diff --git a/local-tests/test.ts b/local-tests/test.ts
index e140a2d913..f4154aa420 100644
--- a/local-tests/test.ts
+++ b/local-tests/test.ts
@@ -44,6 +44,8 @@ import { testUseInvalidLitActionIpfsCodeToGenerateSessionSigs } from './tests/te
 import { testSolAuthSigToEncryptDecryptString } from './tests/testSolAuthSigToEncryptDecryptString';
 import { testEthAuthSigToEncryptDecryptString } from './tests/testEthAuthSigToEncryptDecryptString';
 import { testCosmosAuthSigToEncryptDecryptString } from './tests/testCosmosAuthSigToEncryptDecryptString';
+import { testKeccakEip1271AuthSigToEncryptDecryptString } from './tests/testKeccakEip1271AuthSigToEncryptDecryptString';
+import { testShaEip1271AuthSigToEncryptDecryptString } from './tests/testShaEip1271AuthSigToEncryptDecryptString';
 import { testPkpEthersWithEoaSessionSigsToSignMessage } from './tests/testPkpEthersWithEoaSessionSigsToSignMessage';
 import { testPkpEthersWithEoaSessionSigsToSignWithAuthContext } from './tests/testPkpEthersWithEoaSessionSigsToSignWithAuthContext';
 import { testPkpEthersWithEoaSessionSigsToEthSign } from './tests/testPkpEthersWithEoaSessionSigsToEthSign';
@@ -232,6 +234,11 @@ setLitActionsCodeToLocal();
     testCosmosAuthSigToEncryptDecryptString,
   };
 
+  const eip1271AuthSigTests = {
+    testKeccakEip1271AuthSigToEncryptDecryptString,
+    testShaEip1271AuthSigToEncryptDecryptString,
+  };
+
   const pkpEthersTest = {
     eoaSessionSigs: {
       testPkpEthersWithEoaSessionSigsToSignWithAuthContext,
@@ -294,6 +301,7 @@ setLitActionsCodeToLocal();
       ...litActionIpfsIdSessionSigsTests,
       ...capacityDelegationTests,
       ...bareAuthSigTests,
+      ...eip1271AuthSigTests,
 
       ...pkpEthersTest.eoaSessionSigs,
       ...pkpEthersTest.pkpSessionSigs,
diff --git a/local-tests/tests/testKeccakEip1271AuthSigToEncryptDecryptString.ts b/local-tests/tests/testKeccakEip1271AuthSigToEncryptDecryptString.ts
new file mode 100644
index 0000000000..ac4d9cf0c2
--- /dev/null
+++ b/local-tests/tests/testKeccakEip1271AuthSigToEncryptDecryptString.ts
@@ -0,0 +1,174 @@
+import { AuthSig, BaseSiweMessage, ILitNodeClient } from '@lit-protocol/types';
+import { AccessControlConditions } from 'local-tests/setup/accs/accs';
+import { TinnyEnvironment } from 'local-tests/setup/tinny-environment';
+import { log } from '@lit-protocol/misc';
+import { encryptString, decryptToString } from '@lit-protocol/encryption';
+import { CENTRALISATION_BY_NETWORK } from '@lit-protocol/constants';
+import { createSiweMessage } from '@lit-protocol/auth-helpers';
+import { hashMessage } from 'ethers/lib/utils';
+import { ethers } from 'ethers';
+import { createHash } from 'crypto';
+
+/**
+ * Test Commands:
+ * ✅ NETWORK=datil-dev yarn test:local --filter=testKeccakEip1271AuthSigToEncryptDecryptString
+ * ✅ NETWORK=datil-test yarn test:local --filter=testKeccakEip1271AuthSigToEncryptDecryptString
+ * ✅ NETWORK=custom yarn test:local --filter=testKeccakEip1271AuthSigToEncryptDecryptString
+ */
+export const testKeccakEip1271AuthSigToEncryptDecryptString = async (
+  devEnv: TinnyEnvironment
+) => {
+  const dataToEncrypt = 'Decrypted from EIP1271 AuthSig';
+  const contractAddress = '0x88105De2349f59767278Fd15c0858f806c08d615';
+  const deployerAddress = '0x0b1C5E9E82393AD5d1d1e9a498BF7bAAC13b31Ee'; // No purpose other than to be a random address
+  const abi = [
+    'function setTempOwner(address _tempOwner) external',
+    'function getTempOwner() external view returns (address)',
+    'function isValidSignature(bytes32 _hash, bytes calldata _signature) external view returns (bytes4)',
+  ];
+
+  const alice = await devEnv.createRandomPerson();
+  if (CENTRALISATION_BY_NETWORK[devEnv.network] === 'decentralised') {
+    // The capacity credits NFT owner automatically uses the capacity credits
+    // to pay for the encryption
+    await alice.mintCapacityCreditsNFT();
+  }
+
+  let accs = AccessControlConditions.getEmvBasicAccessControlConditions({
+    userAddress: contractAddress,
+  });
+  accs[0].chain = 'yellowstone'; // Contract deployed on Yellowstone
+
+  const encryptRes = await encryptString(
+    {
+      accessControlConditions: accs,
+      dataToEncrypt,
+    },
+    devEnv.litNodeClient as unknown as ILitNodeClient
+  );
+
+  // log('encryptRes:', encryptRes);
+
+  if (!encryptRes.ciphertext) {
+    throw new Error(`Expected "ciphertext" in encryptRes`);
+  }
+
+  if (!encryptRes.dataToEncryptHash) {
+    throw new Error(`Expected "dataToEncryptHash" to in encryptRes`);
+  }
+
+  // Craft the SiweMessage to be hashed & signed
+  const siweMessage = await createSiweMessage<BaseSiweMessage>({
+    nonce: await devEnv.litNodeClient.getLatestBlockhash(),
+    walletAddress: alice.wallet.address,
+  });
+
+  const siweSignature = await alice.wallet.signMessage(siweMessage);
+  log('siweSignature: ', siweSignature);
+
+  // Internally generate from wallet.signMessage
+  const hash = hashMessage(siweMessage);
+  const hashUint8Array = ethers.utils.arrayify(hash);
+  log('hash:', hash);
+  log('hashUint8Array: ', hashUint8Array); // Match it against the hash done on the nodes before calling verifySignature()
+
+  const eip1271AuthSig: AuthSig = {
+    address: contractAddress,
+    sig: siweSignature,
+    derivedVia: 'EIP1271',
+    signedMessage: siweMessage,
+  };
+
+  // log(eip1271AuthSig);
+
+  // Test from the contract
+  const contract = new ethers.Contract(contractAddress, abi, alice.wallet);
+  const setDeployerAsTempOwnerTx = await contract.setTempOwner(deployerAddress);
+  await setDeployerAsTempOwnerTx.wait();
+
+  log(
+    '0. isValidSignature should FAIL since Alice (AuthSig.sig) is not the tempOwner yet'
+  );
+  try {
+    const isValid = await contract.isValidSignature(hash, siweSignature);
+    if (isValid === '0x1626ba7e') {
+      throw new Error(
+        `Expected isValidSignature to be 0xffffffff but got ${isValid}`
+      );
+    }
+  } catch (error) {
+    log('Error calling isValidSignature:', error);
+    throw error;
+  }
+
+  try {
+    const _decryptRes = await decryptToString(
+      {
+        accessControlConditions: accs,
+        ciphertext: encryptRes.ciphertext,
+        dataToEncryptHash: encryptRes.dataToEncryptHash,
+        authSig: eip1271AuthSig,
+        chain: 'yellowstone', // Deployed chain
+      },
+      devEnv.litNodeClient as unknown as ILitNodeClient
+    );
+  } catch (error) {
+    if (
+      !error.message.includes('NodeContractAuthsigUnauthorized') ||
+      !error.message.includes('Access control failed for Smart contract') ||
+      !error.message.includes(
+        'validation error: Authsig failed for contract 0x88105De2349f59767278Fd15c0858f806c08d615.  Return value was ffffffff.'
+      )
+    ) {
+      throw new Error(
+        `Expected error message to contain specific EIP1271 validation failure, but got: ${error}`
+      );
+    }
+  }
+
+  // Should PASS now
+  log('1. Setting temp owner...');
+  const setTempOwnerTx = await contract.setTempOwner(alice.wallet.address);
+  await setTempOwnerTx.wait();
+  log('Set tempOwner transaction hash: ', setTempOwnerTx.hash);
+
+  const tempOwner = await contract.getTempOwner();
+  if (tempOwner.toLowerCase() !== alice.wallet.address.toLowerCase()) {
+    throw new Error(
+      `Expected temp owner to be ${alice.wallet.address} but got ${tempOwner}`
+    );
+  }
+
+  log('2. Checking isValidSignature...');
+  try {
+    const isValid = await contract.isValidSignature(hash, siweSignature);
+    if (isValid !== '0x1626ba7e') {
+      throw new Error(
+        `Expected isValidSignature to be 0x1626ba7e but got ${isValid}`
+      );
+    }
+  } catch (error) {
+    log('Error calling isValidSignature:', error);
+    throw error;
+  }
+
+  // -- Decrypt the encrypted string
+  const decryptRes = await decryptToString(
+    {
+      accessControlConditions: accs,
+      ciphertext: encryptRes.ciphertext,
+      dataToEncryptHash: encryptRes.dataToEncryptHash,
+      authSig: eip1271AuthSig,
+      chain: 'yellowstone', // Deployed chain
+    },
+    devEnv.litNodeClient as unknown as ILitNodeClient
+  );
+
+  if (decryptRes !== dataToEncrypt) {
+    throw new Error(
+      `Expected decryptRes to be ${dataToEncrypt} but got ${decryptRes}`
+    );
+  }
+
+  log('✅ decryptRes:', decryptRes);
+};
diff --git a/local-tests/tests/testShaEip1271AuthSigToEncryptDecryptString.ts b/local-tests/tests/testShaEip1271AuthSigToEncryptDecryptString.ts
new file mode 100644
index 0000000000..b858f02dec
--- /dev/null
+++ b/local-tests/tests/testShaEip1271AuthSigToEncryptDecryptString.ts
@@ -0,0 +1,177 @@
+import { AuthSig, BaseSiweMessage, ILitNodeClient } from '@lit-protocol/types';
+import { AccessControlConditions } from 'local-tests/setup/accs/accs';
+import { TinnyEnvironment } from 'local-tests/setup/tinny-environment';
+import { log } from '@lit-protocol/misc';
+import { encryptString, decryptToString } from '@lit-protocol/encryption';
+import { CENTRALISATION_BY_NETWORK } from '@lit-protocol/constants';
+import { createSiweMessage } from '@lit-protocol/auth-helpers';
+import { joinSignature } from 'ethers/lib/utils';
+import { ethers } from 'ethers';
+import { createHash } from 'crypto';
+
+/**
+ * Test Commands:
+ * ✅ NETWORK=datil-dev yarn test:local --filter=testShaEip1271AuthSigToEncryptDecryptString
+ * ✅ NETWORK=datil-test yarn test:local --filter=testShaEip1271AuthSigToEncryptDecryptString
+ * ✅ NETWORK=custom yarn test:local --filter=testShaEip1271AuthSigToEncryptDecryptString
+ */
+export const testShaEip1271AuthSigToEncryptDecryptString = async (
+  devEnv: TinnyEnvironment
+) => {
+  const dataToEncrypt = 'Decrypted from EIP1271 AuthSig';
+  const contractAddress = '0x88105De2349f59767278Fd15c0858f806c08d615';
+  const deployerAddress = '0x0b1C5E9E82393AD5d1d1e9a498BF7bAAC13b31Ee'; // No purpose other than to be a random address
+  const abi = [
+    'function setTempOwner(address _tempOwner) external',
+    'function getTempOwner() external view returns (address)',
+    'function isValidSignature(bytes32 _hash, bytes calldata _signature) external view returns (bytes4)',
+  ];
+
+  const alice = await devEnv.createRandomPerson();
+  if (CENTRALISATION_BY_NETWORK[devEnv.network] === 'decentralised') {
+    // The capacity credits NFT owner automatically uses the capacity credits
+    // to pay for the encryption
+    await alice.mintCapacityCreditsNFT();
+  }
+
+  let accs = AccessControlConditions.getEmvBasicAccessControlConditions({
+    userAddress: contractAddress,
+  });
+  accs[0].chain = 'yellowstone'; // Contract deployed on Yellowstone
+
+  const encryptRes = await encryptString(
+    {
+      accessControlConditions: accs,
+      dataToEncrypt,
+    },
+    devEnv.litNodeClient as unknown as ILitNodeClient
+  );
+
+  // log('encryptRes:', encryptRes);
+
+  if (!encryptRes.ciphertext) {
+    throw new Error(`Expected "ciphertext" in encryptRes`);
+  }
+
+  if (!encryptRes.dataToEncryptHash) {
+    throw new Error(`Expected "dataToEncryptHash" to in encryptRes`);
+  }
+
+  // Craft the SiweMessage to be hashed & signed
+  const siweMessage = await createSiweMessage<BaseSiweMessage>({
+    nonce: await devEnv.litNodeClient.getLatestBlockhash(),
+    walletAddress: alice.wallet.address,
+  });
+
+  // Explicitly SHA256 hash the SIWE message
+  const hash = createHash('sha256').update(siweMessage).digest();
+  const hashHex = '0x' + hash.toString('hex');
+  const hashUint8Array = ethers.utils.arrayify(hashHex);
+  log('hash:', hashHex);
+  log('hashUint8Array: ', hashUint8Array); // Match it against the hash done on the nodes before calling verifySignature()
+
+  const siweSignature = joinSignature(
+    alice.wallet._signingKey().signDigest(hashHex)
+  );
+  log('siweSignature: ', siweSignature);
+
+  const eip1271AuthSig: AuthSig = {
+    address: contractAddress,
+    sig: siweSignature,
+    derivedVia: 'EIP1271_SHA256',
+    signedMessage: siweMessage,
+  };
+
+  // log(eip1271AuthSig);
+
+  // Test from the contract
+  const contract = new ethers.Contract(contractAddress, abi, alice.wallet);
+  const setDeployerAsTempOwnerTx = await contract.setTempOwner(deployerAddress);
+  await setDeployerAsTempOwnerTx.wait();
+
+  log(
+    '0. isValidSignature should FAIL since Alice (AuthSig.sig) is not the tempOwner yet'
+  );
+  try {
+    const isValid = await contract.isValidSignature(hash, siweSignature);
+    if (isValid === '0x1626ba7e') {
+      throw new Error(
+        `Expected isValidSignature to be 0xffffffff but got ${isValid}`
+      );
+    }
+  } catch (error) {
+    log('Error calling isValidSignature:', error);
+    throw error;
+  }
+
+  try {
+    const _decryptRes = await decryptToString(
+      {
+        accessControlConditions: accs,
+        ciphertext: encryptRes.ciphertext,
+        dataToEncryptHash: encryptRes.dataToEncryptHash,
+        authSig: eip1271AuthSig,
+        chain: 'yellowstone', // Deployed chain
+      },
+      devEnv.litNodeClient as unknown as ILitNodeClient
+    );
+  } catch (error) {
+    if (
+      !error.message.includes('NodeContractAuthsigUnauthorized') ||
+      !error.message.includes('Access control failed for Smart contract') ||
+      !error.message.includes(
+        'validation error: Authsig failed for contract 0x88105De2349f59767278Fd15c0858f806c08d615.  Return value was ffffffff.'
+      )
+    ) {
+      throw new Error(
+        `Expected error message to contain specific EIP1271 validation failure, but got: ${error}`
+      );
+    }
+  }
+
+  // Should PASS now
+  log('1. Setting temp owner...');
+  const setTempOwnerTx = await contract.setTempOwner(alice.wallet.address);
+  await setTempOwnerTx.wait();
+  log('Set tempOwner transaction hash: ', setTempOwnerTx.hash);
+
+  const tempOwner = await contract.getTempOwner();
+  if (tempOwner.toLowerCase() !== alice.wallet.address.toLowerCase()) {
+    throw new Error(
+      `Expected temp owner to be ${alice.wallet.address} but got ${tempOwner}`
+    );
+  }
+
+  log('2. Checking isValidSignature...');
+  try {
+    const isValid = await contract.isValidSignature(hash, siweSignature);
+    if (isValid !== '0x1626ba7e') {
+      throw new Error(
+        `Expected isValidSignature to be 0x1626ba7e but got ${isValid}`
+      );
+    }
+  } catch (error) {
+    log('Error calling isValidSignature:', error);
+    throw error;
+  }
+
+  // -- Decrypt the encrypted string
+  const decryptRes = await decryptToString(
+    {
+      accessControlConditions: accs,
+      ciphertext: encryptRes.ciphertext,
+      dataToEncryptHash: encryptRes.dataToEncryptHash,
+      authSig: eip1271AuthSig,
+      chain: 'yellowstone', // Deployed chain
+    },
+    devEnv.litNodeClient as unknown as ILitNodeClient
+  );
+
+  if (decryptRes !== dataToEncrypt) {
+    throw new Error(
+      `Expected decryptRes to be ${dataToEncrypt} but got ${decryptRes}`
+    );
+  }
+
+  log('✅ decryptRes:', decryptRes);
+};