Propuesta de Mejora a la Minería de Blockchain

En estas semanas, lei el post 25-second irreversible confirmations for instant payments de @sdlerner, donde menciona:

Bitcoin forwards a block by packing the block header with all the transactions contained in the block. This strategy, while being the most easy to analyze, is known to perform badly, both regarding block propagation latency and bandwidth usage. Since the transactions on a block are generally already known to the network, there is no benefit in transmitting them again.

Las transacciones incluidas en un bloque podrían ser sustituidas por una lista de hashes. El nodo que recibe la información del nuevo bloque minado podría reconstruir las transacciones a partir de los hashes. Tiene un conjunto interno de transacciones pendientes: de ahi puede traducir los hashes a transacciones. Los hashes que no correspondan a transacciones conocidas deben ser entonces pedidas al otro nodo. Otra alternativa es enviar el encabezamiento del bloque:

…Still another improvement is to forward the block header before even checking the transactions, and only checking the block PoW and height at forward time.Still another improvement is to forward the block header before even checking the transactions, and only checking the block PoW and height at forward time. This allows the header to spread over the network in less than a second. Nodes can then start mining an empty block on top of the header even if the transactions are still missing, during a fixed interval. After that interval, they resume mining in whatever block they were mining before.

(el énfasis es mío) No soy experto en minería ni eficiencia de red, pero puedo proponer una mejora a esta alternativa, al menos en Ethereum, donde existe el concepto de cuenta. En vez de propagar solamente el header, el nodo remoto puede enviar además un predicado de cuentas P(acc) con las siguientes propiedades:

– P(acc) es verdadero para cualquier cuenta involucrada en una transacción del bloque recibido

Una “cuenta involucrada en una transacción” es tanto la cuenta que envía fondos como la que los recibo. Debemos considerar las cuentas que reciben SI SON CONTRATOS, pues pueden cambiar de estado más allá de recibir fondos. En una transacción que sea “solo transferencia de fondos”, debemos considerar involucrada a la cuenta que envía. El punto a entender es: el nodo que recibe la información resumida del nuevo bloque minado NO PUEDE ESTAR seguro del estado de cualquier cuenta involucrada en las transacciones de ese bloque. De las otras cuentas, todas mantienen EL MISMO ESTADO que antes de ese nuevo bloque minado.

Entonces, toda transacción pendiente que tenga cuenta enviadora con P(acc) en falso, y (cuenta receptora sin contrato O con tipo contrato con P(acc) en falso), puede ser incluida en el armado de un nuevo bloque.

La mejora propuesta consiste: en vez de comenzar a minar un bloque vacío, el nodo receptor puede comenzar a minar el bloque usando transacciones pendientes, que cumplan con la condición anterior. Las cuentas que no ven afectado su estado, pueden participar de las transacciones del nuevo bloque.

¿Cómo enviar ese predicado? Una opción es tener un Bloom filter. De nuevo, no conozco mucho de filtros Bloom, pero puedo imaginar una lista de bits. Como ejemplo concreto, usaré 16 bits. Si una cuenta, involucrada en una transacción, tiene una dirección pública que termina en el hexadecimal 0, prendo el primer bit. Si la cuenta involucrada tiene dirección que termina en hexadecimal A, prendo el bit undécimo. De esta manera, puede haber falsos positivos en este filtro, pero cada cuenta involucrada en una transacción del bloque satisface el predicado, y no será incluida en el próximo bloque.

La longitud en bits de este campo podría ser optimizada de acuerdo a la cantidad media de transacciones incluidas por bloque. Si el número de transacciones (o cuentas involucradas) por bloque es alrededor de 16, entonces la longitud de este campo podría ser de 32 bits, como para tener alguna probabilidad de transacciones pendientes con cuentas que no satisfagan el filtro, y puedan ser minadas inmediatamente.

¿Podría esta propuesta ser adaptada para Bitcoin y otros similares? No parece sencillo, al no existir el concepto de cuenta. Habría que usar un filtro de transacciones, pero no siempre podemos saber cuáles de las transacciones pendientes es candidata a minar, porque el nodo no puede ASEGURAR que conozca TODAS las transacciones involucradas: podría haber latencia en la diseminación de las transacciones. Pero supongo que el nodo puede arriesgarse igual a producir un bloque, si la probabilidad de insertar una transacción inválida es baja.

No sé evaluar si esta propuesta puede ser implementada, o si agrega valor, pero me pareción un camino interesante para explorar.

Nota: Desde hace tres meses, soy miembro del equipo de desarrollo de @RSKsmart donde @sdlerner es el Chief Scientific Officer.

Nos leemos!

Angel “Java” Lopez
http://www.ajlopez.com
http://twitter.com/ajlopez

Spybot Search & Destroy Weekly Update – May 25, 2016

2016-05-25
Adware
++ Ad.FunPop ++ Ad.InstallBrain ++ Win32.Kraddare
Keyloggers
+ Win32.ActiveKeyLogger
Malware
++ Fraud.KVaccine
PUPS
+ DealPly
Trojans
+ Win32.Bifrost
Total: 2618765 fingerprints in 829903 rules for 7652 products.

 

CryptXXX updated to version 3.0, Decryptors no longer Work

CryptXXX Ransomware Help, Information Guide, and FAQ

Removal instructions for PC Cleaner TSS

What is PC Cleaner TSS?

The Malwarebytes research team has determined that PC Cleaner TSS is a Tech Support Scam. These so-called “Tech Support Scammers” try to trick you into calling their phone number for various reasons, all of which turn out to be fraudulent in the end.
More information about this particular one can be found in this blogpost.
How do I know if my computer is affected by PC Cleaner TSS?

https://forums.malwarebytes.org/topic/183573-removal-instructions-for-pc-cleaner-tss/

How to Enable or Disable User Accounts in Windows 10

User accounts help control which files and apps each person can use and what changes they can make to the PC.

If you have a user account that you want to make unavailable without deleting it, you can disable the account. A disabled account can be enabled again later. Disabling an account is different from deleting an account. If you delete an account, it can’t be restored.

When a user account is disabled, it’s name will be removed from the sign-in screen and Start menu switch user areas so that it can no longer be signed in to.

This tutorial will show you how to enable or disable a user account in Windows 10.

Read more…

Windows Server 2016 et la sécurité…

Bonsoir à tous,

Windows Server, c’est aussi plus de sécurité.

Défendez vous contre les attaques de type Pass the Hash en mettant en place une politique de renouvellement automatique des mots de passe directement via Windows Server. Concrètement, comment ça se passe ?

https://channel9.msdn.com/Blogs/Concretement/Episode-23-Lutter-contre-les-attaques-Pass-the-Hash-avec-Windows-Server-2016?CR_CC=200642249

Bonne soirée.
Patrice.

Windows Server 2016 : le mode “Core”

Bonjour tout le monde,

Configuration initiale de Windows Server 2016 TP4 "Core"

Windows Server 2016 TP4 « Core » est la solution si vous cherchez un mode d’installation simple et optimisé pour la légèreté et la rapidité d’exécution.

https://channel9.msdn.com/Blogs/MVP-Cloud-DataCenter/HowTo–Configuration-initiale-de-Windows-Server-2016-TP4-Core?CR_CC=200642249

Bonne soirée.
Patrice.

Windows Server 2016: les dernières nouveautés

Bonsoir à tous,

Les nouveautés de Windows Server 2016 vous attendent !

La dernière version de Windows Server possède de multiples nouveautés. Découvrez-en les détails dans ce cours.

https://mva.microsoft.com/fr-fr/training-courses/nouveauts-de-windows-server-2016-16140?l=sqSTBGOGC_3905192797&CR_CC=200819826

Bonne soirée Winking smile
Patrice.

Upgrade fails with TF246017: Team Foundation Server could not connect to the database.

Problem

In the middle of the TFS upgrade, it fails with the error message:

Caught exception in ExecuteScripts: Microsoft.TeamFoundation.Framework.Server.DatabaseConnectionException: TF246017: Team Foundation Server could not connect to the database. Verify that the instance is specified correctly, that the server that is hosting the database is operational, and that network problems are not blocking communication with the server. —> System.Data.SqlClient.SqlException: Cannot open database "Tfs_DefaultCollection" requested by the login. The login failed.
[12:44:29.207]   Login failed for user ‘SERVERTOGOTFSSERVICE’.

Potential Cause

While this error message can have multiple causes (invalid credentials, SQL Server not available/not started, etc.), it was strange that it failed during the upgrade process (which means many steps were already successfully executed against that SQL Server instance).

The Windows Event Log is a good candidate where to look for the potential cause. In this case, SQL Server told me that it stopped a transaction, because the transaction log was full.

Increasing the maximum size of the Transaction Log (in SQL Management Studio) resolved the issue.

–Neno

ORMs Meet SQL – My Presentation for Tuga IT 2016

Even having been just a few hours at the Tuga IT conference, I can say that it was a huge success! So many awesome speakers, the chance to meet friends and talk about all the crazy stuff going on was great!

The Tuga IT organization and sponsors really deserve a big applause for making it possible.

image

I will highlight one of them, because I have the feeling that without his enthusiasm, vision and “madness”, this wouldn’t have happened: Niko Neugebauer (@nikoneugebauer), aka, “Columnstore guy”! Well done, man! Winking smile

As for me, thanks to the NetPonto community who selected my presentation, I had a chance to do a light talk about ORMs, which you can find in my OneDrive here. Kudos to NetPonto for having me on board! Winking smile

See you next year, I hope!

Hit by the stealth W10 Upgrade? Here’s what to do!

With the new aggressive approach MS has to upgrading to W10, I suspect that we will be seeing a lot more calls asking what to do. This is a decent article on how to avoid it and what to do if, like my friend, you find that your computer was upgraded while you slept (he actually fell asleep and woke up hours later with W10!).

How to go back to Windows 7 or 8 after an unwanted Windows 10 upgrade

Here’s another article on the same subject. Hope they help!

How to escape that forced Windows 10 upgrade you mistakenly agreed to

One reason not to pay Ransomware: They may not decrypt the files anyway.

Here’s yet another reason not to pay the ransom when hit by ransomware: the scum won’t give you the key. This reinforces the need for us to be prepared with backups (not connected to the network) and up to date AV and Anti-Malware.

Kansas Heart Hospital hit with ransomware; attackers demand two ransoms

Google Apps beat out MS Office on Smart Phones

This kind of surprises me. I understand the idea of using non-MS apps id something that many folks yearn for. Also, the Google apps have been out there for a while and folks are just not interested in switching any software once they’ve gotten used to it. I expected, though, that using familiar Office on the iOS or Droid devices would make them attractive. Frankly, I don’t like the Google apps, especially G-Mail. I *HATE* the interface over Outlook.

I was surprised, though, at the gaps. Oh, well, guess my Chrystal ball is cloudy today… 🙂

Google’s mobile productivity apps bury Microsoft’s

Removal instructions for RelevantKnowledge

What is RelevantKnowledge?

The Malwarebytes research team has determined that RelevantKnowledge is adware. These adware applications display advertisements not originating from the sites you are browsing.
RelevantKnowledge is also considered spyware because of their market research.

https://forums.malwarebytes.org/topic/183518-removal-instructions-for-relevantknowledge/

How to Turn On or Off Double Tap to Wake Up Windows 10 Mobile Phone

The double tap to wake feature allows you to awaken your sleeping phone by tapping twice on the screen. This can be much easier than pressing the phone’s power button to wake the phone.

This tutorial will show you how to turn on or off the double tap to wake up phone feature on your Windows 10 Mobile phone.

Read more…

How to Enable or Disable Game DVR and Game Bar in Windows 10

The Game DVR is a feature of the Xbox app that lets you use the Game bar to record and share game clips and screenshots in Windows 10. However, you can also use the Game bar to record videos and take screenshots of any app in Windows 10.

This tutorial will show you how to enable or disable the Game DVR and Game bar feature from the Xbox app for all users in Windows 10.

Read more…

Yet another variation on Ransomware. This time Bundled with DDoS!!

As if it weren’t enough, here comes a ransomware product that adds insult to injury. Not only are you FUBAR’d, your computer starts to mess with other sites. Bottom line: Practice “Safe Computing” and keep your AV and Anti-Malware software up to date.

This New Ransomware Strain Adds DDoS Bot Causing More Damage

With Memorial Day Coming up, a Reminder

As a Vietnam Veteran, this means a lot. I know it’s early, but keep this in mind on Memorial Day.

13254216_804957842974331_3781948779845709670_n

Toymaster Releases Volume 16 # 21

Security Mailer V16 #21

05/21/16 – Adobe out-of-cycle patch for Acrobat DC and Reader DC; Apple released updates for Apple TV, iOS, watchOS, OS X and security update, Safari, and iTunes; Cisco Advisories; Linux updates; Microsoft fix for slow Win 7 updates?, revisions; General security entries

Part 2

1- 11 Things – ESET posting covers 11 things you can do to protect against ransomware

2- SHA 1 Advisory – Microsoft Advisory and additional information to help you with SHA 1 deprication – I suggest saving this document for reference

3- Simplifying updates – Nathan Mercer covers new changes at Microsoft designed to simplify updating for Windows 7 and Windows 8.1

4- Windows Enforcement of Authenticode – Another document you should save for reference – Affective 7/14/17 Windows 7 and higher will no longer trust new code signed with SHA 1

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