diff --git a/backends/twitter/libtwitcurl/HMAC_SHA1.h b/backends/twitter/libtwitcurl/HMAC_SHA1.h
new file mode 100644
index 0000000000000000000000000000000000000000..7d203f93e237e66bf9e1ac038eb90c425010a01e
--- /dev/null
+++ b/backends/twitter/libtwitcurl/HMAC_SHA1.h
@@ -0,0 +1,53 @@
+/*
+	100% free public domain implementation of the HMAC-SHA1 algorithm
+	by Chien-Chung, Chung (Jim Chung) <jimchung1221@gmail.com>
+*/
+
+
+#ifndef __HMAC_SHA1_H__
+#define __HMAC_SHA1_H__
+
+#include "SHA1.h"
+
+typedef unsigned char BYTE ;
+
+class CHMAC_SHA1 : public CSHA1
+{
+    private:
+		BYTE m_ipad[64];
+        BYTE m_opad[64];
+
+		char * szReport ;
+		char * SHA1_Key ;
+		char * AppendBuf1 ;
+		char * AppendBuf2 ;
+
+
+	public:
+		
+		enum {
+			SHA1_DIGEST_LENGTH	= 20,
+			SHA1_BLOCK_SIZE		= 64,
+			HMAC_BUF_LEN		= 4096
+		} ;
+
+		CHMAC_SHA1()
+			:szReport(new char[HMAC_BUF_LEN]),
+             SHA1_Key(new char[HMAC_BUF_LEN]),
+             AppendBuf1(new char[HMAC_BUF_LEN]),
+             AppendBuf2(new char[HMAC_BUF_LEN])
+		{}
+
+        ~CHMAC_SHA1()
+        {
+            delete[] szReport ;
+            delete[] AppendBuf1 ;
+            delete[] AppendBuf2 ;
+            delete[] SHA1_Key ;
+        }
+
+        void HMAC_SHA1(BYTE *text, int text_len, BYTE *key, int key_len, BYTE *digest);
+};
+
+
+#endif /* __HMAC_SHA1_H__ */