Introduce soter_wipe() function

Themis.xcodeproj/project.pbxproj

@@ -198,6 +198,10 @@
 		9F4A2622223ABEF2005CB63A /* sym_enc_message.c in Sources */ = {isa = PBXBuildFile; fileRef = 9F4A2431223A74AF005CB63A /* sym_enc_message.c */; };
 		9F5391F12293F2D90051DA66 /* portable_endian.h in Headers */ = {isa = PBXBuildFile; fileRef = 9F5391F02293F2D90051DA66 /* portable_endian.h */; };
 		9F5391F22293F2D90051DA66 /* portable_endian.h in Headers */ = {isa = PBXBuildFile; fileRef = 9F5391F02293F2D90051DA66 /* portable_endian.h */; };
+		9F98F32522CCEA5D008E14E6 /* soter_wipe.h in Headers */ = {isa = PBXBuildFile; fileRef = 9F98F32422CCEA5D008E14E6 /* soter_wipe.h */; };
+		9F98F32622CCEA5D008E14E6 /* soter_wipe.h in Headers */ = {isa = PBXBuildFile; fileRef = 9F98F32422CCEA5D008E14E6 /* soter_wipe.h */; };
+		9F98F32822CCEB0E008E14E6 /* soter_wipe.c in Sources */ = {isa = PBXBuildFile; fileRef = 9F98F32722CCEB0E008E14E6 /* soter_wipe.c */; };
+		9F98F32922CCEB0E008E14E6 /* soter_wipe.c in Sources */ = {isa = PBXBuildFile; fileRef = 9F98F32722CCEB0E008E14E6 /* soter_wipe.c */; };
 		9FBD853D223BFB5E009EAEB3 /* openssl.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9FBD853C223BFB5E009EAEB3 /* openssl.framework */; };
 /* End PBXBuildFile section */
 
@@ -400,6 +404,8 @@
 		9F4A24C2223A8FA8005CB63A /* smessage.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = smessage.h; path = "src/wrappers/themis/Obj-C/objcthemis/smessage.h"; sourceTree = "<group>"; };
 		9F4A24C3223A8FA8005CB63A /* scell_token.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = scell_token.h; path = "src/wrappers/themis/Obj-C/objcthemis/scell_token.h"; sourceTree = "<group>"; };
 		9F5391F02293F2D90051DA66 /* portable_endian.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = portable_endian.h; path = src/soter/portable_endian.h; sourceTree = "<group>"; };
+		9F98F32422CCEA5D008E14E6 /* soter_wipe.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = soter_wipe.h; path = src/soter/soter_wipe.h; sourceTree = "<group>"; };
+		9F98F32722CCEB0E008E14E6 /* soter_wipe.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; name = soter_wipe.c; path = src/soter/openssl/soter_wipe.c; sourceTree = "<group>"; };
 		9FBD853C223BFB5E009EAEB3 /* openssl.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = openssl.framework; path = Carthage/Build/iOS/openssl.framework; sourceTree = "<group>"; };
 		9FD4C3522260D41700132A88 /* soter_api.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = soter_api.h; path = src/soter/soter_api.h; sourceTree = "<group>"; };
 		9FD4C3532260D43B00132A88 /* themis_api.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = themis_api.h; path = src/themis/themis_api.h; sourceTree = "<group>"; };
@@ -471,6 +477,7 @@
 				9F4A2344223A73B0005CB63A /* soter_sign_rsa.h */,
 				9F4A2351223A73B1005CB63A /* soter_sign.c */,
 				9F4A2356223A73B1005CB63A /* soter_sym.h */,
+				9F98F32422CCEA5D008E14E6 /* soter_wipe.h */,
 				9F4A2346223A73B0005CB63A /* soter_t.h */,
 				9F4A2345223A73B0005CB63A /* soter.h */,
 			);
@@ -497,6 +504,7 @@
 				9F4A2394223A7426005CB63A /* soter_sym.c */,
 				9F4A2393223A7426005CB63A /* soter_verify_ecdsa.c */,
 				9F4A238D223A7426005CB63A /* soter_verify_rsa.c */,
+				9F98F32722CCEB0E008E14E6 /* soter_wipe.c */,
 			);
 			name = openssl;
 			sourceTree = "<group>";
@@ -659,6 +667,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				9F5391F22293F2D90051DA66 /* portable_endian.h in Headers */,
+				9F98F32622CCEA5D008E14E6 /* soter_wipe.h in Headers */,
 				9F00E8E0223C19E000EC1EF3 /* themis.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -668,6 +677,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				9F5391F12293F2D90051DA66 /* portable_endian.h in Headers */,
+				9F98F32522CCEA5D008E14E6 /* soter_wipe.h in Headers */,
 				9F00E8DF223C19D900EC1EF3 /* themis.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -796,6 +806,7 @@
 				9F00E927223C1AC000EC1EF3 /* soter_rsa_common.c in Sources */,
 				9F00E928223C1AC000EC1EF3 /* soter_rsa_key_pair_gen.c in Sources */,
 				9F00E929223C1AC000EC1EF3 /* soter_rsa_key.c in Sources */,
+				9F98F32922CCEB0E008E14E6 /* soter_wipe.c in Sources */,
 				9F00E92A223C1AC000EC1EF3 /* soter_sign_ecdsa.c in Sources */,
 				9F00E92B223C1AC000EC1EF3 /* soter_sign_rsa.c in Sources */,
 				9F00E92C223C1AC000EC1EF3 /* soter_sym.c in Sources */,
@@ -885,6 +896,7 @@
 				9F4A260A223ABECC005CB63A /* soter_rsa_common.c in Sources */,
 				9F4A260B223ABECC005CB63A /* soter_rsa_key_pair_gen.c in Sources */,
 				9F4A260C223ABECC005CB63A /* soter_rsa_key.c in Sources */,
+				9F98F32822CCEB0E008E14E6 /* soter_wipe.c in Sources */,
 				9F4A260D223ABECC005CB63A /* soter_sign_ecdsa.c in Sources */,
 				9F4A260E223ABECC005CB63A /* soter_sign_rsa.c in Sources */,
 				9F4A260F223ABECC005CB63A /* soter_sym.c in Sources */,

src/soter/boringssl/soter_wipe.c

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2019 Cossack Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "soter/soter_wipe.h"
+
+#include <openssl/crypto.h>
+
+soter_status_t soter_wipe(void* data, size_t length)
+{
+    if (!data) {
+        return SOTER_INVALID_PARAMETER;
+    }
+
+    OPENSSL_cleanse(data, length);
+
+    return SOTER_SUCCESS;
+}

src/soter/openssl/soter_wipe.c

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2019 Cossack Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "soter/soter_wipe.h"
+
+#include <openssl/crypto.h>
+
+soter_status_t soter_wipe(void* data, size_t length)
+{
+    if (!data) {
+        return SOTER_INVALID_PARAMETER;
+    }
+
+    OPENSSL_cleanse(data, length);
+
+    return SOTER_SUCCESS;
+}

src/soter/soter.h

@@ -44,6 +44,7 @@
 #include <soter/soter_rand.h>
 #include <soter/soter_rsa_key_pair_gen.h>
 #include <soter/soter_sym.h>
+#include <soter/soter_wipe.h>
 
 /**@}*/
 #endif /* SOTER_H */

src/soter/soter_hmac.c

@@ -19,6 +19,7 @@
 #include <string.h>
 
 #include "soter/soter_t.h"
+#include "soter/soter_wipe.h"
 
 static size_t hash_block_size(soter_hash_algo_t algo)
 {
@@ -97,7 +98,7 @@ soter_status_t soter_hmac_init(soter_hmac_ctx_t* hmac_ctx,
         return res;
     }
 
-    memset(i_key_pad, 0, sizeof(i_key_pad));
+    soter_wipe(i_key_pad, sizeof(i_key_pad));
 
     for (i = 0; i < block_size; i++) {
         hmac_ctx->o_key_pad[i] ^= 0x5c;

src/soter/soter_kdf.c

@@ -19,6 +19,7 @@
 #include <string.h>
 
 #include "soter/soter_t.h"
+#include "soter/soter_wipe.h"
 
 #define MAX_HMAC_SIZE 64 /* For HMAC-SHA512 */
 #define MIN_VAL(_X_, _Y_) ((_X_ < _Y_) ? (_X_) : (_Y_))
@@ -105,7 +106,7 @@ soter_status_t soter_kdf(const void* key,
 
 err:
 
-    memset(out, 0, sizeof(out));
+    soter_wipe(out, sizeof(out));
 
     soter_hmac_destroy(hmac_ctx);
 

src/soter/soter_wipe.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2019 Cossack Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SOTER_WIPE_H
+#define SOTER_WIPE_H
+
+#include <soter/soter_api.h>
+#include <soter/soter_error.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Securely erases sensitive data from memory.
+ *
+ * Use this function to wipe sensitive data (e.g., passwords, private keys)
+ * after you don't need it anymore. This function call will not be optimized
+ * out by the compiler.
+ *
+ * @param [in] data   pointer to data to wiped
+ * @param [in] length length of the data in bytes
+ * @return SOTER_SUCCESS on success,
+ *         SOTER_INVALID_PARAMETER on NULL data
+ */
+SOTER_API
+soter_status_t soter_wipe(void* data, size_t length);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SOTER_WIPE_H */

src/themis/secure_comparator.c

@@ -55,6 +55,8 @@
 
 #include <string.h>
 
+#include "soter/soter_wipe.h"
+
 #include "themis/secure_comparator_t.h"
 
 static themis_status_t secure_comparator_alice_step1(secure_comparator_t* comp_ctx,
@@ -479,7 +481,8 @@ themis_status_t secure_comparator_cleanup(secure_comparator_t* comp_ctx)
     }
 
     soter_hash_cleanup(&(comp_ctx->hash_ctx));
-    memset(comp_ctx, 0, sizeof(secure_comparator_t));
+
+    soter_wipe(comp_ctx, sizeof(secure_comparator_t));
 
     return THEMIS_SUCCESS;
 }
@@ -938,7 +941,7 @@ static themis_status_t secure_comparator_bob_step4(secure_comparator_t* comp_ctx
         return themis_status;
     }
 
-    memset(comp_ctx->secret, 0, sizeof(comp_ctx->secret));
+    soter_wipe(comp_ctx->secret, sizeof(comp_ctx->secret));
 
     /* Finally Bob sends to Alice on 4 step:
      * Rb || Rb signature
@@ -1005,7 +1008,8 @@ static themis_status_t secure_comparator_alice_step5(secure_comparator_t* comp_c
         comp_ctx->result = ge_cmp(&Rab, &Pa_Pb) ? THEMIS_SCOMPARE_NO_MATCH : THEMIS_SCOMPARE_MATCH;
     }
 
-    memset(comp_ctx->secret, 0, sizeof(comp_ctx->secret));
+    soter_wipe(comp_ctx->secret, sizeof(comp_ctx->secret));
+
     comp_ctx->state_handler = NULL;
 
     return THEMIS_SUCCESS;

src/themis/secure_session.c

@@ -21,6 +21,7 @@
 #include "soter/soter_ec_key.h"
 #include "soter/soter_rsa_key.h"
 #include "soter/soter_t.h"
+#include "soter/soter_wipe.h"
 
 #include "themis/portable_endian.h"
 #include "themis/secure_session_t.h"
@@ -61,7 +62,7 @@ themis_status_t secure_session_cleanup(secure_session_t* session_ctx)
 
     soter_asym_ka_cleanup(&(session_ctx->ecdh_ctx));
 
-    memset(session_ctx, 0, sizeof(secure_session_t));
+    soter_wipe(session_ctx, sizeof(secure_session_t));
 
     return THEMIS_SUCCESS;
 }

src/themis/secure_session_peer.c

@@ -18,9 +18,13 @@
 
 #include <string.h>
 
+#include "soter/soter_wipe.h"
+
 void secure_session_peer_cleanup(secure_session_peer_t* peer)
 {
     if (peer->id) {
+        size_t length = peer->id_length + peer->ecdh_key_length + peer->sign_key_length;
+        soter_wipe(peer->id, length);
         free(peer->id);
     }