diff --git a/packages/mainsail/source/client.service.ts b/packages/mainsail/source/client.service.ts
index 264acc1f..2ecee69b 100644
--- a/packages/mainsail/source/client.service.ts
+++ b/packages/mainsail/source/client.service.ts
@@ -181,11 +181,11 @@ export class ClientService extends Services.AbstractClientService {
 		};
 
 		const mappings: Record<string, string> = {
+			address: "address",
 			cursor: "page",
 			limit: "limit",
 			memo: "vendorField",
 			orderBy: "orderBy",
-			address: "address",
 			recipientId: "recipientId",
 			senderId: "senderId",
 			senderPublicKey: "senderPublicKey",
@@ -219,14 +219,6 @@ export class ClientService extends Services.AbstractClientService {
 					type: Enums.TransactionType.DelegateResignation,
 					typeGroup: Enums.TransactionTypeGroup.Core,
 				},
-				usernameRegistration: {
-					type: Enums.TransactionType.UsernameRegistration,
-					typeGroup: Enums.TransactionTypeGroup.Core,
-				},
-				usernameResignation: {
-					type: Enums.TransactionType.UsernameResignation,
-					typeGroup: Enums.TransactionTypeGroup.Core,
-				},
 				multiPayment: {
 					type: Enums.TransactionType.MultiPayment,
 					typeGroup: Enums.TransactionTypeGroup.Core,
@@ -235,14 +227,18 @@ export class ClientService extends Services.AbstractClientService {
 					type: Enums.TransactionType.MultiSignature,
 					typeGroup: Enums.TransactionTypeGroup.Core,
 				},
-				secondSignature: {
-					type: Enums.TransactionType.SecondSignature,
-					typeGroup: Enums.TransactionTypeGroup.Core,
-				},
 				transfer: {
 					type: Enums.TransactionType.Transfer,
 					typeGroup: Enums.TransactionTypeGroup.Core,
 				},
+				usernameRegistration: {
+					type: Enums.TransactionType.UsernameRegistration,
+					typeGroup: Enums.TransactionTypeGroup.Core,
+				},
+				usernameResignation: {
+					type: Enums.TransactionType.UsernameResignation,
+					typeGroup: Enums.TransactionTypeGroup.Core,
+				},
 				vote: {
 					type: Enums.TransactionType.Vote,
 					typeGroup: Enums.TransactionTypeGroup.Core,
diff --git a/packages/mainsail/source/confirmed-transaction.dto.ts b/packages/mainsail/source/confirmed-transaction.dto.ts
index 9dfe5e34..bb23a3ef 100644
--- a/packages/mainsail/source/confirmed-transaction.dto.ts
+++ b/packages/mainsail/source/confirmed-transaction.dto.ts
@@ -91,7 +91,7 @@ export class ConfirmedTransactionData extends DTO.AbstractConfirmedTransactionDa
 	}
 
 	public override isSecondSignature(): boolean {
-		return TransactionTypeService.isSecondSignature(this.data);
+		throw new Exceptions.NotImplemented(this.constructor.name, this.isSecondSignature.name);
 	}
 
 	public override isUsernameRegistration(): boolean {
diff --git a/packages/mainsail/source/crypto/enums.ts b/packages/mainsail/source/crypto/enums.ts
index 27502326..90ebddc7 100644
--- a/packages/mainsail/source/crypto/enums.ts
+++ b/packages/mainsail/source/crypto/enums.ts
@@ -1,6 +1,5 @@
 export enum TransactionType {
 	Transfer = 0,
-	SecondSignature = 1,
 	DelegateRegistration = 2,
 	Vote = 3,
 	MultiSignature = 4,
diff --git a/packages/mainsail/source/crypto/interfaces/transactions.ts b/packages/mainsail/source/crypto/interfaces/transactions.ts
index debd5f6c..de15d244 100644
--- a/packages/mainsail/source/crypto/interfaces/transactions.ts
+++ b/packages/mainsail/source/crypto/interfaces/transactions.ts
@@ -38,7 +38,6 @@ export interface ITransactionAsset {
 	votes?: string[];
 	multiSignatureLegacy?: IMultiSignatureLegacyAsset;
 	multiSignature?: IMultiSignatureAsset;
-	ipfs?: string;
 	payments?: IMultiPaymentItem[];
 }
 
@@ -63,7 +62,6 @@ export interface ITransactionData {
 
 	id?: string;
 	signature?: string;
-	secondSignature?: string;
 	signSignature?: string;
 	signatures?: string[];
 
@@ -94,14 +92,11 @@ export interface ITransactionJson {
 
 	id?: string;
 	signature?: string;
-	secondSignature?: string;
 	signSignature?: string;
 	signatures?: string[];
 
 	blockId?: string;
 	sequence?: number;
-
-	ipfsHash?: string;
 }
 
 export interface ISchemaValidationResult<T = any> {
@@ -139,6 +134,5 @@ export interface ISerializeOptions {
 	acceptLegacyVersion?: boolean;
 	disableVersionCheck?: boolean;
 	excludeSignature?: boolean;
-	excludeSecondSignature?: boolean;
 	excludeMultiSignature?: boolean;
 }
diff --git a/packages/mainsail/source/crypto/networks/mainnet/milestones.ts b/packages/mainsail/source/crypto/networks/mainnet/milestones.ts
index 9b333f6b..8c6f9d8b 100644
--- a/packages/mainsail/source/crypto/networks/mainnet/milestones.ts
+++ b/packages/mainsail/source/crypto/networks/mainnet/milestones.ts
@@ -13,8 +13,6 @@ export const milestones = [
 			staticFees: {
 				delegateRegistration: 2_500_000_000,
 				delegateResignation: 2_500_000_000,
-				usernameRegistration: 2_500_000_000,
-				usernameResignation: 2_500_000_000,
 				htlcClaim: 0,
 				htlcLock: 10_000_000,
 				htlcRefund: 0,
@@ -23,6 +21,8 @@ export const milestones = [
 				multiSignature: 500_000_000,
 				secondSignature: 500_000_000,
 				transfer: 10_000_000,
+				usernameRegistration: 2_500_000_000,
+				usernameResignation: 2_500_000_000,
 				vote: 100_000_000,
 			},
 		},
diff --git a/packages/mainsail/source/crypto/transactions/deserializer.ts b/packages/mainsail/source/crypto/transactions/deserializer.ts
index 501dcccf..8e30307d 100644
--- a/packages/mainsail/source/crypto/transactions/deserializer.ts
+++ b/packages/mainsail/source/crypto/transactions/deserializer.ts
@@ -80,12 +80,6 @@ export class Deserializer {
 			return marker === 255;
 		};
 
-		// Second Signature
-		if (buf.getRemainderLength() && !beginningMultiSignature()) {
-			const secondSignatureLength: number = currentSignatureLength();
-			transaction.secondSignature = buf.readBuffer(secondSignatureLength).toString("hex");
-		}
-
 		// Multi Signatures
 		if (buf.getRemainderLength() && beginningMultiSignature()) {
 			buf.jump(1);
@@ -106,17 +100,13 @@ export class Deserializer {
 			transaction.signature = buf.readBuffer(64).toString("hex");
 		}
 
-		if (canReadNonMultiSignature()) {
-			transaction.secondSignature = buf.readBuffer(64).toString("hex");
-		}
-
 		if (buf.getRemainderLength()) {
 			if (buf.getRemainderLength() % 65 === 0) {
 				transaction.signatures = [];
 
 				const count: number = buf.getRemainderLength() / 65;
 				const publicKeyIndexes: { [index: number]: boolean } = {};
-				for (let i = 0; i < count; i++) {
+				for (let index = 0; index < count; index++) {
 					const multiSignaturePart: string = buf.readBuffer(65).toString("hex");
 					const publicKeyIndex: number = Number.parseInt(multiSignaturePart.slice(0, 2), 16);
 
diff --git a/packages/mainsail/source/crypto/transactions/serializer.ts b/packages/mainsail/source/crypto/transactions/serializer.ts
index 2dc1da6d..d5654142 100644
--- a/packages/mainsail/source/crypto/transactions/serializer.ts
+++ b/packages/mainsail/source/crypto/transactions/serializer.ts
@@ -90,12 +90,6 @@ export class Serializer {
 			buf.writeBuffer(Buffer.from(transaction.signature, "hex"));
 		}
 
-		const secondSignature: string | undefined = transaction.secondSignature || transaction.signSignature;
-
-		if (secondSignature && !options.excludeSecondSignature) {
-			buf.writeBuffer(Buffer.from(secondSignature, "hex"));
-		}
-
 		if (transaction.signatures && !options.excludeMultiSignature) {
 			buf.writeBuffer(Buffer.from(transaction.signatures.join(""), "hex"));
 		}
diff --git a/packages/mainsail/source/crypto/transactions/signer.ts b/packages/mainsail/source/crypto/transactions/signer.ts
index 24eb1e8f..393f03f7 100644
--- a/packages/mainsail/source/crypto/transactions/signer.ts
+++ b/packages/mainsail/source/crypto/transactions/signer.ts
@@ -6,8 +6,8 @@ import { Utils } from "./utils.js";
 
 export class Signer {
 	public static sign(transaction: ITransactionData, keys: IKeyPair, options?: ISerializeOptions): string {
-		if (!options || (options.excludeSignature === undefined && options.excludeSecondSignature === undefined)) {
-			options = { excludeSecondSignature: true, excludeSignature: true, ...options };
+		if (!options || options.excludeSignature === undefined) {
+			options = { excludeSignature: true, ...options };
 		}
 
 		const hash: Buffer = Utils.toHash(transaction, options);
@@ -20,17 +20,6 @@ export class Signer {
 		return signature;
 	}
 
-	public static secondSign(transaction: ITransactionData, keys: IKeyPair): string {
-		const hash: Buffer = Utils.toHash(transaction, { excludeSecondSignature: true });
-		const signature: string = Hash.signSchnorr(hash, keys);
-
-		if (!transaction.secondSignature) {
-			transaction.secondSignature = signature;
-		}
-
-		return signature;
-	}
-
 	public static async multiSign(
 		transaction: MainsailContracts.Crypto.TransactionData,
 		keys: IKeyPair,
diff --git a/packages/mainsail/source/crypto/transactions/types/schemas.ts b/packages/mainsail/source/crypto/transactions/types/schemas.ts
index 2076ffc9..ffcc622e 100644
--- a/packages/mainsail/source/crypto/transactions/types/schemas.ts
+++ b/packages/mainsail/source/crypto/transactions/types/schemas.ts
@@ -1,6 +1,7 @@
-import { TransactionType } from "../../enums.js";
 import deepmerge from "deepmerge";
 
+import { TransactionType } from "../../enums.js";
+
 const signedTransaction = {
 	anyOf: [
 		{ required: ["id", "signature"] },
@@ -23,11 +24,9 @@ export const transactionBaseSchema: Record<string, any> = {
 		id: { anyOf: [{ $ref: "transactionId" }, { type: "null" }] },
 		network: { $ref: "networkByte" },
 		nonce: { bignumber: { minimum: 0 } },
-		secondSignature: { $ref: "alphanumeric" },
 		senderPublicKey: { $ref: "publicKey" },
 		signSignature: { $ref: "alphanumeric" },
 		signature: { $ref: "alphanumeric" },
-		version: { enum: [1, 2] },
 		signatures: {
 			additionalItems: false,
 			items: { allOf: [{ maxLength: 130, minLength: 130 }, { $ref: "alphanumeric" }] },
@@ -36,8 +35,9 @@ export const transactionBaseSchema: Record<string, any> = {
 			type: "array",
 			uniqueItems: true,
 		},
-		timestamp: { type: "integer", minimum: 0 },
+		timestamp: { minimum: 0, type: "integer" },
 		typeGroup: { minimum: 0, type: "integer" },
+		version: { enum: [1, 2] },
 	},
 	then: { required: ["type", "senderPublicKey", "fee", "amount", "timestamp"] },
 	type: "object",
@@ -70,32 +70,6 @@ export const transfer = extend(transactionBaseSchema, {
 	required: ["recipientId"],
 });
 
-export const secondSignature = extend(transactionBaseSchema, {
-	$id: "secondSignature",
-	properties: {
-		amount: { bignumber: { maximum: 0, minimum: 0 } },
-		asset: {
-			properties: {
-				signature: {
-					properties: {
-						publicKey: {
-							$ref: "publicKey",
-						},
-					},
-					required: ["publicKey"],
-					type: "object",
-				},
-			},
-			required: ["signature"],
-			type: "object",
-		},
-		fee: { bignumber: { minimum: 1 } },
-		secondSignature: { type: "null" },
-		type: { transactionType: TransactionType.SecondSignature },
-	},
-	required: ["asset"],
-});
-
 export const delegateRegistration = extend(transactionBaseSchema, {
 	$id: "delegateRegistration",
 	properties: {
@@ -150,8 +124,8 @@ export const vote = extend(transactionBaseSchema, {
 				votes: {
 					additionalItems: false,
 					items: { $ref: "walletVote" },
-					minItems: 1,
 					maxItems: 2,
+					minItems: 1,
 					type: "array",
 				},
 			},
@@ -180,10 +154,10 @@ export const multiSignature = extend(transactionBaseSchema, {
 						},
 						publicKeys: {
 							additionalItems: false,
-							minItems: 1,
 							items: { $ref: "publicKey" },
-							type: "array",
 							maxItems: 16,
+							minItems: 1,
+							type: "array",
 							uniqueItems: true,
 						},
 					},
@@ -220,24 +194,24 @@ export const multiSignatureLegacy = extend(transactionBaseSchemaNoSignatures, {
 			properties: {
 				multiSignatureLegacy: {
 					properties: {
-						lifetime: {
-							minimum: 1,
-							type: "integer",
-							maximum: 72,
-						},
 						keysgroup: {
-							minItems: 1,
-							type: "array",
 							additionalItems: false,
-							maxItems: 16,
 							items: {
-								allOf: [{ minimum: 67, type: "string", maximum: 67, transform: ["toLowerCase"] }],
+								allOf: [{ maximum: 67, minimum: 67, transform: ["toLowerCase"], type: "string" }],
 							},
+							maxItems: 16,
+							minItems: 1,
+							type: "array",
 						},
-						min: {
-							type: "integer",
+						lifetime: {
+							maximum: 72,
 							minimum: 1,
+							type: "integer",
+						},
+						min: {
 							maximum: { $data: "1/keysgroup/length" },
+							minimum: 1,
+							type: "integer",
 						},
 					},
 					required: ["keysgroup", "min", "lifetime"],
@@ -270,11 +244,11 @@ export const multiPayment = extend(transactionBaseSchema, {
 				payments: {
 					additionalItems: false,
 					items: {
-						required: ["amount", "recipientId"],
 						properties: {
 							amount: { bignumber: { minimum: 1 } },
 							recipientId: { $ref: "address" },
 						},
+						required: ["amount", "recipientId"],
 						type: "object",
 					},
 					minItems: 2,
diff --git a/packages/mainsail/source/crypto/transactions/types/transaction.ts b/packages/mainsail/source/crypto/transactions/types/transaction.ts
index 976cc18c..3c7f746b 100644
--- a/packages/mainsail/source/crypto/transactions/types/transaction.ts
+++ b/packages/mainsail/source/crypto/transactions/types/transaction.ts
@@ -49,10 +49,6 @@ export abstract class Transaction implements ITransaction {
 		return Verifier.verify(this.data, options);
 	}
 
-	public verifySecondSignature(publicKey: string): boolean {
-		return Verifier.verifySecondSignature(this.data, publicKey);
-	}
-
 	public verifySchema(): ISchemaValidationResult {
 		return Verifier.verifySchema(this.data);
 	}
diff --git a/packages/mainsail/source/crypto/transactions/verifier.ts b/packages/mainsail/source/crypto/transactions/verifier.ts
index 5c761d9f..8399e525 100644
--- a/packages/mainsail/source/crypto/transactions/verifier.ts
+++ b/packages/mainsail/source/crypto/transactions/verifier.ts
@@ -1,17 +1,17 @@
+import { DateTime } from "@ardenthq/sdk-intl";
+
 import { DuplicateParticipantInMultiSignatureError, InvalidMultiSignatureAssetError } from "../errors.js";
+import { Hash } from "../hash.js";
 import {
 	IMultiSignatureAsset,
 	ISchemaValidationResult,
 	ITransactionData,
 	IVerifyOptions,
 } from "../interfaces/index.js";
-
-import { DateTime } from "@ardenthq/sdk-intl";
-import { Hash } from "../hash.js";
-import { TransactionTypeFactory } from "./types/factory.js";
-import { Utils } from "./utils.js";
 import { configManager } from "../managers/index.js";
 import { validator } from "../validation/index.js";
+import { TransactionTypeFactory } from "./types/factory.js";
+import { Utils } from "./utils.js";
 
 export class Verifier {
 	public static verify(data: ITransactionData, options?: IVerifyOptions): boolean {
@@ -22,24 +22,6 @@ export class Verifier {
 		return Verifier.verifyHash(data, options?.disableVersionCheck);
 	}
 
-	public static verifySecondSignature(
-		transaction: ITransactionData,
-		publicKey: string,
-		options?: IVerifyOptions,
-	): boolean {
-		const secondSignature: string | undefined = transaction.secondSignature || transaction.signSignature;
-
-		if (!secondSignature) {
-			return false;
-		}
-
-		const hash: Buffer = Utils.toHash(transaction, {
-			disableVersionCheck: options?.disableVersionCheck,
-			excludeSecondSignature: true,
-		});
-		return this.internalVerifySignature(hash, secondSignature, publicKey);
-	}
-
 	public static verifySignatures(transaction: ITransactionData, multiSignature: IMultiSignatureAsset): boolean {
 		if (!multiSignature) {
 			throw new InvalidMultiSignatureAssetError();
@@ -50,7 +32,6 @@ export class Verifier {
 
 		const hash: Buffer = Utils.toHash(transaction, {
 			excludeMultiSignature: true,
-			excludeSecondSignature: true,
 			excludeSignature: true,
 		});
 
@@ -97,7 +78,6 @@ export class Verifier {
 
 		const hash: Buffer = Utils.toHash(data, {
 			disableVersionCheck,
-			excludeSecondSignature: true,
 			excludeSignature: true,
 		});
 
diff --git a/packages/mainsail/source/multi-signature.signer.ts b/packages/mainsail/source/multi-signature.signer.ts
index 222a0dcf..a093d357 100644
--- a/packages/mainsail/source/multi-signature.signer.ts
+++ b/packages/mainsail/source/multi-signature.signer.ts
@@ -93,10 +93,6 @@ export class MultiSignatureSigner {
 				Transactions.Signer.sign(transaction, signingKeys);
 			}
 
-			if (confirmKeys) {
-				Transactions.Signer.secondSign(transaction, confirmKeys);
-			}
-
 			if (signatory.actsWithLedger()) {
 				transaction.signature = await this.#signWithLedger(transaction, signatory);
 			}
@@ -170,7 +166,6 @@ export class MultiSignatureSigner {
 			// @ts-ignore
 			Transactions.Serializer.getBytes(transaction, {
 				excludeMultiSignature,
-				excludeSecondSignature: true,
 				excludeSignature: true,
 			}),
 		);
diff --git a/packages/mainsail/source/signed-transaction.dto.ts b/packages/mainsail/source/signed-transaction.dto.ts
index c4eec11a..a0914259 100644
--- a/packages/mainsail/source/signed-transaction.dto.ts
+++ b/packages/mainsail/source/signed-transaction.dto.ts
@@ -2,8 +2,8 @@ import { Contracts, DTO, Exceptions, IoC } from "@ardenthq/sdk";
 import { BigNumber } from "@ardenthq/sdk-helpers";
 import { DateTime } from "@ardenthq/sdk-intl";
 import { Utils } from "@mainsail/crypto-transaction";
-
 import { Application } from "@mainsail/kernel";
+
 import { BindingType } from "./coin.contract.js";
 import { Hash } from "./crypto/hash.js";
 import { TransactionTypeService } from "./transaction-type.service.js";
@@ -59,7 +59,7 @@ export class SignedTransactionData
 	}
 
 	public override isSecondSignature(): boolean {
-		return TransactionTypeService.isSecondSignature(this.signedData);
+		return false;
 	}
 
 	public override isUsernameRegistration(): boolean {
@@ -145,7 +145,7 @@ export class SignedTransactionData
 		const signatures: string[] = this.signedData.signatures ?? ([] as string[]);
 
 		for (const signature of signatures) {
-			const publicKeyIndex: number = parseInt(signature.slice(0, 2), 16);
+			const publicKeyIndex: number = Number.parseInt(signature.slice(0, 2), 16);
 			const partialSignature: string = signature.slice(2, 130);
 			const publicKey: string = transaction.multiSignature.publicKeys[publicKeyIndex];
 
diff --git a/packages/mainsail/source/transaction-type.service.ts b/packages/mainsail/source/transaction-type.service.ts
index 2db942ec..5786bf3d 100644
--- a/packages/mainsail/source/transaction-type.service.ts
+++ b/packages/mainsail/source/transaction-type.service.ts
@@ -8,7 +8,7 @@ export class TransactionTypeService {
 	}
 
 	public static isSecondSignature(data: TransactionData): boolean {
-		return TransactionTypeService.#typeGroup(data) === 1 && data.type === 1;
+		throw new Exceptions.NotImplemented(this.constructor.name, this.isSecondSignature.name);
 	}
 
 	public static isDelegateRegistration(data: TransactionData): boolean {
diff --git a/packages/mainsail/source/transaction.service.ts b/packages/mainsail/source/transaction.service.ts
index 09232a1c..1bd5524e 100644
--- a/packages/mainsail/source/transaction.service.ts
+++ b/packages/mainsail/source/transaction.service.ts
@@ -7,9 +7,9 @@ import { Application } from "@mainsail/kernel";
 import { BindingType } from "./coin.contract.js";
 import { applyCryptoConfiguration } from "./config.js";
 import { Identities, Interfaces, Transactions } from "./crypto/index.js";
+import { BuilderFactory } from "./crypto/transactions/index.js";
 import { MultiSignatureSigner } from "./multi-signature.signer.js";
 import { Request } from "./request.js";
-import { BuilderFactory } from "./crypto/transactions/index.js";
 
 export class TransactionService extends Services.AbstractTransactionService {
 	readonly #ledgerService!: Services.LedgerService;
@@ -333,7 +333,6 @@ export class TransactionService extends Services.AbstractTransactionService {
 			transaction.data.signature = await this.#ledgerService.signTransaction(
 				input.signatory.signingKey(),
 				Transactions.Serializer.getBytes(transaction.data, {
-					excludeSecondSignature: true,
 					excludeSignature: true,
 				}),
 			);
diff --git a/packages/mainsail/source/wallet.dto.ts b/packages/mainsail/source/wallet.dto.ts
index 0ac5b38f..318a4a3b 100644
--- a/packages/mainsail/source/wallet.dto.ts
+++ b/packages/mainsail/source/wallet.dto.ts
@@ -72,10 +72,6 @@ export class WalletData extends DTO.AbstractWalletData implements Contracts.Wall
 		return !!this.#getProperty(["multiSignature", "attributes.multiSignature"]);
 	}
 
-	public override isSecondSignature(): boolean {
-		return !!this.#getProperty(["secondPublicKey", "attributes.secondPublicKey"]);
-	}
-
 	#getProperty<T>(keys: string[]): T | undefined {
 		for (const key of keys) {
 			if (has(this.data, key)) {