diff --git a/Cargo.toml b/Cargo.toml
index a23edf5..287f70a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,4 +10,7 @@ edition = "2018"
 c_vec = "1.3.3"
 libc = "0.2.60"
 parity-bytes = "0.1.0"
-ethcore-builtin = { path = "../parity-ethereum/ethcore/builtin" }
\ No newline at end of file
+ethcore-builtin = { path = "../parity-ethereum/ethcore/builtin" }
+
+[lib]
+crate-type = ["cdylib"]
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..3b01bad
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+
+CC = gcc
+LIBS = -llibecrecover.so
+LDPATH = -Ltarget/debug
+
+%.o: %.c $(DEPS)
+	$(CC) -c -o $@ $<
+
+
+
+test: src/test.c include/ecrecover.h target/debug/libecrecover.so
+	$(CC) -o $@ $^ $(CFLAGS) $(LDPATH)
diff --git a/include/ecrecover.h b/include/ecrecover.h
new file mode 100644
index 0000000..fc53f50
--- /dev/null
+++ b/include/ecrecover.h
@@ -0,0 +1,2 @@
+
+void ecrecover(const unsigned char *input, unsigned char *output);
diff --git a/src/lib.rs b/src/lib.rs
index 7dee6ee..ccd6751 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,20 +10,16 @@ use c_vec::{CVec};
 use parity_bytes::BytesRef;
 use std::ptr::copy_nonoverlapping;
 
-const LENGTH: usize = 32;
-#[repr(C)]
-struct Buffer {
-    data: *mut [u8;LENGTH],
-}
-
+const INPUT_LENGTH: usize = 512;
+const OUTPUT_LENGTH: usize = 32;
 
 #[no_mangle]
 pub unsafe extern "C" fn ecrecover(input: *const libc::c_uchar, output: *mut libc::c_uchar) {
     let ecrecover = EcRecover { };
     let mut byte_ref = Vec::new();
-    ecrecover.execute(unsafe { std::slice::from_raw_parts(input as *const u8, LENGTH) },
+    ecrecover.execute(unsafe { std::slice::from_raw_parts(input as *const u8, INPUT_LENGTH) },
                       &mut BytesRef::Flexible(&mut byte_ref));
-    let mut ptr: &mut[u8] = unsafe { std::slice::from_raw_parts_mut(output as *mut u8, LENGTH) };
+    let mut ptr: &mut[u8] = unsafe { std::slice::from_raw_parts_mut(output as *mut u8, OUTPUT_LENGTH) };
     ptr.copy_from_slice(byte_ref.as_slice());
 }
 
diff --git a/src/test.c b/src/test.c
new file mode 100644
index 0000000..47e8d45
--- /dev/null
+++ b/src/test.c
@@ -0,0 +1,95 @@
+// -*- C -*-
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#include "../include/ecrecover.h"
+
+
+char *bin2hex(unsigned char*, int);
+
+unsigned char *hex2bin(const char*);
+
+#define OUTPUT_LENGTH 32
+
+int main(int arc, char **argv) {
+  unsigned char *input = hex2bin("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03");
+  unsigned char *expected = "000000000000000000000000c08b5542d177ac6686946920409741463a15dddb";
+  unsigned char *output = malloc(OUTPUT_LENGTH * sizeof(unsigned char));
+  ecrecover(input, output);
+  assert(strcmp(bin2hex(output, OUTPUT_LENGTH), expected) == 0);
+}
+
+
+char *bin2hex(unsigned char *p, int len)
+{
+    char *hex = malloc(((2*len) + 1));
+    char *r = hex;
+
+    while(len && p)
+    {
+        (*r) = ((*p) & 0xF0) >> 4;
+        (*r) = ((*r) <= 9 ? '0' + (*r) : 'a' - 10 + (*r));
+        r++;
+        (*r) = ((*p) & 0x0F);
+        (*r) = ((*r) <= 9 ? '0' + (*r) : 'a' - 10 + (*r));
+        r++;
+        p++;
+        len--;
+    }
+    *r = '\0';
+
+    return hex;
+}
+
+unsigned char *hex2bin(const char *str)
+{
+    int len, h;
+    unsigned char *result, *err, *p, c;
+
+    err = malloc(1);
+    *err = 0;
+
+    if (!str)
+        return err;
+
+    if (!*str)
+        return err;
+
+    len = 0;
+    p = (unsigned char*) str;
+    while (*p++)
+        len++;
+
+    result = malloc((len/2)+1);
+    h = !(len%2) * 4;
+    p = result;
+    *p = 0;
+
+    c = *str;
+    while(c)
+    {
+        if(('0' <= c) && (c <= '9'))
+            *p += (c - '0') << h;
+        else if(('A' <= c) && (c <= 'F'))
+            *p += (c - 'A' + 10) << h;
+        else if(('a' <= c) && (c <= 'f'))
+            *p += (c - 'a' + 10) << h;
+        else
+            return err;
+
+        str++;
+        c = *str;
+
+        if (h)
+            h = 0;
+        else
+        {
+            h = 4;
+            p++;
+            *p = 0;
+        }
+    }
+
+    return result;
+}