Expose internal tag length, 0 if none

TunnelKit/Sources/Core/Crypto.h

@@ -55,6 +55,7 @@ typedef struct {
 
 - (void)configureEncryptionWithCipherKey:(nullable ZeroingData *)cipherKey hmacKey:(nullable ZeroingData *)hmacKey;
 - (int)digestLength;
+- (int)tagLength;
 
 - (NSInteger)encryptionCapacityWithLength:(NSInteger)length;
 - (BOOL)encryptBytes:(const uint8_t *)bytes length:(NSInteger)length dest:(uint8_t *)dest destLength:(NSInteger *)destLength flags:(const CryptoFlags *_Nullable)flags error:(NSError **)error;
@@ -68,6 +69,7 @@ typedef struct {
 
 - (void)configureDecryptionWithCipherKey:(nullable ZeroingData *)cipherKey hmacKey:(nullable ZeroingData *)hmacKey;
 - (int)digestLength;
+- (int)tagLength;
 
 - (NSInteger)encryptionCapacityWithLength:(NSInteger)length;
 - (BOOL)decryptBytes:(const uint8_t *)bytes length:(NSInteger)length dest:(uint8_t *)dest destLength:(NSInteger *)destLength flags:(const CryptoFlags *_Nullable)flags error:(NSError **)error;

TunnelKit/Sources/Core/CryptoAEAD.m

@@ -97,6 +97,11 @@ static const NSInteger CryptoAEADTagLength = 16;
     return 0;
 }
 
+- (int)tagLength
+{
+    return CryptoAEADTagLength;
+}
+
 - (NSInteger)encryptionCapacityWithLength:(NSInteger)length
 {
     return safe_crypto_capacity(length, CryptoAEADTagLength);

TunnelKit/Sources/Core/CryptoBox.h

@@ -73,6 +73,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (id<Decrypter>)decrypter;
 
 - (NSInteger)digestLength;
+- (NSInteger)tagLength;
 
 @end
 

TunnelKit/Sources/Core/CryptoBox.m

@@ -52,6 +52,7 @@
 @property (nonatomic, strong) NSString *cipherAlgorithm;
 @property (nonatomic, strong) NSString *digestAlgorithm;
 @property (nonatomic, assign) NSInteger digestLength;
+@property (nonatomic, assign) NSInteger tagLength;
 
 @property (nonatomic, strong) id<Encrypter> encrypter;
 @property (nonatomic, strong) id<Decrypter> decrypter;
@@ -147,6 +148,7 @@
 
     NSAssert(self.encrypter.digestLength == self.decrypter.digestLength, @"Digest length mismatch in encrypter/decrypter");
     self.digestLength = self.encrypter.digestLength;
+    self.tagLength = self.encrypter.tagLength;
 
     return YES;
 }

TunnelKit/Sources/Core/CryptoCBC.m

@@ -113,6 +113,11 @@ const NSInteger CryptoCBCMaxHMACLength = 100;
     self.digest = NULL;
 }
 
+- (int)tagLength
+{
+    return 0;
+}
+
 - (NSInteger)encryptionCapacityWithLength:(NSInteger)length
 {
     return safe_crypto_capacity(length, self.digestLength + self.cipherIVLength);

TunnelKit/Sources/Core/CryptoCTR.m

@@ -95,6 +95,11 @@ static const NSInteger CryptoCTRTagLength = 32;
     self.digest = NULL;
 }
 
+- (int)tagLength
+{
+    return CryptoCTRTagLength;
+}
+
 - (NSInteger)encryptionCapacityWithLength:(NSInteger)length
 {
     return safe_crypto_capacity(length, PacketOpcodeLength + PacketSessionIdLength + PacketReplayIdLength + PacketReplayTimestampLength + CryptoCTRTagLength);