1 files changed, 67 insertions, 0 deletions

diff --git a/src/PolarSSL++/AesCfb128Decryptor.cpp b/src/PolarSSL++/AesCfb128Decryptor.cpp
new file mode 100644
index 000000000..af0d5106e
--- /dev/null
+++ b/src/PolarSSL++/AesCfb128Decryptor.cpp
@@ -0,0 +1,67 @@
+
+// AesCfb128Decryptor.cpp
+
+// Implements the cAesCfb128Decryptor class decrypting data using AES CFB-128
+
+#include "Globals.h"
+#include "AesCfb128Decryptor.h"
+
+
+
+
+
+cAesCfb128Decryptor::cAesCfb128Decryptor(void) :
+	m_IVOffset(0),
+	m_IsValid(false)
+{
+}
+
+
+
+
+
+cAesCfb128Decryptor::~cAesCfb128Decryptor()
+{
+	// Clear the leftover in-memory data, so that they can't be accessed by a backdoor
+	memset(&m_Aes, 0, sizeof(m_Aes));
+}
+
+
+
+
+
+void cAesCfb128Decryptor::Init(const Byte a_Key[16], const Byte a_IV[16])
+{
+	ASSERT(!IsValid());  // Cannot Init twice
+	
+	memcpy(m_IV, a_IV, 16);
+	aes_setkey_enc(&m_Aes, a_Key, 128);
+	m_IsValid = true;
+}
+
+
+
+
+
+void cAesCfb128Decryptor::ProcessData(Byte * a_DecryptedOut, const Byte * a_EncryptedIn, size_t a_Length)
+{
+	ASSERT(IsValid());  // Must Init() first
+	
+	// PolarSSL doesn't support AES-CFB8, need to implement it manually:
+	for (size_t i = 0; i < a_Length; i++)
+	{
+		Byte Buffer[sizeof(m_IV)];
+		aes_crypt_ecb(&m_Aes, AES_ENCRYPT, m_IV, Buffer);
+		for (size_t idx = 0; idx < sizeof(m_IV) - 1; idx++)
+		{
+			m_IV[idx] = m_IV[idx + 1];
+		}
+		m_IV[sizeof(m_IV) - 1] = a_EncryptedIn[i];
+		a_DecryptedOut[i] = a_EncryptedIn[i] ^ Buffer[0];
+	}
+}
+
+
+
+
+