split hash utils into directory

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/hash/sha256.rs

@@ -0,0 +1,9 @@
+use ring::{digest, digest::SHA256};
+
+#[tracing::instrument(skip_all)]
+pub(super) fn hash(keys: &[&[u8]]) -> Vec<u8> {
+	// We only hash the pdu's event ids, not the whole pdu
+	let bytes = keys.join(&0xFF);
+	let hash = digest::digest(&SHA256, &bytes);
+	hash.as_ref().to_owned()
+}