Commit graph

17 commits

Author SHA1 Message Date
moneromooo-monero
611639710d
a few minor (but easy) performance tweaks
Found by codacy.com
2018-11-23 15:36:48 +00:00
moneromooo-monero
5ffb2ff9b7
v8: per byte fee, pad bulletproofs, fixed 11 ring size 2018-09-11 13:38:07 +00:00
moneromooo-monero
9ce9f8caf6
bulletproofs: add multi output bulletproofs to rct 2018-09-11 13:37:28 +00:00
stoffu
cb9c7972b6
Fix output shuffling for multisig 2018-05-20 09:38:41 +09:00
stoffu
402c9eef0e
cryptonote_tx_utils: fixed logic bug in get_destination_view_key_pub 2018-01-29 17:05:07 +09:00
xmr-eric
18216f19dd Update 2018 copyright 2018-01-26 10:03:20 -05:00
moneromooo-monero
fa5697127f
make multisig work with subaddresses
Thanks to kenshi84 for help getting this work
2017-12-17 16:12:27 +00:00
moneromooo-monero
4c313324b1
Add N/N multisig tx generation and signing
Scheme by luigi1111:

    Multisig for RingCT on Monero

    2 of 2

    User A (coordinator):
    Spendkey b,B
    Viewkey a,A (shared)

    User B:
    Spendkey c,C
    Viewkey a,A (shared)

    Public Address: C+B, A

    Both have their own watch only wallet via C+B, a

    A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)

    A and B watch for incoming outputs

    B creates "half" key images for discovered output D:
    I2_D = (Hs(aR)+c) * Hp(D)

    B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
    and sending the pubkeys with I2_D.

    A also creates "half" key images:
    I1_D = (Hs(aR)+b) * Hp(D)

    Then I_D = I1_D + I2_D

    Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).

    A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
    to his own generated ones where they are needed (secret row L, R).

    At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
    which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).

    B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).

    B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
    to his cache, allowing him to verify spent status as well.

    NOTE:
    A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
    Otherwise, trickery like the following becomes possible:
    A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
    B creates a fake key C = zG - B. B sends C back to A.
    The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
    The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).

    2 of 3

    User A (coordinator)
    Shared viewkey a,A
    "spendkey" j,J

    User B
    "spendkey" k,K

    User C
    "spendkey" m,M

    A collects K and M from B and C
    B collects J and M from A and C
    C collects J and K from A and B

    A computes N = nG, n = Hs(jK)
    A computes O = oG, o = Hs(jM)

    B anc C compute P = pG, p = Hs(kM) || Hs(mK)
    B and C can also compute N and O respectively if they wish to be able to coordinate

    Address: N+O+P, A

    The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
    needed part of the signature/key images from either of the other two.

    Alternatively, if secure communication exists between parties:
    A gives j to B
    B gives k to C
    C gives m to A

    Address: J+K+M, A

    3 of 3

    Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
    The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
    or send it back to A.

    N-1 of N

    Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
    (using either the secure or insecure method).
    For example (ignoring viewkey so letters line up):
    [4 of 5]
    User: spendkey
    A: a
    B: b
    C: c
    D: d
    E: e

    a -> B, b -> C, c -> D, d -> E, e -> A

    Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
    the transaction so the signers know if they should use 1 or both keys.
    Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
    Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
    1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
    2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
    must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.

    You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
    also be straightforward enough to support with minimal changes from N-1 format.
    You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.

The process is somewhat cumbersome:

To create a N/N multisig wallet:

 - each participant creates a normal wallet
 - each participant runs "prepare_multisig", and sends the resulting string to every other participant
 - each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)

As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:

 - each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
 - each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants

Then, a transaction may be initiated:

 - one of the participants runs "transfer ADDRESS AMOUNT"
 - this partly signed transaction will be written to the "multisig_monero_tx" file
 - the initiator sends this file to another participant
 - that other participant runs "sign_multisig multisig_monero_tx"
 - the resulting transaction is written to the "multisig_monero_tx" file again
 - if the threshold was not reached, the file must be sent to another participant, until enough have signed
 - the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
2017-12-17 16:11:57 +00:00
moneromooo-monero
d58835b2f6
integrate bulletproofs into monero 2017-12-08 13:48:15 +00:00
moneromooo-monero
01dc829784
wallet: transfer RPC can now return tx metadata (pending_tx) 2017-11-24 14:03:52 +00:00
kenshi84
88ebfd646a
core_tests: fix for subaddress patch 2017-10-17 22:29:01 +09:00
kenshi84
53ad5a0f42
Subaddresses 2017-10-07 13:06:21 +09:00
stoffu
cbc5508b15
construct_tx_and_get_tx_key: return sorted sources for print_ring_memebrs to work properly 2017-10-03 08:12:28 +09:00
moneromooo-monero
16afab900d
core: sort ins and outs key key image and public key, respectively
This avoids leaking some small amount of information
2017-09-13 09:25:05 +01:00
moneromooo-monero
214fd81e93
some include cleanup 2017-07-31 16:36:52 +01:00
Riccardo Spagni
c3599fa7b9
update copyright year, fix occasional lack of newline at line end 2017-02-21 19:38:18 +02:00
kenshi84
8027ce0c75 extract some basic code from libcryptonote_core into libcryptonote_basic 2017-02-08 22:45:15 +09:00