[Note:  I was in the middle of writing this when ranochigo posted.  Thus some of the redundancy.]


If you don’t want technical discussion, then why are you posting in “Development & Technical Discussion”?  Ask in another forum.  I dumb things down for people over there, or I stay away.  Also, I personally couldn’t care less what you say is “good for ordinary people”.

But if you desire a technical education, this is an excellent place.


You never defined a “fake” transaction.  I will infer a precise definition:  A transaction which does one or more of (0) violating consensus rules, and/or (1) spending inputs which were already spent (viz. a double-spend tx).

Protection against (1) is the purpose and the only purpose of miners and “confirmation”.  The technical term is that “confirmation” provides Byzantine fault tolerance in the ordering of transactions.  Ordering is important, that is what chooses between multiple conflicting transactions in a double-spend scenario.  “Byzantine fault tolerance” means in effect that untrusted and mutually untrusting parties with unreliable communications can reliably converge on a common agreement, excluding malicious cheaters.

Full protection against (0) is built into Core, which validates each and every transaction according to a stringent set of rules.  Every bit and byte of each and every transaction must pass validation, or else the whole transaction is simply discarded.  Full nodes also validate whole blocks of transactions, according to yet more rules; this prevents malicious miners from messing with the network.  A Core node follows whichever fully valid chain has the highest total proof-of-work.

If a transaction passes all consensus rule validation and has been “confirmed”, then by definition it is not fake.

If you can’t run a full node, then what you are saying is that you can’t have full validation.  There’s no magical means to wave that away.  The better light clients (such as Electrum) are good enough for most light consumer use; but they will never have the security of a Core node.


I haven’t bothered to pick that apart and see what’s going on.  But as kahc noted, it’s probably just exploiting a bug in blockchain.info’s (notoriously buggy) software.  Solution:  Run Core.


The only way to protect against double-spends is with confirmations.  Unconfirmed transactions are never safe.  They always have some possibility of being overridden with a double-spend.  It is impossible that you could “detect” that; and if there were such a way, we wouldn’t need miners.  Whatever you are doing, it is not achieving what you suppose.


Segwit, which activated 24th August 2017 at Block #481824, was a “softfork”.  It still permits old-style transactions.  Indeed, if your address starts with a “1”, then you are still sending non-Segwit transactions and vastly overpaying in fees.  This is important if you want to save on fees (and also help the network), so I will briefly explain.

Oversimplifying a bit:  Whether or not a transaction is a Segwit tx is determined by the address of the sender.  So if you want to send Segwit tx and get a sharp fee discount, you need to use a Segwit address.  There are two kinds of Segwit addresses:

• Backwards-compatible P2WPKH-nested-in-P2SH addresses, such as the one in my signature: 36finjay27E5XPDtSdLEsPR1RypfhNW8D8.  These start with a “3”; but not all addresses starting with a “3” are Segwit addresses (just as all dogs are animals, but not all animals are dogs).  There is no way to distinguish whether or not a “3” address is Segwit, just by looking at it.  These addresses have some disadvantages, but one important advantage:  Every Bitcoin client made in the past few years can send money to them.
• Bech32 addresses, which I call “Bravo Charlie One” addresses because they always start with “bc1”.  Those look like this:  bc1qnym7k9hfl77zgrstcrjhphm0llne5j4w0m3fuu  That’s the Bitcoin address of the future, redesigned with error-correcting codes and no upper/lowercase distinction.  But Bech32 has one temporary disadvantage:  Only people who have upgraded to the newest software can send money to it.  I want people to send me money, so I’m still using nested P2SH; I hope to switch to Bech32 in about 6–12 months.

Ok, bye!  Don’t let the door hit your butt on the way out.

Bitcoin doesn’t need you.  Big money is now involved, and big money is competing with itself.  I am perpetually amused by how people don’t realize that even if you’re a “whale”, you need Bitcoin and Bitcoin does not need you.  You’re not doing Bitcoin any favours.

So sell now, SELL SELL SELL, dump your BTC, and go away.  You will be crying a few years from now, when the 2017 market looks like the 2012 market does now.  But by then, it will be too late; and neither Bitcoin nor I will give a damn what happens to you.

I’m happy to help people who love Bitcoin.  I volunteer many hours of my time explaining how to get an instant fee discount with Segwit, how to generate nested P2SH Segwit addresses with the popular Electrum wallet, etc., etc.  See above!  But if you “choose another coin very soon”, I will be pleased to laugh at your future regrets.