diff --git a/biscuit_test.py b/biscuit_test.py
index 8d49186..ac308fa 100644
--- a/biscuit_test.py
+++ b/biscuit_test.py
@@ -217,7 +217,7 @@ def choose_key(kid):
         elif kid == 1:
             return root.public_key
         else:
-            raise Exception("Unknown key identifier") 
+            raise Exception("Unknown key identifier")
 
     biscuit_builder0 = BiscuitBuilder("user({id})", { 'id': "1234" })
     token0 = biscuit_builder0.build(other_root.private_key).to_base64()
@@ -386,10 +386,10 @@ def test_biscuit_inspection():
     builder.set_root_key_id(42)
     token2 = builder.build(kp.private_key).append(BlockBuilder('test(false);'))
     print(token2.to_base64())
-    
+
     utoken1 = UnverifiedBiscuit.from_base64(token1.to_base64())
     utoken2 = UnverifiedBiscuit.from_base64(token2.to_base64())
-    
+
     assert utoken1.root_key_id() is None
     assert utoken2.root_key_id() == 42
 
@@ -463,3 +463,33 @@ def test(left, right):
     policy = authorizer.build_unauthenticated().authorize()
     assert policy == 0
 
+def test_append_third_party():
+    root_kp = KeyPair()
+    biscuit_builder = BiscuitBuilder("user({id})", { 'id': "1234" })
+    biscuit = biscuit_builder.build(root_kp.private_key)
+
+    third_party_kp = KeyPair()
+    new_block = BlockBuilder("external_fact({fact})", { 'fact': "56" })
+    third_party_request = biscuit.third_party_request()
+    third_party_block = third_party_request.create_block(third_party_kp.private_key, new_block)
+    biscuit_with_third_party_block = biscuit.append_third_party(third_party_kp.public_key, third_party_block)
+
+    assert repr(biscuit_with_third_party_block.block_external_key(1)) == repr(third_party_kp.public_key)
+
+def test_read_third_party_facts():
+    root_kp = KeyPair()
+    biscuit_builder = BiscuitBuilder("user({id})", { 'id': "1234" })
+    biscuit = biscuit_builder.build(root_kp.private_key)
+
+    third_party_kp = KeyPair()
+    new_block = BlockBuilder("external_fact({fact})", { 'fact': "56" })
+    third_party_request = biscuit.third_party_request()
+    third_party_block = third_party_request.create_block(third_party_kp.private_key, new_block)
+    biscuit_with_third_party_block = biscuit.append_third_party(third_party_kp.public_key, third_party_block)
+
+
+    authorizer  = AuthorizerBuilder("allow if true").build(biscuit_with_third_party_block)
+    rule = Rule(f"ext_fact($fact) <- external_fact($fact) trusting {third_party_kp.public_key}")
+    facts = authorizer.query(rule)
+
+    assert facts[0].terms[0] == "56"
diff --git a/src/lib.rs b/src/lib.rs
index cf049dd..2bdb8a4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,6 +11,8 @@ use ::biscuit_auth::builder::MapKey;
 use ::biscuit_auth::datalog::ExternFunc;
 use ::biscuit_auth::AuthorizerBuilder;
 use ::biscuit_auth::RootKeyProvider;
+use ::biscuit_auth::ThirdPartyBlock;
+use ::biscuit_auth::ThirdPartyRequest;
 use ::biscuit_auth::UnverifiedBiscuit;
 use chrono::DateTime;
 use chrono::Duration;
@@ -397,6 +399,36 @@ impl PyBiscuit {
             .map(PyBiscuit)
     }
 
+    /// Create a new `Biscuit` by appending a third-party attenuation block
+    ///
+    /// :param external_key: the public key of the third-party that signed the block.
+    /// :type external_key: PublicKey
+    /// :param block: the third party block to append
+    /// :type block: ThirdPartyBlock
+    /// :return: the attenuated biscuit
+    /// :rtype: Biscuit
+    pub fn append_third_party(
+        &self,
+        external_key: &PyPublicKey,
+        block: &PyThirdPartyBlock,
+    ) -> PyResult<PyBiscuit> {
+        self.0
+            .append_third_party(external_key.0, block.0.clone())
+            .map_err(|e| BiscuitBuildError::new_err(e.to_string()))
+            .map(PyBiscuit)
+    }
+
+    /// Create a third-party request for generating third-party blocks.
+    ///
+    /// :return: the third-party request
+    /// :rtype: ThirdPartyRequest
+    pub fn third_party_request(&self) -> PyResult<PyThirdPartyRequest> {
+        self.0
+            .third_party_request()
+            .map_err(|e| BiscuitBuildError::new_err(e.to_string()))
+            .map(|request| PyThirdPartyRequest(Some(request)))
+    }
+
     /// The revocation ids of the token, encoded as hexadecimal strings
     #[getter]
     pub fn revocation_ids(&self) -> Vec<String> {
@@ -407,6 +439,21 @@ impl PyBiscuit {
             .collect()
     }
 
+    /// Get the external key of a block if it exists
+    ///
+    /// :param index: the block index
+    /// :type index: int
+    /// :return: the public key if it exists
+    /// :rtype: str | None
+    pub fn block_external_key(&self, index: usize) -> PyResult<Option<PyPublicKey>> {
+        let opt_key = self
+            .0
+            .block_external_key(index)
+            .map_err(|e| BiscuitBlockError::new_err(e.to_string()))?;
+
+        Ok(opt_key.map(PyPublicKey))
+    }
+
     fn __repr__(&self) -> String {
         self.0.print()
     }
@@ -1018,6 +1065,41 @@ impl PyBlockBuilder {
     }
 }
 
+#[pyclass(name = "ThirdPartyRequest")]
+pub struct PyThirdPartyRequest(Option<ThirdPartyRequest>);
+
+#[pymethods]
+impl PyThirdPartyRequest {
+    /// Create a third-party block
+    ///
+    /// :param private_key: the third-party's private key used to sign the block
+    /// :type external_key: PrivateKey
+    /// :param block: the block builder to be signed
+    /// :type block: BlockBuilder
+    /// :return: a signed block that can be appended to a Biscuit
+    /// :rtype: ThirdPartyBlock
+    ///
+    /// :note: this method consumes the `ThirdPartyRequest` object.
+    pub fn create_block(
+        &mut self,
+        private_key: &PyPrivateKey,
+        block: &PyBlockBuilder,
+    ) -> PyResult<PyThirdPartyBlock> {
+        self.0
+            .take()
+            .expect("third party request already consumed")
+            .create_block(
+                &private_key.0,
+                block.0.clone().expect("builder already consumed"),
+            )
+            .map_err(|e| BiscuitBuildError::new_err(e.to_string()))
+            .map(PyThirdPartyBlock)
+    }
+}
+
+#[pyclass(name = "ThirdPartyBlock")]
+pub struct PyThirdPartyBlock(ThirdPartyBlock);
+
 /// ed25519 keypair
 #[pyclass(name = "KeyPair")]
 pub struct PyKeyPair(KeyPair);