Security-54.tar.gz

[apple/security.git] / AppleCSP / DiffieHellman / DH_exchange.cpp

diff --git a/AppleCSP/DiffieHellman/DH_exchange.cpp b/AppleCSP/DiffieHellman/DH_exchange.cpp
new file mode 100644 (file)
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+++ b/AppleCSP/DiffieHellman/DH_exchange.cpp
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+/*
+ * Copyright (c) 2000-2002 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * The contents of this file constitute Original Code as defined in and are
+ * subject to the Apple Public Source License Version 1.2 (the 'License').
+ * You may not use this file except in compliance with the License. Please obtain
+ * a copy of the License at http://www.apple.com/publicsource and read it before
+ * using this file.
+ * 
+ * This Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
+ * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
+ * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
+ * specific language governing rights and limitations under the License.
+ */
+
+
+/*
+ * DH_exchange.cp - Diffie-Hellman key exchange
+ */
+ 
+#include "DH_exchange.h"
+#include <Security/cssmerr.h>
+#include <Security/utilities.h>
+#include "DH_utils.h"
+#include <strings.h>
+#include <open_ssl/opensslUtils/opensslUtils.h>
+
+void DeriveKey_DH (
+       const Context &context,
+       const CssmData &Param,                  // other's public key
+       CSSM_DATA *keyData,                             // mallocd by caller
+                                                                       // we fill in keyData->Length bytes
+       AppleCSPSession &session)
+{
+       bool mallocdKey;
+       size_t privSize;
+       
+       /* private DH key from context */
+       DH *privKey = contextToDhKey(context, session, CSSM_KEYUSE_DERIVE, 
+               mallocdKey);
+       privSize = DH_size(privKey);
+       if(privSize < keyData->Length) {
+               /* we've been asked for more bits than this key can generate */
+               CssmError::throwMe(CSSMERR_CSP_UNSUPPORTED_KEY_SIZE);
+       }
+       BIGNUM *pubKey = BN_bin2bn(Param.Data, Param.Length, NULL);
+       if(pubKey == NULL) {
+               CssmError::throwMe(CSSMERR_CSP_MEMORY_ERROR);
+       }
+       unsigned char *buf = (unsigned char *)session.malloc(privSize);
+       int rtn = DH_compute_key(buf, pubKey, privKey);
+       if(rtn >= 0) {
+               /*
+                * FIXME : I have not found a specification describing *which*
+                * bytes of the value we just computed we are supposed to
+                * use as the actual key bytes. We use the M.S. bytes.
+                */
+               memmove(keyData->Data, buf, keyData->Length);
+       }
+       if(mallocdKey) {
+               DH_free(privKey);
+       }
+       BN_free(pubKey);
+       session.free(buf);
+       if(rtn < 0) {
+               throwRsaDsa("DH_compute_key");
+       }
+}
+