diff --git a/Cargo.toml b/Cargo.toml
index ac31d53..5ec93c5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,5 +28,4 @@ serde_derive = "^1.0"
 byteorder = "1.1.0"
 ring = "0.11.0"
 webpki = "0.16.0"
-untrusted = "0.5.1"
-crypto-hash = "0.3.0"
\ No newline at end of file
+untrusted = "0.5.1"
\ No newline at end of file
diff --git a/example/static/index.html b/example/static/index.html
index 59e2f2c..87805bb 100644
--- a/example/static/index.html
+++ b/example/static/index.html
@@ -52,7 +52,7 @@ <h1>Rust U2F App test</h1>
         function authenticate() {
             $.getJSON('/api/sign_request')
             .done(function(req) {
-                console.log(req);
+                showNotification("Authentication");
                 u2f.sign(req.appId, req.challenge, req.registeredKeys, postSignedResponse, 30);
             }).fail(function(response) {
                 sweetAlert("Authentication failed", response.responseText, "error");
@@ -61,15 +61,16 @@ <h1>Rust U2F App test</h1>
 
         /* Verify the results on the server  */
         function postSignedResponse(response) {
-            if (response.errorCode === u2f.ErrorCodes['OK']) {
-                $.post('/api/sign_response', JSON.stringify(response))
+            if (typeof response.errorCode === 'undefined' || response.errorCode === u2f.ErrorCodes['OK']) {
+                console.log(response);
+                postJSON('/api/sign_response', response)
                 .done(function() {
                     swal("Authenticated!");
                 }).fail(function(response) {
                     sweetAlert("Authentication failed", response.responseText, "error");
                 }); 
             } else {
-                alert(parseError(response.errorCode));
+                sweetAlert("Authentication failed", (parseError(response.errorCode)), "error");
             }
         }
       
diff --git a/src/authorization.rs b/src/authorization.rs
index f873dd1..74f7792 100644
--- a/src/authorization.rs
+++ b/src/authorization.rs
@@ -1,8 +1,8 @@
 use bytes::{Bytes, Buf, BufMut, BigEndian};
 use std::io::Cursor;
-use ring::{error, signature};
+use ring::{digest};
 use untrusted::Input;
-use crypto_hash::{Algorithm, hex_digest};
+use webpki::{SignatureAlgorithm, EndEntityCert, ECDSA_P256_SHA256};
 
 use util::*;
 use u2ferror::U2fError;
@@ -17,32 +17,43 @@ pub struct Authorization {
     pub user_presence: bool,
 }
 
-pub fn parse_sign_response(app_id: String, client_data: Vec<u8>, pub_key: Vec<u8>, sign_data: Vec<u8>) -> Result<Authorization> {    
-    
+pub fn parse_sign_response(app_id: String, client_data: Vec<u8>, attestation_certificate: Vec<u8>, sign_data: Vec<u8>) -> Result<Authorization> { 
     if get_user_presence(&sign_data[..]) != 1 {
         return Err(U2fError::InvalidUserPresenceByte);
     }    
     
     //Start parsing ... 
     let mut mem = Bytes::from(sign_data);
-    let _ = mem.split_to(1); // advance the user presence byte.
+    let user_presence_flag = mem.split_to(1);
     let counter = mem.split_to(4);
-    let signature_len = asn_length(mem.clone()).unwrap();
-    let signature = mem.split_to(signature_len as usize);
-
-    let app_id_hash = hex_digest(Algorithm::SHA256, &app_id.into_bytes());
-    let client_data_hash = hex_digest(Algorithm::SHA256, &client_data);
-
-    let mut sign_base = vec![];
-    sign_base.put(app_id_hash);
-    sign_base.put(client_data_hash);
-    sign_base.put(counter.clone());  
-
-    let input_pub_key = Input::from(&pub_key[..]);
-    let input_sign = Input::from(&signature[..]);
-    let input_sign_base = Input::from(&sign_base[..]);
-    signature::verify(&signature::ECDSA_P256_SHA256_FIXED, input_pub_key, input_sign_base, input_sign)
-        .map_err(|error::Unspecified| U2fError::BadSignature)?;
+    
+    let raw_data = mem.clone();
+    
+    let sig_len = asn_length(mem.clone()).unwrap();
+    let signature = mem.split_to(sig_len);
+
+    // Let's build the msg to verify the signature
+    let app_id_hash = digest::digest(&digest::SHA256, &app_id.into_bytes());
+    let client_data_hash = digest::digest(&digest::SHA256, &client_data[..]);
+
+    let mut msg = vec![];
+    msg.put(app_id_hash.as_ref());
+    msg.put(user_presence_flag.clone()); 
+    msg.put(raw_data.clone());  
+    msg.put(client_data_hash.as_ref());
+
+    let msg_hash = digest::digest(&digest::SHA256, &msg);
+
+    let input_sig = Input::from(&signature[..]);
+    let input_msg = Input::from(msg_hash.as_ref());
+
+    // The signature is to be verified by the relying party using the public key certified
+    // in the attestation certificate.
+    let cert = EndEntityCert::from(Input::from(&attestation_certificate[..]))
+        .map_err(|_e| U2fError::BadCertificate)?;
+
+    let algo : &[&SignatureAlgorithm] = &[&ECDSA_P256_SHA256];
+    cert.verify_signature(algo[0], input_msg, input_sig).map_err(|_e| U2fError::BadSignature)?;
 
     let authorization = Authorization {
         counter: get_counter(counter),
diff --git a/src/lib.rs b/src/lib.rs
index ed2a234..b8c2ed2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,7 +11,6 @@ extern crate chrono;
 extern crate base64;
 extern crate webpki;
 extern crate untrusted;
-extern crate crypto_hash;
 
 mod util;
 
diff --git a/src/protocol.rs b/src/protocol.rs
index eb085c5..3e99f46 100644
--- a/src/protocol.rs
+++ b/src/protocol.rs
@@ -3,7 +3,7 @@ use messages::*;
 use register::*;
 use authorization::*;
 
-use base64::{encode, decode, decode_config, Config, CharacterSet, LineWrap};
+use base64::{encode, decode_config, Config, CharacterSet, LineWrap};
 use chrono::prelude::*;
 use time::Duration;
 use u2ferror::U2fError;
@@ -120,19 +120,18 @@ impl U2f {
             return Err(U2fError::ChallengeExpired);
         }
 
-        if sign_resp.key_handle != encode(&reg.key_handle[..]) {
+        if sign_resp.key_handle != get_encoded(&reg.key_handle[..]) {            
             return Err(U2fError::WrongKeyHandler);
         }
 
-        decode(&sign_resp.client_data).map_err(|_e| U2fError::InvalidClientData)?;
-        decode(&sign_resp.signature_data).map_err(|_e| U2fError::InvalidSignatureData)?;
-
         let config = Config::new(CharacterSet::UrlSafe, true, false, LineWrap::NoWrap);
-        let client_data: Vec<u8> = decode_config(&sign_resp.client_data[..], config).unwrap();
-        let sign_data: Vec<u8> = decode_config(&sign_resp.signature_data[..], config).unwrap();
-        
-        let auth = parse_sign_response(self.app_id.clone(), client_data.clone(), reg.pub_key, sign_data.clone());
+        let client_data: Vec<u8> = decode_config(&sign_resp.client_data[..], config).map_err(|_e| U2fError::InvalidClientData)?;
+        let sign_data: Vec<u8> = decode_config(&sign_resp.signature_data[..], config).map_err(|_e| U2fError::InvalidSignatureData)?;
 
+        let cert = reg.attestation_cert.unwrap();
+
+        let auth = parse_sign_response(self.app_id.clone(), client_data.clone(), cert, sign_data.clone());
+        
         Ok(auth.unwrap().counter)
     }       
 }
\ No newline at end of file
diff --git a/src/register.rs b/src/register.rs
index 7ca0835..f146d44 100644
--- a/src/register.rs
+++ b/src/register.rs
@@ -1,10 +1,8 @@
 use bytes::{Bytes, BufMut};
-use base64::{encode};
-use ring::{error, signature};
+use ring::{digest};
 use untrusted::Input;
 use byteorder::{ByteOrder, BigEndian};
-use crypto_hash::{Algorithm, hex_digest};
-use webpki::trust_anchor_util;
+use webpki::{SignatureAlgorithm, trust_anchor_util, EndEntityCert, ECDSA_P256_SHA256};
 
 use util::*;
 use messages::RegisteredKey;
@@ -48,29 +46,32 @@ pub fn parse_registration(app_id: String, client_data: Vec<u8>, registration_dat
     let attestation_certificate = mem.split_to(cert_len);
 
     // Check certificate as trust anchor
-    let anchor = trust_anchor_util::cert_der_as_trust_anchor(
-        Input::from(&attestation_certificate[..])).unwrap();
-  
+    trust_anchor_util::cert_der_as_trust_anchor(Input::from(&attestation_certificate[..]))
+      .map_err(|_e| U2fError::NotTrustedAnchor)?;
+
     // Remaining data corresponds to the signature 
     let signature = mem;
 
-    let app_id_hash = hex_digest(Algorithm::SHA256, &app_id.into_bytes());
-    let client_data_hash = hex_digest(Algorithm::SHA256, &client_data[..]);
+    // Let's build the msg to verify the signature
+    let app_id_hash = digest::digest(&digest::SHA256, &app_id.into_bytes());
+    let client_data_hash = digest::digest(&digest::SHA256, &client_data[..]);
 
-    let mut sig_base = vec![0x00]; // A byte reserved for future use [1 byte] with the value 0x00
-    sig_base.put(app_id_hash);
-    sig_base.put(client_data_hash);
-    sig_base.put(key_handle.clone()); 
-    sig_base.put(public_key.clone()); 
+    let mut msg = vec![0x00]; // A byte reserved for future use [1 byte] with the value 0x00
+    msg.put(app_id_hash.as_ref());
+    msg.put(client_data_hash.as_ref());
+    msg.put(key_handle.clone()); 
+    msg.put(public_key.clone()); 
 
-    let input_pub_key = Input::from(&anchor.spki[..]);
     let input_sig = Input::from(&signature[..]);
-    let input_sig_base = Input::from(&sig_base[..]);
+    let input_msg = Input::from(&msg[..]);
 
     // The signature is to be verified by the relying party using the public key certified
     // in the attestation certificate.
-    signature::verify(&signature::ECDSA_P256_SHA256_ASN1, input_pub_key, input_sig_base, input_sig)
-        .map_err(|error::Unspecified| U2fError::BadSignature)?;
+    let cert = EndEntityCert::from(Input::from(&attestation_certificate[..]))
+        .map_err(|_e| U2fError::BadCertificate)?;
+
+    let algo : &[&SignatureAlgorithm] = &[&ECDSA_P256_SHA256];
+    cert.verify_signature(algo[0], input_msg, input_sig).map_err(|_e| U2fError::BadSignature)?;
 
     let registration = Registration {
         key_handle: key_handle[..].to_vec(),
@@ -85,6 +86,6 @@ pub fn get_registered_key(app_id: String, key_handle: Vec<u8>) -> RegisteredKey
     RegisteredKey {
         app_id: app_id,
         version: U2F_V2.into(),
-        key_handle: Some(encode(&key_handle[..]))
+        key_handle: Some(get_encoded(key_handle.as_slice()))
     }
 }
\ No newline at end of file
diff --git a/src/u2ferror.rs b/src/u2ferror.rs
index 42bbbce..14ac19d 100644
--- a/src/u2ferror.rs
+++ b/src/u2ferror.rs
@@ -11,7 +11,9 @@ pub enum U2fError {
     WrongKeyHandler,
     InvalidClientData,
     InvalidSignatureData,
-    InvalidUserPresenceByte
+    InvalidUserPresenceByte,
+    BadCertificate,
+    NotTrustedAnchor
 }
 
 impl fmt::Display for U2fError {
@@ -26,6 +28,8 @@ impl fmt::Display for U2fError {
             U2fError::InvalidClientData => write!(f, "Invalid Client Data"),
             U2fError::InvalidSignatureData => write!(f, "Invalid Signature Data"),
             U2fError::InvalidUserPresenceByte => write!(f, "Invalid User Presence Byte"),
+            U2fError::BadCertificate => write!(f, "Failed to parse certificate"),
+            U2fError::NotTrustedAnchor => write!(f, "Not Trusted Anchor"),
         }
     }
 }
@@ -42,6 +46,8 @@ impl error::Error for U2fError {
             U2fError::InvalidClientData => "Invalid Client Data",
             U2fError::InvalidSignatureData => "Invalid Signature Data",
             U2fError::InvalidUserPresenceByte => "Invalid User Presence Byte",
+            U2fError::BadCertificate => "Failed to parse certificate",
+            U2fError::NotTrustedAnchor => "Not Trusted Anchor",
         }
     }
 
@@ -55,7 +61,9 @@ impl error::Error for U2fError {
             U2fError::WrongKeyHandler => None,
             U2fError::InvalidClientData => None,
             U2fError::InvalidSignatureData => None,
-            U2fError::InvalidUserPresenceByte => None,            
+            U2fError::InvalidUserPresenceByte => None,  
+            U2fError::BadCertificate => None,
+            U2fError::NotTrustedAnchor => None,
         }
     }
 }
\ No newline at end of file
diff --git a/src/util.rs b/src/util.rs
index 3b7deeb..76ee689 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -2,6 +2,7 @@ use chrono::prelude::*;
 use time::Duration;
 use ring::rand::{SecureRandom, SystemRandom};
 use bytes::{Bytes};
+use base64::{encode_config, Config, CharacterSet, LineWrap};
 use u2ferror::U2fError;
 
 /// The `Result` type used in this crate.
@@ -57,4 +58,12 @@ pub fn asn_length(mem: Bytes) -> Result<usize> {
     }
 
     Ok(length + 2) // Add the 2 initial bytes: type and length.
+}
+
+pub fn get_encoded(data: &[u8]) -> String {
+    let config = Config::new(CharacterSet::UrlSafe, true, false, LineWrap::NoWrap);
+
+    let encoded: String = encode_config(data, config);
+
+    encoded.trim_right_matches('=').to_string()
 }
\ No newline at end of file