Beginning with this commit, every MMGen wallet now has a two sets of associated
subwallets with “long“ and “short” seeds.
MMGen wallets and subwallets are functionally equivalent and externally
indistinguishable. This has benefits, especially for real-world security, as
well as drawbacks. For more information, see the `mmgen-subwalletgen` help
screen: https://github.com/mmgen/mmgen/wiki/subwalletgen-[MMGen-command-help]
This patch provides subwallet generation functionality and subseed display
utilities. Support for transaction signing and address generation using a
subwallet's parent wallet will be added in a forthcoming patch.
Examples:
# Create a bogus wallet in mnemonic format for testing purposes:
$ echo $(yes bee | head -n24) > bogus.mmwords
# List the wallet's first five subseed pairs:
$ mmgen-tool list_subseeds 1-5 wallet=bogus.mmwords
Parent Seed: DF449DA4 (256 bits)
Long Subseeds Short Subseeds
------------- --------------
1L: FC9A8735 1S: 930E1AD5
2L: 62B02F54 2S: DF14AB49
3L: 9E884E99 3S: AD3ABD98
4L: DB595AE1 4S: 3E885EC4
5L: 36D5A0D1 5S: 30D66FF5
# Generate the 5th short (128-bit) subwallet from the wallet:
$ mmgen-subwalletgen bogus.mmwords 5S
# Same as above, but output subwallet to mnemonic (seed phrase) format:
$ mmgen-subwalletgen -o mn bogus.mmwords 5S
...
Mnemonic data written to file '30D66FF5[128].mmwords'
# View the subwallet's seed phrase:
$ cat 30D66FF5[128].mmwords
object capture field heart page observe road bond mother loser really army
# Generate 10 addresses from the subwallet seed phrase:
$ mmgen-addrgen 30D66FF5[128].mmwords 1-10
...
Addresses written to file '30D66FF5[1-10].addrs'
