Please see http://www.eskimo.com/~weidai/egcs.txt and then apply this
patch if you get template errors while compiling Crypto++ 3.0.

---
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/config.h crypto-3.0/config.h
--- ../import/crypto-3.0/config.h  Fri Dec 18 19:17:54 1998
+++ crypto-3.0/config.h  Thu Jan 14 08:32:33 1999
@@ -8,7 +8,12 @@
 // define this if your compiler doesn't support namespaces
 
 #ifdef __GNUC__
-#define NO_NAMESPACE
+//#define NO_NAMESPACE
+#endif
+
+// define this if your compiler needs the external template.
+#ifdef __GNUC__
+#define EXTERN_TEMPLATE extern
 #endif
 
 // switch between different secure memory allocation mechnisms, this is the only
@@ -75,15 +80,23 @@ typedef unsigned int word;
 typedef unsigned long dword;
 #endif
 
+/* We need it to do conversion. */
+union dword_union
+{
+  dword_union (const dword &d) { dw = d; }
+  dword dw;
+  word w [2];
+};
+
 const unsigned int WORD_SIZE = sizeof(word);
 const unsigned int WORD_BITS = WORD_SIZE * 8;
 
 #define LOW_WORD(x) (word)(x)
 
 #ifdef IS_LITTLE_ENDIAN
-#define HIGH_WORD(x) (*(((word *)&(x))+1))
+#define HIGH_WORD(x) (((dword_union) (x)).w [1])
 #else
-#define HIGH_WORD(x) (*((word *)&(x)))
+#define HIGH_WORD(x) (((dword_union) (x)).w [0])
 #endif
 
 // if the above HIGH_WORD macro doesn't work (if you are not sure, compile it
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/luc.cpp crypto-3.0/luc.cpp
--- ../import/crypto-3.0/luc.cpp  Tue Dec 29 23:53:38 1998
+++ crypto-3.0/luc.cpp  Thu Jan 14 08:30:12 1999
@@ -11,7 +11,7 @@
 
 NAMESPACE_BEGIN(CryptoPP)
 
-template class OAEP<SHA>;
+EXTERN_TEMPLATE template class OAEP<SHA>;
 INSTANTIATE_PUBKEY_TEMPLATES_MACRO(OAEP<SHA>, PKCS_SignaturePaddingScheme, LUCFunction, InvertableLUCFunction);
 
 LUCFunction::LUCFunction(BufferedTransformation &bt)
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/oaepsha.cpp crypto-3.0/oaepsha.cpp
--- ../import/crypto-3.0/oaepsha.cpp  Wed Dec 31 16:00:00 1969
+++ crypto-3.0/oaepsha.cpp  Thu Jan 14 08:31:09 1999
@@ -0,0 +1,17 @@
+// oaepsha.cpp - written and placed in the public domain by Wei Dai
+
+#include "config.h"
+
+#ifdef EXTERN_TEMPLATE
+#include "pch.h"
+#include "asn.h"
+#include "nbtheory.h"
+#include "sha.h"
+
+#include "pubkey.cpp"
+#include "oaep.cpp"
+
+NAMESPACE_BEGIN(CryptoPP)
+template class OAEP<SHA>;
+NAMESPACE_END
+#endif
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/rabin.cpp crypto-3.0/rabin.cpp
--- ../import/crypto-3.0/rabin.cpp  Fri Dec 18 19:18:10 1998
+++ crypto-3.0/rabin.cpp  Thu Jan 14 08:30:07 1999
@@ -11,7 +11,7 @@
 
 NAMESPACE_BEGIN(CryptoPP)
 
-template class OAEP<SHA>;
+EXTERN_TEMPLATE template class OAEP<SHA>;
 template class DecryptorTemplate<OAEP<SHA>, InvertableRabinFunction>;
 template class EncryptorTemplate<OAEP<SHA>, RabinFunction>;
 
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/rsa.cpp crypto-3.0/rsa.cpp
--- ../import/crypto-3.0/rsa.cpp  Fri Dec 18 19:18:12 1998
+++ crypto-3.0/rsa.cpp  Thu Jan 14 08:30:01 1999
@@ -12,7 +12,7 @@
 NAMESPACE_BEGIN(CryptoPP)
 
 INSTANTIATE_PUBKEY_TEMPLATES_MACRO(PKCS_EncryptionPaddingScheme, PKCS_SignaturePaddingScheme, RSAFunction, InvertableRSAFunction);
-template class OAEP<SHA>;
+EXTERN_TEMPLATE template class OAEP<SHA>;
 template class DecryptorTemplate<OAEP<SHA>, InvertableRSAFunction>;
 template class EncryptorTemplate<OAEP<SHA>, RSAFunction>;
 
diff -x *.out --new-file -upr -x Makefile -x *.o ../import/crypto-3.0/xormac.h crypto-3.0/xormac.h
--- ../import/crypto-3.0/xormac.h  Sat Dec 12 14:23:50 1998
+++ crypto-3.0/xormac.h  Wed Jan 13 09:40:19 1999
@@ -37,7 +37,7 @@ private:
 };
 
 template <class T> XMACC<T>::XMACC(const byte *userKey, word32 counter)
-  : IteratedHash<T::HashWordType>(DATASIZE, T::DIGESTSIZE)
+  : IteratedHash<typename T::HashWordType>(DATASIZE, T::DIGESTSIZE)
   , key(KEYLENGTH)
   , buffer(T::DIGESTSIZE/sizeof(HashWordType))
   , counter(counter)