diff --git a/packages/protocol/Cargo.toml b/packages/protocol/Cargo.toml
index 5dd479a..6c3316e 100644
--- a/packages/protocol/Cargo.toml
+++ b/packages/protocol/Cargo.toml
@@ -14,3 +14,4 @@ jacquard-lexicon = { version = "=0.12.2", default-features = false }
 poem-openapi = "=5.1.16"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+sha2 = "0.10"
diff --git a/packages/protocol/src/records.rs b/packages/protocol/src/records.rs
index 56a7f63..d6853ba 100644
--- a/packages/protocol/src/records.rs
+++ b/packages/protocol/src/records.rs
@@ -1,6 +1,7 @@
 pub use atrium_api::types::TypedBlobRef as BlobRef;
 use jacquard_derive::LexiconSchema;
 use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
 
 pub const FILE_COLLECTION: &str = "network.crate.file";
 pub const VERSION_COLLECTION: &str = "network.crate.fileVersion";
@@ -8,6 +9,12 @@ pub const NAME_COLLECTION: &str = "network.crate.fileName";
 pub const SPACE_TYPE: &str = "network.crate.drive";
 pub const MAX_FILE_BYTES: usize = 1_073_741_824;
 
+/// Lowercase SHA-256 of the compact UTF-8 JSON array `[parentId-or-null, name]`.
+pub fn name_claim_key(parent_id: Option<&str>, name: &str) -> String {
+    let input = serde_json::to_vec(&(parent_id, name)).expect("strings always serialize");
+    format!("{:x}", Sha256::digest(input))
+}
+
 /// A mutable file head, addressed by its stable record key in a private drive space.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, LexiconSchema)]
 #[serde(rename_all = "camelCase")]
diff --git a/packages/protocol/tests/contracts.rs b/packages/protocol/tests/contracts.rs
index 5dcf592..60f8469 100644
--- a/packages/protocol/tests/contracts.rs
+++ b/packages/protocol/tests/contracts.rs
@@ -141,3 +141,25 @@ fn metadata_update_requires_name_and_revision() {
     let update = UpdateFile::parse_from_json(Some(json!({"revision":CID,"name":"New"}))).unwrap();
     assert!(update.parent_id.is_none());
 }
+
+#[test]
+fn name_claims_are_scoped_and_unambiguous() {
+    use crate_protocol::name_claim_key;
+    assert_eq!(
+        name_claim_key(None, "Documents"),
+        "cc78b9e5ea9ff8bd300f79190f7f7754b7befd1b77d87460dcf77288c4f7e27f"
+    );
+    assert_eq!(
+        name_claim_key(Some("3mabcdef12345"), "café.txt"),
+        "7d91c5e0f4fdb569e9fad9dc48bb18b7ca66fa09824eed7eddeb17e4a53d2961"
+    );
+    assert_ne!(
+        name_claim_key(None, "Documents"),
+        name_claim_key(Some("parent"), "Documents")
+    );
+    assert_ne!(
+        name_claim_key(Some("ab"), "c"),
+        name_claim_key(Some("a"), "bc")
+    );
+    assert_ne!(name_claim_key(None, "A"), name_claim_key(None, "a"));
+}