Fix XTS GetValidKeyLength (GH #891)

2 files changed, 11 insertions, 3 deletions

diff --git a/xts.cpp b/xts.cpp
index fb6d2e2f..c4eeca18 100644
--- a/xts.cpp
+++ b/xts.cpp
@@ -206,9 +206,16 @@ ANONYMOUS_NAMESPACE_END
 

 NAMESPACE_BEGIN(CryptoPP)

 

+void XTS_ModeBase::ThrowIfInvalidKeyLength(size_t length)

+{

+    if (!AccessBlockCipher().IsValidKeyLength((length+1)/2))

+        throw InvalidKeyLength(AlgorithmName(), length);

+}

+

 void XTS_ModeBase::SetKey(const byte *key, size_t length, const NameValuePairs &params)

 {

     CRYPTOPP_ASSERT(length % 2 == 0);

+    ThrowIfInvalidKeyLength(length);

 

 #if (CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS == 0)

     CRYPTOPP_ASSERT(BlockSize() == 16);

diff --git a/xts.h b/xts.h
index 76c7b9ce..6559dcc7 100644
--- a/xts.h
+++ b/xts.h
@@ -61,9 +61,10 @@ public:
     size_t DefaultKeyLength() const

         {return GetBlockCipher().DefaultKeyLength()*2;}

     size_t GetValidKeyLength(size_t n) const

-        {return GetBlockCipher().GetValidKeyLength((n+1)/2);}

+        {return 2*GetBlockCipher().GetValidKeyLength((n+1)/2);}

     bool IsValidKeyLength(size_t keylength) const

         {return keylength == GetValidKeyLength(keylength);}

+    void ThrowIfInvalidKeyLength(size_t length);

 

     /// Provides the block size of the cipher

     /// \return the block size of the cipher, in bytes

@@ -111,8 +112,8 @@ template <class CIPHER>
 class CRYPTOPP_NO_VTABLE XTS_Final : public XTS_ModeBase

 {

 public:

-    static std::string CRYPTOPP_API StaticAlgorithmName()

-        {return std::string(CIPHER::StaticAlgorithmName()) + "/XTS";}

+    static const char* CRYPTOPP_API StaticAlgorithmName()

+        {return "XTS";}

 

 protected:

     BlockCipher& AccessBlockCipher()