr.keyClass(),                // same as incoming
 344                 unwrappedKeyAttrFlags,
 345                 unwrappedHdr.KeyUsage);
 346         wrappedHdr.LogicalKeySizeInBits = unwrappedHdr.LogicalKeySizeInBits;
 347         wrappedHdr.WrapAlgorithmId = Context.algorithm();       // true for null
 348                                                                                                                 // and non-Null
 349         wrappedHdr.StartDate = unwrappedHdr.StartDate;
 350         wrappedHdr.EndDate = unwrappedHdr.EndDate;
 351         wrappedHdr.Format = wrapFormat;
 352         if(isNullWrap) {
 353                 wrappedHdr.BlobType = CSSM_KEYBLOB_RAW;
 354         }
 355         else {
 356                 wrappedHdr.BlobType = CSSM_KEYBLOB_WRAPPED;
 357         }
 358
 359         /*
 360          * special cases - break out here for Apple Custom and OpenSSHv1
 361          */
 362         if(!isNullWrap) {
 363                 switch(wrapFormat) {
 364                         case CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM:
 365                                 try {
 366                                         WrapKeyCms(CCHandle,
 367                                                 Context,
 368                                                 AccessCred,
 369                                                 UnwrappedKey,
 370                                                 rawBlob,
 371                                                 allocdRawBlob,
 372                                                 DescriptiveData,
 373                                                 WrappedKey,
 374                                                 Privilege);
 375                                 }
 376                                 catch(...) {
 377                                         if(allocdRawBlob) {
 378                                                 freeCssmData(rawBlob, privAllocator);
 379                                         }
 380                                         throw;
 381                                 }
 382                                 if(allocdRawBlob) {
 383                                         freeCssmData(rawBlob, privAllocator);
 384                                 }
 385                                 return;
 386                         case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1:
 387                         {
 388                                 /*
 389                                  * 1. We don't have to worry about allocdRawBlob since this
 390                                  *    operation only works on reference keys and we did not
 391                                  *    obtain the raw blob from the BinaryKey.
 392                                  * 2. This is a redundant lookupRefKey, I know, but since
 393                                  *    that returns a reference, it would just be too messy to have
 394                                  *    the previous call be in the same scope as this.
 395                                  */
 396                                 BinaryKey &binKey = lookupRefKey(UnwrappedKey);
 397                                 WrapKeyOpenSSH1(CCHandle,
 398                                         Context,
 399                                         AccessCred,
 400                                         binKey,
 401                                         rawBlob,
 402                                         allocdRawBlob,
 403                                         DescriptiveData,
 404                                         WrappedKey,
 405                                         Privilege);
 406                                 return;
 407                         }
 408                         default:
 409                                 /* proceed to encrypt blob */
 410                                 break;
 411                 }
 412         }       /* !isNullWrap */
 413
 414
 415         /*
 416          * Generate wrapped blob. Careful, we need to conditionally free
 417          * rawBlob on error.
 418          */
 419         CssmData encryptedBlob;
 420         CssmData remData;
 421         WrappedKey.KeyData.Data = NULL;         // ignore possible incoming KeyData
 422         WrappedKey.KeyData.Length = 0;
 423
 424         try {
 425                 if(isNullWrap) {
 426                         /* copy raw blob to caller's wrappedKey */
 427                         copyCssmData(rawBlob,
 428                                 CssmData::overlay(WrappedKey.KeyData),
 429                                 normAllocator);
 430                         wrappedHdr.Format   = rawFormat;
 431                 }
 432                 else {
 433                         /* encrypt rawBlob using caller's context, then encode to
 434                          * WrappedKey.KeyData */
 435                         CSSM_SIZE bytesEncrypted;
 436                         EncryptData(CCHandle,
 437                                 Context,
 438                                 &rawBlob,                       // ClearBufs[]
 439                                 1,                                      // ClearBufCount
 440                                 &encryptedBlob,         // CipherBufs[],
 441                                 1,                                      // CipherBufCount,
 442                                 bytesEncrypted,
 443                                 remData,
 444                                 Privilege);
 445
 446                         // I'm not 100% sure about this....
 447                         assert(remData.Length == 0);
 448                         encryptedBlob.Length = bytesEncrypted;
 449                         WrappedKey.KeyData = encryptedBlob;
 450                         wrappedHdr.BlobType = CSSM_KEYBLOB_WRAPPED;
 451                         // OK to be zero or not present
 452                         wrappedHdr.WrapMode = Context.getInt(
 453                                 CSSM_ATTRIBUTE_MODE);
 454                 }
 455         }
 456         catch (...) {
 457                 errorLog0("WrapKey: EncryptData() threw exception\n");
 458                 if(allocdRawBlob) {
 459                         freeCssmData(rawBlob, privAllocator);
 460                 }
 461                 freeCssmData(remData,normAllocator);
 462                 throw;
 463         }
 464         if(allocdRawBlob) {
 465                 freeCssmData(rawBlob, privAllocator);
 466         }
 467         freeCssmData(remData, normAllocator);
 468 }
 469
 470 /*
 471  * Unwrap key function. Used for:
 472  *
 473  * -- Given key of BlobType CSSM_KEYBLOB_WRAPPED, decode and decrypt
 474  *    it, yielding a key in either raw or reference format. Unwrapping
 475  *    key may be either raw or reference. The context must match
 476  *    the unwrapping key (ALGCLASS_SYMMETRIC  or ALGCLASS_ASYMMETRIC).
 477  *
 478  *        Private keys are assumed to be PKCS8 encoded; session keys
 479  *    are assumed to be PKCS7 encoded.
 480  *
 481  * -- Convert a Raw key to a reference key (with no decrypting).
 482  *    This is called a NULL unwrap; no unwrapping key need be present in
 483  *    the context, but the context must be of class
 484  *    ALGCLASS_SYMMETRIC and algorithm ALGID_NONE.
 485  */
 486 void AppleCSPSession::UnwrapKey(
 487                 CSSM_CC_HANDLE CCHandle,
 488                 const Context &Context,
 489                 const CssmKey *PublicKey,
 490                 const CssmKey &WrappedKey,
 491                 uint32 KeyUsage,
 492                 uint32 KeyAttr,
 493                 const CssmData *KeyLabel,
 494                 const CSSM_RESOURCE_CONTROL_CONTEXT *CredAndAclEntry,
 495                 CssmKey &UnwrappedKey,
 496                 CssmData &DescriptiveData,
 497                 CSSM_PRIVILEGE Privilege)
 498 {
 499         bool                                    isNullUnwrap = false;
 500         CssmKey                                 *unwrappingKey = NULL;
 501         cspKeyType                              keyType;                                // CKT_Public, etc.
 502         CSSM_KEYBLOB_FORMAT             wrapFormat = WrappedKey.blobFormat();
 503
 504         /* obtain unwrapping key if present */
 505         unwrappingKey = Context.get<CssmKey>(CSSM_ATTRIBUTE_KEY);
 506         if(unwrappingKey == NULL) {
 507                 if((Context.algorithm() == CSSM_ALGID_NONE) &&
 508                    (Context.type() == CSSM_ALGCLASS_SYMMETRIC)) {
 509                                 // NULL unwrap, OK
 510                                 isNullUnwrap = true;
 511                 }
 512                 else {
 513                         errorLog0("UnwrapKey: missing wrapping key\n");
 514                         CssmError::throwMe(CSSMERR_CSP_MISSING_ATTR_KEY);
 515                 }
 516         }
 517
 518         /*
 519          * validate unwrappingKey
 520          */
 521         if(!isNullUnwrap) {
 522                 /* make sure unwrapping key type matches context */
 523                 CSSM_CONTEXT_TYPE unwrapType;
 524                 switch(unwrappingKey->KeyHeader.KeyClass) {
 525                         case CSSM_KEYCLASS_PUBLIC_KEY:
 526                         case CSSM_KEYCLASS_PRIVATE_KEY:
 527                                 unwrapType = CSSM_ALGCLASS_ASYMMETRIC;
 528                                 break;
 529                         case CSSM_KEYCLASS_SESSION_KEY:
 530                                 unwrapType = CSSM_ALGCLASS_SYMMETRIC;
 531                                 break;
 532                         default:
 533                                 errorLog0("UnwrapKey: bad class of wrappingKey\n");
 534                                 CssmError::throwMe(CSSMERR_CSP_INVALID_ATTR_KEY);
 535                 }
 536                 if(unwrapType != Context.type()) {
 537                         errorLog0("UnwrapKey: mismatch unwrappingKey/contextType\n");
 538                         CssmError::throwMe(CSSMERR_CSP_INVALID_CONTEXT);
 539                 }
 540                 if(Context.algorithm() == CSSM_ALGID_NONE) {
 541                         errorLog0("UnwrapKey: null wrap alg, non-null key\n");
 542                         CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 543                 }
 544                 cspValidateIntendedKeyUsage(&unwrappingKey->KeyHeader, CSSM_KEYUSE_UNWRAP);
 545                 cspVerifyKeyTimes(unwrappingKey->KeyHeader);
 546         }
 547
 548         /* validate WrappedKey */
 549         switch(WrappedKey.keyClass()) {
 550                 case CSSM_KEYCLASS_PUBLIC_KEY:
 551                         #if     !ALLOW_PUB_KEY_WRAP
 552                         if(!isNullUnwrap) {
 553                                 errorLog0("UnwrapKey: unwrap of public key illegal\n");
 554                                 CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 555                         }
 556                         #endif  /* ALLOW_PUB_KEY_WRAP */
 557                         keyType = CKT_Public;
 558                         break;
 559                 case CSSM_KEYCLASS_PRIVATE_KEY:
 560                         keyType = CKT_Private;
 561                         break;
 562                 case CSSM_KEYCLASS_SESSION_KEY:
 563                         keyType = CKT_Session;
 564                         break;
 565                 default:
 566                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 567         }
 568         if(isNullUnwrap) {
 569                 if(WrappedKey.blobType() != CSSM_KEYBLOB_RAW) {
 570                         errorLog0("UnwrapKey: expected raw blobType\n");
 571                         CssmError::throwMe(CSSMERR_CSP_KEY_BLOB_TYPE_INCORRECT);
 572                 }
 573         }
 574         else {
 575                 if(WrappedKey.blobType() != CSSM_KEYBLOB_WRAPPED) {
 576                         errorLog0("UnwrapKey: expected wrapped blobType\n");
 577                         CssmError::throwMe(CSSMERR_CSP_KEY_BLOB_TYPE_INCORRECT);
 578                 }
 579         }
 580
 581         /* validate requested storage and usage */
 582         cspKeyStorage keyStorage = cspParseKeyAttr(keyType, KeyAttr);
 583         switch(keyStorage) {
 584                 case CKS_Ref:
 585                 case CKS_Data:
 586                         break;          // OK
 587                 default:
 588                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEYATTR_MASK);
 589         }
 590         cspValidateKeyUsageBits(keyType,  KeyUsage);
 591
 592         /* prepare outgoing header */
 593         CssmKey::Header &unwrappedHdr = UnwrappedKey.header();
 594         const CssmKey::Header &wrappedHdr   = WrappedKey.header();
 595         setKeyHeader(unwrappedHdr,
 596                 plugin.myGuid(),
 597                 wrappedHdr.algorithm(),         // same as incoming
 598                 wrappedHdr.keyClass(),          // same as incoming
 599                 KeyAttr & ~KEY_ATTR_RETURN_MASK,
 600                 KeyUsage);
 601         unwrappedHdr.LogicalKeySizeInBits = wrappedHdr.LogicalKeySizeInBits;
 602         unwrappedHdr.StartDate = wrappedHdr.StartDate;
 603         unwrappedHdr.EndDate = wrappedHdr.EndDate;
 604         UnwrappedKey.KeyData.Data = NULL;       // ignore possible incoming KeyData
 605         UnwrappedKey.KeyData.Length = 0;
 606
 607         /* validate wrappedKey format */
 608         if(!isNullUnwrap) {
 609                 switch(wrapFormat) {
 610                         case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS7:
 611                                 if(WrappedKey.keyClass() != CSSM_KEYCLASS_SESSION_KEY) {
 612                                         /* this unwrapping style only for symmetric keys */
 613                                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 614                                 }
 615                                 break;
 616                         case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS8:
 617                         case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSL:
 618                                 if(WrappedKey.keyClass() != CSSM_KEYCLASS_PRIVATE_KEY) {
 619                                         /* these unwrapping styles only for private keys */
 620                                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 621                                 }
 622                                 break;
 623                         case CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM:
 624                                 UnwrapKeyCms(CCHandle,
 625                                                 Context,
 626                                                 WrappedKey,
 627                                                 CredAndAclEntry,
 628                                                 UnwrappedKey,
 629                                                 DescriptiveData,
 630                                                 Privilege,
 631                                                 keyStorage);
 632                                 return;
 633                         case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSH1:
 634                                 /* RSA private key, unwrap to ref key only */
 635                                 if(WrappedKey.keyClass() != CSSM_KEYCLASS_PRIVATE_KEY) {
 636                                         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 637                                 }
 638                                 if(WrappedKey.algorithm() != CSSM_ALGID_RSA) {
 639                                         CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 640                                 }
 641                                 if(keyStorage != CKS_Ref) {
 642                                         errorLog0("UNwrapKey: OPENSSH1 only wraps to reference key\n");
 643                                         CssmError::throwMe(CSSMERR_CSP_KEY_BLOB_TYPE_INCORRECT);
 644                                 }
 645                                 UnwrapKeyOpenSSH1(CCHandle,
 646                                                 Context,
 647                                                 WrappedKey,
 648                                                 CredAndAclEntry,
 649                                                 UnwrappedKey,
 650                                                 DescriptiveData,
 651                                                 Privilege,
 652                                                 keyStorage);
 653                                 return;
 654                         default:
 655                                 CssmError::throwMe(CSSMERR_CSP_INVALID_ATTR_WRAPPED_KEY_FORMAT);
 656                 }
 657         }
 658
 659         /* Get key blob, decoding and decrypting if necessary */
 660         CssmData decodedBlob;
 661         CssmData remData;
 662         try {
 663                 if(isNullUnwrap) {
 664                         /* simple copy of raw blob */
 665                         copyData(WrappedKey.KeyData,
 666                                 UnwrappedKey.KeyData,
 667                                 normAllocator);
 668                         unwrappedHdr.BlobType = CSSM_KEYBLOB_RAW;
 669                         unwrappedHdr.Format   = wrapFormat;
 670                 }
 671                 else {
 672                         decodedBlob = CssmData::overlay(WrappedKey.KeyData);
 673                         CSSM_SIZE bytesDecrypted;
 674                         CssmData *unwrapData =
 675                                 CssmData::overlay(&UnwrappedKey.KeyData);
 676
 677                         DecryptData(CCHandle,
 678                                 Context,
 679                                 &decodedBlob,           // CipherBufs[],
 680                                 1,                                      // CipherBufCount,
 681                                 unwrapData,                     // ClearBufs[]
 682                                 1,                                      // ClearBufCount
 683                                 bytesDecrypted,
 684                                 remData,
 685                                 Privilege);
 686
 687                         // I'm not 100% sure about this....
 688                         assert(remData.Length == 0);
 689                         UnwrappedKey.KeyData.Length = bytesDecrypted;
 690                         unwrappedHdr.BlobType = CSSM_KEYBLOB_RAW;
 691
 692                         /*
 693                          * Figure out various header fields from resulting blob
 694                          */
 695                         switch(wrapFormat) {
 696                                 case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS7:
 697                                         unwrappedHdr.Format =
 698                                                 CSSM_KEYBLOB_RAW_FORMAT_OCTET_STRING;
 699                                         if(unwrappedHdr.LogicalKeySizeInBits == 0) {
 700                                                 unwrappedHdr.LogicalKeySizeInBits =
 701                                                         (unsigned)(bytesDecrypted * 8);
 702                                         }
 703                                         /* app has to infer/know algorithm */
 704                                         break;
 705                                 case CSSM_KEYBLOB_WRAPPED_FORMAT_PKCS8:
 706                                         pkcs8InferKeyHeader(UnwrappedKey);
 707                                         break;
 708                                 case CSSM_KEYBLOB_WRAPPED_FORMAT_OPENSSL:
 709                                         /*
 710                                          * App told us key algorithm (in WrappedKey).
 711                                          * Infer format and key size.
 712                                          */
 713                                         opensslInferKeyHeader(UnwrappedKey);
 714                                         break;
 715                         }
 716                 }
 717         }
 718         catch (...) {
 719                 errorLog0("UnwrapKey: DecryptData() threw exception\n");
 720                 freeCssmData(remData, normAllocator);
 721                 throw;
 722         }
 723         freeCssmData(remData, normAllocator);
 724
 725         /*
 726          * One more thing: cook up a BinaryKey if caller wants a
 727          * reference key.
 728          */
 729         if(keyStorage == CKS_Ref) {
 730                 /*
 731                  * We have a key in raw format; convert to BinaryKey.
 732                  */
 733                 BinaryKey *binKey = NULL;
 734                 CSPKeyInfoProvider *provider = infoProvider(UnwrappedKey);
 735                 /* optional parameter-bearing key */
 736                 CssmKey *paramKey = Context.get<CssmKey>(CSSM_ATTRIBUTE_PARAM_KEY);
 737                 provider->CssmKeyToBinary(paramKey, UnwrappedKey.KeyHeader.KeyAttr, &binKey);
 738                 addRefKey(*binKey, UnwrappedKey);
 739                 delete provider;
 740         }
 741 }
 742