Respond to code review.

SignalServiceKit/src/Network/API/Requests/TSRequest.h

@@ -5,8 +5,8 @@
 @interface TSRequest : NSMutableURLRequest
 
 @property (nonatomic) BOOL shouldHaveAuthorizationHeaders;
-@property (nullable) NSString *authUsername;
-@property (nullable) NSString *authPassword;
+@property (atomic, nullable) NSString *authUsername;
+@property (atomic, nullable) NSString *authPassword;
 
 @property (nonatomic, readonly) NSDictionary *parameters;
 

SignalServiceKit/src/Network/API/Requests/TSRequest.m

@@ -58,8 +58,6 @@
     _parameters = parameters ?: @{};
     [self setHTTPMethod:method];
     self.shouldHaveAuthorizationHeaders = YES;
-    _authUsername = [TSAccountManager localNumber];
-    _authPassword = [TSAccountManager serverAuthToken];
 
     return self;
 }
@@ -71,4 +69,19 @@
     return [[TSRequest alloc] initWithURL:url method:method parameters:parameters];
 }
 
+#pragma mark - Authorization
+
+- (NSString *)authUsername
+{
+    OWSAssert(self.shouldHaveAuthorizationHeaders);
+    return (_authUsername ?: [TSAccountManager localNumber]);
+}
+
+- (NSString *)authPassword
+{
+    OWSAssert(self.shouldHaveAuthorizationHeaders);
+    return (_authPassword ?: [TSAccountManager serverAuthToken]);
+}
+
+
 @end

SignalServiceKit/src/Util/Cryptography.h

@@ -32,6 +32,7 @@ extern const NSUInteger kAES256_KeyByteLength;
 @property (nonatomic, readonly) NSData *initializationVector;
 @property (nonatomic, readonly) NSData *authTag;
 
+- (instancetype)init NS_UNAVAILABLE;
 - (nullable instancetype)initWithCipherText:(NSData *)cipherText
                        initializationVector:(NSData *)initializationVector
                                     authTag:(NSData *)authTag NS_DESIGNATED_INITIALIZER;

SignalServiceKit/src/Util/Cryptography.m

@@ -111,7 +111,8 @@ const NSUInteger kAES256_KeyByteLength = 32;
     _initializationVector = [initializationVector copy];
     _authTag = [authTag copy];
 
-    if (_ciphertext == nil || _initializationVector == nil || _authTag == nil) {
+    if (_ciphertext == nil || _initializationVector.length != kAESGCM256_IVLength
+        || _authTag.length != kAESGCM256_TagLength) {
         return nil;
     }