SAN FRANCISCO -- While hundreds of investors and entrepreneurs assembled here to talk about ushering bitcoin into the mainstream, a poll released Tuesday said most Americans remain distrustful of the digital currency that is not controlled by any government or bank.

According to a survey by market research firm Harris Interactive, just more than one-tenth of the adults in the U.S. who know about bitcoin say they would choose to invest in it. And the more people know about bitcoin, the less they trust it, according to the December survey of 2,000 adults. People in the Western U.S. knew the most, and yet were more wary of bitcoin than any other region -- just 7 percent would invest in it over gold, compared to 13 percent across all respondents.

But on the first day of CoinSummit, a two-day conference to discuss bitcoin and its future, enthusiasm for the digital currency was everywhere.

"It's as bulletproof as anything I have ever seen, said Marc Andreessen, founder of Menlo Park venture capital firm Andreessen Horowitz.

The firm has invested about $50 million into bitcoin-related projects, and is eager to invest millions more to build a robust bitcoin portfolio, Andreessen said Tuesday. The firm was a lead investor into San Francisco's Coinbase, a digital wallet to store bitcoins in the cloud.

Bitcoin is a cyber currency and payments network that was created in 2009 by a mathematical formula. The total amount of bitcoins that can be created is capped at 21 million, and bitcoin can be bought on global Internet exchanges. No company, government or organization controls the currency, and no traditional banks are involved in any transactions. On Tuesday, the Internal Revenue Service announced it would tax bitcoin as property, and not recognize it as legal currency.

Last month, the world's largest bitcoin exchange, Japan-based Mt. Gox, filed for bankruptcy after saying it had lost more than 750,000 bitcoins -- and then found 200,000 of them in a forgotten wallet. And Vircurex, an exchange and trading platform, announced on Monday it would halt operations after hacking incidents last year depleted users' account, and Vircurex was left to cover the loses.

Supporters say the bitcoin community is learning from the mistakes of Mt. Gox, and compare the recent bitcoin scandals to the early days of the Internet, when AOL and Hotmail accounts were hacked, and international hacking groups siphoned millions from big banks.

"It forced other players to get better at security," said David Johnston, co-founder of BitAngels, an angel investors group focused on advancing bitcoin technology.

Supporters are pushing for more ecommerce companies and retailers to accept bitcoin as payments. San Francisco-based Gyft, a digital gift card startup, is now allowing customers to purchase Walmart gift cards using bitcoin. And Patrick Bryne, chief executive of online discount retailer Overstock.com, became an unofficial spokesman for the currency when in January his company became the first large online retailer to accept bitcoin.

Contact Heather Somerville at 510-208-6413. Follow her at Twitter.com/heathersomervil.