chore: Remove unencrypted logs from private functions (except private_token_contract)

yarn-project/noir-contracts/src/contracts/easy_private_token_contract/src/main.nr

@@ -14,7 +14,6 @@ contract EasyPrivateToken {
         abi,
         abi::PrivateContextInputs,
         context::PrivateContext,
-        log::emit_unencrypted_log,
         note::{
             note_header::NoteHeader,
             utils as note_utils,
@@ -39,8 +38,6 @@ contract EasyPrivateToken {
 
         balances.at(owner).add(&mut context, initial_supply, owner);
 
-        emit_unencrypted_log(&mut context, "Balance set in constructor");
-
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel.
         context.finish()
     }
@@ -60,8 +57,6 @@ contract EasyPrivateToken {
 
         balances.at(owner).add(&mut context, amount, owner);
 
-        emit_unencrypted_log(&mut context, "Coins minted");
-
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
         context.finish()
     }
@@ -83,8 +78,6 @@ contract EasyPrivateToken {
         balances.at(sender).sub(&mut context, amount, sender);
 
         balances.at(recipient).add(&mut context, amount, recipient);
-
-        emit_unencrypted_log(&mut context, "Coins transferred");
 
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
         context.finish()

yarn-project/noir-contracts/src/contracts/example_public_state_increment_BROKE/src/main.nr

@@ -8,7 +8,6 @@ contract ExamplePublicStateIncrement {
         PrivateContext,
         PublicContext,
     };
-    use dep::aztec::oracle::logs::emit_unencrypted_log;
     use dep::aztec::types::point::Point;
     use crate::storage::Storage;
     use dep::aztec::state_vars::{

yarn-project/noir-contracts/src/contracts/lending_contract/src/main.nr

@@ -21,7 +21,6 @@ contract Lending {
         PrivateContext,
         PublicContext
     };
-    use dep::aztec::oracle::{logs::emit_unencrypted_log};
     use dep::aztec::public_call_stack_item::PublicCallStackItem;
     use crate::storage::{Storage, Asset};
     use crate::safe_math::SafeU120;

yarn-project/noir-contracts/src/contracts/private_token_airdrop_contract/src/main.nr

@@ -16,7 +16,6 @@ contract PrivateTokenAirdrop {
         note_header::NoteHeader,
         utils as note_utils,
     };
-    use dep::aztec::log::emit_unencrypted_log;
 
     use crate::storage::Storage;
     use crate::claim_note::{ClaimNote, ClaimNoteMethods};
@@ -38,7 +37,6 @@ contract PrivateTokenAirdrop {
         let owner_balance = storage.balances.at(owner);
         if (initial_supply != 0) {
             send_note(&mut context, owner_balance, initial_supply, owner);
-            emit_unencrypted_log(&mut context, "Balance set in constructor");
         }
 
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel.
@@ -60,7 +58,6 @@ contract PrivateTokenAirdrop {
         // Insert new note to a set of user notes and emit the newly created encrypted note preimage via oracle call.
         let owner_balance = storage.balances.at(owner);
         send_note(&mut context, owner_balance, amount, owner);
-        emit_unencrypted_log(&mut context, "Coins minted");
 
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
         context.finish()
@@ -86,8 +83,6 @@ contract PrivateTokenAirdrop {
         // Creates new note for the recipient.
         let recipient_balance = storage.balances.at(recipient);
         send_note(&mut context, recipient_balance, amount, recipient);
-
-        emit_unencrypted_log(&mut context, "Coins transferred");
 
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
         context.finish()
@@ -185,12 +180,6 @@ contract PrivateTokenAirdrop {
 
         send_notes(&mut context, [recipient1_balance, recipient2_balance, recipient3_balance], amounts, recipients);
 
-        // Also emit an unencrypted log, eg. "Coins transferred"
-        // In this example, we emit the first output note's commitment to ensure that the unencrypted log
-        // for each call to this function is distinct. This is done to detect any issues while collecting 
-        // logs when building a transaction. See: https://github.com/AztecProtocol/aztec-packages/issues/987
-        emit_unencrypted_log(&mut context, context.new_commitments.storage[0]);
-
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
         context.finish()
     }

yarn-project/noir-contracts/src/contracts/private_token_contract/src/main.nr

@@ -43,6 +43,9 @@ contract PrivateToken {
         let owner_balance = storage.balances.at(owner);
         if (initial_supply != 0) {
             send_note(&mut context, owner_balance, initial_supply, owner);
+
+            // TODO(1757) Remove this for public release.
+            // Private functions must not emit unencrypted logs to avoid leaking any information.
             emit_unencrypted_log(&mut context, "Balance set in constructor");
         }
 
@@ -70,6 +73,8 @@ contract PrivateToken {
 
         // docs:start:unencrypted
 
+        // TODO(1757) Remove this for public release.
+        // Private functions must not emit unencrypted logs to avoid leaking any information.
         emit_unencrypted_log(&mut context, "Coins minted");
 
         // docs:end:unencrypted
@@ -101,6 +106,8 @@ contract PrivateToken {
         let recipient_balance = storage.balances.at(recipient);
         send_note(&mut context, recipient_balance, amount, recipient);
 
+        // TODO(1757) Remove this for public release.
+        // Private functions must not emit unencrypted logs to avoid leaking any information.
         emit_unencrypted_log(&mut context, "Coins transferred");
 
         // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..

yarn-project/noir-libs/noir-aztec/src/oracle/logs.nr

@@ -27,6 +27,7 @@ unconstrained fn emit_encrypted_log<N>(
 #[oracle(emitUnencryptedLog)]
 fn emit_unencrypted_log_oracle<T>(_message: T)  -> Field {}
 
+// SECURITY WARNING: Do not use emit_unencrypted_log in private functions to avoid leaking any information.
 unconstrained fn emit_unencrypted_log<T>(message: T) -> [Field; NUM_FIELDS_PER_SHA256] {
     // https://github.com/AztecProtocol/aztec-packages/issues/885
     [emit_unencrypted_log_oracle(message), 0]