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nadams 2017-05-11 06:58:57 -07:00
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@ -766,6 +766,7 @@ Eugenia could advertise a randomly generated address (e.g., +1J7mdg5rbQyUHENYdx3
In both cases, one of the risks of using a single fixed address (rather than a separate dynamic address per donor) is that a thief might be able to infiltrate your website and replace it with his own address, thereby diverting donations to himself. If you have advertised your donation address in a number of different places, your users may visually inspect the address before making a payment to ensure it is the same one they saw on your website, on your email, and on your flyer. In the case of a random address like +1J7mdg5rbQyUHENYdx39WVWK7fsLpEoXZy+, the average user will perhaps inspect the first few characters "1J7mdg" and be satisfied that the address matches. Using a vanity address generator, someone with the intent to steal by substituting a similar-looking address can quickly generate addresses that match the first few characters, as shown in <<table_4-13>>.
[[table_4-13]]
[role="pagebreak-before"]
.Generating vanity addresses to match a random address
|=======
| *Original Random Address* | 1J7mdg5rbQyUHENYdx39WVWK7fsLpEoXZy
@ -795,14 +796,12 @@ Paper wallets come in many shapes, sizes, and designs, but at a very basic level
Paper wallets can be generated easily using a tool such as the client-side JavaScript generator at _bitaddress.org_. This page contains all the code necessary to generate keys and paper wallets, even while completely disconnected from the internet. To use it, save the HTML page on your local drive or on an external USB flash drive. Disconnect from the internet and open the file in a browser. Even better, boot your computer using a pristine operating system, such as a CD-ROM bootable Linux OS. Any keys generated with this tool while offline can be printed on a local printer over a USB cable (not wirelessly), thereby creating paper wallets whose keys exist only on the paper and have never been stored on any online system. Put these paper wallets in a fireproof safe and "send" bitcoin to their bitcoin address, to implement a simple yet highly effective "cold storage" solution. <<paper_wallet_simple>> shows a paper wallet generated from the bitaddress.org site.
[[paper_wallet_simple]]
[role="smallersixty"]
.An example of a simple paper wallet from bitaddress.org
image::images/mbc2_0408.png[]
((("bitcoin improvement proposals", "Encrypted Private Keys (BIP-38)")))The disadvantage of a simple paper wallet system is that the printed keys are vulnerable to theft. A thief who is able to gain access to the paper can either steal it or photograph the keys and take control of the bitcoin locked with those keys. A more sophisticated paper wallet storage system uses BIP-38 encrypted private keys. The keys printed on the paper wallet are protected by a passphrase that the owner has memorized. Without the passphrase, the encrypted keys are useless. Yet, they still are superior to a passphrase-protected wallet because the keys have never been online and must be physically retrieved from a safe or other physically secured storage. <<paper_wallet_encrypted>> shows a paper wallet with an encrypted private key (BIP-38) created on the bitaddress.org site.
[[paper_wallet_encrypted]]
[role="smallersixty"]
.An example of an encrypted paper wallet from bitaddress.org. The passphrase is "test."
image::images/mbc2_0409.png[]