Nigerian programmer Adebiyi David Adedoyin hears knocking at his apartment door. He’s just woken up and headed to the bathroom. He decides to take his time. He'll answer in a minute.

But the knocking grows louder – and more urgent. 

Inching open the bathroom door, Adedoyin sees someone clawing open his apartment window. 

"Someone's there," a voice says.

It's probably the police trying to break in, he realizes, from all the stories he's heard.

Adedoyin is sure he hasn't done anything wrong. But with the Nigerian police, that doesn't matter. He still might need to brace for trouble. 

As he thinks through what to do next, Adedoyin is thankful a chunk of his money is stored in bitcoin. His crypto wallet is in a hiding spot the officers probably won't think to check. That means they're less likely to steal it.

While there are many principled police officers in Nigeria who help tackle crimes, police corruption is pervasive. Many Nigerian police are known for extorting and even sometimes torturing citizens rather than helping them solve legal quandaries. 

"Right there in the bathroom, where I was in my boxers with just my phone, AirPods and pack of cigarettes, I could hear them shouting for me to come open the door," Adedoyin told CoinDesk.

This is a well-documented phenomenon in Nigeria. Over the past several years, an online social media movement has emerged against the police. On Twitter, people use the hashtag #EndSARS to publicize the poor treatment they've received from police. SARS stands for Special Anti-Robbery Squad, which is a particularly brutal and mistrusted wing of the Nigerian police force.

Human rights research organization Human Rights Watch released a 102-page report outlining the abuses in painful detail in 2010. 

"Human Rights Watch's research revealed that people refusing to pay bribes are routinely subjected to arbitrary arrest, unlawful detention and threats until they or their family members negotiate payment for their release. Extortion-related confrontations between the police and motorists often escalate into more serious abuses. The evidence suggests that police officers have on numerous occasions severely beaten, sexually assaulted, or shot to death ordinary citizens who failed to pay the bribes demanded," the report reads.

Adedoyin notes that Nigerians have to develop their own tricks to avoid police extortion, especially the younger Nigerians who are the main targets. Some people walk along different routes to avoid walking near the police.

 "Now it’s up to each person to prevent oneself from entering such situations," he said.

The practice is common enough that Adedoyin has been extorted by police officers more than once, and his friends have, too.

Corrupt police officers take their detainee's phone. They scan through it looking for SMS or email messages signalling how much money the detainee has in the bank. 

If the police officer finds the detainee doesn't have any money, they're less likely to waste their time.

Locked in the bathroom, Adedoyin rapidly scrolls through his most recent messages, deleting any bank statements or emails showing how much money he has.

The bathroom door lock breaks. 

Adedoyin is confronted by four police officers, all carrying guns. One slaps Adedoyin and asks him why he didn't come open the door. As Adedoyin expected, another officer snatches his phone and scans through for any grain of evidence that Adedoyin has money.

Adedoyin didn't have time to delete everything. The officer finds some evidence of how much money he makes. They finally let him go once he pays.

It was a bad experience. But Adedoyin is happy that his bitcoin trick worked – most of his money is still safe. 

"The money they collected to let me go in that case would have been a lot more if I had more money in my account. But I had most of my money in bitcoin," Adedoyin said.

Why does using bitcoin help in this situation? Adedoyin's ploy is to pretend that he doesn't have much money to extort. His solution is to store his money in a bitcoin wallet instead of in a bricks-and-mortar bank. Since bitcoin's less common, it's less likely the police officers find it.

Put another way, he's not putting his money into bitcoin as a safeguard because of its decentralization properties. Rather, he just thinks police officers are far less likely to look for a crypto balance than a fiat balance to see if he's ripe for extortion. 

"[The officers] don’t think to check [bitcoin] wallet apps, because most of them don’t even know what bitcoin is and even think bitcoin is a scam," Adedoyin said.

The second reason he has bitcoin is he hopes the price will keep rising. Like many other bitcoiners in the region, he sees it as an investment that might pay off in the future. 

But for now, he keeps most of his money in bitcoin as security against the next time the police come banging on his door.