diff --git a/tests/fuzz/common.c b/tests/fuzz/common.c
index 450f74b..a9d3d3b 100644
--- a/tests/fuzz/common.c
+++ b/tests/fuzz/common.c
@@ -1,14 +1,85 @@
 #include "common.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "mbedtls/ctr_drbg.h"
 
-mbedtls_time_t dummy_constant_time( mbedtls_time_t* time ) {
+mbedtls_time_t dummy_constant_time( mbedtls_time_t* time )
+{
     (void) time;
     return 0x5af2a056;
 }
 
-void dummy_init() {
+void dummy_init()
+{
 #if defined(MBEDTLS_PLATFORM_TIME_ALT)
     mbedtls_platform_set_time( dummy_constant_time );
 #else
     fprintf(stderr, "Warning: fuzzing without constant time\n");
 #endif
 }
+
+int dummy_send( void *ctx, const unsigned char *buf, size_t len )
+{
+    //silence warning about unused parameter
+    (void) ctx;
+    (void) buf;
+
+    //pretends we wrote everything ok
+    return( len );
+}
+
+int fuzz_recv( void *ctx, unsigned char *buf, size_t len )
+{
+    //reads from the buffer from fuzzer
+    fuzzBufferOffset_t * biomemfuzz = (fuzzBufferOffset_t *) ctx;
+
+    if (biomemfuzz->Offset == biomemfuzz->Size) {
+        //EOF
+        return (0);
+    }
+    if (len + biomemfuzz->Offset > biomemfuzz->Size) {
+        //do not overflow
+        len = biomemfuzz->Size - biomemfuzz->Offset;
+    }
+    memcpy(buf, biomemfuzz->Data + biomemfuzz->Offset, len);
+    biomemfuzz->Offset += len;
+    return( len );
+}
+
+int dummy_random( void *p_rng, unsigned char *output, size_t output_len )
+{
+    int ret;
+    size_t i;
+
+    //use mbedtls_ctr_drbg_random to find bugs in it
+    ret = mbedtls_ctr_drbg_random(p_rng, output, output_len);
+    for (i=0; i<output_len; i++) {
+        //replace result with pseudo random
+        output[i] = (unsigned char) rand();
+    }
+    return( ret );
+}
+
+int dummy_entropy( void *data, unsigned char *output, size_t len )
+{
+    size_t i;
+    (void) data;
+
+    //use mbedtls_entropy_func to find bugs in it
+    //test performance impact of entropy
+    //ret = mbedtls_entropy_func(data, output, len);
+    for (i=0; i<len; i++) {
+        //replace result with pseudo random
+        output[i] = (unsigned char) rand();
+    }
+    return( 0 );
+}
+
+int fuzz_recv_timeout( void *ctx, unsigned char *buf, size_t len,
+                      uint32_t timeout )
+{
+    (void) timeout;
+
+    return fuzz_recv(ctx, buf, len);
+}