BlackBank Market Now Offering MultiSig Escrow

3 minute read

Posted by: DeepDotWeb

February 16, 2014

We have Just found out that BlackBank Market has implemented the use of Multisig transactions, once every market that does that in the correct way deserve our support, you can find the market at this address:  http://omo6o7akcampiryq.onion

Or at our list of marketplaces

We have pasted here the fully usage guide of their multisig, from the wiki page at this url: http://u5z75duioy7kpwun.onion/wiki/index.php/Multi-Sig_Escrow

You can discuss this new feature at their reddit thread here:


After researching several methods and implementations of Multi-Sig Escrow, there has been a compromise in terms of ease of use and security. In order to provide the best experience, Multi-Sig security applies only to Escrow, as this is the only time funds would be inaccessible. In every other case, BlackBank should not be used to store funds in the system.

  1. Buyer deposits BTC into BlackBank and after 6 confirmations can make purchases.
  2. If the item has escrow, the Buyer enters a public key. At this point, the funds are not locked yet and can be cancelled and withdrawn at anytime.
  3. If the Vendor accepts the escrow, the vendor enters his/her public key.
  4. BlackBank automatically will generate it’s own public key and create a multisig BTC address to lock the funds.
  5. In order to access and finalize the order, 2 of 3 keys are required:
    1. Buyer + BlackBank (ex. finalize order/dispute)
    2. Vendor + BlackBank (ex. dispute)
    3. Buyer + Vendor (ex. BlackBank unavailable)
  6. When an order is finalized, the funds will not return to BlackBank. The funds will go directly to the address provided during purchase or accepting an order.

Create a Public and Private Key Pair

Before you make a purchase, you will need a public and private key pair. You will use the public key to “lock” the funds and a private key to “unlock” the funds later. The easiest way to create a public and private key is to go to (note: you will need to use Javascript here):

Buyer’s Guide

Making a Multi-Sig Escrow Purchase

Purchasing an Item

After you have your public and private key pair, you will use your public key to make a purchase. Store your private key someplace safe; keep it with your public key for cross-reference. After selecting the options, enter your public key and refund address to purchase:

Cancel Purchase

If a purchase has not been accept by the vendor yet, you can always cancel the purchase:

Releasing Escrow

After you are satisfied with your item or service, you release your escrow by entering your private key:

Guide for Vendors

Handling Multi-Sig Purchases

How to Accept a Purchase

When accepting a purchase, please enter your public key and a withdrawal address:

Options after accepting a purchase

After a purchase is made, there will be additional details provided:

  • Public Key: for reference on which private key to use
  • Manual FE Code: for manually finalizing outside of BlackBank
  • Payment Address: make sure this is correct as this is where the payment will go when the funds are released

Finalizing Outside of BlackBank

In the event that BlackBank is unavailable to finalize an order, every step has been taken to make it easy for the buyer and vendor to finalize outside of the market. A finalize early code is provided to both the buyer and vendor. At this time, there is only a finalize to vendor code. If there is demand for a refund code, please let me know in the forum and I will implement it.

How to use the Manual FE Code

Step-by-Step Guide:

1. After you have copied the code, it will look like the below:

signrawtransaction '010000000125fbb54693f306f3b57a6e72772af2a55ea9f2dc8269ae67a08d9064d2abb6170100000000ffffffff01fb9a1000000000001976a9146f8eeafa1e979a730994c644dc8484c9493271f388ac00000000' '[{"txid":"17b6abd264908da067ae6982dcf2a95ea5f22a77726e7ab5f306f39346b5fb25","vout":1,"scriptPubKey":"a914069d1d7e42b361e76861b4782c2978d8b09b6c7a87","redeemScript":"5221024de3191645cc5d7d6bf1326fa3ae8e154cdc65544c9f012b491017b6c800824e21024de3191645cc5d7d6bf1326fa3ae8e154cdc65544c9f012b491017b6c800824e2102a96896a9c9bd5ee6e2adf8bcf6d7954c6b44b811f7fdd3a86f84b0cd632fdff153ae"}]' '["PRIVATE_KEY_A","PRIVATE_KEY_B"]'

2. Replace PRIVATE_KEY_A and PRIVATE_KEY_B with the Buyer and Vendor private keys.

3. Using the official Bitcoin-QT Wallet Client, select “Help” followed by “Debug window”:

4. Select the “Console” tab and enter the code with the Private Keys from both Vendor and Buyer into the input box at the bottom and submit.

5. You will get the following result:

6. If “complete” is false, this means that one of the Private Keys is incorrect. If complete is true, copy the “hex” portion of the code.

{ "hex" : "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", "complete" : true }

7. After you copied the code, you will now finalize the transaction by sending it. Use the console again and enter the following command:

sendrawtransaction [the hex code]

sendrawtransaction 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

8. The transaction has now been manually finalized. This will provide you with a transaction ID; you can share it with the other party as reference.

You can find BlackBank Market on our list of hidden marketplace

Updated: 2014-02-16