taproot – What makes cross input signature aggregation complicated to implement?

Pieter Wuille answered this on Twitter.

The most important complication of cross input aggregation is explained in this Bitcoin dev mailing list post by AJ Towns.

TL;DR: if softforks change which signatures are checked, they mustn’t
change what is aggregated together. This is especially complicated when they interact with BIP341’s OP_SUCCESSx upgrade mechanism, which could easily let future softforks change script semantics entirely. There is nothing fundamentally hard here – it’s just engineering complexity to make sure everything works well together.

Pieter added at a London BitDevs Socratic Seminar on BIP-Taproot:

Graftroot and cross input aggregation are such deeply conceptual changes. You can’t permit building them later. It is such a structural change to how scripts work. These things are not something that can be just added later on top of Taproot. You need a successor. Cross input aggregation, the concept of script verification is no longer a per input thing but it is a per transaction thing. You can’t do it with optimal efficiency, I guess you can invent things. The type of extensibility that is built in is new opcodes, new types of public keys, new sighash types, all these things are made fairly easy and come with almost no downsides compared to not doing them immediately. Real structural changes to script execution, they need something else.

Simple cross platform style guide for mobile apps or a recommended approach?

Having joined a new project recently I’ve found a lot of padding / margin sizes etc set in the App which had variuous names and isn’t consistent.

I’ve also been briefly looking at style guides blog posts.

I’m trying to come up with a simple style guide, which will cater font sizes, margins and padding.

However, I’m trying to arrive at something simply which will cater for most scenarios.

I’ve previously encountered policies based on a number aka 4 or 5 and margins had to be multiples of that. I think that was along the lines of bootstrap.

Can anyone point me at something similar which would work for Android and iOS…

Authentication and keeping track of users for a cross platform game (Steam+mobile)

I’ve got a question about authentication/user accounts. I’m building a game using Unity that’ll be sold on Desktop (through Steam) and Mobile (Play/App Store).

The game has online multiplayer functionality. I’d like to be able to verify if the clients that connect to the server have actually bought the game and have the option to store data for these profiles (nickname, scores, etc.). Obviously I’ll need some sort of account system/database for that, but I’d like to know what the most common approach to this problem is for games that are sold on different platforms.

What I’d like to avoid is having to create my own account system, since then I’d have to deal with password reset functionality, e-mails, GDPR, that kind of thing. Also I’d like for the user to have a seamless experience after buying the game and not having to register yet another account specifically for my game.

cross chain recovery – senting wrong address from BCH to BTC address PLEASE HELP!

Just did the same blunder. Spent the better part of the day working around it.

In my case I sent bitcoin cash (BTH) from Coinbase to a mycelium wallet.

Here is how I recovered the funds.

First installed on my phone a wallet that supports BCH (mycelium is working on that, but even though I installed the mycelium bitcoin cash module app, no new app appeared and nothing changed in my existing mycelium app).

The wallet of choice was Coinomi.

Then I used the 12-word BIP39 mnemonic to restore the mycelium wallet into coinomi and also added Bitcoincash support (upper left corner, tap burger menu, bottom has +COINS where you add supported coins to see in your dashboard).

Afterwards, went on my PC (needed PC screen to scan a QR code with the coinomi app) to https://iancoleman.io/bip39/ and typed again my BIP39 mnemonic. Then scrolled down to Derived addresses. Looked up under column Address the BTC public address to which I had sent the BTH and ended up with this mess in the first place. Hovered mouse over Private key value corresponding to the BTC public address that received the funds. This showed up a QR code.

Back to coinomi, clicked the QR scan icon and in Ian Colmen’s BIP39 page I scanned the QR of the private key mentioned above.

Happy ending.

Link to github issue for reference.

equation solving – A four cross four matrix which is a function of [Omega]. But the determinant is scalar

I have four equations that I have written in matrix form. The matrix is a function of ω. But When I extract the determinant of the matrix it turned out to be a scalar value. What is the reason for this?

Y = 2*^11;
ρ = 7850;
aa = 0.1*0.1;
Iyy = 0.1^4/12;
L1 = 4;
γ = 0.5*L1;
beta1 = 1.8751;

W1 = a1*((Cos(β*x) - 
         x)) - (((Cos(β*L1) + 
          Cosh(β*L1))/(Sin(β*L1) + 
          Sinh(β*L1)))*(Sin(β*x) - 
         Sinh(β*x)))) /. β -> beta1/L1
W1xx = Expand(D(W1, {x, 2}))
v1 = 0.5*Y*Iyy*Integrate(Expand((W1xx)^2), {x, 0, L1})
t1 = 0.5*ρ*aa*ω^2 Integrate(Expand((W1)^2), {x, 0, L1})

W2 = b1*((Cos(β*x) - 
         x)) - (((Cos(β*γ) + 
          Cosh(β*γ))/(Sin(β*γ) + 
          Sinh(β*γ)))*(Sin(β*x) - 
         Sinh(β*x)))) /. β -> beta1/γ
W2xx = Expand(D(W2, {x, 2}))
v2 = 0.5*Y*Iyy*Integrate(Expand((W2xx)^2), {x, 0, γ})
t2 = 0.5*ρ*
  aa*ω^2 Integrate(Expand((W2)^2), {x, 0, γ})

dispcon = λ1 ((W1 /. x -> L1) - (W2 /. x -> γ))
slopcon = λ2 ((D(W1, {x, 1}) /. x -> L1) - (D(W2, {x, 1}) /. 
      x -> γ))

T = t1 + t2
V = v1 + v2

Lg = (T - V) + dispcon + slopcon
var = {a1, b1, λ1, λ2}

eq = Table(D(Lg, {var((i)), 1}), {i, 1, Length(var)})
Rarz = Normal@CoefficientArrays(eq, var)((2));

magento2 – Magento 2 : How to change the cross sell text in product Edit page

i have overwritten the Related.php file but nothing happen


<preference for="MagentoCatalogUiDataProviderProductFormModifierRelated" type="VendorModuleUiDataProviderProductFormModifierRelated" />


namespace VendorModuleUiDataProviderProductFormModifier;

class Related extends MagentoCatalogUiDataProviderProductFormModifierRelated

 public function modifyMeta(array $meta)
   echo "test"; die;


Please help this issue.

Reliant Funding Partners with Cross River Bank to Facilitate Paycheck Protection Program Loans for Small Businesses – Seekingfin

Leading alternative finance company and authorized lender of the Small Business Administration (SBA) work in tandem to speed up funding during coronavirus crisis

reliant funding logoApril 27, 2020 (San Diego, CA) – Today, Reliant Funding, a leading small business finance provider, announces its partnership with Cross River Bank (“Cross River”), a leading innovator and provider of banking services for technology companies, to deliver Paycheck Protection Program (PPP) loans to small businesses. Experts expect demand for funding from small businesses to outpace the first round and banks must be prepared to double down to streamline processes and mitigate customer frustration.

“Reliant Funding was born in the midst of the 2008 financial crisis and our team of dedicated and trained professionals is equipped to ensure our small businesses are supported – financially and emotionally – through these trying times,” said CEO of Reliant Funding Adam Stettner. “We’re committed to helping small businesses get back on their feet after this pandemic is over, and we know our partnership with Cross River will create a seamless application process that will do just that.”

Beginning on April 27, Reliant Funding and Cross River Bank will work in tandem to facilitate loans to ensure the process is as seamless as possible for American small businesses, as well as deliver transparency and answer any questions throughout the application process. In addition to applying for money from the government, small businesses will have the opportunity to apply for working capital through Reliant Funding.

The program ends on June 30. For more information, or to apply for a PPP loan, please visit ReliantFunding.com/PPP.

For more information on Reliant Funding, please click here.

Reliant Funding provides customized, short-term funding to small and mid-sized businesses nationwide. Headquartered in San Diego with an office in New York, Reliant Funding has surpassed $1.5 billion in total funding and has been recognized by Inc. Magazine as part of the 5000 fastest growing privately held companies in America for seven consecutive years. Adam Stettner, the Founder of Reliant Funding, was named Ernst & Young’s Entrepreneur of the Year in 2019. For more information, please visit www.reliantfunding.com.

backup – MongoDB cross datacenter replication without elections or high data availaility

I want to replicate a MongoDB database to another node, located in another datacenter.
This is to help guard against data loss in the case of a hardware failure.

We don’t want/need high availability or elections; just a ‘close to live’ read-only copy of the database, located in another DC.

Everything I read says that you need an odd number of nodes, due to elections, but this isn’t something we need/want and I can’t find anything related to just having one primary, and one secondary (I might be being blind).

Is this something we can achieve with MongoDB, and if so are there any ‘gotchas’ or serious downsides we should consider?

html – Are there security issues around controlled cross site sharing behind SSO?

Very simply we have a ton of websites at our company behind SSO.

I am having a hard time figuring out what security issues there are if we open cross-site sharing between these sites but wanted to get a broader view. This is really a result of browser updates around cross site sharing in iframes in chrome and IE a few months back. With those security features disabled at the browser level (yes we will not have users do that) iframing within our sites work fine.

Let me give you context of the specific problem:

  1. example.com – main site
  2. subdomain1.example.com – subdomain we have a ton
  3. subdomain2.example.com – another sub
  4. example.login.com – SSO server we authenticate to
  5. example.cms.com – random vendor that uses our SSO

So right now as long as the servers in 1, 2, and 3 allow cross site sharing iframes work… as long as your cookie/token is already active. If it is not active then it just errors out trying to connect to example.login.com.

We are discussing changing the CORS/sharing settings on the login server and others brought up possible security issues. I just don’t see how there are issues with clickjacking or anything else when we control all of the sites ourselves. Am I missing something here? Are there security issues with sharing between controlled tenets? Let me know if I need to provide anymore info.

\machinename cannot open network share while \ipaddress work in cross domain

We have established a two-way trusted domain environment. All servers are Windows Server 2019. In server1.domainA.com there is shared drive. In server2.domainB.com, we tried to browse with \server1 it prompt for access denied. But it works for \server1.domainA.com or \IPaddress.

On server2, “ping server1” resolve to correct IP. The result is same as “ping server1.domainA.com”.

We checked conditional forwarder is setup on both domain’s DNS already.

What could be the issue and how to troubleshoot?