feat: Actually compute selectors (#2686)

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AztecProtocol · Oct 5, 2023 · dcb65e1 · dcb65e1
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diff --git a/docs/docs/dev_docs/contracts/syntax/functions.md b/docs/docs/dev_docs/contracts/syntax/functions.md
@@ -100,7 +100,7 @@ Oracles introduce **non-determinism** into a circuit, and thus are `unconstraine
 
 ### A few useful inbuilt oracles
 
-- [`compute_selector`](https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/aztec-nr/aztec/src/oracle/compute_selector.nr) - Computes the selector of a function. This is useful for when you want to call a function from within a circuit, but don't have an interface at hand and don't want to hardcode the selector in hex.
+- [`compute_selector`](https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/aztec-nr/aztec/src/selector.nr) - Computes the selector of a function. This is useful for when you want to call a function from within a circuit, but don't have an interface at hand and don't want to hardcode the selector in hex.
 - [`debug_log`](https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/aztec-nr/aztec/src/oracle/debug_log.nr) - Provides a couple of debug functions that can be used to log information to the console.
 - [`auth_witness`](https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/aztec-nr/aztec/src/oracle/auth_witness.nr) - Provides a way to fetch the authentication witness for a given address. This is useful when building account contracts to support approve-like functionality.
 - [`get_l1_to_l2_message`](https://github.com/AztecProtocol/aztec-packages/blob/master/yarn-project/aztec-nr/aztec/src/oracle/get_l1_to_l2_message.nr) - Useful for application that receive messages from L1 to be consumed on L2, such as token bridges or other cross-chain applications.
@@ -307,7 +307,6 @@ When a [`Storage` struct](./storage.md) is declared within a contract, the `stor
 
 Any state variables declared in the `Storage` struct can now be accessed as normal struct members.
 
-
 **Returning the function context to the kernel.**
 #include_code context-example-finish /yarn-project/noir-contracts/src/contracts/docs_example_contract/src/main.nr rust
 

diff --git a/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts b/yarn-project/acir-simulator/src/acvm/oracle/oracle.ts
@@ -23,12 +23,6 @@ import { TypedOracle } from './typed_oracle.js';
 export class Oracle {
   constructor(private typedOracle: TypedOracle, private log = createDebugLogger('aztec:simulator:oracle')) {}
 
-  computeSelector(...args: ACVMField[][]): ACVMField {
-    const signature = oracleDebugCallToFormattedStr(args);
-    const selector = this.typedOracle.computeSelector(signature);
-    return toACVMField(selector);
-  }
-
   getRandomField(): ACVMField {
     const val = this.typedOracle.getRandomField();
     return toACVMField(val);

diff --git a/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts b/yarn-project/acir-simulator/src/acvm/oracle/typed_oracle.ts
@@ -60,10 +60,6 @@ export interface L1ToL2MessageOracleReturnData extends MessageLoadOracleInputs {
  * and are unavailable by default.
  */
 export abstract class TypedOracle {
-  computeSelector(signature: string): Fr {
-    return FunctionSelector.fromSignature(signature).toField();
-  }
-
   getRandomField(): Fr {
     return Fr.random();
   }

diff --git a/yarn-project/aztec-nr/authwit/src/account.nr b/yarn-project/aztec-nr/authwit/src/account.nr
@@ -2,7 +2,7 @@ mod entrypoint;
 mod auth;
 
 use dep::aztec::context::{PrivateContext, PublicContext, Context};
-use dep::aztec::oracle::compute_selector::compute_selector;
+use dep::aztec::selector::compute_selector;
 use dep::aztec::state_vars::{map::Map, public_state::PublicState};
 use dep::aztec::types::type_serialization::bool_serialization::{BoolSerializationMethods,BOOL_SERIALIZED_LEN};
 

diff --git a/yarn-project/aztec-nr/aztec/src/lib.nr b/yarn-project/aztec-nr/aztec/src/lib.nr
@@ -9,6 +9,7 @@ mod note;
 mod oracle;
 mod private_call_stack_item;
 mod public_call_stack_item;
+mod selector;
 mod state_vars;
 mod types;
 mod utils;
diff --git a/yarn-project/aztec-nr/aztec/src/oracle.nr b/yarn-project/aztec-nr/aztec/src/oracle.nr
@@ -15,4 +15,3 @@ mod public_call;
 mod notes;
 mod storage;
 mod logs;
-mod compute_selector;
diff --git a/yarn-project/aztec-nr/aztec/src/oracle/compute_selector.nr b/yarn-project/aztec-nr/aztec/src/oracle/compute_selector.nr
diff --git a/yarn-project/aztec-nr/aztec/src/selector.nr b/yarn-project/aztec-nr/aztec/src/selector.nr
@@ -0,0 +1,15 @@
+use crate::utils::field_from_bytes;
+
+global SELECTOR_SIZE = 4;
+
+fn compute_selector<N>(signature: str<N>) -> Field {
+    let bytes = signature.as_bytes();
+    let hash = dep::std::hash::keccak256(bytes, bytes.len() as u32);
+
+    let mut selector_be_bytes = [0; SELECTOR_SIZE];
+    for i in 0..SELECTOR_SIZE {
+        selector_be_bytes[i] = hash[i];
+    }
+
+    field_from_bytes(selector_be_bytes, true)
+}
diff --git a/yarn-project/aztec-nr/aztec/src/utils.nr b/yarn-project/aztec-nr/aztec/src/utils.nr
@@ -7,4 +7,20 @@ fn arr_copy_slice<T, N, M>(
         dst[i] = src[i + offset];
     }
     dst
+}
+
+fn field_from_bytes<N>(bytes: [u8; N], big_endian: bool) -> Field {
+    assert(bytes.len() as u32 < 32, "field_from_bytes: N must be less than 32");
+    let mut as_field = 0;
+    let mut offset = 1;
+    for i in 0..N {
+        let mut index = i;
+        if big_endian {
+            index = N - i - 1;
+        }
+        as_field += (bytes[index] as Field) * offset;
+        offset *= 256;
+    }
+
+    as_field
 }
diff --git a/yarn-project/noir-contracts/src/contracts/benchmarking_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/benchmarking_contract/src/main.nr
@@ -13,7 +13,7 @@ contract Benchmarking {
     use dep::aztec::{
         context::{Context},
         note::note_getter_options::NoteGetterOptions,
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
         log::emit_unencrypted_log,
         state_vars::{map::Map, public_state::PublicState, set::Set},
         types::type_serialization::field_serialization::{FieldSerializationMethods, FIELD_SERIALIZED_LEN},

diff --git a/yarn-project/noir-contracts/src/contracts/card_game_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/card_game_contract/src/main.nr
@@ -30,7 +30,7 @@ contract CardGame {
             note_header::NoteHeader,
             utils as note_utils,
         },
-        oracle::compute_selector::compute_selector
+        selector::compute_selector
     };
 
     use crate::cards::{

diff --git a/yarn-project/noir-contracts/src/contracts/child_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/child_contract/src/main.nr
@@ -5,7 +5,7 @@ contract Child {
     use dep::aztec::{
         abi::CallContext,
         context::{PrivateContext, PublicContext, Context},
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
         log::emit_unencrypted_log,
         state_vars::public_state::PublicState,
         types::type_serialization::field_serialization::{FieldSerializationMethods, FIELD_SERIALIZED_LEN},

diff --git a/yarn-project/noir-contracts/src/contracts/escrow_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/escrow_contract/src/main.nr
@@ -13,7 +13,7 @@ contract Escrow {
             utils as note_utils,
         },
         oracle::get_public_key::get_public_key,
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
         state_vars::set::Set,
     };
 

diff --git a/yarn-project/noir-contracts/src/contracts/lending_contract/src/interfaces.nr b/yarn-project/noir-contracts/src/contracts/lending_contract/src/interfaces.nr
@@ -5,7 +5,7 @@ use dep::aztec::context::{
 
 use crate::asset::Asset;
 use dep::aztec::constants_gen::RETURN_VALUES_LENGTH;
-use dep::aztec::oracle::compute_selector::compute_selector;
+use dep::aztec::selector::compute_selector;
 
 struct PriceFeed {
   address: Field,

diff --git a/yarn-project/noir-contracts/src/contracts/lending_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/lending_contract/src/main.nr
@@ -15,7 +15,7 @@ contract Lending {
     use dep::std::option::Option;
     use dep::aztec::{
         context::{PrivateContext, PublicContext, Context},
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
         state_vars::{
             map::Map,
             public_state::PublicState,

diff --git a/yarn-project/noir-contracts/src/contracts/non_native_token_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/non_native_token_contract/src/main.nr
@@ -39,7 +39,7 @@ contract NonNativeToken {
             note_header::NoteHeader,
             utils as note_utils,
         },
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
         state_vars::{map::Map, public_state::PublicState, set::Set},
         types::type_serialization::field_serialization::{
             FieldSerializationMethods, FIELD_SERIALIZED_LEN,

diff --git a/yarn-project/noir-contracts/src/contracts/parent_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/parent_contract/src/main.nr
@@ -1,6 +1,6 @@
 // A contract used along with `Child` contract to test nested calls.
 contract Parent {
-    use dep::aztec::oracle::compute_selector::compute_selector;
+    use dep::aztec::selector::compute_selector;
 
     #[aztec(private)]
     fn constructor() {}

diff --git a/yarn-project/noir-contracts/src/contracts/token_bridge_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/token_bridge_contract/src/main.nr
@@ -15,7 +15,7 @@ contract TokenBridge {
             FieldSerializationMethods, FIELD_SERIALIZED_LEN,
         },
         types::address::{AztecAddress, EthereumAddress},
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
     };
 
     use crate::token_interface::Token;

diff --git a/yarn-project/noir-contracts/src/contracts/token_bridge_contract/src/token_interface.nr b/yarn-project/noir-contracts/src/contracts/token_bridge_contract/src/token_interface.nr
@@ -1,6 +1,6 @@
 use dep::aztec::{
   context::{ PrivateContext, PublicContext, Context },
-  oracle::compute_selector::compute_selector,
+  selector::compute_selector,
 };
 
 struct Token {

diff --git a/yarn-project/noir-contracts/src/contracts/token_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/token_contract/src/main.nr
@@ -30,7 +30,7 @@ contract Token {
             aztec_address_serialization::{AztecAddressSerializationMethods, AZTEC_ADDRESS_SERIALIZED_LEN},
         },
         types::address::{AztecAddress},
-        oracle::compute_selector::compute_selector,
+        selector::compute_selector,
     };
 
     use dep::authwit::{

diff --git a/yarn-project/noir-contracts/src/contracts/uniswap_contract/src/interfaces.nr b/yarn-project/noir-contracts/src/contracts/uniswap_contract/src/interfaces.nr
@@ -1,6 +1,6 @@
 use dep::aztec::{
   context::{ PrivateContext, PublicContext, Context },
-  oracle::compute_selector::compute_selector,
+  selector::compute_selector,
   types::address::AztecAddress,
 };
 

diff --git a/yarn-project/noir-contracts/src/contracts/uniswap_contract/src/main.nr b/yarn-project/noir-contracts/src/contracts/uniswap_contract/src/main.nr
@@ -7,7 +7,7 @@ mod util;
 contract Uniswap {
     use dep::aztec::{
         context::{PrivateContext, PublicContext, Context},
-        oracle::{compute_selector::compute_selector, context::get_portal_address},
+        oracle::{context::get_portal_address},
         state_vars::{map::Map, public_state::PublicState},
         types::address::{AztecAddress, EthereumAddress},
         types::type_serialization::bool_serialization::{
@@ -16,6 +16,7 @@ contract Uniswap {
         types::type_serialization::field_serialization::{
             FieldSerializationMethods, FIELD_SERIALIZED_LEN,
         },
+        selector::compute_selector,
     };
 
     use dep::authwit::auth::{IS_VALID_SELECTOR, assert_current_call_valid_authwit_public, compute_authwit_message_hash};