What is multipliers.txt?

[picobit]

Hi,

I can see in the armory directory a file called multipliers.txt.  It contains lines of the type

Code:

PrvChain (pkh, mult): ,<256-bit hex number>

and occationally

Code:

PubChain (pkh, mult): <160-bit hex number>,<256-bit hex number>

What are these numbers?  Do they expose information about my wallets?  (I guess not, you guys seem to know what you are doing, but better safe than sorry)

[etotheipi]

Hi,

I can see in the armory directory a file called multipliers.txt.  It contains lines of the type

Code:

PrvChain (pkh, mult): ,<256-bit hex number>

and occationally

Code:

PubChain (pkh, mult): <160-bit hex number>,<256-bit hex number>

What are these numbers?  Do they expose information about my wallets?  (I guess not, you guys seem to know what you are doing, but better safe than sorry)

Due to some concerns in the past that RAM errors could result in erroneous key calculations we decided to be extra safe and save off the byproduct of the deterministic key calculation into this file (the multipliers).  The data in that file cannot be used to figure out any private keys if you don't know them, but does allow you to confirm/regenerate the private keychain if you have the root private key.  Under nominal conditions, it's irrelevant.  But if there was a RAM error that calculated a bad public key on a WO wallet, you could use multipliers.txt and the paper backup to compute the private key for the erroneous public key.

We've never had to use this file on anyone's wallet, so we don't even have a script that does what I said above.  But we have seen wallet consistency errors that led us to believe this is possible, which is why we added it along with doing many key calculations multiple times and confirming they match.

[picobit]

OK, so in principle they do not leak any information.  But if I somehow leaked a private key, then would this one would give away the rest?  Or would it require the root key itself to gain any info?  Not that I plan to leak any private keys - nor export them to wallets/services that I believe (for the time) to be safe