diff --git a/src/blst/index.ts b/src/blst/index.ts
index 83d05a4..f4d8b1b 100644
--- a/src/blst/index.ts
+++ b/src/blst/index.ts
@@ -1,11 +1,10 @@
-import assert from "assert";
 import {Keypair} from "./keypair";
 import {PrivateKey} from "./privateKey";
 import {PublicKey} from "./publicKey";
 import {Signature} from "./signature";
-import {toBuffer} from "../helpers/utils";
 import {IBls} from "../interface";
 export * from "../constants";
+import {functionalInterfaceFactory} from "../functional";
 
 export {Keypair, PrivateKey, PublicKey, Signature};
 
@@ -16,113 +15,13 @@ export function destroy(): void {
   // Native bindings require no destroy() call
 }
 
-/**
- * Signs given message using secret key.
- * @param secretKey
- * @param messageHash
- */
-export function sign(secretKey: Uint8Array, messageHash: Uint8Array): Buffer {
-  assert(secretKey, "secretKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  const privateKey = PrivateKey.fromBytes(toBuffer(secretKey));
-  return privateKey.signMessage(toBuffer(messageHash)).toBytes();
-}
-
-/**
- * Compines all given signature into one.
- * @param signatures
- */
-export function aggregateSignatures(signatures: Uint8Array[]): Buffer {
-  const agg = Signature.aggregate(signatures.map((p) => Signature.fromBytes(p)));
-  return agg.toBytes();
-}
-
-/**
- * Combines all given public keys into single one
- * @param publicKeys
- */
-export function aggregatePubkeys(publicKeys: Uint8Array[]): Buffer {
-  const agg = PublicKey.aggregate(publicKeys.map((p) => PublicKey.fromBytes(p)));
-  return agg.toBytes();
-}
-
-/**
- * Verifies if signature is message signed with given public key.
- * @param publicKey
- * @param messageHash
- * @param signature
- */
-export function verify(publicKey: Uint8Array, messageHash: Uint8Array, signature: Uint8Array): boolean {
-  assert(publicKey, "publicKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-  try {
-    return PublicKey.fromBytes(publicKey).verifyMessage(
-      Signature.fromBytes(toBuffer(signature)),
-      toBuffer(messageHash)
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
-/**
- * Verifies if aggregated signature is same message signed with given public keys.
- * @param publicKeys
- * @param messageHash
- * @param signature
- */
-export function verifyAggregate(publicKeys: Uint8Array[], messageHash: Uint8Array, signature: Uint8Array): boolean {
-  assert(publicKeys, "publicKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-  try {
-    return Signature.fromBytes(signature).verifyAggregate(
-      publicKeys.map((pubkey) => PublicKey.fromBytes(pubkey)),
-      messageHash
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
-/**
- * Verifies if signature is list of message signed with corresponding public key.
- * @param publicKeys
- * @param messageHashes
- * @param signature
- * @param fast Check if all messages are different
- */
-export function verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Array[], signature: Uint8Array): boolean {
-  assert(publicKeys, "publicKey is null or undefined");
-  assert(messageHashes, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-
-  if (publicKeys.length === 0 || publicKeys.length != messageHashes.length) {
-    return false;
-  }
-  try {
-    return Signature.fromBytes(toBuffer(signature)).verifyMultiple(
-      publicKeys.map((key) => PublicKey.fromBytes(toBuffer(key))),
-      messageHashes.map((m) => toBuffer(m))
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
-const bls: IBls = {
-  sign,
-  aggregateSignatures,
-  aggregatePubkeys,
-  verify,
-  verifyAggregate,
-  verifyMultiple,
-
+export const bls: IBls = {
   // Keypair,
   PrivateKey,
   PublicKey,
   Signature,
+
+  ...functionalInterfaceFactory({PrivateKey, PublicKey, Signature}),
   initBLS,
   destroy,
 };
diff --git a/src/functional.ts b/src/functional.ts
new file mode 100644
index 0000000..ef78f8c
--- /dev/null
+++ b/src/functional.ts
@@ -0,0 +1,109 @@
+import assert from "assert";
+import {IBls} from "./interface";
+
+export function functionalInterfaceFactory({
+  PrivateKey,
+  PublicKey,
+  Signature,
+}: Pick<IBls, "PrivateKey" | "PublicKey" | "Signature">) {
+  /**
+   * Signs given message using secret key.
+   * @param secretKey
+   * @param messageHash
+   */
+  function sign(secretKey: Uint8Array, messageHash: Uint8Array): Buffer {
+    assert(secretKey, "secretKey is null or undefined");
+    assert(messageHash, "messageHash is null or undefined");
+    const privateKey = PrivateKey.fromBytes(secretKey);
+    return privateKey.signMessage(messageHash).toBytes();
+  }
+
+  /**
+   * Compines all given signature into one.
+   * @param signatures
+   */
+  function aggregateSignatures(signatures: Uint8Array[]): Buffer {
+    const agg = Signature.aggregate(signatures.map((p) => Signature.fromBytes(p)));
+    return agg.toBytes();
+  }
+
+  /**
+   * Combines all given public keys into single one
+   * @param publicKeys
+   */
+  function aggregatePubkeys(publicKeys: Uint8Array[]): Buffer {
+    const agg = PublicKey.aggregate(publicKeys.map((p) => PublicKey.fromBytes(p)));
+    return agg.toBytes();
+  }
+
+  /**
+   * Verifies if signature is message signed with given public key.
+   * @param publicKey
+   * @param messageHash
+   * @param signature
+   */
+  function verify(publicKey: Uint8Array, messageHash: Uint8Array, signature: Uint8Array): boolean {
+    assert(publicKey, "publicKey is null or undefined");
+    assert(messageHash, "messageHash is null or undefined");
+    assert(signature, "signature is null or undefined");
+    try {
+      return Signature.fromBytes(signature).verify(PublicKey.fromBytes(publicKey), messageHash);
+    } catch (e) {
+      return false;
+    }
+  }
+
+  /**
+   * Verifies if aggregated signature is same message signed with given public keys.
+   * @param publicKeys
+   * @param messageHash
+   * @param signature
+   */
+  function verifyAggregate(publicKeys: Uint8Array[], messageHash: Uint8Array, signature: Uint8Array): boolean {
+    assert(publicKeys, "publicKey is null or undefined");
+    assert(messageHash, "messageHash is null or undefined");
+    assert(signature, "signature is null or undefined");
+    try {
+      return Signature.fromBytes(signature).verifyAggregate(
+        publicKeys.map((pubkey) => PublicKey.fromBytes(pubkey)),
+        messageHash
+      );
+    } catch (e) {
+      return false;
+    }
+  }
+
+  /**
+   * Verifies if signature is list of message signed with corresponding public key.
+   * @param publicKeys
+   * @param messageHashes
+   * @param signature
+   * @param fast Check if all messages are different
+   */
+  function verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Array[], signature: Uint8Array): boolean {
+    assert(publicKeys, "publicKey is null or undefined");
+    assert(messageHashes, "messageHash is null or undefined");
+    assert(signature, "signature is null or undefined");
+
+    if (publicKeys.length === 0 || publicKeys.length != messageHashes.length) {
+      return false;
+    }
+    try {
+      return Signature.fromBytes(signature).verifyMultiple(
+        publicKeys.map((publicKey) => PublicKey.fromBytes(publicKey)),
+        messageHashes.map((msg) => msg)
+      );
+    } catch (e) {
+      return false;
+    }
+  }
+
+  return {
+    sign,
+    aggregateSignatures,
+    aggregatePubkeys,
+    verify,
+    verifyAggregate,
+    verifyMultiple,
+  };
+}
diff --git a/src/herumi/index.ts b/src/herumi/index.ts
index 6c03481..a8afed8 100644
--- a/src/herumi/index.ts
+++ b/src/herumi/index.ts
@@ -3,120 +3,18 @@ import {PrivateKey} from "./privateKey";
 import {PublicKey} from "./publicKey";
 import {Signature} from "./signature";
 import {initBLS, destroy} from "./context";
-import assert from "assert";
-import {toBuffer} from "../helpers/utils";
 import {IBls} from "../interface";
+import {functionalInterfaceFactory} from "../functional";
 
 export {Keypair, PrivateKey, PublicKey, Signature, initBLS, destroy};
 
-/**
- * Signs given message using secret key.
- * @param secretKey
- * @param messageHash
- */
-export function sign(secretKey: Uint8Array, messageHash: Uint8Array): Buffer {
-  assert(secretKey, "secretKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  const privateKey = PrivateKey.fromBytes(toBuffer(secretKey));
-  return privateKey.signMessage(toBuffer(messageHash)).toBytes();
-}
-
-/**
- * Compines all given signature into one.
- * @param signatures
- */
-export function aggregateSignatures(signatures: Uint8Array[]): Buffer {
-  assert(signatures, "signatures is null or undefined");
-  const agg = Signature.aggregate(signatures.map((signature): Signature => Signature.fromBytes(signature)));
-  return agg.toBytes();
-}
-
-/**
- * Combines all given public keys into single one
- * @param publicKeys
- */
-export function aggregatePubkeys(publicKeys: Uint8Array[]): Buffer {
-  assert(publicKeys, "publicKeys is null or undefined");
-  const agg = PublicKey.aggregate(publicKeys.map((pk) => PublicKey.fromBytes(pk)));
-  return agg.toBytes();
-}
-
-/**
- * Verifies if signature is message signed with given public key.
- * @param publicKey
- * @param messageHash
- * @param signature
- */
-export function verify(publicKey: Uint8Array, messageHash: Uint8Array, signature: Uint8Array): boolean {
-  assert(publicKey, "publicKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-  try {
-    return PublicKey.fromBytes(publicKey).verifyMessage(
-      Signature.fromBytes(toBuffer(signature)),
-      toBuffer(messageHash)
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
-/**
- * Verifies if aggregated signature is same message signed with given public keys.
- * @param publicKeys
- * @param messageHash
- * @param signature
- */
-export function verifyAggregate(publicKeys: Uint8Array[], messageHash: Uint8Array, signature: Uint8Array): boolean {
-  assert(publicKeys, "publicKey is null or undefined");
-  assert(messageHash, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-  try {
-    return Signature.fromBytes(signature).verifyAggregate(
-      publicKeys.map((pubkey) => PublicKey.fromBytes(pubkey)),
-      messageHash
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
-/**
- * Verifies if signature is list of message signed with corresponding public key.
- * @param publicKeys
- * @param messageHashes
- * @param signature
- */
-export function verifyMultiple(publicKeys: Uint8Array[], messageHashes: Uint8Array[], signature: Uint8Array): boolean {
-  assert(publicKeys, "publicKey is null or undefined");
-  assert(messageHashes, "messageHash is null or undefined");
-  assert(signature, "signature is null or undefined");
-
-  if (publicKeys.length === 0 || publicKeys.length != messageHashes.length) {
-    return false;
-  }
-  try {
-    return Signature.fromBytes(toBuffer(signature)).verifyMultiple(
-      publicKeys.map((key) => PublicKey.fromBytes(toBuffer(key))),
-      messageHashes.map((m) => toBuffer(m))
-    );
-  } catch (e) {
-    return false;
-  }
-}
-
 const bls: IBls = {
-  sign,
-  aggregateSignatures,
-  aggregatePubkeys,
-  verify,
-  verifyAggregate,
-  verifyMultiple,
-
   // Keypair,
   PrivateKey,
   PublicKey,
   Signature,
+
+  ...functionalInterfaceFactory({PrivateKey, PublicKey, Signature}),
   initBLS,
   destroy,
 };