refactor: cleanup the encrypted log incoming body (AztecProtocol#6325)

Cleans up the incoming body slightly to make it more clear that it is incoming and not to be used for both incoming and outgoing.
zkpassport · May 15, 2024 · e88c209 · e88c209
1 parent 9df0602
commit e88c209
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Showing 8 changed files with 48 additions and 45 deletions.
diff --git a/noir-projects/aztec-nr/aztec/src/encrypted_logs.nr b/noir-projects/aztec-nr/aztec/src/encrypted_logs.nr
@@ -1,2 +1,2 @@
 mod header;
-mod body;
+mod incoming_body;
diff --git a/...aztec-nr/aztec/src/encrypted_logs/body.nr → ...aztec/src/encrypted_logs/incoming_body.nr b/...aztec-nr/aztec/src/encrypted_logs/body.nr → ...aztec/src/encrypted_logs/incoming_body.nr
@@ -4,13 +4,13 @@ use dep::protocol_types::{grumpkin_private_key::GrumpkinPrivateKey, grumpkin_poi
 use dep::std::aes128::aes128_encrypt_slice;
 use crate::keys::point_to_symmetric_key::point_to_symmetric_key;
 
-struct EncryptedLogBody<Note> {
+struct EncryptedLogIncomingBody<Note> {
     storage_slot: Field,
     note_type_id: Field,
     note: Note,
 }
 
-impl<Note> EncryptedLogBody<Note> {
+impl<Note> EncryptedLogIncomingBody<Note> {
     pub fn new<N>(
         storage_slot: Field,
         note_type_id: Field,
@@ -21,8 +21,8 @@ impl<Note> EncryptedLogBody<Note> {
 
     pub fn compute_ciphertext<N>(
         self,
-        secret: GrumpkinPrivateKey,
-        point: GrumpkinPoint
+        eph_sk: GrumpkinPrivateKey,
+        ivpk_app: GrumpkinPoint
     ) -> [u8] where Note: NoteInterface<N> {
         let serialized_note: [Field; N] = self.note.serialize_content();
 
@@ -46,7 +46,7 @@ impl<Note> EncryptedLogBody<Note> {
             }
         }
 
-        let full_key = point_to_symmetric_key(secret, point);
+        let full_key = point_to_symmetric_key(eph_sk, ivpk_app);
         let mut sym_key = [0; 16];
         let mut iv = [0; 16];
 
@@ -59,7 +59,7 @@ impl<Note> EncryptedLogBody<Note> {
 }
 
 mod test {
-    use crate::encrypted_logs::body::EncryptedLogBody;
+    use crate::encrypted_logs::incoming_body::EncryptedLogIncomingBody;
     use dep::protocol_types::{
         address::AztecAddress, traits::Empty, constants::GENERATOR_INDEX__NOTE_NULLIFIER,
         grumpkin_private_key::GrumpkinPrivateKey, grumpkin_point::GrumpkinPoint
@@ -109,7 +109,7 @@ mod test {
     }
 
     #[test]
-    fn test_encrypted_log_body() {
+    fn test_encrypted_log_incoming_body() {
         let note = AddressNote::new(
             AztecAddress::from_field(0x1),
             AztecAddress::from_field(0x2),
@@ -118,18 +118,18 @@ mod test {
 
         let note_type_id = 1;
         let storage_slot = 2;
-        let body = EncryptedLogBody::new(storage_slot, note_type_id, note);
+        let body = EncryptedLogIncomingBody::new(storage_slot, note_type_id, note);
 
-        let secret = GrumpkinPrivateKey::new(
+        let eph_sk = GrumpkinPrivateKey::new(
             0x0000000000000000000000000000000023b3127c127b1f29a7adff5cccf8fb06,
             0x00000000000000000000000000000000649e7ca01d9de27b21624098b897babd
         );
-        let point = GrumpkinPoint::new(
+        let ivpk_app = GrumpkinPoint::new(
             0x2688431c705a5ff3e6c6f2573c9e3ba1c1026d2251d0dbbf2d810aa53fd1d186,
             0x1e96887b117afca01c00468264f4f80b5bb16d94c1808a448595f115556e5c8e
         );
 
-        let ciphertext = body.compute_ciphertext(secret, point);
+        let ciphertext = body.compute_ciphertext(eph_sk, ivpk_app);
 
         let expected_body_ciphertext = [
             131, 119, 105, 129, 244, 32, 151, 205, 12, 99, 93, 62, 10, 180, 72, 21, 47, 232, 95, 17, 240, 230, 80, 129, 174, 158, 23, 76, 114, 185, 43, 18, 254, 148, 147, 230, 66, 216, 167, 62, 180, 213, 238, 33, 108, 29, 84, 139, 99, 206, 212, 253, 92, 116, 137, 31, 0, 104, 45, 91, 250, 109, 141, 114, 189, 53, 35, 60, 108, 156, 170, 206, 150, 114, 150, 187, 198, 13, 62, 153, 133, 13, 169, 167, 242, 221, 40, 168, 186, 203, 104, 82, 47, 238, 142, 179, 90, 37, 9, 70, 245, 176, 122, 247, 42, 87, 75, 7, 20, 89, 166, 123, 14, 26, 230, 156, 49, 94, 0, 94, 72, 58, 171, 239, 115, 174, 155, 7, 151, 17, 60, 206, 193, 134, 70, 87, 215, 88, 21, 194, 63, 26, 106, 105, 124, 213, 252, 152, 192, 71, 115, 13, 181, 5, 169, 15, 170, 196, 174, 228, 170, 192, 91, 76, 110, 220, 89, 47, 248, 144, 189, 251, 167, 149, 248, 226

diff --git a/noir-projects/noir-contracts/contracts/test_contract/src/main.nr b/noir-projects/noir-contracts/contracts/test_contract/src/main.nr
@@ -16,7 +16,7 @@ contract Test {
     };
 
     use dep::aztec::encrypted_logs::header::EncryptedLogHeader;
-    use dep::aztec::encrypted_logs::body::EncryptedLogBody;
+    use dep::aztec::encrypted_logs::incoming_body::EncryptedLogIncomingBody;
 
     use dep::aztec::note::constants::MAX_NOTES_PER_PAGE;
 
@@ -364,14 +364,14 @@ contract Test {
 
     // 64 bytes + 32 * #fields + 16 = 112 bytes
     #[aztec(private)]
-    fn compute_note_body_ciphertext(
+    fn compute_incoming_log_body_ciphertext(
         secret: GrumpkinPrivateKey,
         point: GrumpkinPoint,
         storage_slot: Field,
         value: Field
     ) -> [u8; 112] {
         let note = TestNote::new(value);
-        EncryptedLogBody::new(storage_slot, TestNote::get_note_type_id(), note).compute_ciphertext(secret, point).as_array()
+        EncryptedLogIncomingBody::new(storage_slot, TestNote::get_note_type_id(), note).compute_ciphertext(secret, point).as_array()
     }
 
     #[aztec(public)]

diff --git a/yarn-project/aztec.js/src/index.ts b/yarn-project/aztec.js/src/index.ts
@@ -124,7 +124,7 @@ export {
   Comparator,
   SiblingPath,
   EncryptedLogHeader,
-  EncryptedLogBody,
+  EncryptedLogIncomingBody,
 } from '@aztec/circuit-types';
 export { NodeInfo } from '@aztec/types/interfaces';
 

diff --git a/...types/src/logs/encrypted_log_body.test.ts → .../logs/encrypted_log_incoming_body.test.ts b/...types/src/logs/encrypted_log_body.test.ts → .../logs/encrypted_log_incoming_body.test.ts
@@ -2,17 +2,17 @@ import { Fr, GrumpkinScalar } from '@aztec/circuits.js';
 import { Grumpkin } from '@aztec/circuits.js/barretenberg';
 import { updateInlineTestData } from '@aztec/foundation/testing';
 
-import { EncryptedLogBody } from './encrypted_log_body.js';
+import { EncryptedLogIncomingBody } from './encrypted_log_incoming_body.js';
 import { Note } from './l1_note_payload/note.js';
 
-describe('encrypt log body', () => {
+describe('encrypt log incoming body', () => {
   let grumpkin: Grumpkin;
 
   beforeAll(() => {
     grumpkin = new Grumpkin();
   });
 
-  it('encrypt and decrypt a log body', () => {
+  it('encrypt and decrypt a log incoming body', () => {
     const ephSecretKey = GrumpkinScalar.random();
     const viewingSecretKey = GrumpkinScalar.random();
 
@@ -23,16 +23,16 @@ describe('encrypt log body', () => {
     const noteTypeId = Fr.random();
     const storageSlot = Fr.random();
 
-    const body = new EncryptedLogBody(noteTypeId, storageSlot, note);
+    const body = new EncryptedLogIncomingBody(noteTypeId, storageSlot, note);
 
     const encrypted = body.computeCiphertext(ephSecretKey, viewingPubKey);
 
-    const recreated = EncryptedLogBody.fromCiphertext(encrypted, viewingSecretKey, ephPubKey);
+    const recreated = EncryptedLogIncomingBody.fromCiphertext(encrypted, viewingSecretKey, ephPubKey);
 
     expect(recreated.toBuffer()).toEqual(body.toBuffer());
   });
 
-  it('encrypt a log body, generate input for noir test', () => {
+  it('encrypt a log incoming body, generate input for noir test', () => {
     // The following 2 are arbitrary fixed values - fixed in order to test a match with Noir
     const viewingSecretKey: GrumpkinScalar = new GrumpkinScalar(
       0x23b3127c127b1f29a7adff5cccf8fb06649e7ca01d9de27b21624098b897babdn,
@@ -47,7 +47,7 @@ describe('encrypt log body', () => {
     const noteTypeId = new Fr(1);
     const storageSlot = new Fr(2);
 
-    const body = new EncryptedLogBody(storageSlot, noteTypeId, note);
+    const body = new EncryptedLogIncomingBody(storageSlot, noteTypeId, note);
 
     const encrypted = body.computeCiphertext(ephSecretKey, viewingPubKey);
 
@@ -58,7 +58,7 @@ describe('encrypt log body', () => {
 
     // Run with AZTEC_GENERATE_TEST_DATA=1 to update noir test data
     updateInlineTestData(
-      'noir-projects/aztec-nr/aztec/src/encrypted_logs/body.nr',
+      'noir-projects/aztec-nr/aztec/src/encrypted_logs/incoming_body.nr',
       'expected_body_ciphertext',
       byteArrayString,
     );

diff --git a/...cuit-types/src/logs/encrypted_log_body.ts → ...s/src/logs/encrypted_log_incoming_body.ts b/...cuit-types/src/logs/encrypted_log_body.ts → ...s/src/logs/encrypted_log_incoming_body.ts
@@ -4,7 +4,7 @@ import { BufferReader, serializeToBuffer } from '@aztec/foundation/serialize';
 
 import { Note, deriveAESSecret } from './l1_note_payload/index.js';
 
-export class EncryptedLogBody {
+export class EncryptedLogIncomingBody {
   constructor(public storageSlot: Fr, public noteTypeId: Fr, public note: Note) {}
 
   /**
@@ -23,7 +23,7 @@ export class EncryptedLogBody {
    * @param buf - The buffer to deserialize
    * @returns The deserialized log body
    */
-  public static fromBuffer(buf: Buffer): EncryptedLogBody {
+  public static fromBuffer(buf: Buffer): EncryptedLogIncomingBody {
     const reader = BufferReader.asReader(buf);
     const storageSlot = Fr.fromBuffer(reader);
     const noteTypeId = Fr.fromBuffer(reader);
@@ -32,19 +32,19 @@ export class EncryptedLogBody {
     const fieldsInNote = reader.getLength() / 32 - 2;
     const note = new Note(reader.readArray(fieldsInNote, Fr));
 
-    return new EncryptedLogBody(storageSlot, noteTypeId, note);
+    return new EncryptedLogIncomingBody(storageSlot, noteTypeId, note);
   }
 
   /**
    * Encrypts a log body
    *
-   * @param secret - The ephemeral secret key
-   * @param publicKey - The incoming viewing key for the recipient of this log
+   * @param ephSk - The ephemeral secret key
+   * @param ivpkApp - The application scoped incoming viewing key for the recipient of this log
    *
    * @returns The ciphertext of the encrypted log body
    */
-  public computeCiphertext(secret: GrumpkinPrivateKey, publicKey: PublicKey) {
-    const aesSecret = deriveAESSecret(secret, publicKey);
+  public computeCiphertext(ephSk: GrumpkinPrivateKey, ivpkApp: PublicKey) {
+    const aesSecret = deriveAESSecret(ephSk, ivpkApp);
     const key = aesSecret.subarray(0, 16);
     const iv = aesSecret.subarray(16, 32);
 
@@ -58,24 +58,27 @@ export class EncryptedLogBody {
    * Decrypts a log body
    *
    * @param ciphertext - The ciphertext buffer
-   * @param secret - The private key matching the public key used in encryption (the viewing key secret)
-   * @param publicKey - The public key generated with the ephemeral secret key used in encryption
+   * @param ivskAppOrEphSk - The private key matching the public key used in encryption (the viewing key secret or)
+   * @param ephPkOrIvpkApp - The public key generated with the ephemeral secret key used in encryption
+   *
+   * The "odd" input stems from ivskApp * ephPk == ivpkApp * ephSk producing the same value.
+   * This is used to allow for the same decryption function to be used by both the sender and the recipient.
    *
    * @returns The decrypted log body
    */
   public static fromCiphertext(
     ciphertext: Buffer | bigint[],
-    secret: GrumpkinPrivateKey,
-    publicKey: PublicKey,
-  ): EncryptedLogBody {
+    ivskAppOrEphSk: GrumpkinPrivateKey,
+    ephPkOrIvpkApp: PublicKey,
+  ): EncryptedLogIncomingBody {
     const input = Buffer.isBuffer(ciphertext) ? ciphertext : Buffer.from(ciphertext.map((x: bigint) => Number(x)));
 
-    const aesSecret = deriveAESSecret(secret, publicKey);
+    const aesSecret = deriveAESSecret(ivskAppOrEphSk, ephPkOrIvpkApp);
     const key = aesSecret.subarray(0, 16);
     const iv = aesSecret.subarray(16, 32);
 
     const aes128 = new Aes128();
     const buffer = aes128.decryptBufferCBC(input, iv, key);
-    return EncryptedLogBody.fromBuffer(buffer);
+    return EncryptedLogIncomingBody.fromBuffer(buffer);
   }
 }
diff --git a/yarn-project/circuit-types/src/logs/index.ts b/yarn-project/circuit-types/src/logs/index.ts
@@ -11,4 +11,4 @@ export * from './tx_l2_logs.js';
 export * from './unencrypted_l2_log.js';
 export * from './extended_unencrypted_l2_log.js';
 export * from './encrypted_log_header.js';
-export * from './encrypted_log_body.js';
+export * from './encrypted_log_incoming_body.js';
diff --git a/yarn-project/end-to-end/src/e2e_encryption.test.ts b/yarn-project/end-to-end/src/e2e_encryption.test.ts
@@ -1,4 +1,4 @@
-import { EncryptedLogBody, EncryptedLogHeader, Fr, GrumpkinScalar, Note, type Wallet } from '@aztec/aztec.js';
+import { EncryptedLogHeader, EncryptedLogIncomingBody, Fr, GrumpkinScalar, Note, type Wallet } from '@aztec/aztec.js';
 import { Aes128, Grumpkin } from '@aztec/circuits.js/barretenberg';
 import { TestContract } from '@aztec/noir-contracts.js';
 
@@ -55,7 +55,7 @@ describe('e2e_encryption', () => {
     expect(ciphertext).toEqual(expectedCiphertext);
   });
 
-  it('encrypts header', async () => {
+  it('encrypts log header', async () => {
     const ephSecretKey = GrumpkinScalar.random();
     const viewingSecretKey = GrumpkinScalar.random();
 
@@ -73,7 +73,7 @@ describe('e2e_encryption', () => {
     expect(recreated.address).toEqual(contract.address);
   });
 
-  it('encrypted body', async () => {
+  it('encrypts log incoming body', async () => {
     const ephSecretKey = GrumpkinScalar.random();
     const viewingSecretKey = GrumpkinScalar.random();
 
@@ -85,17 +85,17 @@ describe('e2e_encryption', () => {
     const value = Fr.random();
     const note = new Note([value]);
 
-    const body = new EncryptedLogBody(storageSlot, noteTypeId, note);
+    const body = new EncryptedLogIncomingBody(storageSlot, noteTypeId, note);
 
     const encrypted = await contract.methods
-      .compute_note_body_ciphertext(ephSecretKey, viewingPubKey, storageSlot, value)
+      .compute_incoming_log_body_ciphertext(ephSecretKey, viewingPubKey, storageSlot, value)
       .simulate();
 
     expect(Buffer.from(encrypted.map((x: bigint) => Number(x)))).toEqual(
       body.computeCiphertext(ephSecretKey, viewingPubKey),
     );
 
-    const recreated = EncryptedLogBody.fromCiphertext(encrypted, viewingSecretKey, ephPubKey);
+    const recreated = EncryptedLogIncomingBody.fromCiphertext(encrypted, viewingSecretKey, ephPubKey);
 
     expect(recreated.toBuffer()).toEqual(body.toBuffer());
   });