diff --git a/.changeset/curly-lemons-act.md b/.changeset/curly-lemons-act.md
new file mode 100644
index 0000000000000..6dd4cfefca8f5
--- /dev/null
+++ b/.changeset/curly-lemons-act.md
@@ -0,0 +1,5 @@
+---
+'@mysten/zklogin': patch
+---
+
+Remove BCS export and introduce new getZkSignature export.
diff --git a/apps/wallet/src/background/accounts/zk/ZkAccount.ts b/apps/wallet/src/background/accounts/zk/ZkAccount.ts
index f56bbf30904b2..f99dec4328c35 100644
--- a/apps/wallet/src/background/accounts/zk/ZkAccount.ts
+++ b/apps/wallet/src/background/accounts/zk/ZkAccount.ts
@@ -4,11 +4,9 @@
 import {
 	type SerializedSignature,
 	type ExportedKeypair,
-	SIGNATURE_SCHEME_TO_FLAG,
 	toSerializedSignature,
 } from '@mysten/sui.js/cryptography';
-import { fromB64, toB64 } from '@mysten/sui.js/utils';
-import { computeZkAddress, zkBcs } from '@mysten/zklogin';
+import { computeZkAddress, getZkSignature } from '@mysten/zklogin';
 import { blake2b } from '@noble/hashes/blake2b';
 import { decodeJwt } from 'jose';
 import { getCurrentEpoch } from './current-epoch';
@@ -230,25 +228,13 @@ export class ZkAccount
 		}
 		const { ephemeralKeyPair, proofs, maxEpoch } = credentials;
 		const keyPair = fromExportedKeypair(ephemeralKeyPair);
+
 		const userSignature = toSerializedSignature({
 			signature: await keyPair.sign(digest),
 			signatureScheme: keyPair.getKeyScheme(),
 			publicKey: keyPair.getPublicKey(),
 		});
-		const bytes = zkBcs
-			.ser(
-				'ZkSignature',
-				{
-					inputs: proofs,
-					max_epoch: maxEpoch,
-					user_signature: fromB64(userSignature),
-				},
-				{ maxSize: 2048 },
-			)
-			.toBytes();
-		const signatureBytes = new Uint8Array(bytes.length + 1);
-		signatureBytes.set([SIGNATURE_SCHEME_TO_FLAG['Zk']]);
-		signatureBytes.set(bytes, 1);
-		return toB64(signatureBytes);
+
+		return getZkSignature({ inputs: proofs, maxEpoch, userSignature });
 	}
 }
diff --git a/sdk/zklogin/src/address.ts b/sdk/zklogin/src/address.ts
index fe1ca7e7b01ad..fce52fde906c5 100644
--- a/sdk/zklogin/src/address.ts
+++ b/sdk/zklogin/src/address.ts
@@ -11,13 +11,7 @@ import { genAddressSeed, toBufferBE } from './utils.js';
 
 export function jwtToAddress(jwt: string, userSalt: bigint) {
 	const decodedJWT = decodeJwt(jwt);
-	if (
-		!decodedJWT.sub ||
-		!decodedJWT.iss ||
-		!decodedJWT.aud ||
-		!decodedJWT.email ||
-		typeof decodedJWT.email !== 'string'
-	) {
+	if (!decodedJWT.sub || !decodedJWT.iss || !decodedJWT.aud) {
 		throw new Error('Missing jwt data');
 	}
 
diff --git a/sdk/zklogin/src/bcs.ts b/sdk/zklogin/src/bcs.ts
index 897e3fbb18e24..c76e556e9a17b 100644
--- a/sdk/zklogin/src/bcs.ts
+++ b/sdk/zklogin/src/bcs.ts
@@ -1,7 +1,8 @@
 // Copyright (c) Mysten Labs, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-import { BCS } from '@mysten/bcs';
+import { BCS, fromB64, toB64 } from '@mysten/bcs';
+import { SIGNATURE_SCHEME_TO_FLAG } from '@mysten/sui.js/cryptography';
 import { bcs } from '@mysten/sui.js/bcs';
 
 export const zkBcs = new BCS(bcs);
@@ -17,6 +18,31 @@ zkBcs.registerStructType('ZkClaim', {
 	index_mod_4: BCS.U8,
 });
 
+type Claim = {
+	name: string;
+	value_base64: string;
+	index_mod_4: number;
+};
+
+export interface ProofPoints {
+	pi_a: string[];
+	pi_b: string[][];
+	pi_c: string[];
+}
+
+export interface ZkSignatureInputs {
+	proof_points: ProofPoints;
+	address_seed: string;
+	claims: Claim[];
+	header_base64: string;
+}
+
+export interface ZkSignature {
+	inputs: ZkSignatureInputs;
+	maxEpoch: number;
+	userSignature: string | Uint8Array;
+}
+
 zkBcs.registerStructType('ZkSignature', {
 	inputs: {
 		proof_points: {
@@ -31,3 +57,25 @@ zkBcs.registerStructType('ZkSignature', {
 	max_epoch: BCS.U64,
 	user_signature: [BCS.VECTOR, BCS.U8],
 });
+
+function getZkSignatureBytes({ inputs, maxEpoch, userSignature }: ZkSignature) {
+	return zkBcs
+		.ser(
+			'ZkSignature',
+			{
+				inputs,
+				max_epoch: maxEpoch,
+				user_signature: typeof userSignature === 'string' ? fromB64(userSignature) : userSignature,
+			},
+			{ maxSize: 2048 },
+		)
+		.toBytes();
+}
+
+export function getZkSignature({ inputs, maxEpoch, userSignature }: ZkSignature) {
+	const bytes = getZkSignatureBytes({ inputs, maxEpoch, userSignature });
+	const signatureBytes = new Uint8Array(bytes.length + 1);
+	signatureBytes.set([SIGNATURE_SCHEME_TO_FLAG['Zk']]);
+	signatureBytes.set(bytes, 1);
+	return toB64(signatureBytes);
+}
diff --git a/sdk/zklogin/src/index.ts b/sdk/zklogin/src/index.ts
index 652bbcaf03ae0..bf699cc400aa5 100644
--- a/sdk/zklogin/src/index.ts
+++ b/sdk/zklogin/src/index.ts
@@ -4,7 +4,7 @@
 export { computeZkAddress, jwtToAddress } from './address.js';
 export type { ComputeZKAddressOptions } from './address.js';
 
-export { zkBcs } from './bcs.js';
+export { getZkSignature } from './bcs.js';
 
 export { poseidonHash } from './poseidon.js';