Document a pair of panics requiring 256 GB of RAM/4 GB of a context

crypto/dkg/src/tests/mod.rs

@@ -31,6 +31,8 @@ pub fn clone_without<K: Clone + std::cmp::Eq + std::hash::Hash, V: Clone>(
 }
 
 /// Recover the secret from a collection of keys.
+///
+/// This will panic if no keys, an insufficient amount of keys, or the wrong keys are provided.
 pub fn recover_key<C: Ciphersuite>(keys: &HashMap<Participant, ThresholdKeys<C>>) -> C::F {
   let first = keys.values().next().expect("no keys provided");
   assert!(keys.len() >= first.params().t().into(), "not enough keys provided");

crypto/schnorr/src/aggregate.rs

@@ -89,6 +89,8 @@ impl<C: Ciphersuite> SchnorrAggregate<C> {
   }
 
   /// Write a SchnorrAggregate to something implementing Write.
+  ///
+  /// This will panic if more than 4 billion signatures were aggregated.
   pub fn write<W: Write>(&self, writer: &mut W) -> io::Result<()> {
     writer.write_all(
       &u32::try_from(self.Rs.len())

crypto/schnorrkel/src/lib.rs

@@ -60,6 +60,8 @@ pub struct Schnorrkel {
 
 impl Schnorrkel {
   /// Create a new algorithm with the specified context.
+  ///
+  /// If the context is greater than or equal to 4 GB in size, this will panic.
   pub fn new(context: &'static [u8]) -> Schnorrkel {
     Schnorrkel {
       context,