diff --git a/examples/lakers-c-native/main.c b/examples/lakers-c-native/main.c
index fa765f1c..35b87549 100644
--- a/examples/lakers-c-native/main.c
+++ b/examples/lakers-c-native/main.c
@@ -112,9 +112,9 @@ int main(void)
 
     // lakers init
     puts("loading credentials.");
-    CredentialRPK cred_i = {0}, cred_r = {0};
-    credential_rpk_new(&cred_i, CRED_I, 107);
-    credential_rpk_new(&cred_r, CRED_R, 84);
+    CredentialC cred_i = {0}, cred_r = {0};
+    credential_new(&cred_i, CRED_I, 107);
+    credential_new(&cred_r, CRED_R, 84);
     puts("creating edhoc initiator.");
     EdhocInitiator initiator = {0};
     initiator_new(&initiator);
@@ -153,7 +153,7 @@ int main(void)
     memcpy(message_2.content, coap_response_payload, coap_response_payload_len);
     EADItemC ead_2 = {0};
     uint8_t c_r;
-    CredentialRPK id_cred_r = {0};
+    CredentialC id_cred_r = {0};
 #ifdef LAKERS_EAD_AUTHZ
     // res = initiator_parse_message_2(&initiator, &message_2, &cred_r, &c_r, &id_cred_r, &ead_2);
     res = initiator_parse_message_2(&initiator, &message_2, &c_r, &id_cred_r, &ead_2);
@@ -166,14 +166,15 @@ int main(void)
         return 1;
     }
     // FIXME: failing on native when cred_expected is NULL (memory allocation of 48 bytes failed)
-    res = credential_check_or_fetch(&cred_r, &id_cred_r);
+    CredentialC fetched_cred_r = {0};
+    res = credential_check_or_fetch(&cred_r, &id_cred_r, &fetched_cred_r);
     if (res != 0) {
         printf("Error handling credential: %d\n", res);
         return 1;
     }
 #ifdef LAKERS_EAD_AUTHZ
     puts("processing ead2");
-    res = authz_device_process_ead_2(&device, &ead_2, &id_cred_r);
+    res = authz_device_process_ead_2(&device, &ead_2, &fetched_cred_r);
     if (res != 0) {
         printf("Error process ead2 (authz): %d\n", res);
         return 1;
@@ -181,7 +182,7 @@ int main(void)
         puts("ead-authz voucher received and validated");
     }
 #endif
-    res = initiator_verify_message_2(&initiator, &I, &cred_i, &id_cred_r);
+    res = initiator_verify_message_2(&initiator, &I, &cred_i, &fetched_cred_r);
     if (res != 0) {
         printf("Error verify msg2: %d\n", res);
         return 1;
diff --git a/lakers-c/cbindgen.toml b/lakers-c/cbindgen.toml
index 3354f038..18aa3a1f 100644
--- a/lakers-c/cbindgen.toml
+++ b/lakers-c/cbindgen.toml
@@ -14,3 +14,8 @@ cpp_compat = true
 
 [parse.expand]
 all_features = true
+
+[export]
+include = [
+    "CredentialC"
+]
diff --git a/lakers-c/src/ead_authz.rs b/lakers-c/src/ead_authz.rs
index 85feae2b..0d72715f 100644
--- a/lakers-c/src/ead_authz.rs
+++ b/lakers-c/src/ead_authz.rs
@@ -57,12 +57,13 @@ pub unsafe extern "C" fn authz_device_process_ead_2(
     // input parans
     device_c: *mut EadAuthzDevice,
     ead_2_c: *mut EADItemC,
-    cred_v: *mut CredentialRPK,
+    cred_v: *mut CredentialC,
 ) -> i8 {
     let crypto = &mut default_crypto();
     let device = &(*device_c);
     let ead_2 = (*ead_2_c).to_rust();
-    let cred_v = (*cred_v).value.as_slice();
+    let cred_v = (*cred_v).to_rust();
+    let cred_v = cred_v.bytes.as_slice();
     match device.wait_ead2.process_ead_2(crypto, ead_2, cred_v) {
         Ok(device) => {
             (*device_c).done = device;
diff --git a/lakers-c/src/initiator.rs b/lakers-c/src/initiator.rs
index da99a4a3..3d3802b3 100644
--- a/lakers-c/src/initiator.rs
+++ b/lakers-c/src/initiator.rs
@@ -1,5 +1,5 @@
 use lakers::{
-    EdhocInitiator as EdhocInitiatorRust, // alias to conflict with the C-compatible struct
+    // EdhocInitiator as EdhocInitiatorRust, // alias to conflict with the C-compatible struct
     *,
 };
 use lakers_crypto::{default_crypto, CryptoTrait};
@@ -15,7 +15,7 @@ pub struct EdhocInitiator {
     pub wait_m2: WaitM2,
     pub processing_m2: ProcessingM2C,
     pub processed_m2: ProcessedM2,
-    pub cred_i: *mut CredentialRPK,
+    pub cred_i: *mut CredentialC,
     pub completed: Completed,
 }
 
@@ -86,7 +86,7 @@ pub unsafe extern "C" fn initiator_parse_message_2(
     message_2: *const EdhocMessageBuffer,
     // output params
     c_r_out: *mut u8,
-    id_cred_r_out: *mut CredentialRPK,
+    id_cred_r_out: *mut IdCred,
     ead_2_c_out: *mut EADItemC,
 ) -> i8 {
     // this is a parsing function, so all output parameters are mandatory
@@ -129,8 +129,8 @@ pub unsafe extern "C" fn initiator_verify_message_2(
     // input params
     initiator_c: *mut EdhocInitiator,
     i: *const BytesP256ElemLen,
-    mut cred_i: *mut CredentialRPK,
-    valid_cred_r: *mut CredentialRPK,
+    cred_i: *mut CredentialC,
+    valid_cred_r: *mut CredentialC,
 ) -> i8 {
     if initiator_c.is_null() || i.is_null() {
         return -1;
@@ -139,7 +139,7 @@ pub unsafe extern "C" fn initiator_verify_message_2(
 
     let state = core::ptr::read(&(*initiator_c).processing_m2).to_rust();
 
-    match i_verify_message_2(&state, crypto, *valid_cred_r, &(*i)) {
+    match i_verify_message_2(&state, crypto, (*valid_cred_r).to_rust(), &(*i)) {
         Ok(state) => {
             (*initiator_c).processed_m2 = state;
             (*initiator_c).cred_i = cred_i;
@@ -176,7 +176,7 @@ pub unsafe extern "C" fn initiator_prepare_message_3(
     match i_prepare_message_3(
         &state,
         crypto,
-        *(*initiator_c).cred_i,
+        (*(*initiator_c).cred_i).to_rust(),
         cred_transfer,
         &ead_3,
     ) {
diff --git a/lakers-c/src/lib.rs b/lakers-c/src/lib.rs
index 1476e30c..8cf80f79 100644
--- a/lakers-c/src/lib.rs
+++ b/lakers-c/src/lib.rs
@@ -59,6 +59,7 @@ pub struct ProcessingM2C {
     pub g_y: BytesP256ElemLen,
     pub plaintext_2: EdhocMessageBuffer,
     pub c_r: u8,
+    pub id_cred_r: IdCred,
     pub ead_2: *mut EADItemC,
 }
 
@@ -72,6 +73,7 @@ impl Default for ProcessingM2C {
             g_y: Default::default(),
             plaintext_2: Default::default(),
             c_r: Default::default(),
+            id_cred_r: Default::default(),
             ead_2: core::ptr::null_mut(),
         }
     }
@@ -87,6 +89,7 @@ impl ProcessingM2C {
             g_y: self.g_y,
             plaintext_2: self.plaintext_2,
             c_r: ConnId::from_int_raw(self.c_r),
+            id_cred_r: self.id_cred_r.clone(),
             ead_2: if self.ead_2.is_null() {
                 None
             } else {
@@ -110,19 +113,50 @@ impl ProcessingM2C {
         let c_r = processing_m2.c_r.as_slice();
         assert_eq!(c_r.len(), 1, "C API only supports short C_R");
         (*processing_m2_c).c_r = c_r[0];
+        (*processing_m2_c).id_cred_r = processing_m2.id_cred_r;
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(C)]
+pub struct CredentialC {
+    pub bytes: BufferCred,
+    pub key: CredentialKey,
+    /// differs from Rust: here we assume the kid is always present
+    /// this is to simplify the C API, since C doesn't support Option<T>
+    /// the alternative would be to use a pointer, but then we need to care about memory management
+    pub kid: BufferKid,
+    pub cred_type: CredentialType,
+}
+
+impl CredentialC {
+    pub fn to_rust(&self) -> Credential {
+        Credential {
+            bytes: self.bytes,
+            key: self.key,
+            kid: Some(self.kid),
+            cred_type: self.cred_type,
+        }
+    }
+
+    pub unsafe fn copy_into_c(cred: Credential, cred_c: *mut CredentialC) {
+        (*cred_c).bytes = cred.bytes;
+        (*cred_c).key = cred.key;
+        (*cred_c).kid = cred.kid.unwrap();
+        (*cred_c).cred_type = cred.cred_type;
     }
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn credential_rpk_new(
-    cred: *mut CredentialRPK,
+pub unsafe extern "C" fn credential_new(
+    cred: *mut CredentialC,
     value: *const u8,
     value_len: usize,
 ) -> i8 {
     let value = core::slice::from_raw_parts(value, value_len);
-    match CredentialRPK::new(EdhocMessageBuffer::new_from_slice(value).unwrap()) {
-        Ok(cred_rpk) => {
-            *cred = cred_rpk;
+    match Credential::parse_ccs(value) {
+        Ok(cred_parsed) => {
+            CredentialC::copy_into_c(cred_parsed, cred);
             0
         }
         Err(_) => -1,
@@ -131,19 +165,20 @@ pub unsafe extern "C" fn credential_rpk_new(
 
 #[no_mangle]
 pub unsafe extern "C" fn credential_check_or_fetch(
-    cred_expected: *mut CredentialRPK,
-    id_cred_received: *mut CredentialRPK,
+    cred_expected: *mut CredentialC,
+    id_cred_received: *mut IdCred,
+    cred_out: *mut CredentialC,
 ) -> i8 {
     let cred_expected = if cred_expected.is_null() {
         None
     } else {
-        Some(*cred_expected)
+        Some((*cred_expected).to_rust())
     };
 
     let id_cred_received_value = *id_cred_received;
     match credential_check_or_fetch_rust(cred_expected, id_cred_received_value) {
         Ok(valid_cred) => {
-            *id_cred_received = valid_cred;
+            CredentialC::copy_into_c(valid_cred, cred_out);
             0
         }
         Err(err) => err as i8,
diff --git a/shared/cbindgen.toml b/shared/cbindgen.toml
index e3392a2a..ff11b562 100644
--- a/shared/cbindgen.toml
+++ b/shared/cbindgen.toml
@@ -17,7 +17,10 @@ cpp_compat = true
 [export]
 include = [
     "EdhocMessageBuffer", "BytesMac", "BytesMac2",
-    "EADItemC", "CredentialRPK", "CredentialTransfer",
+    "EADItemC",
+    "EdhocBuffer", "BufferKid", "BufferCred", "BufferIdCred",
+    "CredentialKey", "CredentialType", "IdCred",
+    "CredentialTransfer",
     "InitiatorStart", "WaitM2", "Completed", "ProcessedM2",
     "EdhocInitiatorC", "EdhocInitiatorWaitM2C", "EdhocInitiatorProcessingM2C", "EdhocInitiatorProcessedM2C", "EdhocInitiatorDoneC",
 ]
diff --git a/shared/src/buffer.rs b/shared/src/buffer.rs
index e4f60770..b60078b8 100644
--- a/shared/src/buffer.rs
+++ b/shared/src/buffer.rs
@@ -17,8 +17,8 @@ pub enum EdhocBufferError {
 /// so that in the future it can be hot-swappable by the application.
 // TODO: replace EdhocMessageBuffer with EdhocBuffer all over the library
 // NOTE: how would this const generic thing work across the C and Python bindings?
-#[repr(C)]
 #[derive(PartialEq, Debug, Copy, Clone)]
+#[repr(C)]
 pub struct EdhocBuffer<const N: usize> {
     pub content: [u8; N],
     pub len: usize,
diff --git a/shared/src/cred.rs b/shared/src/cred.rs
index 700ff374..393816c9 100644
--- a/shared/src/cred.rs
+++ b/shared/src/cred.rs
@@ -7,6 +7,7 @@ pub type BytesKeyAES128 = [u8; 16];
 pub type BytesKeyEC2 = [u8; 32];
 
 #[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(C)]
 pub enum CredentialKey {
     Symmetric(BytesKeyAES128),
     EC2Compact(BytesKeyEC2),
@@ -14,6 +15,7 @@ pub enum CredentialKey {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(C)]
 pub enum CredentialType {
     CCS,
     #[allow(non_camel_case_types)]
@@ -41,6 +43,7 @@ impl From<u8> for IdCredType {
 ///
 /// Possible values include key IDs, credentials by value and others.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[repr(C)]
 pub struct IdCred {
     /// The value is always stored in the ID_CRED_x form as a serialized one-element dictionary;
     /// while this technically wastes two bytes, it has the convenient property of having the full
@@ -137,8 +140,8 @@ impl IdCred {
 /// Experimental support for CCS_PSK credentials is also available.
 // TODO: add back support for C and Python bindings
 #[cfg_attr(feature = "python-bindings", pyclass)]
-// #[repr(C)]
 #[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(C)]
 pub struct Credential {
     /// Original bytes of the credential, CBOR-encoded
     ///