Talk:BIP 0039

Here is a simple implementation of my proposal to 'mine' for a seed:

from electrum import mnemonic
import ecdsa
import time
import hmac
import hashlib

PREFIX = "100"
n = len(PREFIX)
entropy = ecdsa.util.randrange( pow(2,160) )
nonce = 0

while True:
  ss = "%040x"%(entropy+nonce)
  s = hashlib.sha256(ss.decode('hex')).digest().encode('hex')
  words = mnemonic.mn_encode(s)[0:13] # 13 random words                                                                                                                          
  seed = ' '.join(words)
  I = hmac.new("Bitcoin mnemonic", seed, hashlib.sha512).digest().encode('hex')
  if I[0:n] == PREFIX:
    break
  nonce += 1

print seed
print I

PREFIX contains metadata about the wallet version.

The first 4 or 12 bits of PREFIX encode the length of the metadata (0 to e, f00 to fff)

The length of the metadata in bits is 4*(n+1) where n is the value that is encoded.

The format of the metadata itself remains to be defined.

The most compact way to use it is probably to allocate version numbers.

Examples:

• 00 to 0f : length = 4 bits. 16 possible version numbers
• 100 to 1ff : length = 8 bits. 256 possible version numbers. (00 is used for Electrum's wallet structure)
• 2000 to 2fff
• etc.