fix transfer invariant, credits to @holiman for finding the edge case (…

…#916)
ethereum · Apr 14, 2019 · be86f96 · be86f96
1 parent f88f081
commit be86f96
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
@@ -2416,6 +2416,8 @@ def process_transfer(state: BeaconState, transfer: Transfer) -> None:
         get_balance(state, transfer.sender) == transfer.amount + transfer.fee or
         get_balance(state, transfer.sender) >= transfer.amount + transfer.fee + MIN_DEPOSIT_AMOUNT
     )
+    # No self-transfers (to enforce >= MIN_DEPOSIT_AMOUNT or zero balance invariant)
+    assert transfer.sender != transfer.recipient
     # A transfer is valid in only one slot
     assert state.slot == transfer.slot
     # Only withdrawn or not-yet-deposited accounts can transfer