Bitcoin eWallet Inputs.io was left unable to pay an undisclosed number of user balances after the service was hacked on Thursday and relieved of 4,100 Bitcoins. That translates to about $1.1 million.

“The attacker compromised the hosting account through compromising email accounts (some very old, and without phone numbers attached, so it was easy to reset),” according to a post on the Inputs.io website. “The attacker was able to bypass [two-factor authentication] due to a flaw on the server host side.”

Bitcoins are a form of peer-to-peer internet currency – also known as cryptocurrency – and Inputs.io built something of a reputation in the Bitcoin-trading community for its security, which includes bcrypted passwords, two-factor authentication and GPG authentication.