From 20a9eb54f570ced435c0decf2e985c8560a0f926 Mon Sep 17 00:00:00 2001
From: julio4 <jules.doumeche@gmail.com>
Date: Wed, 14 Feb 2024 19:25:23 +0900
Subject: [PATCH 1/6] SmartContract: removed `sender` getter, added
 `sender.getUnconstrained` and `sender.getAndRequireSignature`

---
 .../mina/account-update-layout.unit-test.ts   |  6 +-
 src/lib/zkapp.ts                              | 61 +++++++++++--------
 2 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/src/lib/mina/account-update-layout.unit-test.ts b/src/lib/mina/account-update-layout.unit-test.ts
index 4adaeca841..0be36c05f4 100644
--- a/src/lib/mina/account-update-layout.unit-test.ts
+++ b/src/lib/mina/account-update-layout.unit-test.ts
@@ -7,12 +7,14 @@ import { SmartContract, method } from '../zkapp.js';
 
 class NestedCall extends SmartContract {
   @method deposit() {
-    let payerUpdate = AccountUpdate.createSigned(this.sender);
+    let sender = this.sender.getUnconstrained();
+    let payerUpdate = AccountUpdate.createSigned(sender);
     payerUpdate.send({ to: this.address, amount: UInt64.one });
   }
 
   @method depositUsingTree() {
-    let payerUpdate = AccountUpdate.createSigned(this.sender);
+    let sender = this.sender.getUnconstrained();
+    let payerUpdate = AccountUpdate.createSigned(sender);
     let receiverUpdate = AccountUpdate.create(this.address);
     payerUpdate.send({ to: receiverUpdate, amount: UInt64.one });
 
diff --git a/src/lib/zkapp.ts b/src/lib/zkapp.ts
index d927c490ae..bea4e9a9ea 100644
--- a/src/lib/zkapp.ts
+++ b/src/lib/zkapp.ts
@@ -799,31 +799,44 @@ super.init();
 
   #_senderState: { sender: PublicKey; transactionId: number };
 
-  /**
-   * The public key of the current transaction's sender account.
-   *
-   * Throws an error if not inside a transaction, or the sender wasn't passed in.
-   *
-   * **Warning**: The fact that this public key equals the current sender is not part of the proof.
-   * A malicious prover could use any other public key without affecting the validity of the proof.
-   */
-  get sender(): PublicKey {
-    // TODO this logic now has some overlap with this.self, we should combine them somehow
-    // (but with care since the logic in this.self is a bit more complicated)
-    if (!Mina.currentTransaction.has()) {
-      throw Error(
-        `this.sender is not available outside a transaction. Make sure you only use it within \`Mina.transaction\` blocks or smart contract methods.`
-      );
-    }
-    let transactionId = Mina.currentTransaction.id();
-    if (this.#_senderState?.transactionId === transactionId) {
-      return this.#_senderState.sender;
-    } else {
-      let sender = Provable.witness(PublicKey, () => Mina.sender());
-      this.#_senderState = { transactionId, sender };
+  sender: {
+    self: SmartContract;
+    getUnconstrained(): PublicKey;
+    getAndRequireSignature(): PublicKey;
+  } = {
+    self: this,
+    /**
+     * The public key of the current transaction's sender account.
+     *
+     * Throws an error if not inside a transaction, or the sender wasn't passed in.
+     *
+     * **Warning**: The fact that this public key equals the current sender is not part of the proof.
+     * A malicious prover could use any other public key without affecting the validity of the proof.
+     */
+    getUnconstrained(): PublicKey {
+      // TODO this logic now has some overlap with this.self, we should combine them somehow
+      // (but with care since the logic in this.self is a bit more complicated)
+      if (!Mina.currentTransaction.has()) {
+        throw Error(
+          `this.sender is not available outside a transaction. Make sure you only use it within \`Mina.transaction\` blocks or smart contract methods.`
+        );
+      }
+      let transactionId = Mina.currentTransaction.id();
+      if (this.self.#_senderState?.transactionId === transactionId) {
+        return this.self.#_senderState.sender;
+      } else {
+        let sender = Provable.witness(PublicKey, () => Mina.sender());
+        this.self.#_senderState = { transactionId, sender };
+        return sender;
+      }
+    },
+
+    getAndRequireSignature(): PublicKey {
+      let sender = this.getUnconstrained();
+      AccountUpdate.createSigned(sender);
       return sender;
-    }
-  }
+    },
+  };
 
   /**
    * Current account of the {@link SmartContract}.

From 0a828d9a3ebbc4a64d2eded485bee9cbf2093fb8 Mon Sep 17 00:00:00 2001
From: julio4 <jules.doumeche@gmail.com>
Date: Wed, 14 Feb 2024 23:27:03 +0900
Subject: [PATCH 2/6] Fix: use safe sender getters in contract examples

---
 src/examples/zkapps/dex/dex-with-actions.ts | 23 ++++++++++++---------
 src/examples/zkapps/dex/dex.ts              | 22 ++++++++++++--------
 src/examples/zkapps/simple-zkapp-payment.ts |  4 ++--
 tests/integration/simple-zkapp.js           |  3 ++-
 4 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/src/examples/zkapps/dex/dex-with-actions.ts b/src/examples/zkapps/dex/dex-with-actions.ts
index add16ae08b..65fdf4c4b4 100644
--- a/src/examples/zkapps/dex/dex-with-actions.ts
+++ b/src/examples/zkapps/dex/dex-with-actions.ts
@@ -71,7 +71,7 @@ class Dex extends SmartContract {
   }
 
   @method createAccount() {
-    this.token.mint({ address: this.sender, amount: UInt64.from(0) });
+    this.token.mint({ address: this.sender.getUnconstrained(), amount: UInt64.from(0) });
   }
 
   /**
@@ -85,7 +85,7 @@ class Dex extends SmartContract {
    * instead, the input X and Y amounts determine the initial ratio.
    */
   @method supplyLiquidityBase(dx: UInt64, dy: UInt64): UInt64 {
-    let user = this.sender;
+    let user = this.sender.getUnconstrained();
     let tokenX = new TokenContract(this.tokenX);
     let tokenY = new TokenContract(this.tokenY);
 
@@ -156,14 +156,15 @@ class Dex extends SmartContract {
    * contracts pay you tokens when reducing the action.
    */
   @method redeemInitialize(dl: UInt64) {
-    this.reducer.dispatch(new RedeemAction({ address: this.sender, dl }));
-    this.token.burn({ address: this.sender, amount: dl });
+    let sender = this.sender.getAndRequireSignature();
+    this.reducer.dispatch(new RedeemAction({ address: sender, dl }));
+    this.token.burn({ address: sender, amount: dl });
     // TODO: preconditioning on the state here ruins concurrent interactions,
     // there should be another `finalize` DEX method which reduces actions & updates state
     this.totalSupply.set(this.totalSupply.getAndRequireEquals().sub(dl));
 
     // emit event
-    this.typedEvents.emit('redeem-liquidity', { address: this.sender, dl });
+    this.typedEvents.emit('redeem-liquidity', { address: sender, dl });
   }
 
   /**
@@ -186,10 +187,11 @@ class Dex extends SmartContract {
    * the called methods which requires proof authorization.
    */
   swapX(dx: UInt64): UInt64 {
+    let sender = this.sender.getAndRequireSignature();
     let tokenY = new TokenContract(this.tokenY);
     let dexY = new DexTokenHolder(this.address, tokenY.token.id);
-    let dy = dexY.swap(this.sender, dx, this.tokenX);
-    tokenY.transfer(dexY.self, this.sender, dy);
+    let dy = dexY.swap(sender, dx, this.tokenX);
+    tokenY.transfer(dexY.self, sender, dy);
     return dy;
   }
 
@@ -204,10 +206,11 @@ class Dex extends SmartContract {
    * the called methods which requires proof authorization.
    */
   swapY(dy: UInt64): UInt64 {
+    let sender = this.sender.getAndRequireSignature();
     let tokenX = new TokenContract(this.tokenX);
     let dexX = new DexTokenHolder(this.address, tokenX.token.id);
-    let dx = dexX.swap(this.sender, dy, this.tokenY);
-    tokenX.transfer(dexX.self, this.sender, dx);
+    let dx = dexX.swap(sender, dy, this.tokenY);
+    tokenX.transfer(dexX.self, sender, dx);
     return dx;
   }
 
@@ -308,7 +311,7 @@ class DexTokenHolder extends SmartContract {
     this.balance.subInPlace(dy);
 
     // emit event
-    this.typedEvents.emit('swap', { address: this.sender, dx });
+    this.typedEvents.emit('swap', { address: this.sender.getAndRequireSignature(), dx });
 
     return dy;
   }
diff --git a/src/examples/zkapps/dex/dex.ts b/src/examples/zkapps/dex/dex.ts
index 5799e6f80a..ac71b8a531 100644
--- a/src/examples/zkapps/dex/dex.ts
+++ b/src/examples/zkapps/dex/dex.ts
@@ -48,7 +48,7 @@ function createDex({
      * instead, the input X and Y amounts determine the initial ratio.
      */
     @method supplyLiquidityBase(dx: UInt64, dy: UInt64): UInt64 {
-      let user = this.sender;
+      let user = this.sender.getAndRequireSignature();
       let tokenX = new TokenContract(this.tokenX);
       let tokenY = new TokenContract(this.tokenY);
 
@@ -135,11 +135,12 @@ function createDex({
      */
     redeemLiquidity(dl: UInt64) {
       // call the token X holder inside a token X-approved callback
+      let sender = this.sender.getAndRequireSignature();
       let tokenX = new TokenContract(this.tokenX);
       let dexX = new DexTokenHolder(this.address, tokenX.token.id);
-      let dxdy = dexX.redeemLiquidity(this.sender, dl, this.tokenY);
+      let dxdy = dexX.redeemLiquidity(sender, dl, this.tokenY);
       let dx = dxdy[0];
-      tokenX.transfer(dexX.self, this.sender, dx);
+      tokenX.transfer(dexX.self, sender, dx);
       return dxdy;
     }
 
@@ -151,10 +152,11 @@ function createDex({
      * The transaction needs to be signed by the user's private key.
      */
     @method swapX(dx: UInt64): UInt64 {
+      let sender = this.sender.getAndRequireSignature();
       let tokenY = new TokenContract(this.tokenY);
       let dexY = new DexTokenHolder(this.address, tokenY.token.id);
-      let dy = dexY.swap(this.sender, dx, this.tokenX);
-      tokenY.transfer(dexY.self, this.sender, dy);
+      let dy = dexY.swap(sender, dx, this.tokenX);
+      tokenY.transfer(dexY.self, sender, dy);
       return dy;
     }
 
@@ -166,10 +168,11 @@ function createDex({
      * The transaction needs to be signed by the user's private key.
      */
     @method swapY(dy: UInt64): UInt64 {
+      let sender = this.sender.getAndRequireSignature();
       let tokenX = new TokenContract(this.tokenX);
       let dexX = new DexTokenHolder(this.address, tokenX.token.id);
-      let dx = dexX.swap(this.sender, dy, this.tokenY);
-      tokenX.transfer(dexX.self, this.sender, dx);
+      let dx = dexX.swap(sender, dy, this.tokenY);
+      tokenX.transfer(dexX.self, sender, dx);
       return dx;
     }
 
@@ -200,10 +203,11 @@ function createDex({
 
   class ModifiedDex extends Dex {
     @method swapX(dx: UInt64): UInt64 {
+      let sender = this.sender.getAndRequireSignature();
       let tokenY = new TokenContract(this.tokenY);
       let dexY = new ModifiedDexTokenHolder(this.address, tokenY.token.id);
-      let dy = dexY.swap(this.sender, dx, this.tokenX);
-      tokenY.transfer(dexY.self, this.sender, dy);
+      let dy = dexY.swap(sender, dx, this.tokenX);
+      tokenY.transfer(dexY.self, sender, dy);
       return dy;
     }
   }
diff --git a/src/examples/zkapps/simple-zkapp-payment.ts b/src/examples/zkapps/simple-zkapp-payment.ts
index 2fe6f4d215..598d98ea0d 100644
--- a/src/examples/zkapps/simple-zkapp-payment.ts
+++ b/src/examples/zkapps/simple-zkapp-payment.ts
@@ -22,11 +22,11 @@ class SendMINAExample extends SmartContract {
   }
 
   @method withdraw(amount: UInt64) {
-    this.send({ to: this.sender, amount });
+    this.send({ to: this.sender.getAndRequireSignature(), amount });
   }
 
   @method deposit(amount: UInt64) {
-    let senderUpdate = AccountUpdate.createSigned(this.sender);
+    let senderUpdate = AccountUpdate.createSigned(this.sender.getAndRequireSignature());
     senderUpdate.send({ to: this, amount });
   }
 }
diff --git a/tests/integration/simple-zkapp.js b/tests/integration/simple-zkapp.js
index 5df6113c3d..f083a56aaf 100644
--- a/tests/integration/simple-zkapp.js
+++ b/tests/integration/simple-zkapp.js
@@ -61,7 +61,8 @@ class NotSoSimpleZkapp extends SmartContract {
   }
 
   deposit(amount) {
-    let senderUpdate = AccountUpdate.createSigned(this.sender);
+    let sender = this.sender.getAndRequireSignature();
+    let senderUpdate = AccountUpdate.createSigned(sender);
     senderUpdate.send({ to: this, amount });
   }
 }

From a16b5737f8e49874b5708bb0544ce19737b59f07 Mon Sep 17 00:00:00 2001
From: Gregor <gregor.mitscha-baude@gmx.at>
Date: Thu, 7 Mar 2024 12:23:50 +0100
Subject: [PATCH 3/6] simplify type

---
 src/lib/zkapp.ts | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/lib/zkapp.ts b/src/lib/zkapp.ts
index ffc3cbad60..ffba37a9da 100644
--- a/src/lib/zkapp.ts
+++ b/src/lib/zkapp.ts
@@ -821,12 +821,8 @@ super.init();
 
   #_senderState: { sender: PublicKey; transactionId: number };
 
-  sender: {
-    self: SmartContract;
-    getUnconstrained(): PublicKey;
-    getAndRequireSignature(): PublicKey;
-  } = {
-    self: this,
+  sender = {
+    self: this as SmartContract,
     /**
      * The public key of the current transaction's sender account.
      *

From ccba9799b08d89860d0c2d072b962d4d79264251 Mon Sep 17 00:00:00 2001
From: Gregor <gregor.mitscha-baude@gmx.at>
Date: Thu, 7 Mar 2024 12:24:36 +0100
Subject: [PATCH 4/6] fix usage of sender, use unconstrained

---
 src/examples/zkapps/dex/dex-with-actions.ts | 26 ++++++++++++++-------
 src/examples/zkapps/dex/dex.ts              | 24 +++++++++----------
 src/examples/zkapps/simple-zkapp-payment.ts |  7 ++++--
 tests/integration/simple-zkapp.js           |  2 +-
 4 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/src/examples/zkapps/dex/dex-with-actions.ts b/src/examples/zkapps/dex/dex-with-actions.ts
index a6e6135d07..b61eec6515 100644
--- a/src/examples/zkapps/dex/dex-with-actions.ts
+++ b/src/examples/zkapps/dex/dex-with-actions.ts
@@ -79,7 +79,11 @@ class Dex extends TokenContract {
   }
 
   @method createAccount() {
-    this.internal.mint({ address: this.sender, amount: UInt64.from(0) });
+    this.internal.mint({
+      // unconstrained because we don't care which account is created
+      address: this.sender.getUnconstrained(),
+      amount: UInt64.from(0),
+    });
   }
 
   /**
@@ -93,7 +97,8 @@ class Dex extends TokenContract {
    * instead, the input X and Y amounts determine the initial ratio.
    */
   @method supplyLiquidityBase(dx: UInt64, dy: UInt64): UInt64 {
-    let user = this.sender;
+    // unconstrained because `transfer()` requires sender signature anyway
+    let user = this.sender.getUnconstrained();
     let tokenX = new TrivialCoin(this.tokenX);
     let tokenY = new TrivialCoin(this.tokenY);
 
@@ -164,8 +169,9 @@ class Dex extends TokenContract {
    * contracts pay you tokens when reducing the action.
    */
   @method redeemInitialize(dl: UInt64) {
-    this.reducer.dispatch(new RedeemAction({ address: this.sender, dl }));
-    this.internal.burn({ address: this.sender, amount: dl });
+    let sender = this.sender.getUnconstrained(); // unconstrained because `burn()` requires sender signature anyway
+    this.reducer.dispatch(new RedeemAction({ address: sender, dl }));
+    this.internal.burn({ address: sender, amount: dl });
     // TODO: preconditioning on the state here ruins concurrent interactions,
     // there should be another `finalize` DEX method which reduces actions & updates state
     this.totalSupply.set(this.totalSupply.getAndRequireEquals().sub(dl));
@@ -194,10 +200,11 @@ class Dex extends TokenContract {
    * the called methods which requires proof authorization.
    */
   swapX(dx: UInt64): UInt64 {
+    let user = this.sender.getUnconstrained(); // unconstrained because `swap()` requires sender signature anyway
     let tokenY = new TrivialCoin(this.tokenY);
     let dexY = new DexTokenHolder(this.address, tokenY.deriveTokenId());
-    let dy = dexY.swap(this.sender, dx, this.tokenX);
-    tokenY.transfer(dexY.self, this.sender, dy);
+    let dy = dexY.swap(user, dx, this.tokenX);
+    tokenY.transfer(dexY.self, user, dy);
     return dy;
   }
 
@@ -212,10 +219,11 @@ class Dex extends TokenContract {
    * the called methods which requires proof authorization.
    */
   swapY(dy: UInt64): UInt64 {
+    let user = this.sender.getUnconstrained(); // unconstrained because `swap()` requires sender signature anyway
     let tokenX = new TrivialCoin(this.tokenX);
     let dexX = new DexTokenHolder(this.address, tokenX.deriveTokenId());
-    let dx = dexX.swap(this.sender, dy, this.tokenY);
-    tokenX.transfer(dexX.self, this.sender, dx);
+    let dx = dexX.swap(user, dy, this.tokenY);
+    tokenX.transfer(dexX.self, user, dx);
     return dx;
   }
 }
@@ -312,7 +320,7 @@ class DexTokenHolder extends SmartContract {
     this.balance.subInPlace(dy);
 
     // emit event
-    this.typedEvents.emit('swap', { address: this.sender.getAndRequireSignature(), dx });
+    this.typedEvents.emit('swap', { address: user, dx });
 
     return dy;
   }
diff --git a/src/examples/zkapps/dex/dex.ts b/src/examples/zkapps/dex/dex.ts
index 697edab4b8..57479e7304 100644
--- a/src/examples/zkapps/dex/dex.ts
+++ b/src/examples/zkapps/dex/dex.ts
@@ -55,7 +55,7 @@ function createDex({
      * instead, the input X and Y amounts determine the initial ratio.
      */
     @method supplyLiquidityBase(dx: UInt64, dy: UInt64): UInt64 {
-      let user = this.sender.getAndRequireSignature();
+      let user = this.sender.getUnconstrained(); // unconstrained because transfer() requires the signature anyway
       let tokenX = new TokenContract(this.tokenX);
       let tokenY = new TokenContract(this.tokenY);
 
@@ -148,10 +148,10 @@ function createDex({
      */
     redeemLiquidity(dl: UInt64) {
       // call the token X holder inside a token X-approved callback
-      let sender = this.sender.getAndRequireSignature();
+      let sender = this.sender.getUnconstrained(); // unconstrained because redeemLiquidity() requires the signature anyway
       let tokenX = new TokenContract(this.tokenX);
       let dexX = new DexTokenHolder(this.address, tokenX.deriveTokenId());
-      let dxdy = dexX.redeemLiquidity(this.sender, dl, this.tokenY);
+      let dxdy = dexX.redeemLiquidity(sender, dl, this.tokenY);
       let dx = dxdy[0];
       tokenX.transfer(dexX.self, sender, dx);
       return dxdy;
@@ -165,11 +165,11 @@ function createDex({
      * The transaction needs to be signed by the user's private key.
      */
     @method swapX(dx: UInt64): UInt64 {
-      let sender = this.sender.getAndRequireSignature();
+      let sender = this.sender.getUnconstrained(); // unconstrained because swap() requires the signature anyway
       let tokenY = new TokenContract(this.tokenY);
       let dexY = new DexTokenHolder(this.address, tokenY.deriveTokenId());
-      let dy = dexY.swap(this.sender, dx, this.tokenX);
-      tokenY.transfer(dexY.self, this.sender, dy);
+      let dy = dexY.swap(sender, dx, this.tokenX);
+      tokenY.transfer(dexY.self, sender, dy);
       return dy;
     }
 
@@ -181,11 +181,11 @@ function createDex({
      * The transaction needs to be signed by the user's private key.
      */
     @method swapY(dy: UInt64): UInt64 {
-      let sender = this.sender.getAndRequireSignature();
+      let sender = this.sender.getUnconstrained(); // unconstrained because swap() requires the signature anyway
       let tokenX = new TokenContract(this.tokenX);
       let dexX = new DexTokenHolder(this.address, tokenX.deriveTokenId());
-      let dx = dexX.swap(this.sender, dy, this.tokenY);
-      tokenX.transfer(dexX.self, this.sender, dx);
+      let dx = dexX.swap(sender, dy, this.tokenY);
+      tokenX.transfer(dexX.self, sender, dx);
       return dx;
     }
 
@@ -218,14 +218,14 @@ function createDex({
     }
 
     @method swapX(dx: UInt64): UInt64 {
-      let sender = this.sender.getAndRequireSignature();
+      let sender = this.sender.getUnconstrained(); // unconstrained because swap() requires the signature anyway
       let tokenY = new TokenContract(this.tokenY);
       let dexY = new ModifiedDexTokenHolder(
         this.address,
         tokenY.deriveTokenId()
       );
-      let dy = dexY.swap(this.sender, dx, this.tokenX);
-      tokenY.transfer(dexY.self, this.sender, dy);
+      let dy = dexY.swap(sender, dx, this.tokenX);
+      tokenY.transfer(dexY.self, sender, dy);
       return dy;
     }
   }
diff --git a/src/examples/zkapps/simple-zkapp-payment.ts b/src/examples/zkapps/simple-zkapp-payment.ts
index 0594a01728..2995f10451 100644
--- a/src/examples/zkapps/simple-zkapp-payment.ts
+++ b/src/examples/zkapps/simple-zkapp-payment.ts
@@ -22,11 +22,14 @@ class SendMINAExample extends SmartContract {
   }
 
   @method withdraw(amount: UInt64) {
-    this.send({ to: this.sender.getAndRequireSignature(), amount });
+    // unconstrained because we don't care where the user wants to withdraw to
+    let to = this.sender.getUnconstrained();
+    this.send({ to, amount });
   }
 
   @method deposit(amount: UInt64) {
-    let senderUpdate = AccountUpdate.createSigned(this.sender.getAndRequireSignature());
+    let sender = this.sender.getUnconstrained(); // unconstrained because we're already requiring a signature in the next line
+    let senderUpdate = AccountUpdate.createSigned(sender);
     senderUpdate.send({ to: this, amount });
   }
 }
diff --git a/tests/integration/simple-zkapp.js b/tests/integration/simple-zkapp.js
index 86df100643..bea66cc0ba 100644
--- a/tests/integration/simple-zkapp.js
+++ b/tests/integration/simple-zkapp.js
@@ -61,7 +61,7 @@ class NotSoSimpleZkapp extends SmartContract {
   }
 
   deposit(amount) {
-    let sender = this.sender.getAndRequireSignature();
+    let sender = this.sender.getUnconstrained(); // unconstrained because we're already requiring a signature in the next line
     let senderUpdate = AccountUpdate.createSigned(sender);
     senderUpdate.send({ to: this, amount });
   }

From 348ea1e9b6535633df821dda79a642f165acc4a5 Mon Sep 17 00:00:00 2001
From: Gregor <gregor.mitscha-baude@gmx.at>
Date: Thu, 7 Mar 2024 12:54:16 +0100
Subject: [PATCH 5/6] changelog

---
 CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 18c72e73ba..ffdcb91508 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
   - `Provable.runAndCheck()`, `Provable.constraintSystem()` and `{SmartContract,ZkProgram}.digest()` are also async now
   - These changes were made to add internal support for async circuits
   - `Provable.runAndCheckSync()` added and immediately deprecated for a smoother upgrade path for tests
+- Remove `this.sender` which unintuitively did not prove that its value was the actual sender of the transaction https://github.com/o1-labs/o1js/pull/1464  
+  Replaced by more explicit APIs:
+  - `this.sender.getUnconstrained()` which has the old behavior of `this.sender`, and returns an unconstrained value (which means that the prover can set it to any value they want)
+  - `this.sender.getAndRequireSignature()` which requires a signature from the sender's public key and therefore proves that whoever created the transaction really owns the sender account
 - `Reducer.reduce()` requires the maximum number of actions per method as an explicit (optional) argument https://github.com/o1-labs/o1js/pull/1450
   - The default value is 1 and should work for most existing contracts
 

From d65902af6b5036fb264238b2a6f922d5a1030e44 Mon Sep 17 00:00:00 2001
From: Gregor <gregor.mitscha-baude@gmx.at>
Date: Thu, 7 Mar 2024 12:55:45 +0100
Subject: [PATCH 6/6] tweak changelog

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ffdcb91508..2539232e29 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,7 +25,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
   - `Provable.runAndCheck()`, `Provable.constraintSystem()` and `{SmartContract,ZkProgram}.digest()` are also async now
   - These changes were made to add internal support for async circuits
   - `Provable.runAndCheckSync()` added and immediately deprecated for a smoother upgrade path for tests
-- Remove `this.sender` which unintuitively did not prove that its value was the actual sender of the transaction https://github.com/o1-labs/o1js/pull/1464  
+- Remove `this.sender` which unintuitively did not prove that its value was the actual sender of the transaction https://github.com/o1-labs/o1js/pull/1464 [@julio4](https://github.com/julio4)
   Replaced by more explicit APIs:
   - `this.sender.getUnconstrained()` which has the old behavior of `this.sender`, and returns an unconstrained value (which means that the prover can set it to any value they want)
   - `this.sender.getAndRequireSignature()` which requires a signature from the sender's public key and therefore proves that whoever created the transaction really owns the sender account