Backing Up Your Wallet

Why does a 12-word phrase use a list of exactly 2,048 words?

• It is the number of common English words
• Each word stands for 11 bits, and 2^11 = 2,048
• More words would make phrases too long to write down

You keep two full copies of your phrase. What does the second copy add, and what does it cost?

• It survives a disaster at the first place, but it is one more place a thief could find the whole phrase
• It adds nothing, because one copy is enough
• It makes the phrase harder to guess