Merge pull request #70 from matrix-org/manuroe/objc_pk

OLMKit: Add objc wrappers for pk encryption/decryption

1 files changed, 111 insertions, 0 deletions

diff --git a/xcode/OLMKit/OLMPKEncryption.m b/xcode/OLMKit/OLMPKEncryption.m
new file mode 100644
index 0000000..c2e3d04
--- /dev/null
+++ b/xcode/OLMKit/OLMPKEncryption.m
@@ -0,0 +1,111 @@
+/*
+ Copyright 2018 New Vector Ltd
+
+ 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.
+ */
+
+#import "OLMPkEncryption.h"
+
+#include "olm/olm.h"
+#include "olm/pk.h"
+#include "OLMUtility.h"
+
+@interface OLMPkEncryption ()
+{
+    OlmPkEncryption *session;
+}
+@end
+
+@implementation OLMPkEncryption
+
+- (void)dealloc {
+    olm_clear_pk_encryption(session);
+    free(session);
+}
+
+
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        session = (OlmPkEncryption *)malloc(olm_pk_encryption_size());
+        olm_pk_encryption(session);
+    }
+    return self;
+}
+
+- (void)setRecipientKey:(NSString*)recipientKey {
+    NSData *recipientKeyData = [recipientKey dataUsingEncoding:NSUTF8StringEncoding];
+    olm_pk_encryption_set_recipient_key(session, recipientKeyData.bytes, recipientKeyData.length);
+}
+
+- (OLMPkMessage *)encryptMessage:(NSString *)message error:(NSError *__autoreleasing  _Nullable *)error {
+    NSData *plaintextData = [message dataUsingEncoding:NSUTF8StringEncoding];
+
+    size_t randomLength = olm_pk_encrypt_random_length(session);
+    NSMutableData *random = [OLMUtility randomBytesOfLength:randomLength];
+    if (!random) {
+        return nil;
+    }
+
+    size_t ciphertextLength = olm_pk_ciphertext_length(session, plaintextData.length);
+    NSMutableData *ciphertext = [NSMutableData dataWithLength:ciphertextLength];
+    if (!ciphertext) {
+        return nil;
+    }
+
+    size_t macLength = olm_pk_mac_length(session);
+    NSMutableData *macData = [NSMutableData dataWithLength:macLength];
+    if (!ciphertext) {
+        return nil;
+    }
+
+    size_t ephemeralKeyLength = olm_pk_key_length();
+    NSMutableData *ephemeralKeyData = [NSMutableData dataWithLength:ephemeralKeyLength];
+    if (!ciphertext) {
+        return nil;
+    }
+
+    size_t result = olm_pk_encrypt(session,
+                                   plaintextData.bytes, plaintextData.length,
+                                   ciphertext.mutableBytes, ciphertext.length,
+                                   macData.mutableBytes, macLength,
+                                   ephemeralKeyData.mutableBytes, ephemeralKeyLength,
+                                   random.mutableBytes, randomLength);
+    if (result == olm_error()) {
+        const char *olm_error = olm_pk_encryption_last_error(session);
+
+        NSString *errorString = [NSString stringWithUTF8String:olm_error];
+        NSLog(@"[OLMPkEncryption] encryptMessage: olm_group_encrypt error: %@", errorString);
+
+        if (error && olm_error && errorString) {
+            *error = [NSError errorWithDomain:OLMErrorDomain
+                                         code:0
+                                     userInfo:@{
+                                                NSLocalizedDescriptionKey: errorString,
+                                                NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:@"olm_group_encrypt error: %@", errorString]
+                                                }];
+        }
+
+        return nil;
+    }
+
+    OLMPkMessage *encryptedMessage = [[OLMPkMessage alloc]
+                                      initWithCiphertext:[[NSString alloc] initWithData:ciphertext encoding:NSUTF8StringEncoding]
+                                      mac:[[NSString alloc] initWithData:macData encoding:NSUTF8StringEncoding]
+                                      ephemeralKey:[[NSString alloc] initWithData:ephemeralKeyData encoding:NSUTF8StringEncoding]];
+
+
+    return encryptedMessage;
+}
+
+@end