src/dbcrypto.cpp

   1 /*
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   3  *
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   8  * Version 2.0 (the 'License'). You may not use this file except in
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  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
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  23
  24
  25 //
  26 // dbcrypto - cryptographic core for database and key blob cryptography
  27 //
  28 #include "dbcrypto.h"
  29 #include <securityd_client/ssblob.h>
  30 #include "server.h"             // just for Server::csp()
  31 #include <security_cdsa_client/genkey.h>
  32 #include <security_cdsa_client/cryptoclient.h>
  33 #include <security_cdsa_client/keyclient.h>
  34 #include <security_cdsa_client/macclient.h>
  35 #include <security_cdsa_client/wrapkey.h>
  36 #include <security_cdsa_utilities/cssmendian.h>
  37
  38 using namespace CssmClient;
  39 using LowLevelMemoryUtilities::fieldOffsetOf;
  40
  41
  42 //
  43 // The CryptoCore constructor doesn't do anything interesting.
  44 // It just initializes us to "empty".
  45 //
  46 DatabaseCryptoCore::DatabaseCryptoCore() : mHaveMaster(false), mIsValid(false)
  47 {
  48 }
  49
  50 DatabaseCryptoCore::~DatabaseCryptoCore()
  51 {
  52     // key objects take care of themselves
  53 }
  54
  55
  56 //
  57 // Forget the secrets
  58 //
  59 void DatabaseCryptoCore::invalidate()
  60 {
  61         mMasterKey.release();
  62         mHaveMaster = false;
  63
  64         mEncryptionKey.release();
  65         mSigningKey.release();
  66         mIsValid = false;
  67 }
  68
  69
  70 //
  71 // Generate new secrets for this crypto core.
  72 //
  73 void DatabaseCryptoCore::generateNewSecrets()
  74 {
  75     // create a random DES3 key
  76     GenerateKey desGenerator(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE, 24 * 8);
  77     mEncryptionKey = desGenerator(KeySpec(CSSM_KEYUSE_WRAP | CSSM_KEYUSE_UNWRAP,
  78         CSSM_KEYATTR_RETURN_DATA | CSSM_KEYATTR_EXTRACTABLE));
  79
  80     // create a random 20 byte HMAC/SHA1 signing "key"
  81     GenerateKey signGenerator(Server::csp(), CSSM_ALGID_SHA1HMAC,
  82         sizeof(DbBlob::PrivateBlob::SigningKey) * 8);
  83     mSigningKey = signGenerator(KeySpec(CSSM_KEYUSE_SIGN | CSSM_KEYUSE_VERIFY,
  84         CSSM_KEYATTR_RETURN_DATA | CSSM_KEYATTR_EXTRACTABLE));
  85
  86     // secrets established
  87     mIsValid = true;
  88 }
  89
  90
  91 CssmClient::Key DatabaseCryptoCore::masterKey()
  92 {
  93         assert(mHaveMaster);
  94         return mMasterKey;
  95 }
  96
  97
  98 //
  99 // Establish the master secret as derived from a passphrase passed in.
 100 // If a DbBlob is passed, take the salt from it and remember it.
 101 // If a NULL DbBlob is passed, generate a new (random) salt.
 102 // Note that the passphrase is NOT remembered; only the master key.
 103 //
 104 void DatabaseCryptoCore::setup(const DbBlob *blob, const CssmData &passphrase)
 105 {
 106         if (blob)
 107                 memcpy(mSalt, blob->salt, sizeof(mSalt));
 108         else
 109                 Server::active().random(mSalt);
 110     mMasterKey = deriveDbMasterKey(passphrase);
 111         mHaveMaster = true;
 112 }
 113
 114
 115 //
 116 // Establish the master secret directly from a master key passed in.
 117 // We will copy the KeyData (caller still owns its copy).
 118 // Blob/salt handling as above.
 119 //
 120 void DatabaseCryptoCore::setup(const DbBlob *blob, CssmClient::Key master)
 121 {
 122         // pre-screen the key
 123         CssmKey::Header header = master.header();
 124         if (header.keyClass() != CSSM_KEYCLASS_SESSION_KEY)
 125                 CssmError::throwMe(CSSMERR_CSP_INVALID_KEY_CLASS);
 126         if (header.algorithm() != CSSM_ALGID_3DES_3KEY_EDE)
 127                 CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 128
 129         // accept it
 130         if (blob)
 131                 memcpy(mSalt, blob->salt, sizeof(mSalt));
 132         else
 133                 Server::active().random(mSalt);
 134         mMasterKey = master;
 135         mHaveMaster = true;
 136 }
 137
 138 bool DatabaseCryptoCore::get_encryption_key(CssmOwnedData &data)
 139 {
 140     bool result = false;
 141     if (isValid()) {
 142         data = mEncryptionKey->keyData();
 143         result = true;
 144     }
 145     return result;
 146 }
 147
 148 //
 149 // Given a putative passphrase, determine whether that passphrase
 150 // properly generates the database's master secret.
 151 // Return a boolean accordingly. Do not change our state.
 152 // The database must have a master secret (to compare with).
 153 // Note that any errors thrown by the cryptography here will actually
 154 // throw out of validatePassphrase, since they "should not happen" and
 155 // thus indicate a problem *beyond* (just) a bad passphrase.
 156 //
 157 bool DatabaseCryptoCore::validatePassphrase(const CssmData &passphrase)
 158 {
 159         assert(hasMaster());
 160         CssmClient::Key master = deriveDbMasterKey(passphrase);
 161
 162         // to compare master with mMaster, see if they encrypt alike
 163         StringData probe
 164                 ("Now is the time for all good processes to come to the aid of their kernel.");
 165         CssmData noRemainder((void *)1, 0);     // no cipher overflow
 166         Encrypt cryptor(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE);
 167         cryptor.mode(CSSM_ALGMODE_CBCPadIV8);
 168         cryptor.padding(CSSM_PADDING_PKCS1);
 169         uint8 iv[8];    // leave uninitialized; pseudo-random is cool
 170         cryptor.initVector(CssmData::wrap(iv));
 171
 172         cryptor.key(master);
 173         CssmAutoData cipher1(Server::csp().allocator());
 174         cryptor.encrypt(probe, cipher1.get(), noRemainder);
 175
 176         cryptor.key(mMasterKey);
 177         CssmAutoData cipher2(Server::csp().allocator());
 178         cryptor.encrypt(probe, cipher2.get(), noRemainder);
 179
 180         return cipher1 == cipher2;
 181 }
 182
 183
 184 //
 185 // Encode a database blob from the core.
 186 //
 187 DbBlob *DatabaseCryptoCore::encodeCore(const DbBlob &blobTemplate,
 188     const CssmData &publicAcl, const CssmData &privateAcl) const
 189 {
 190     assert(isValid());          // must have secrets to work from
 191
 192     // make a new IV
 193     uint8 iv[8];
 194     Server::active().random(iv);
 195
 196     // build the encrypted section blob
 197     CssmData &encryptionBits = *mEncryptionKey;
 198     CssmData &signingBits = *mSigningKey;
 199     CssmData incrypt[3];
 200     incrypt[0] = encryptionBits;
 201     incrypt[1] = signingBits;
 202     incrypt[2] = privateAcl;
 203     CssmData cryptoBlob, remData;
 204     Encrypt cryptor(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE);
 205     cryptor.mode(CSSM_ALGMODE_CBCPadIV8);
 206     cryptor.padding(CSSM_PADDING_PKCS1);
 207     cryptor.key(mMasterKey);
 208     CssmData ivd(iv, sizeof(iv)); cryptor.initVector(ivd);
 209     cryptor.encrypt(incrypt, 3, &cryptoBlob, 1, remData);
 210
 211     // allocate the final DbBlob, uh, blob
 212     size_t length = sizeof(DbBlob) + publicAcl.length() + cryptoBlob.length();
 213     DbBlob *blob = Allocator::standard().malloc<DbBlob>(length);
 214
 215     // assemble the DbBlob
 216     memset(blob, 0x7d, sizeof(DbBlob)); // deterministically fill any alignment gaps
 217     blob->initialize();
 218     blob->randomSignature = blobTemplate.randomSignature;
 219     blob->sequence = blobTemplate.sequence;
 220     blob->params = blobTemplate.params;
 221         memcpy(blob->salt, mSalt, sizeof(blob->salt));
 222     memcpy(blob->iv, iv, sizeof(iv));
 223     memcpy(blob->publicAclBlob(), publicAcl, publicAcl.length());
 224     blob->startCryptoBlob = sizeof(DbBlob) + publicAcl.length();
 225     memcpy(blob->cryptoBlob(), cryptoBlob, cryptoBlob.length());
 226     blob->totalLength = blob->startCryptoBlob + cryptoBlob.length();
 227
 228     // sign the blob
 229     CssmData signChunk[] = {
 230                 CssmData(blob->data(), fieldOffsetOf(&DbBlob::blobSignature)),
 231                 CssmData(blob->publicAclBlob(), publicAcl.length() + cryptoBlob.length())
 232         };
 233     CssmData signature(blob->blobSignature, sizeof(blob->blobSignature));
 234     GenerateMac signer(Server::csp(), CSSM_ALGID_SHA1HMAC_LEGACY);
 235     signer.key(mSigningKey);
 236     signer.sign(signChunk, 2, signature);
 237     assert(signature.length() == sizeof(blob->blobSignature));
 238
 239     // all done. Clean up
 240     Server::csp()->allocator().free(cryptoBlob);
 241     return blob;
 242 }
 243
 244
 245 //
 246 // Decode a database blob into the core.
 247 // Throws exceptions if decoding fails.
 248 // Memory returned in privateAclBlob is allocated and becomes owned by caller.
 249 //
 250 void DatabaseCryptoCore::decodeCore(const DbBlob *blob, void **privateAclBlob)
 251 {
 252         assert(mHaveMaster);    // must have master key installed
 253
 254     // try to decrypt the cryptoblob section
 255     Decrypt decryptor(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE);
 256     decryptor.mode(CSSM_ALGMODE_CBCPadIV8);
 257     decryptor.padding(CSSM_PADDING_PKCS1);
 258     decryptor.key(mMasterKey);
 259     CssmData ivd = CssmData::wrap(blob->iv); decryptor.initVector(ivd);
 260     CssmData cryptoBlob = CssmData::wrap(blob->cryptoBlob(), blob->cryptoBlobLength());
 261     CssmData decryptedBlob, remData;
 262     decryptor.decrypt(cryptoBlob, decryptedBlob, remData);
 263     DbBlob::PrivateBlob *privateBlob = decryptedBlob.interpretedAs<DbBlob::PrivateBlob>();
 264
 265     // tentatively establish keys
 266     mEncryptionKey = makeRawKey(privateBlob->encryptionKey,
 267         sizeof(privateBlob->encryptionKey), CSSM_ALGID_3DES_3KEY_EDE,
 268         CSSM_KEYUSE_WRAP | CSSM_KEYUSE_UNWRAP);
 269     mSigningKey = makeRawKey(privateBlob->signingKey,
 270         sizeof(privateBlob->signingKey), CSSM_ALGID_SHA1HMAC,
 271         CSSM_KEYUSE_SIGN | CSSM_KEYUSE_VERIFY);
 272
 273     // verify signature on the whole blob
 274     CssmData signChunk[] = {
 275                 CssmData::wrap(blob->data(), fieldOffsetOf(&DbBlob::blobSignature)),
 276         CssmData::wrap(blob->publicAclBlob(), blob->publicAclBlobLength() + blob->cryptoBlobLength())
 277         };
 278     CSSM_ALGORITHMS verifyAlgorithm = CSSM_ALGID_SHA1HMAC;
 279 #if defined(COMPAT_OSX_10_0)
 280     if (blob->version() == blob->version_MacOS_10_0)
 281         verifyAlgorithm = CSSM_ALGID_SHA1HMAC_LEGACY;   // BSafe bug compatibility
 282 #endif
 283     VerifyMac verifier(Server::csp(), verifyAlgorithm);
 284     verifier.key(mSigningKey);
 285     verifier.verify(signChunk, 2, CssmData::wrap(blob->blobSignature));
 286
 287     // all checks out; start extracting fields
 288     if (privateAclBlob) {
 289         // extract private ACL blob as a separately allocated area
 290         uint32 blobLength = decryptedBlob.length() - sizeof(DbBlob::PrivateBlob);
 291         *privateAclBlob = Allocator::standard().malloc(blobLength);
 292         memcpy(*privateAclBlob, privateBlob->privateAclBlob(), blobLength);
 293     }
 294
 295     // secrets have been established
 296     mIsValid = true;
 297     Allocator::standard().free(privateBlob);
 298 }
 299
 300
 301 //
 302 // Make another DatabaseCryptoCore's operational secrets our own.
 303 // Intended for keychain synchronization.
 304 //
 305 void DatabaseCryptoCore::importSecrets(const DatabaseCryptoCore &src)
 306 {
 307         assert(src.isValid());  // must have called src.decodeCore() first
 308         assert(hasMaster());
 309         mEncryptionKey = src.mEncryptionKey;
 310         mSigningKey = src.mSigningKey;
 311     mIsValid = true;
 312 }
 313
 314 //
 315 // Encode a key blob
 316 //
 317 KeyBlob *DatabaseCryptoCore::encodeKeyCore(const CssmKey &inKey,
 318     const CssmData &publicAcl, const CssmData &privateAcl,
 319         bool inTheClear) const
 320 {
 321     CssmKey key = inKey;
 322         uint8 iv[8];
 323         CssmKey wrappedKey;
 324
 325         if(inTheClear && (privateAcl.Length != 0)) {
 326                 /* can't store private ACL component in the clear */
 327                 CssmError::throwMe(CSSMERR_DL_INVALID_ACCESS_CREDENTIALS);
 328         }
 329
 330     // extract and hold some header bits the CSP does not want to see
 331     uint32 heldAttributes = key.attributes() & managedAttributes;
 332     key.clearAttribute(managedAttributes);
 333         key.setAttribute(forcedAttributes);
 334
 335         if(inTheClear) {
 336                 /* NULL wrap of public key */
 337                 WrapKey wrap(Server::csp(), CSSM_ALGID_NONE);
 338                 wrap(key, wrappedKey, NULL);
 339         }
 340         else {
 341                 assert(isValid());              // need our database secrets
 342
 343                 // create new IV
 344                 Server::active().random(iv);
 345
 346            // use a CMS wrap to encrypt the key
 347                 WrapKey wrap(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE);
 348                 wrap.key(mEncryptionKey);
 349                 wrap.mode(CSSM_ALGMODE_CBCPadIV8);
 350                 wrap.padding(CSSM_PADDING_PKCS1);
 351                 CssmData ivd(iv, sizeof(iv)); wrap.initVector(ivd);
 352                 wrap.add(CSSM_ATTRIBUTE_WRAPPED_KEY_FORMAT,
 353                         uint32(CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM));
 354                 wrap(key, wrappedKey, &privateAcl);
 355     }
 356
 357     // stick the held attribute bits back in
 358         key.clearAttribute(forcedAttributes);
 359     key.setAttribute(heldAttributes);
 360
 361     // allocate the final KeyBlob, uh, blob
 362     size_t length = sizeof(KeyBlob) + publicAcl.length() + wrappedKey.length();
 363     KeyBlob *blob = Allocator::standard().malloc<KeyBlob>(length);
 364
 365     // assemble the KeyBlob
 366     memset(blob, 0, sizeof(KeyBlob));   // fill alignment gaps
 367     blob->initialize();
 368         if(!inTheClear) {
 369                 memcpy(blob->iv, iv, sizeof(iv));
 370         }
 371     blob->header = key.header();
 372         h2ni(blob->header);     // endian-correct the header
 373     blob->wrappedHeader.blobType = wrappedKey.blobType();
 374     blob->wrappedHeader.blobFormat = wrappedKey.blobFormat();
 375     blob->wrappedHeader.wrapAlgorithm = wrappedKey.wrapAlgorithm();
 376     blob->wrappedHeader.wrapMode = wrappedKey.wrapMode();
 377     memcpy(blob->publicAclBlob(), publicAcl, publicAcl.length());
 378     blob->startCryptoBlob = sizeof(KeyBlob) + publicAcl.length();
 379     memcpy(blob->cryptoBlob(), wrappedKey.data(), wrappedKey.length());
 380     blob->totalLength = blob->startCryptoBlob + wrappedKey.length();
 381
 382         if(inTheClear) {
 383                 /* indicate that this is cleartext for decoding */
 384                 blob->setClearTextSignature();
 385         }
 386         else {
 387                 // sign the blob
 388                 CssmData signChunk[] = {
 389                         CssmData(blob->data(), fieldOffsetOf(&KeyBlob::blobSignature)),
 390                         CssmData(blob->publicAclBlob(), blob->publicAclBlobLength() + blob->cryptoBlobLength())
 391                 };
 392                 CssmData signature(blob->blobSignature, sizeof(blob->blobSignature));
 393                 GenerateMac signer(Server::csp(), CSSM_ALGID_SHA1HMAC_LEGACY);  //@@@!!! CRUD
 394                 signer.key(mSigningKey);
 395                 signer.sign(signChunk, 2, signature);
 396                 assert(signature.length() == sizeof(blob->blobSignature));
 397     }
 398
 399     // all done. Clean up
 400     Server::csp()->allocator().free(wrappedKey);
 401     return blob;
 402 }
 403
 404
 405 //
 406 // Decode a key blob
 407 //
 408 void DatabaseCryptoCore::decodeKeyCore(KeyBlob *blob,
 409     CssmKey &key, void * &pubAcl, void * &privAcl) const
 410 {
 411     // Assemble the encrypted blob as a CSSM "wrapped key"
 412     CssmKey wrappedKey;
 413     wrappedKey.KeyHeader = blob->header;
 414         h2ni(wrappedKey.KeyHeader);
 415     wrappedKey.blobType(blob->wrappedHeader.blobType);
 416     wrappedKey.blobFormat(blob->wrappedHeader.blobFormat);
 417     wrappedKey.wrapAlgorithm(blob->wrappedHeader.wrapAlgorithm);
 418     wrappedKey.wrapMode(blob->wrappedHeader.wrapMode);
 419     wrappedKey.KeyData = CssmData(blob->cryptoBlob(), blob->cryptoBlobLength());
 420
 421         bool inTheClear = blob->isClearText();
 422         if(!inTheClear) {
 423                 // verify signature (check against corruption)
 424                 assert(isValid());              // need our database secrets
 425                 CssmData signChunk[] = {
 426                         CssmData::wrap(blob, fieldOffsetOf(&KeyBlob::blobSignature)),
 427                         CssmData(blob->publicAclBlob(), blob->publicAclBlobLength() + blob->cryptoBlobLength())
 428                 };
 429                 CSSM_ALGORITHMS verifyAlgorithm = CSSM_ALGID_SHA1HMAC;
 430         #if defined(COMPAT_OSX_10_0)
 431                 if (blob->version() == blob->version_MacOS_10_0)
 432                         verifyAlgorithm = CSSM_ALGID_SHA1HMAC_LEGACY;   // BSafe bug compatibility
 433         #endif
 434                 VerifyMac verifier(Server::csp(), verifyAlgorithm);
 435                 verifier.key(mSigningKey);
 436                 CssmData signature(blob->blobSignature, sizeof(blob->blobSignature));
 437                 verifier.verify(signChunk, 2, signature);
 438     }
 439         /* else signature indicates cleartext */
 440
 441     // extract and hold some header bits the CSP does not want to see
 442     uint32 heldAttributes = n2h(blob->header.attributes()) & managedAttributes;
 443
 444         CssmData privAclData;
 445         if(inTheClear) {
 446                 /* NULL unwrap */
 447                 UnwrapKey unwrap(Server::csp(), CSSM_ALGID_NONE);
 448                 wrappedKey.clearAttribute(managedAttributes);    //@@@ shouldn't be needed(?)
 449                 unwrap(wrappedKey,
 450                         KeySpec(n2h(blob->header.usage()),
 451                                 (n2h(blob->header.attributes()) & ~managedAttributes) | forcedAttributes),
 452                         key, &privAclData);
 453         }
 454         else {
 455                 // decrypt the key using an unwrapping operation
 456                 UnwrapKey unwrap(Server::csp(), CSSM_ALGID_3DES_3KEY_EDE);
 457                 unwrap.key(mEncryptionKey);
 458                 unwrap.mode(CSSM_ALGMODE_CBCPadIV8);
 459                 unwrap.padding(CSSM_PADDING_PKCS1);
 460                 CssmData ivd(blob->iv, sizeof(blob->iv)); unwrap.initVector(ivd);
 461                 unwrap.add(CSSM_ATTRIBUTE_WRAPPED_KEY_FORMAT,
 462                         uint32(CSSM_KEYBLOB_WRAPPED_FORMAT_APPLE_CUSTOM));
 463                 wrappedKey.clearAttribute(managedAttributes);    //@@@ shouldn't be needed(?)
 464                 unwrap(wrappedKey,
 465                         KeySpec(n2h(blob->header.usage()),
 466                                 (n2h(blob->header.attributes()) & ~managedAttributes) | forcedAttributes),
 467                         key, &privAclData);
 468     }
 469
 470     // compare retrieved key headers with blob headers (sanity check)
 471     // @@@ this should probably be checked over carefully
 472     CssmKey::Header &real = key.header();
 473     CssmKey::Header &incoming = blob->header;
 474         n2hi(incoming);
 475
 476     if (real.HeaderVersion != incoming.HeaderVersion ||
 477         real.cspGuid() != incoming.cspGuid())
 478         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY);
 479     if (real.algorithm() != incoming.algorithm())
 480         CssmError::throwMe(CSSMERR_CSP_INVALID_ALGORITHM);
 481
 482     // re-insert held bits
 483     key.header().KeyAttr |= heldAttributes;
 484
 485         if(inTheClear && (real.keyClass() != CSSM_KEYCLASS_PUBLIC_KEY)) {
 486                 /* Spoof - cleartext KeyBlob passed off as private key */
 487         CssmError::throwMe(CSSMERR_CSP_INVALID_KEY);
 488         }
 489
 490     // got a valid key: return the pieces
 491     pubAcl = blob->publicAclBlob();             // points into blob (shared)
 492     privAcl = privAclData;                              // was allocated by CSP decrypt, else NULL for
 493                                                                                 // cleatext keys
 494     // key was set by unwrap operation
 495 }
 496
 497
 498 //
 499 // Derive the blob-specific database blob encryption key from the passphrase and the salt.
 500 //
 501 CssmClient::Key DatabaseCryptoCore::deriveDbMasterKey(const CssmData &passphrase) const
 502 {
 503     // derive an encryption key and IV from passphrase and salt
 504     CssmClient::DeriveKey makeKey(Server::csp(),
 505         CSSM_ALGID_PKCS5_PBKDF2, CSSM_ALGID_3DES_3KEY_EDE, 24 * 8);
 506     makeKey.iterationCount(1000);
 507         CssmData salt = CssmData::wrap(mSalt);
 508     makeKey.salt(salt);
 509     CSSM_PKCS5_PBKDF2_PARAMS params;
 510     params.Passphrase = passphrase;
 511     params.PseudoRandomFunction = CSSM_PKCS5_PBKDF2_PRF_HMAC_SHA1;
 512         CssmData paramData = CssmData::wrap(params);
 513     return makeKey(&paramData, KeySpec(CSSM_KEYUSE_ENCRYPT | CSSM_KEYUSE_DECRYPT,
 514         CSSM_KEYATTR_RETURN_DATA | CSSM_KEYATTR_EXTRACTABLE));
 515 }
 516
 517
 518 //
 519 // Turn raw keybits into a symmetric key in the CSP
 520 //
 521 CssmClient::Key DatabaseCryptoCore::makeRawKey(void *data, size_t length,
 522     CSSM_ALGORITHMS algid, CSSM_KEYUSE usage)
 523 {
 524     // build a fake key
 525     CssmKey key;
 526     key.header().BlobType = CSSM_KEYBLOB_RAW;
 527     key.header().Format = CSSM_KEYBLOB_RAW_FORMAT_OCTET_STRING;
 528     key.header().AlgorithmId = algid;
 529     key.header().KeyClass = CSSM_KEYCLASS_SESSION_KEY;
 530     key.header().KeyUsage = usage;
 531     key.header().KeyAttr = 0;
 532     key.KeyData = CssmData(data, length);
 533
 534     // unwrap it into the CSP (but keep it raw)
 535     UnwrapKey unwrap(Server::csp(), CSSM_ALGID_NONE);
 536     CssmKey unwrappedKey;
 537     CssmData descriptiveData;
 538     unwrap(key,
 539         KeySpec(CSSM_KEYUSE_ANY, CSSM_KEYATTR_RETURN_DATA | CSSM_KEYATTR_EXTRACTABLE),
 540         unwrappedKey, &descriptiveData, NULL);
 541     return CssmClient::Key(Server::csp(), unwrappedKey);
 542 }