diff --git a/contracts/okp4-dataverse/src/registrar/credential.rs b/contracts/okp4-dataverse/src/registrar/credential.rs
index 3f462872..4e094240 100644
--- a/contracts/okp4-dataverse/src/registrar/credential.rs
+++ b/contracts/okp4-dataverse/src/registrar/credential.rs
@@ -1,9 +1,10 @@
 use crate::credential::rdf_marker::IRI_VC_TYPE;
 use crate::credential::vc::VerifiableCredential;
+use crate::registrar::rdf::VC_CLAIM;
 use crate::ContractError;
 use cosmwasm_std::Addr;
 use itertools::Itertools;
-use okp4_rdf::dataset::Dataset;
+use rio_api::model::{BlankNode, NamedNode, Subject, Term, Triple};
 
 #[derive(Debug, PartialEq)]
 pub struct DataverseCredential<'a> {
@@ -14,7 +15,7 @@ pub struct DataverseCredential<'a> {
     pub valid_from: &'a str,
     pub valid_until: Option<&'a str>,
     pub subject: &'a str,
-    pub claim: &'a Dataset<'a>,
+    pub claim: Vec<Triple<'a>>,
 }
 
 impl<'a> DataverseCredential<'a> {
@@ -33,16 +34,46 @@ impl<'a> DataverseCredential<'a> {
 
     fn extract_vc_claim(
         vc: &'a VerifiableCredential<'a>,
-    ) -> Result<(&'a str, &'a Dataset<'a>), ContractError> {
-        vc.claims
+    ) -> Result<(&'a str, Vec<Triple<'a>>), ContractError> {
+        //todo: use the canon identifier issuer instead and rename all blank nodes
+        let claim_node = BlankNode { id: "c0" };
+
+        let claim = vc.claims.iter().exactly_one().map_err(|_| {
+            ContractError::UnsupportedCredential(
+                "credential is expected to contain exactly one claim".to_string(),
+            )
+        })?;
+
+        let mut triples = claim
+            .content
             .iter()
-            .exactly_one()
-            .map(|claim| (claim.id, &(claim.content)))
-            .map_err(|_| {
-                ContractError::UnsupportedCredential(
-                    "credential is expected to contain exactly one claim".to_string(),
-                )
+            .map(|q| {
+                let subject = match q.subject {
+                    Subject::NamedNode(n) => {
+                        if n.iri != claim.id {
+                            Err(ContractError::UnsupportedCredential(
+                                "claim hierarchy can be forge only through blank nodes".to_string(),
+                            ))?;
+                        }
+                        Subject::BlankNode(claim_node)
+                    }
+                    _ => q.subject,
+                };
+                Ok(Triple {
+                    subject,
+                    predicate: q.predicate,
+                    object: q.object,
+                })
             })
+            .collect::<Result<Vec<Triple<'a>>, ContractError>>()?;
+
+        triples.push(Triple {
+            subject: Subject::NamedNode(NamedNode { iri: vc.id }),
+            predicate: VC_CLAIM,
+            object: Term::BlankNode(BlankNode { id: "c0" }),
+        });
+
+        Ok((claim.id, triples))
     }
 }
 
diff --git a/contracts/okp4-dataverse/src/registrar/rdf.rs b/contracts/okp4-dataverse/src/registrar/rdf.rs
index 03685cca..42160981 100644
--- a/contracts/okp4-dataverse/src/registrar/rdf.rs
+++ b/contracts/okp4-dataverse/src/registrar/rdf.rs
@@ -3,7 +3,7 @@ use crate::registrar::credential::DataverseCredential;
 use crate::ContractError;
 use cosmwasm_std::{Binary, StdError};
 use okp4_rdf::serde::{DataFormat, TripleWriter};
-use rio_api::model::{BlankNode, Literal, NamedNode, Subject, Term, Triple};
+use rio_api::model::{Literal, NamedNode, Subject, Term, Triple};
 
 pub const VC_SUBMITTER_ADDRESS: NamedNode<'_> = NamedNode {
     iri: "dataverse:credential#submitterAddress",
@@ -27,13 +27,9 @@ pub const VC_CLAIM: NamedNode<'_> = NamedNode {
     iri: "dataverse:credential#claim",
 };
 
-impl<'a> TryFrom<&'a DataverseCredential<'a>> for Vec<Triple<'a>> {
-    type Error = ContractError;
-
-    fn try_from(credential: &'a DataverseCredential<'a>) -> Result<Self, Self::Error> {
+impl<'a> From<&'a DataverseCredential<'a>> for Vec<Triple<'a>> {
+    fn from(credential: &'a DataverseCredential<'a>) -> Self {
         let c_subject = Subject::NamedNode(NamedNode { iri: credential.id });
-        //todo: use the canon identifier issuer instead and rename all blank nodes
-        let claim_node = BlankNode { id: "c0" };
 
         let mut triples = vec![
             Triple {
@@ -72,26 +68,9 @@ impl<'a> TryFrom<&'a DataverseCredential<'a>> for Vec<Triple<'a>> {
                     iri: credential.subject,
                 }),
             },
-            Triple {
-                subject: c_subject,
-                predicate: VC_CLAIM,
-                object: Term::BlankNode(claim_node),
-            },
         ];
 
-        triples.extend(credential.claim.iter().map(|q| {
-            let subject = match q.subject {
-                Subject::NamedNode(n) if n.iri == credential.subject => {
-                    Subject::BlankNode(claim_node)
-                }
-                _ => q.subject,
-            };
-            Triple {
-                subject,
-                predicate: q.predicate,
-                object: q.object,
-            }
-        }));
+        triples.extend(credential.claim.as_slice());
 
         if let Some(valid_until) = credential.valid_until {
             triples.push(Triple {
@@ -104,7 +83,7 @@ impl<'a> TryFrom<&'a DataverseCredential<'a>> for Vec<Triple<'a>> {
             });
         }
 
-        Ok(triples)
+        triples
     }
 }
 
@@ -112,7 +91,7 @@ pub fn serialize(
     credential: &DataverseCredential<'_>,
     format: DataFormat,
 ) -> Result<Binary, ContractError> {
-    let triples: Vec<Triple<'_>> = credential.try_into()?;
+    let triples: Vec<Triple<'_>> = credential.into();
     let out: Vec<u8> = Vec::default();
     let mut writer = TripleWriter::new(&format, out);
     for triple in triples {