Add new payment method: Japan Bank Transfer

[wiz]

Japan Bank Transfer 🇯🇵

Summary

This PR adds support for Bisq trades using the Japanese Bankers Association (Zenginkyo) payment processing network, known casually to everyone in Japan as "furikomi".

• Country Restrictions: Japan only
• Currency Restrictions: JPY only
• Chargeback Risks: None, cannot reverse or chargeback
• Per-Trade Risk Limit: LOW (0.5 BTC * 2.0 multiplier = 1 BTC)
• Per-Trade Time Limit: DAY (transfers are near-instant, and 24/7/365 for major banks)

Overview

• In Japan, over 98% of population has a bank account[1].
• Transfers take minutes to complete, and fees are very low.
• Almost all major banks are now supporting 24/7/365 transfers.
• Japan's post office is the world's largest deposit holder[2], and can be used.
• Security, Privacy, and Freedom of Japanese banking is better than most countries.

Security

Compared to USA style bank accounts or Visa style credit cards, where anyone who knows your routing/account number can initiate fraudulent transfers out of your account, Japan's bank transfer system is secure:

• Banks give everyone a hardware security token to authorize transfers
• Bank transfers can only be authorized by the account holder directly
• Bank transfers are not reversible or chargeback-able (details below)

Privacy

In Japan, your bank account details are not considered sensitive information:

• Bank account info can be published publicly, like a Bitcoin address
• Companies publish their bank account info on their website/invoices

Of course, banks and governments can see all transactions that flow through their systems. However, the nature of the transaction, and source of funds, etc. are not requested or recorded, as the transfer is fully electronic and not processed by humans. Because of this, ihe trading parties actually have decent privacy compared to other country's bank transfer methods. Additionally, no tax ID or other personal information are exchanged for the transaction, so it is very unlikely that users of this payment method will have their bank accounts frozen or shut down as a result.

Freedom

Since the system is inheriently secure, banks don't need to police the system:

• Banks don't generally "freeze" any "suspicious looking" transactions
• Banks don't generally have restrictions on domestic bank transfers
• Banks don't generally enforce arbitrary limits or capital controls

The fully automated and electronic system does not censor transactions.

How it works

• Cost is low ($0 ~ $3)
• Transfers are fast (0 ~ 5 minutes)
• Available 24/7/365 with most larger banks

Account Information

To send a Japan Bank Transfer, the sender needs the following information:

• Bank name/number (4 digits)
• Branch name/number (3 digits)
• Account type/number (7 digits)

Sending a Transfer

After the sender inputs the above data into their online banking, the receiving account holder's name is displayed to the sender so they can verify they are sending funds to the correct account before they finalize the transaction.

The transfer is usually completed almost instantly (less than 5 minutes), or on the next business day if the sender's bank does not support 24/7/365 transfers outside of normal banking hours.

Fraud Risks

1. If you transfer funds to an invalid account (i.e. the destination account is closed or cannot be located), the funds are automatically returned to the sender's account within 24 hours.

2. If you transfer funds to a valid account, once that accounts receives it (which is usually less than 2 minutes), you can request a chargeback if this transfer was a mistake. However, "The recipient bank will contact the payee and the funds will not be returned without the recipient's consent."[3]

3. If a stolen or hacked bank account is used to transfer funds to you, the bank will not reverse the transaction just because the account was hacked. The sender would have to go the police and utilize the court system to get refunded, but this is presumably hard to do, and not likely to happen unless transaction amount is very high.

Therefore, the Japan Bank Transfer payment method is requested to be added with "LOW" risk setting, which limits each trade to 0.5 BTC by default, and after multiplying by the current DAO parameter (200%), this means Japan Bank Transfers will be limited to 1 BTC per trade at this time of this PR.

Footnotes

1. "Japan population (ages 15+) 98.24%"
   Source: World Bank Account ownership at a financial institution
   URL: https://data.worldbank.org/indicator/FX.OWN.TOTL.ZS

2. "As of November 2008, it was reported as being the world's biggest deposit holder."
   Source: Japan Post Bank, Wikipedia, the free encyclopedia
   URL: https://en.wikipedia.org/wiki/Japan_Post_Bank

3. "振込先銀行より受取人に連絡し、受取人の了解がないと資金は戻りません。"
   Source: Sumitomo Mitsui Banking Corporation support page on transfer reversals
   URL: https://www.smbc.co.jp/kojin/direct/ib/help/help_kumimodoshi.html

Screenshots

Create Account

Form empty (English)

Form empty (Japanese)

Form filled (English)

Form filled (Japanese)

Bank search functionality

String validation for Japanese-only input fields

Trade limits

Display Account

Offer View

Maker view showing full details

Taker view showing Japan Bank Transfer payment method

Trade in progress (Japanese)

Trade requires attention for Buyer (Japanese)

Trade requires attention for Seller (English)

Trade information (English)

Trade information (Japanese)

Implementation Details

Input Validation

Bank Code: automatically entered from selected bank
Bank Name: must be selected from hard-coded list of 500 banks
Branch Name: must be Japanese characters
Branch Code: must be 3 digits
Account Name: must be Japanese characters
Account Number must be 4 ~ 8 digits
Account Type: radio buttons of 2 choices

Protobuf template

message JapanBankAccountPayload {
    string bank_name = 1;
    string bank_code = 2;                                   
    string bank_branch_name = 3;
    string bank_branch_code = 4;
    string bank_account_type = 5;
    string bank_account_name = 6;
    string bank_account_number = 7;
}

JSON contract payload

  "makerPaymentAccountPayload": {
    "bankName": "三井住友銀行",
    "bankCode": "0009",
    "bankBranchName": "銀座",
    "bankBranchCode": "042",
    "bankAccountType": "普通",
    "bankAccountName": "ナカモト サトシ",
    "bankAccountNumber": "1337",
    "paymentMethodId": "JAPAN_BANK",
    "id": "6d75ef11-2556-40ad-9059-bd73973f19e8",
    "maxTradePeriod": -1
  },
  "takerPaymentAccountPayload": {
    "bankName": "三井住友銀行",
    "bankCode": "0009",
    "bankBranchName": "東京",
    "bankBranchCode": "132",
    "bankAccountType": "普通",
    "bankAccountName": "山田太郎",
    "bankAccountNumber": "8765674",
    "paymentMethodId": "JAPAN_BANK",
    "id": "689185f5-93b7-4e77-a1ef-61ab4acc5a35",
    "maxTradePeriod": -1
  },

[chimp1984]

Wow, the world has to learn a lot from Japan!

[ripcurlx]

NACK - Although it wasn't up for review - here some minor change suggestions. @wiz Do you plan to open this PR for public review soon? utACK - Great work @wiz!

[tdhr0917]

I've reviewed now. It seems good.