diff --git a/src/commands/actions/arguments/index.ts b/src/commands/actions/arguments/index.ts
new file mode 100644
index 0000000..98c6510
--- /dev/null
+++ b/src/commands/actions/arguments/index.ts
@@ -0,0 +1,19 @@
+import keystoreArgument from './keystore';
+import keystorePathArgument from './keystore-path';
+import ownerNonceArgument from './owner-nonce';
+import operatorIdsArgument from './operator-ids';
+import ownerAddressArgument from './owner-address';
+import keystorePasswordArgument from './password';
+import outputFolderArgument from './output-folder';
+import operatorPublicKeysArgument from './operator-public-keys';
+
+export {
+  keystoreArgument,
+  keystorePathArgument,
+  ownerNonceArgument,
+  operatorIdsArgument,
+  ownerAddressArgument,
+  keystorePasswordArgument,
+  outputFolderArgument,
+  operatorPublicKeysArgument
+};
diff --git a/src/commands/actions/arguments/keystore.ts b/src/commands/actions/arguments/keystore.ts
new file mode 100644
index 0000000..140dd8a
--- /dev/null
+++ b/src/commands/actions/arguments/keystore.ts
@@ -0,0 +1,32 @@
+import { fileExistsValidator, jsonFileValidator, sanitizePath } from '../validators';
+
+/**
+ * Keystore argument validates if keystore file exists and is valid keystore file.
+ */
+export default {
+  arg1: '-ks',
+  arg2: '--keystore',
+  options: {
+    required: false,
+    type: String,
+    help: 'The validator keystore file path. Only one keystore file can be specified using this argument'
+  },
+  interactive: {
+    options: {
+      type: 'text',
+      message: 'Provide the keystore file path',
+      validateSingle: (filePath: string): any => {
+        filePath = sanitizePath(String(filePath).trim());
+        let isValid = fileExistsValidator(filePath);
+        if (isValid !== true) {
+          return isValid;
+        }
+        isValid = jsonFileValidator(filePath);
+        if (isValid !== true) {
+          return isValid;
+        }
+        return true;
+      },
+    }
+  }
+};
diff --git a/src/commands/actions/validators/index.ts b/src/commands/actions/validators/index.ts
new file mode 100644
index 0000000..d008b66
--- /dev/null
+++ b/src/commands/actions/validators/index.ts
@@ -0,0 +1,13 @@
+import { sanitizePath, fileExistsValidator, jsonFileValidator } from './file';
+import { keystorePasswordValidator } from './keystore-password';
+import { isOperatorsLengthValid } from "./operator-ids";
+import { operatorPublicKeyValidator } from './operator';
+
+export {
+  sanitizePath,
+  jsonFileValidator,
+  fileExistsValidator,
+  isOperatorsLengthValid,
+  keystorePasswordValidator,
+  operatorPublicKeyValidator,
+}
diff --git a/src/lib/KeyShares/KeySharesData/validators/index.ts b/src/lib/KeyShares/KeySharesData/validators/index.ts
new file mode 100644
index 0000000..d4c47c4
--- /dev/null
+++ b/src/lib/KeyShares/KeySharesData/validators/index.ts
@@ -0,0 +1,15 @@
+import { OpeatorsListValidator } from './operator-unique';
+import { PublicKeyValidator } from './public-key';
+import { OwnerAddressValidator } from './owner-address';
+import { OwnerNonceValidator } from './owner-nonce';
+import { MatchLengthValidator } from './match';
+import { OpeatorPublicKeyValidator } from './operator-public-key';
+
+export {
+  OpeatorsListValidator,
+  PublicKeyValidator,
+  OwnerAddressValidator,
+  OwnerNonceValidator,
+  MatchLengthValidator,
+  OpeatorPublicKeyValidator,
+}
diff --git a/src/lib/KeyShares/KeySharesItem.ts b/src/lib/KeyShares/KeySharesItem.ts
new file mode 100644
index 0000000..fde882a
--- /dev/null
+++ b/src/lib/KeyShares/KeySharesItem.ts
@@ -0,0 +1,193 @@
+import * as ethers from 'ethers';
+import * as web3Helper from '../helpers/web3.helper';
+import {
+  IsOptional,
+  ValidateNested,
+  validateSync
+} from 'class-validator';
+
+import { KeySharesData } from './KeySharesData/KeySharesData';
+import { KeySharesPayload } from './KeySharesData/KeySharesPayload';
+import { EncryptShare } from '../Encryption/Encryption';
+import { IKeySharesPartitialData } from './KeySharesData/IKeySharesData';
+import { IOperator } from './KeySharesData/IOperator';
+import { operatorSortedList } from '../helpers/operator.helper';
+import { OwnerAddressFormatError, OwnerNonceFormatError } from '../exceptions/keystore';
+
+export interface IKeySharesPayloadData {
+  publicKey: string,
+  operators: IOperator[],
+  encryptedShares: EncryptShare[],
+}
+
+export interface IKeySharesToSignatureData {
+  ownerAddress: string,
+  ownerNonce: number,
+  privateKey: string,
+}
+
+export interface IKeySharesFromSignatureData {
+  ownerAddress: string,
+  ownerNonce: number,
+  publicKey: string,
+}
+
+const SIGNATURE_LENGHT = 192;
+const PUBLIC_KEY_LENGHT = 96;
+
+/**
+ * Key shares file data interface.
+ */
+export class KeySharesItem {
+  @IsOptional()
+  @ValidateNested()
+  public data: KeySharesData;
+
+  @IsOptional()
+  @ValidateNested()
+  public payload: KeySharesPayload;
+
+  constructor() {
+    this.data = new KeySharesData();
+    this.payload = new KeySharesPayload();
+  }
+
+  /**
+   * Build payload from operators list, encrypted shares and validator public key
+   * @param publicKey
+   * @param operatorIds
+   * @param encryptedShares
+   */
+  async buildPayload(metaData: IKeySharesPayloadData, toSignatureData: IKeySharesToSignatureData): Promise<any> {
+    const {
+      ownerAddress,
+      ownerNonce,
+      privateKey,
+    } = toSignatureData;
+
+    if (!Number.isInteger(ownerNonce) || ownerNonce < 0) {
+      throw new OwnerNonceFormatError(ownerNonce, 'Owner nonce is not positive integer');
+    }
+
+    let address;
+    try {
+      address = web3Helper.web3.utils.toChecksumAddress(ownerAddress);
+    } catch {
+      throw new OwnerAddressFormatError(ownerAddress, 'Owner address is not a valid Ethereum address');
+    }
+
+    const payload = this.payload.build({
+      publicKey: metaData.publicKey,
+      operatorIds: operatorSortedList(metaData.operators).map(operator => operator.id),
+      encryptedShares: metaData.encryptedShares,
+    });
+
+    const signature = await web3Helper.buildSignature(`${address}:${ownerNonce}`, privateKey);
+    const signSharesBytes = web3Helper.hexArrayToBytes([signature, payload.sharesData]);
+
+    payload.sharesData = `0x${signSharesBytes.toString('hex')}`;
+
+    // verify signature
+    await this.validateSingleShares(payload.sharesData, {
+      ownerAddress,
+      ownerNonce,
+      publicKey: await web3Helper.privateToPublicKey(privateKey),
+    });
+
+    return payload;
+  }
+
+
+  async validateSingleShares(shares: string, fromSignatureData: IKeySharesFromSignatureData): Promise<void> {
+    const { ownerAddress, ownerNonce, publicKey } = fromSignatureData;
+
+    if (!Number.isInteger(ownerNonce) || ownerNonce < 0) {
+      throw new OwnerNonceFormatError(ownerNonce, 'Owner nonce is not positive integer');
+    }
+
+    const address = web3Helper.web3.utils.toChecksumAddress(ownerAddress);
+    const signaturePt = shares.replace('0x', '').substring(0, SIGNATURE_LENGHT);
+
+    await web3Helper.validateSignature(`${address}:${ownerNonce}`, `0x${signaturePt}`, publicKey);
+  }
+
+  /**
+   * Build shares from bytes string and operators list length
+   * @param bytes
+   * @param operatorCount
+   */
+  buildSharesFromBytes(bytes: string, operatorCount: number): any {
+    const sharesPt = bytes.replace('0x', '').substring(SIGNATURE_LENGHT);
+
+    const pkSplit = sharesPt.substring(0, operatorCount * PUBLIC_KEY_LENGHT);
+    const pkArray = ethers.utils.arrayify('0x' + pkSplit);
+    const sharesPublicKeys = this.splitArray(operatorCount, pkArray)
+      .map(item => ethers.utils.hexlify(item));
+
+    const eSplit = bytes.substring(operatorCount * PUBLIC_KEY_LENGHT);
+    const eArray = ethers.utils.arrayify('0x' + eSplit);
+    const encryptedKeys = this.splitArray(operatorCount, eArray).map(item =>
+      Buffer.from(ethers.utils.hexlify(item).replace('0x', ''), 'hex').toString(
+        'base64',
+      ),
+    );
+
+    return { sharesPublicKeys, encryptedKeys };
+  }
+
+  /**
+   * Updates the current instance with partial data and payload, and validates.
+   * @param data Partial key shares data.
+   * @param payload Partial key shares payload.
+   */
+  update(data: IKeySharesPartitialData): void {
+    this.data.update(data);
+    this.validate();
+  }
+
+  /**
+   * Validate everything
+   */
+  validate(): any {
+    validateSync(this);
+  }
+
+  /**
+   * Initialise from JSON or object data.
+   */
+  async fromJson(content: string | any): Promise<KeySharesItem> {
+    const body = typeof content === 'string' ? JSON.parse(content) : content;
+    this.data.update(body.data);
+    this.payload.update(body.payload);
+    this.validate();
+    // Custom validation: verify signature
+    await this.validateSingleShares(this.payload.sharesData, {
+      ownerAddress: this.data.ownerAddress as string,
+      ownerNonce: this.data.ownerNonce as number,
+      publicKey: this.data.publicKey as string,
+    });
+
+    return this;
+  }
+
+  /**
+   * Stringify key shares to be ready for saving in file.
+   */
+  toJson(): string {
+    return JSON.stringify({
+      data: this.data || null,
+      payload: this.payload || null,
+    }, null, 2);
+  }
+
+  private splitArray(parts: number, arr: Uint8Array) {
+    const partLength = Math.floor(arr.length / parts);
+    const partsArr = [];
+    for (let i = 0; i < parts; i++) {
+      const start = i * partLength;
+      const end = start + partLength;
+      partsArr.push(arr.slice(start, end));
+    }
+    return partsArr;
+  }
+}
diff --git a/src/lib/exceptions/base.ts b/src/lib/exceptions/base.ts
new file mode 100644
index 0000000..c86bb03
--- /dev/null
+++ b/src/lib/exceptions/base.ts
@@ -0,0 +1,8 @@
+export class BaseCustomError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = this.constructor.name;
+    Error.captureStackTrace(this, this.constructor);
+    this.stack = `${this.name}: ${this.message}`; // Customizing stack
+  }
+}