- Generalized external private key implementation handling (like PKCS#11) in SSL/TLS

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index b44af2b..3e1b056 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -30,10 +30,6 @@
 #include "polarssl/debug.h"
 #include "polarssl/ssl.h"
 
-#if defined(POLARSSL_PKCS11_C)
-#include "polarssl/pkcs11.h"
-#endif /* defined(POLARSSL_PKCS11_C) */
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <time.h>
@@ -1115,15 +1111,8 @@
 
     if( ssl->rsa_key == NULL )
     {
-#if defined(POLARSSL_PKCS11_C)
-        if( ssl->pkcs11_key == NULL )
-        {
-#endif /* defined(POLARSSL_PKCS11_C) */
-            SSL_DEBUG_MSG( 1, ( "got no private key" ) );
-            return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
-#if defined(POLARSSL_PKCS11_C)
-        }
-#endif /* defined(POLARSSL_PKCS11_C) */
+        SSL_DEBUG_MSG( 1, ( "got no private key" ) );
+        return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
     }
 
     /*
@@ -1132,11 +1121,7 @@
     ssl->handshake->calc_verify( ssl, hash );
 
     if ( ssl->rsa_key )
-        n = ssl->rsa_key->len;
-#if defined(POLARSSL_PKCS11_C)
-    else
-        n = ssl->pkcs11_key->len;
-#endif  /* defined(POLARSSL_PKCS11_C) */
+        n = ssl->rsa_key_len ( ssl->rsa_key );
 
     if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
     {
@@ -1164,14 +1149,9 @@
 
     if( ssl->rsa_key )
     {
-        ret = rsa_pkcs1_sign( ssl->rsa_key, ssl->f_rng, ssl->p_rng,
-                              RSA_PRIVATE, hash_id,
-                              hashlen, hash, ssl->out_msg + 6 + offset );
-    } else {
-#if defined(POLARSSL_PKCS11_C)
-        ret = pkcs11_sign( ssl->pkcs11_key, RSA_PRIVATE, hash_id,
-                           hashlen, hash, ssl->out_msg + 6 + offset );
-#endif  /* defined(POLARSSL_PKCS11_C) */
+        ret = ssl->rsa_sign( ssl->rsa_key, ssl->f_rng, ssl->p_rng,
+                             RSA_PRIVATE, hash_id,
+                             hashlen, hash, ssl->out_msg + 6 + offset );
     }
 
     if (ret != 0)
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 64b0d2d..e311458 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -30,10 +30,6 @@
 #include "polarssl/debug.h"
 #include "polarssl/ssl.h"
 
-#if defined(POLARSSL_PKCS11_C)
-#include "polarssl/pkcs11.h"
-#endif /* defined(POLARSSL_PKCS11_C) */
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <time.h>
@@ -644,15 +640,8 @@
 
     if( ssl->rsa_key == NULL )
     {
-#if defined(POLARSSL_PKCS11_C)
-        if( ssl->pkcs11_key == NULL )
-        {
-#endif /* defined(POLARSSL_PKCS11_C) */
-            SSL_DEBUG_MSG( 1, ( "got no private key" ) );
-            return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
-#if defined(POLARSSL_PKCS11_C)
-        }
-#endif /* defined(POLARSSL_PKCS11_C) */
+        SSL_DEBUG_MSG( 1, ( "got no private key" ) );
+        return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
     }
 
     /*
@@ -738,11 +727,7 @@
     SSL_DEBUG_BUF( 3, "parameters hash", hash, hashlen );
 
     if ( ssl->rsa_key )
-        rsa_key_len = ssl->rsa_key->len;
-#if defined(POLARSSL_PKCS11_C)
-    else
-        rsa_key_len = ssl->pkcs11_key->len;
-#endif /* defined(POLARSSL_PKCS11_C) */
+        rsa_key_len = ssl->rsa_key_len( ssl->rsa_key );
 
     if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
     {
@@ -758,16 +743,11 @@
 
     if ( ssl->rsa_key )
     {
-        ret = rsa_pkcs1_sign( ssl->rsa_key, ssl->f_rng, ssl->p_rng,
-                              RSA_PRIVATE,
-                              hash_id, hashlen, hash, ssl->out_msg + 6 + n );
+        ret = ssl->rsa_sign( ssl->rsa_key, ssl->f_rng, ssl->p_rng,
+                             RSA_PRIVATE,
+                             hash_id, hashlen, hash,
+                             ssl->out_msg + 6 + n );
     }
-#if defined(POLARSSL_PKCS11_C)
-    else {
-        ret = pkcs11_sign( ssl->pkcs11_key, RSA_PRIVATE,
-                              hash_id, hashlen, hash, ssl->out_msg + 6 + n );
-    }
-#endif  /* defined(POLARSSL_PKCS11_C) */
 
     if( ret != 0 )
     {
@@ -898,15 +878,8 @@
     {
         if( ssl->rsa_key == NULL )
         {
-#if defined(POLARSSL_PKCS11_C)
-                if( ssl->pkcs11_key == NULL )
-                {
-#endif
-                    SSL_DEBUG_MSG( 1, ( "got no private key" ) );
-                    return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
-#if defined(POLARSSL_PKCS11_C)
-                }
-#endif
+            SSL_DEBUG_MSG( 1, ( "got no private key" ) );
+            return( POLARSSL_ERR_SSL_PRIVATE_KEY_REQUIRED );
         }
 
         /*
@@ -914,11 +887,7 @@
          */
         i = 4;
         if( ssl->rsa_key )
-            n = ssl->rsa_key->len;
-#if defined(POLARSSL_PKCS11_C)
-        else
-            n = ssl->pkcs11_key->len;
-#endif
+            n = ssl->rsa_key_len( ssl->rsa_key );
         ssl->handshake->pmslen = 48;
 
         if( ssl->minor_ver != SSL_MINOR_VERSION_0 )
@@ -939,21 +908,12 @@
         }
 
         if( ssl->rsa_key ) {
-            ret = rsa_pkcs1_decrypt(  ssl->rsa_key, RSA_PRIVATE,
-                                     &ssl->handshake->pmslen,
-                                      ssl->in_msg + i,
-                                      ssl->handshake->premaster,
-                                      sizeof(ssl->handshake->premaster) );
+            ret = ssl->rsa_decrypt( ssl->rsa_key, RSA_PRIVATE,
+                                   &ssl->handshake->pmslen,
+                                    ssl->in_msg + i,
+                                    ssl->handshake->premaster,
+                                    sizeof(ssl->handshake->premaster) );
         }
-#if defined(POLARSSL_PKCS11_C)
-        else {
-            ret = pkcs11_decrypt(  ssl->pkcs11_key, RSA_PRIVATE,
-                                  &ssl->handshake->pmslen,
-                                   ssl->in_msg + i,
-                                   ssl->handshake->premaster,
-                                   sizeof(ssl->handshake->premaster) );
-        }
-#endif  /* defined(POLARSSL_PKCS11_C) */
 
         if( ret != 0 || ssl->handshake->pmslen != 48 ||
             ssl->handshake->premaster[0] != ssl->max_major_ver ||
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 6192004..cc0f65c 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -65,6 +65,28 @@
 int (*ssl_hw_record_finish)(ssl_context *ssl) = NULL;
 #endif
 
+static int ssl_rsa_decrypt( void *ctx, int mode, size_t *olen,
+                        const unsigned char *input, unsigned char *output,
+                        size_t output_max_len )
+{
+    return rsa_pkcs1_decrypt( (rsa_context *) ctx, mode, olen, input, output,
+                              output_max_len );
+}
+
+static int ssl_rsa_sign( void *ctx,
+                    int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+                    int mode, int hash_id, unsigned int hashlen,
+                    const unsigned char *hash, unsigned char *sig )
+{
+    return rsa_pkcs1_sign( (rsa_context *) ctx, f_rng, p_rng, mode, hash_id,
+                           hashlen, hash, sig );
+}
+
+static size_t ssl_rsa_key_len( void *ctx )
+{
+    return ( (rsa_context *) ctx )->len;
+}
+
 /*
  * Key material generation
  */
@@ -2826,6 +2848,10 @@
 
     memset( ssl, 0, sizeof( ssl_context ) );
 
+    ssl->rsa_decrypt = ssl_rsa_decrypt;
+    ssl->rsa_sign = ssl_rsa_sign;
+    ssl->rsa_key_len = ssl_rsa_key_len;
+
     ssl->in_ctr = (unsigned char *) malloc( len );
     ssl->in_hdr = ssl->in_ctr +  8;
     ssl->in_msg = ssl->in_ctr + 13;
@@ -3002,14 +3028,19 @@
     ssl->rsa_key    = rsa_key;
 }
 
-#if defined(POLARSSL_PKCS11_C)
-void ssl_set_own_cert_pkcs11( ssl_context *ssl, x509_cert *own_cert,
-                       pkcs11_context *pkcs11_key )
+void ssl_set_own_cert_alt( ssl_context *ssl, x509_cert *own_cert,
+                           void *rsa_key,
+                           rsa_decrypt_func rsa_decrypt,
+                           rsa_sign_func rsa_sign,
+                           rsa_key_len_func rsa_key_len )
 {
     ssl->own_cert   = own_cert;
-    ssl->pkcs11_key = pkcs11_key;
+    ssl->rsa_key    = rsa_key;
+    ssl->rsa_decrypt = rsa_decrypt;
+    ssl->rsa_sign = rsa_sign;
+    ssl->rsa_key_len = rsa_key_len;
 }
-#endif
+
 
 #if defined(POLARSSL_DHM_C)
 int ssl_set_dh_param( ssl_context *ssl, const char *dhm_P, const char *dhm_G )