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Recent events in Canada, the government actions against truck drivers protesting, and people sending money to the truck drivers, have increased concerns about making bitcoin transactions privately.
Furtunately, there is a simple way to do this, even if you are fundraising and you need to publish one link to accept money from your supporters.
Most of the problem comes from what is known as "address reuse" issue. Since blockchain transactions are public, if you use the same bitcoin wallet address for multiple transactions, this creates a privacy issue.
The issue is explained well in bitcoin.it wiki
Worked Example 1 - Savings Revealed
You save in bitcoin, using a single-address paper wallet.
All your bitcoin savings to this same address, let's say it contains $1 million worth.
You buy a small amount of bitcoins to add to your savings, depositing in the paper wallet.
The person who sold you the bitcoins follows their trail on the blockchain and finds your paper wallet containing $1 million.
He mentions it to someone in a cafe or bar.
Word gets around. A burglar raids your home. Kidnappers capture your children and know exactly how much to demand in ransom.
Worked Example 2 - Exchange Front Running
You have an account on a bitcoin exchange, you want to deposit some bitcoins to sell.
You send bitcoins to the same exchange deposit address you have used in the past.
Because of the address reuse, its easy to see on the blockchain that some bitcoins are being sent to an exchange.
The exchange requires 3 confirmations before crediting your account, but in that time the price has already moved against you as other traders become aware of your deposit transaction.
You sell the bitcoins for a less attractive price than you otherwise would have.
This is easily avoided by clicking the Generate New Deposit Address button on the exchange's website and depositing there.
Worked Example 3
You use a single Bitcoin address for all your earning and spending. Anyone you trade with can see a complete history of your finances.
Your landlord can see your salary, when he raises the rent he knows exactly how much to ask for.
Your shopkeeper can see your spending. Gossip gets around of how much you spend on pornography and how little on church donations.
Your employer can see your spending. When you pay labour union dues or donate to wikileaks or another non-profit, your boss knows who not to trust.
The issue is solved by BIP47. Bip 47 generates a payment code, and each payment done using this code is sent to another bitcoin wallet address.
All the bitcoin wallet addresses are hierarchically deterministic wallets. Meaning the person controlling the parent with his private key wallet gets to control all the bitcoin in child wallets. But from an outsider watching blockchain transactions, they are all different separate wallets.
It is a relatively new standard, and not all bitcoin wallets have adapted this.
But one of the more privacy focused wallets, Samourai Wallet, have already implemented this standard, and made it easy for end-users to use BIP47 codes.
Here is how to get bitcoin donations privately:
Download Samourai Wallet, and set up a new wallet (or recover an old wallet from seed phrase).
Claim your paynym.is address
Publish your paynym.is address online for supporters
paynym.is makes sharing your BIP47 payment code easy, with a short human-readable link.
Likewise, even as a sender, it is important for you to use a different address for each donation.
Samourai wallet also has other privacy-enhancing features, like connecting internet over TOR, and using whirlpool to mix coins to make tracking your bitcoins much harder.
At a time when governments track and punish truck drivers protesting and their financial supporters, but not the clients of Epstein-Maxwell pedo ring, tools like these can save people a lot of trouble.
As Canada showed us:
Your money in the bank can be seized.
You can get arrested.
Your kids and pets may be taken away from you. Your pets may be killed.
If you simply donate to some cause the government does not like.
This can be avoided simply by using paynym.is link to a BIP47 code.
If you want to donate me some money, or see an example of a paynym.is link, here is my link: