Security-55163.44.tar.gz

[apple/security.git] / libsecurity_apple_csp / lib / DH_exchange.cpp

diff --git a/libsecurity_apple_csp/lib/DH_exchange.cpp b/libsecurity_apple_csp/lib/DH_exchange.cpp
new file mode 100644 (file)
index 0000000..ae5f1ee
--- /dev/null
+++ b/libsecurity_apple_csp/lib/DH_exchange.cpp
@@ -0,0 +1,118 @@
+/*
+ * 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 "DH_utils.h"
+#include "DH_keys.h"
+#include <strings.h>
+#include <opensslUtils/opensslUtils.h>
+
+void DeriveKey_DH (
+       const Context &context,
+       const CssmData &Param,                  // other's public key. may be empty
+       CSSM_DATA *keyData,                             // mallocd by caller
+                                                                       // we fill in keyData->Length bytes
+       AppleCSPSession &session)
+{
+       bool mallocdPrivKey;
+       size_t privSize;
+       
+       /* private DH key from context - required */
+       DH *privKey = contextToDhKey(context, session, CSSM_ATTRIBUTE_KEY,
+               CSSM_KEYCLASS_PRIVATE_KEY, CSSM_KEYUSE_DERIVE, mallocdPrivKey);
+       if(privKey == NULL) {
+               CssmError::throwMe(CSSMERR_CSP_MISSING_ATTR_KEY);
+       }
+       cspDhDebug("DeriveKey_DH, privKey %p", privKey);
+       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);
+       }
+       
+       /*
+        * Public key ("their" key) can come from two places:
+        * -- in the context as a CSSM_ATTRIBUTE_PUBLIC_KEY. This is how 
+        *    public keys in X509 format must be used in this function
+        * -- in the incoming Param, the raw unformatted (PKCS3) form 
+        */
+       bool mallocdPubKey = false;
+       BIGNUM *pubKeyBn = NULL;
+       bool allocdPubKeyBn = false;
+       DH *pubKey = contextToDhKey(context, session, CSSM_ATTRIBUTE_PUBLIC_KEY,
+               CSSM_KEYCLASS_PUBLIC_KEY, CSSM_KEYUSE_DERIVE, mallocdPubKey);
+       if(pubKey != NULL) {
+               if(pubKey->pub_key == NULL) {
+                       errorLog0("DeriveKey_DH: public key in context with no pub_key\n");
+                       CssmError::throwMe(CSSMERR_CSP_INVALID_KEY);
+               }
+               pubKeyBn = pubKey->pub_key;
+               cspDhDebug("DeriveKey_DH, pubKey from context %p", pubKey);
+       }
+       else {
+               if((Param.Data == NULL) || (Param.Length == 0)) {
+                       errorLog0("DeriveKey_DH: no pub_key, no Param\n");
+                       CssmError::throwMe(CSSMERR_CSP_INVALID_KEY);
+               }
+               pubKeyBn = BN_bin2bn(Param.Data, Param.Length, NULL);
+               if(pubKeyBn == NULL) {
+                       CssmError::throwMe(CSSMERR_CSP_MEMORY_ERROR);
+               }
+               allocdPubKeyBn = true;
+               cspDhDebug("DeriveKey_DH, no pubKey in context");
+       }
+       unsigned char *buf = (unsigned char *)session.malloc(privSize);
+       int rtn = DH_compute_key(buf, pubKeyBn, 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.
+                *
+                * Note that due to modulo arithmetic, we may have gotten fewer
+                * bytes than we asked for. If so, the caller will have
+                * to deal with that if they really need privSize bytes.
+                */
+               assert((uint32)rtn <= privSize);
+               uint32 toMove = keyData->Length;
+               if((uint32)rtn < toMove) {
+                       toMove = (uint32)rtn;
+               }
+               memmove(keyData->Data, buf, toMove);
+               keyData->Length = toMove;
+       }
+       if(mallocdPrivKey) {
+               DH_free(privKey);
+       }
+       if(mallocdPubKey) {
+               DH_free(pubKey);
+       }
+       if(allocdPubKeyBn) {
+               BN_free(pubKeyBn);
+       }
+       session.free(buf);
+       if(rtn <= 0) {
+               throwRsaDsa("DH_compute_key");
+       }
+}
+