diff --git a/src/keeper/contracts/DIDRegistry.ts b/src/keeper/contracts/DIDRegistry.ts
index 2608d5f..d60d16d 100644
--- a/src/keeper/contracts/DIDRegistry.ts
+++ b/src/keeper/contracts/DIDRegistry.ts
@@ -15,21 +15,21 @@ export default class DIDRegistry extends ContractBase {
                                    value: string, ownerAddress: string): Promise<Receipt> {
 
         return this.send("registerAttribute",
-            ownerAddress, [did, type, Web3Provider.getWeb3().utils.fromAscii(key), value],
+            ownerAddress, ["0x" + did, type, Web3Provider.getWeb3().utils.fromAscii(key), value],
         )
     }
 
     public async getOwner(did: string): Promise<string> {
 
         return this.call("getOwner",
-            [did],
+            ["0x" + did],
         )
     }
 
     public async getUpdateAt(did: string): Promise<number> {
 
         const blockNum = await this.call("getUpdateAt",
-            [did],
+            ["0x" + did],
         )
 
         return parseInt(blockNum, 10)
diff --git a/src/keeper/contracts/ServiceAgreement.ts b/src/keeper/contracts/ServiceAgreement.ts
index 0b5d624..c2637b4 100644
--- a/src/keeper/contracts/ServiceAgreement.ts
+++ b/src/keeper/contracts/ServiceAgreement.ts
@@ -49,7 +49,7 @@ export default class ServiceAgreement extends ContractBase {
 
         return this.send("executeAgreement", publisherAddress, [
             serviceAgreementTemplateId, serviceAgreementSignatureHash, consumerAddress, valueHashes,
-            timeoutValues, serviceAgreementId, did.replace("did:op:", ""),
+            timeoutValues, serviceAgreementId, "0x" + did.replace("did:op:", ""),
         ])
     }
 }
diff --git a/src/keeper/contracts/conditions/AccessConditions.ts b/src/keeper/contracts/conditions/AccessConditions.ts
index b02f998..9eacfea 100644
--- a/src/keeper/contracts/conditions/AccessConditions.ts
+++ b/src/keeper/contracts/conditions/AccessConditions.ts
@@ -14,7 +14,7 @@ export default class AccessConditions extends ContractBase {
     public async grantAccess(serviceAgreementId: any, assetId: any, documentKeyId: any, publisherAddress: string)
         : Promise<Receipt> {
         return this.send("grantAccess", publisherAddress, [
-            serviceAgreementId, assetId, documentKeyId,
+            serviceAgreementId, "0x" + assetId, "0x" + documentKeyId,
         ])
     }
 }
diff --git a/src/keeper/contracts/conditions/PaymentConditions.ts b/src/keeper/contracts/conditions/PaymentConditions.ts
index 7cc045a..40656cc 100644
--- a/src/keeper/contracts/conditions/PaymentConditions.ts
+++ b/src/keeper/contracts/conditions/PaymentConditions.ts
@@ -12,7 +12,7 @@ export default class PaymentConditions extends ContractBase {
     public async lockPayment(serviceAgreementId: string, assetId: string, price: number, consumerAddress: string)
         : Promise<Receipt> {
         return this.send("lockPayment", consumerAddress, [
-            serviceAgreementId, assetId, price,
+            serviceAgreementId, "0x" + assetId, price,
         ])
     }
 }
diff --git a/src/ocean/IdGenerator.ts b/src/ocean/IdGenerator.ts
index a740f6d..9fc37f9 100644
--- a/src/ocean/IdGenerator.ts
+++ b/src/ocean/IdGenerator.ts
@@ -1,4 +1,4 @@
-import { v4 } from "uuid"
+import {v4} from "uuid"
 
 export default class IdGenerator {
     public static generateId(): string {
diff --git a/src/ocean/Ocean.ts b/src/ocean/Ocean.ts
index d51808a..8c29fae 100644
--- a/src/ocean/Ocean.ts
+++ b/src/ocean/Ocean.ts
@@ -66,7 +66,7 @@ export default class Ocean {
         const aquarius = AquariusProvider.getAquarius()
         const brizo = BrizoProvider.getBrizo()
 
-        const assetId: string = IdGenerator.generatePrefixedId()
+        const assetId: string = IdGenerator.generateId()
         const did: string = `did:op:${assetId}`
         const accessServiceDefinitionId: string = "0"
         const computeServiceDefintionId: string = "1"
diff --git a/test/keeper/DIDRegistry.test.ts b/test/keeper/DIDRegistry.test.ts
index 6768cd7..3b9b17b 100644
--- a/test/keeper/DIDRegistry.test.ts
+++ b/test/keeper/DIDRegistry.test.ts
@@ -26,7 +26,7 @@ describe("DIDRegistry", () => {
 
         it("should register an attribute in a new did", async () => {
             const ownerAccount: Account = (await ocean.getAccounts())[0]
-            const did = IdGenerator.generatePrefixedId()
+            const did = IdGenerator.generateId()
             const providerKey = Web3Provider.getWeb3().utils.fromAscii("provider")
             const data = "my nice provider, is nice"
             const receipt = await didRegistry.registerAttribute(did, ValueType.DID, providerKey,
@@ -37,7 +37,7 @@ describe("DIDRegistry", () => {
 
         it("should register another attribute in the same did", async () => {
             const ownerAccount: Account = (await ocean.getAccounts())[0]
-            const did = IdGenerator.generatePrefixedId()
+            const did = IdGenerator.generateId()
             {
                 // register the first attribute
                 const providerKey = Web3Provider.getWeb3().utils.fromAscii("provider")
@@ -62,7 +62,7 @@ describe("DIDRegistry", () => {
 
         it("should get the owner of a did properly", async () => {
             const ownerAccount: Account = (await ocean.getAccounts())[0]
-            const did = IdGenerator.generatePrefixedId()
+            const did = IdGenerator.generateId()
             const providerKey = Web3Provider.getWeb3().utils.fromAscii("provider")
             const data = "my nice provider, is nice"
             await didRegistry.registerAttribute(did, ValueType.DID, providerKey,
@@ -74,7 +74,7 @@ describe("DIDRegistry", () => {
         })
 
         it("should get 0x00.. for a not registered did", async () => {
-            const owner = await didRegistry.getOwner("0x1234")
+            const owner = await didRegistry.getOwner("1234")
             assert(owner === "0x0000000000000000000000000000000000000000")
         })
 
@@ -84,7 +84,7 @@ describe("DIDRegistry", () => {
 
         it("should the block number of the last update of the did attribute", async () => {
             const ownerAccount: Account = (await ocean.getAccounts())[0]
-            const did = IdGenerator.generatePrefixedId()
+            const did = IdGenerator.generateId()
             const providerKey = Web3Provider.getWeb3().utils.fromAscii("provider")
             const data = "my nice provider, is nice"
             await didRegistry.registerAttribute(did, ValueType.DID, providerKey,
diff --git a/test/ocean/ServiceAgreement.test.ts b/test/ocean/ServiceAgreement.test.ts
index d8a64c4..c68ba7e 100644
--- a/test/ocean/ServiceAgreement.test.ts
+++ b/test/ocean/ServiceAgreement.test.ts
@@ -23,7 +23,7 @@ let consumerAccount: Account
 let accessService: Service
 let metaDataService: Service
 
-const assetId: string = IdGenerator.generatePrefixedId()
+const assetId: string = IdGenerator.generateId()
 
 describe("ServiceAgreement", () => {