Make struct cipher_base_t opaque
diff --git a/include/mbedtls/cipher_wrap.h b/include/mbedtls/cipher_wrap.h
index c619267..8b7fd7f 100644
--- a/include/mbedtls/cipher_wrap.h
+++ b/include/mbedtls/cipher_wrap.h
@@ -38,6 +38,61 @@
 extern "C" {
 #endif
 
+/**
+ * Base cipher information. The non-mode specific functions and values.
+ */
+struct mbedtls_cipher_base_t
+{
+    /** Base Cipher type (e.g. MBEDTLS_CIPHER_ID_AES) */
+    mbedtls_cipher_id_t cipher;
+
+    /** Encrypt using ECB */
+    int (*ecb_func)( void *ctx, mbedtls_operation_t mode,
+                     const unsigned char *input, unsigned char *output );
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    /** Encrypt using CBC */
+    int (*cbc_func)( void *ctx, mbedtls_operation_t mode, size_t length,
+                     unsigned char *iv, const unsigned char *input,
+                     unsigned char *output );
+#endif
+
+#if defined(MBEDTLS_CIPHER_MODE_CFB)
+    /** Encrypt using CFB (Full length) */
+    int (*cfb_func)( void *ctx, mbedtls_operation_t mode, size_t length, size_t *iv_off,
+                     unsigned char *iv, const unsigned char *input,
+                     unsigned char *output );
+#endif
+
+#if defined(MBEDTLS_CIPHER_MODE_CTR)
+    /** Encrypt using CTR */
+    int (*ctr_func)( void *ctx, size_t length, size_t *nc_off,
+                     unsigned char *nonce_counter, unsigned char *stream_block,
+                     const unsigned char *input, unsigned char *output );
+#endif
+
+#if defined(MBEDTLS_CIPHER_MODE_STREAM)
+    /** Encrypt using STREAM */
+    int (*stream_func)( void *ctx, size_t length,
+                        const unsigned char *input, unsigned char *output );
+#endif
+
+    /** Set key for encryption purposes */
+    int (*setkey_enc_func)( void *ctx, const unsigned char *key,
+                            unsigned int key_length );
+
+    /** Set key for decryption purposes */
+    int (*setkey_dec_func)( void *ctx, const unsigned char *key,
+                            unsigned int key_length);
+
+    /** Allocate a new context */
+    void * (*ctx_alloc_func)( void );
+
+    /** Free the given context */
+    void (*ctx_free_func)( void *ctx );
+
+};
+
 typedef struct
 {
     mbedtls_cipher_type_t type;