WiP! SturdyRef

src/syndicate/sturdy.nim

@@ -0,0 +1,30 @@
+import preserves, preserves/parse
+import ../syndicate/protocols/schemas/sturdy, ./private/hmacs
+
+proc mint*(key: openarray[byte]; oid: Value): SturdyRef =
+  SturdyRef(oid: oid, sig: hmacSha256(key, encode(oid), key.len))
+
+proc attenuate*(r: SturdyRef; caveats: Attenuation): SturdyRef =
+  result = SturdyRef(
+    oid: r.oid,
+    caveatChain: r.caveatChain,
+    sig: hmacSha256(r.sig, caveats.encode))
+  result.caveatChain.add caveats
+
+proc validate*(key: openarray[byte]; r: SturdyRef): bool =
+  var sig = hmacSha256(key, r.oid.encode, key.len)
+  for a in r.caveatChain:
+    sig = hmacSha256(sig, a.encode)
+  r.sig == sig
+
+when isMainModule:
+  import unittest
+  test "mint":
+    var
+      key: array[16, byte]
+      oid = "syndicate".toPreserve(EmbeddedType)
+      sRef = mint(key, oid)
+      control = parsePreserves"""<ref "syndicate" [] #[pkgN9TBmEd3Q04grVG4Zdw]>"""
+    check(sRef.toPreserve == control)
+    let aRef = attenuate(sRef, newSeq[Caveat]())
+    check validate(key, aRef)