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1  Economy / Collectibles / [WTS] Casascius 25 BTC on: March 20, 2017, 09:30:06 PM

Hi All - What is the market rate for a Casascius 25BTC? Ungraded, but condition is excellent. Original owner. Can't be too many of these about.

Likely to unseal within 24hrs unless I have a compelling reason not to - which I appreciate makes me a terrible human being.

You would need to be in London, England.

Let me know if there is any interest, though to set expectations I'd prob be looking for something over 28 to part with it.
2  Bitcoin / Development & Technical Discussion / Crypto security question on: January 23, 2016, 02:21:20 PM
Hi - looking for a bit of tech help

Pre-conditions:

1. Alice has encrypted the text "red" with her private key, and stores the ciphertext on a public ledger.
2. Her public key is known.
3. Bob knows that Alice has stored a ciphertext corresponding with either "red" or "white" on the ledger.

My Question:

Using the public key, the ciphertext, and knowing the possible cleartext values, is it possible for Bob to determine the value which has been stored?

To put the question another way: If required could Alice prove that the cleartext value is "Red" without using her private key?
3  Economy / Computer hardware / WTS Assorted PC Cables (UK) on: March 06, 2015, 01:03:20 PM

Noticed someone looking to buy similar cables recently (in the US) and remembered I have a heap of old cables, most of which are unused.

Anyone interested? Make me an offer, will sell the lot for best offers over £25 by next Saturday morning (Mar 14th) - payment in BTC.

I have no idea what the stuff is worth so apologies if the price is too high, i figured £5 for postage, and £20 for the goods is the minimum that would get my ass down to the post office, otherwise i'll just keep them.

Will consider partial offers but remember the 'ass-to-post-office' threshold stands











4  Bitcoin / Bitcoin Discussion / More phishing emails - Localbitcoins on: January 26, 2015, 11:47:03 PM
got this a few mins back, don't have an account



Edit: what does a guy have to do to post an image around here?

Edit Edit: Oh, thaat.
5  Bitcoin / Bitcoin Discussion / Long list of addresses and (private?) keys on: January 16, 2015, 11:54:33 PM
Can anyone explain what this is?

http://directory.io/1#5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU

Looks like someone has spent a lot of time generating addresses.

I checked about 5 of the addresses, weirdly one has been used in the past, possibly some kind of test (https://blockchain.info/address/1QAALUJNskZWEbvwKXoTteowgs9xGGeAZR)

No idea if the private keys are actual private keys.
6  Bitcoin / Bitcoin Discussion / Another scam/phishing attempt - blockchain users beware on: June 29, 2014, 09:48:53 PM
OK...

These tweets: https://twitter.com/search?f=realtime&q=follow%20%40shodandice%20for%20latest%20news&src=typd

Suggest a bitcoin exchange has been hacked.

They lead to this pastebin dump: http://pastebin.com/zxj24E6p

Which in turn provides a link to the front page of the "exchange" [link not posted - proceed with caution].

http://imgur.com/QIyHlGJ

A rather shoddy site, and strange, it isn't in the press, but I'm far too curious, surprise surprise, all of the compromised accounts contain funds, and not only that but the option to withdraw them is practically jumping out of the same page at me!

http://imgur.com/oNZ2OOk,pkvY0Q4#0

Clearly my luck is in, hackers have gained access to all user accounts and have benevolently opted to leave the money contained in them to anyone who wants it.

Immediately attempting to withdraw my new found wealth leads to a quick confirmation message "Transaction processed, please check wallet" (or something like that), followed by auto-redirect to a "blockchain" page.

http://imgur.com/oNZ2OOk,pkvY0Q4#1

The blockchain page is not a blockchain page (see URL), and so I assume the plan is to target blockchain users (only?), I am asked to enter my account id and password - and presumably my account gets emptied as soon as details are entered.

They also threw in a malicious file auto-download somewhere along the way (quarantined immediately) - so treat with extreme caution if investigating (I used a local client with NO wallet data anywhere near it, and with restricted permissions).

http://imgur.com/iJaJDcQ

PS - to pre-empt the inevitable accusations that I was attempting to steal these, it just isn't worth the argument, for everyone's sake please humor me with the assumption that I am honest.

7  Bitcoin / Bitcoin Discussion / Most interesting Bitcoin words / phrases / memes - little help? on: June 16, 2014, 11:17:19 PM
I'm pulling together a list of the most interesting words/phrases/memes to have sprung forth from the bitcoin community (and mostly within this forum)... please add those I have surely missed (esp with original sources)...

"Zhou-tongued"
Genesis:   https://bitcointalk.org/index.php?topic=49445.msg588749#msg588749
Credit:     Cypherdoc
Meaning:  To be wiped out, have a position liquidated, lose everything.
Example:  "shit, I went all in long at 5:1 leverage, then bad news came out of China and the spot dropped 200 points, wipeout, I've been completely fucking zhou tonged, my wife's gonna kill me"

"The new wealthy elite"
Genesis:   https://bitcointalk.org/index.php?topic=12156.0
Credit:     Atlas
Meaning:  Literal. Tongue in cheek reference to the gains some early bitcoin holders may experience.
Example:  https://www.youtube.com/watch?v=K2ku1A5Ox8U (2:22)

"Two more weeks"
Genesis:   https://bitcointalk.org/index.php?topic=119351.msg1314335#msg1314335
Credit:     Inaba / Josh (Butterfly Labs)
Meaning:  Now infamous phrase meaning anything but two weeks, read "We hope to ship in maybe two weeks" as "You may receive something vaguely related to your order in a year, or so". Born during the Butterfly Labs mining hardware shipping-delay-debacle.

"Bitcoin user not affected"
Genesis:   https://bitcointalk.org/index.php?topic=144152.0
Credit:     Zerohedge user community
Meaning:  The worlds financial systems may be falling apart, but all is good in the world of bitcoin, where normal problems don't apply.
Examples: Click link above)

"Goxxed"
Genesis:   ??
Credit:     ??
Meaning:  To experience a massive personal financial catastrophy, attributable in some form to mismanagement at Mt Gox.
Example:  Yesterday I had enough bitcoins to buy a car, then Gox was hit by a DDOS and went offline, my sell order was queued up but the trading engine was lagging 45 minutes behind, eventually my order was filled at the bottom of a 50% crash, now I can barely afford a bike - totally Goxxed"

"HODL" / "HODLING" / "SODLING"
Genesis:   https://bitcointalk.org/index.php?topic=375643
Credit:     GameKyuubi
Meaning:  Hold / Holding / Selling
Example:  "HODL!" https://bitcointalk.org/index.php?topic=375643.msg4023137#msg4023137

"To the moon!"
Genesis:   ??
Meaning:  Up, hopefully an exorbitant amount.
Credit:     ??
8  Economy / Reputation / Rastapool +1 on: November 29, 2013, 09:49:53 PM
I randomly sent Rastapool a bitcoin by accident (don't ask), all it took was a polite request and he sent it straight back.

@rastapool
Thanks man - figured you deserved some public praise for your honesty. Smiley
9  Bitcoin / Bitcoin Discussion / Help spread the word - and read something interesting! on: October 23, 2013, 06:53:57 PM

So here's the deal, I work for Deloitte and I love Bitcoin.

I have been trying to raise the profile of Bitcoin within the company for a while but for a global consultancy firm that actually works with most of today's largest banks, and which typically targets established market opportunities that offer a low risk profile - I gotta be honest it's a hard sell!

Anyway - I've finally had an article approved for the Deloitte public blog, if I can drum up enough interest I might be able to convince the powers that be to let me write a white paper on Bitcoin, which in turn just might lead to a conversation happening between two people important enough to change the way a large organisation thinks about (or even uses) Bitcoin.  I think that would be a good thing.

My ask is this:

1. Read the blog: it's short, and you might even like it!

2. SHARE IT using the buttons on the page

It is the SHARES that are measured, not the views, there is a quarterly in-house scoreboard and if I can top that list we'll be getting somewhere.

http://blogs.deloitte.co.uk/customer/2013/10/bitcoin-currency-20.html?utm_source=email&utm_medium=social_media&utm_content=email1&utm_campaign=email_cus_to_bitcoin_virtual_currency

I can't promise much in return, no children on the way any time soon but a possible cat on the horizon, if i can get 1000 shares i will name the cat Bitcoin.

Thanks for your time
10  Bitcoin / Bitcoin Discussion / ebay on: September 30, 2013, 09:20:24 PM
This is a few days old and is by no means revelatory, but the following is a short excerpt from the transcript of a presentation (followed by Q&A) with Tom Hudson (eBay Inc. - VP Investor Relations) at the CLSA Investors Forum - 24th Sep 2013.


Question: Going back to the transaction medium, how do you see the rise of some virtual currencies like even bitcoin or QQ currencies, or something like that? How do you see the trend going forward for this kind of electronic currencies?

"Yes, the reality is something like bitcoin or what have you, to be determined what happens with something like that. It's clear that the monetary systems -- we can potentially enable that source of funding on PayPal. I mean the reality is PayPal is used to fund Facebook credits, as an example. So we can certainly participate in that as a funding mechanism. Where they grow? I don't know. I don't want to speculate.

The reality is what I know about the financial system is that regulation is only moving in one direction. And it appears the world is getting more complicated and regulatory burden is actually rising. I think that creates higher hurdles for new business models.

Is there opportunity for something like a virtual currency like a bitcoin? I'm not sure. I don't want to speculate."

Question: Do you see any opportunities for eBay to accept this kind of transaction medium?

"The reality is potentially; but obviously you need to then be able to convert that medium to cash.

Take something like a bitcoin, we have seen competitors on the payment side actually have challenges and assets seized as a result of that, because it's operating outside of the financial system. So as an entity that's cooperative with the regulatory in terms of the financial environments, the reality is we are going to operate within the parameters. And if something changes and it becomes more accepted by the powers that be, then expect eBay to potentially move."
11  Economy / Trading Discussion / Ripple account connection map visualiser - URL needed on: April 22, 2013, 08:55:23 PM
I was browsing yesterday and found a very cool site which visually mapped out connected ripple addresses, and also displayed balance info by currency, as well as recent transaction history and open trade book orders for each address.  It was an interactive map, clicking into a node opened up the further connections of that node etc...

Today - I cannot find it for the life of me, anyone know it?

Any help appreciated...
12  Economy / Service Discussion / *Unofficial* ICBIT (BTC Futures Trading) - Help & FAQ's on: April 01, 2013, 08:17:49 PM
This thread is intended to support and mutually benefit the ICBIT user community, I'll try (edit: failing miserably) to keep up to date as poss - corrections or additional info/clarifications welcome.

UPDATE - 19/07/2014 - semi-official training guide available.

There is a nice trading guide called ICBIT Futures for Dummies. Check it out.

INTRODUCTION TO ICBIT FUTURES TRADING

https://icbit.se/

You want to hedge, arbitrage, or simply open a leveraged position against BTC price changes.  ICBIT offers leveraged trades through "futures" contracts, which are exchanged as a quantity of units between buyers and sellers.

Update: there is now an official rules page: https://icbit.se/rules

CONTRACT VALUE

https://icbit.se/BUH4 (example contract spec)

Each contract unit represents $10 worth of BTC at the specified price in $, so:

   > 1 unit at a trade price of $100 represents $10 worth of BTC, or 0.1 BTC in contract value.
   > 100 units at a trade price of $100 represents $1000 worth of BTC, or 10BTC in contract value.

The current trade value of each open futures instrument is not pegged to the underlying spot price, but is instead based on speculation as to what the final settlement value will be.  For this reason it is not guaranteed/expected to rise and fall as the spot price does.  Final settlement value is determined on listed the day of settlement for each instrument (currently 14th Apr, 14th Jun and 16th Sep), and the final settlement value is the 24 hour volume weighted average price (VWAP) from the largest exchange at the time of the settlement (i.e. 20:00 UTC).


OPENING A POSITION

Use the Buy/Sell buttons if you want to place an order with specific price conditions, if no corresponding offers exist at the specified price, then the order will enter the order book and become visible to others as an active bid/ask, if another user places an order which meets the specified price, the order will be filled and contract positions activated.

Use the Buy/Sell at Market button if you simply want to purchase at the most favorable currently available price.

To open a position, the following key fields must be populated.

  • Quantity  = The number of $10 chunks of Bitcoin you want to bet on.
  • Price       = The price you are prepared to buy/sell at.
  • Amount   = Calculated field displaying the amount of underlying BTC you are effectively betting on (Quantity * 10 / Price).
  • Margin    = Calculated field displaying the amount in BTC which must be "reserved" in the account to cover any potential loss incurred against the position (15% I believe).

CLEARING

The nature of the contracts is such that ongoing profit or loss against open contracts is re-distributed twice a day (08:00 and 20:00 UTC / GMT) in a system wide clearing process (rather than only being realised when a position is closed).

During Clearing all contract positions are evaluated and the latest trade price is used to determine the relative gain loss between the buyer and seller of each open contract. This difference (variance) is then transferred from the loser to the gainer, the contract remains active and will be re-evaluated at the next clearing session.

So if trade prices increase from 100 to 110, then the variance will be ((100*10)/100)-(100*10/110) = 10 - 9.09 = 0.91.  
     > Prior to clearing, the sellers account would show an unrealised loss of 0.91BTC, and the buyer +0.91BTC.
     > At clearing the loss of 0.91 would be deducted from the sellers account, and credited to the buyers account.  
     > After clearing:
               > "Unrealised P/L" balance reverts to 0 for both buyer and seller.
               > "Execution Price" for the open position is reset to the trade price upon which the variance adjustment was made.
               > "Margin" will also be adjusted (again, not sure of the precise margin calculation).

So, open a position of 100 units at around $100 and sell after a rise/fall of say 10 bucks, you are looking at just under 1BTC profit/loss (excluding fees).


RANGE

Another feature of the contract format is the use of trading range controls, an upper and lower limit on each instrument beyond which trading cannot occur within the current (12hr) session.  The range for the session is set during clearing based on the variable weighted average price (VWAP) price plus or minus 10% (edit: some newer instruments have wider range boundaries), so if the last trade price was 100 at clearing, the range for the following session will be set to 90 - 110.

Range boundaries are a safety feature to protect market participants from exceptional price swings in the underlying spot market, and limits risk exposure to traders (e.g. during intraday spikes/dips), given Bitcoin price volatility it is not unusual to see prices reaching upper/lower range limits, resulting at times in cessation of trade as no-one is prepared to buy/sell within session range threshold.

FEES

Each trading instrument will operate one of two fee models:
  • Lower transaction fees, but a twice-daily holding fee per contract applied at clearing (designed to encourage day-trading)
  • Higher per-transaction fees, but no holding fees (designed to support longer term trades)

Per transaction fees are calculated in BTC and are chargeable at the point of contract purchase/sale, therefore each position will incur fees twice (open and close).  Fees are charged according to the quantity of contracts being bought/sold, so whilst the fee is not displayed prior to purchase, it can be calculated by multiplying the quantity by the fee (and double if you also need to consider closure fees).

Actual fees are listed on the instrument reference pages (e.g. https://icbit.se/BUH4) and vary per instrument, usually with lower fees on contracts which are furthest form settlement.

Update 01/04/13: Fee discounts based on trade volume - fee discounts are now applied based on trading volumes, so if you trade a lot your fees will be lower - as outlined here: https://bitcointalk.org/index.php?topic=50817.msg1717445#msg1717445

MARGIN CALLS AND FORCED LIQUIDATION

https://icbit.se/margincall

Already spelled out pretty well on the ICBIT site, but many people still ask this, so here is the text:

"Every user's balance is continually checked by the trading engine if that user has any open positions. Margin call (forced close) is issued when his balance (actual money in the account plus total variation margin) is less than or equal to 75% of the total maintenance (initial) margin necessary to keep the positions.

If there are no respective bids/asks in the order book, the worst case scenario begins. The trading engine will go through users holding counter positions and forcibly close them by such a price that the user's balance who has the loss never goes negative."

API

https://icbit.se/api

There is an API available which offers full access to order book info, as well as order execution capabilities.  Personally I think the specs page could be improved through the inclusion of some additional specific worked examples, as well as instructions for the configuration of a very simple user control interface (excel/vba would be a start)... submissions welcome!

edit: example code here http://captainbodgit.blogspot.co.uk/2013/04/exploring-icbit-bitcoin-exchange-api.html


BUGS, HOT ISSUES

[NOW CLOSED] 1. Unscheduled clearing.
There is currently some controversy surrounding the use of unscheduled clearing sessions.  These appear to be run as exceptional events when large variations in BTC/USD spot price occur, and form part of a risk management strategy used to limit ICBIT's potential exposure to loss where over-leveraged contract losses can exceed the available account balances before any forced position closure has occurred.

There have been several instances of unscheduled clearing resulting in trading range increase/reduction, and subsequent forced closure of positions resulting in trading losses to individuals, prompting heated discussion of the legitimacy of such clearing.

Solution agreed and implemented (10/04/13): Fireball has confirmed ICBIT will now operate two daily clearing sessions, 20:00 and 08:00 UTC, and ad-hoc clearing sessions should no longer take place.

[NOW CLOSED] 2. Range Manipulation during the clearing process.

Each day during clearing the trading range for the following session is adjusted for each instrument, previously the adjustment is based on the price of the last single trade prior to clearing.  As a result, there were frequent attempts to influence the adjustment by shooting low/high orders in at the last second before clearing.  Range adjustment manipulation is attempted as a means of limiting losses and maximising the potential for profit during the following trading session, it can also result in forced closure of otherwise profitable trading positions, and has resulted in much heated discussion.

Solution implemented (December 2013): Range and variance adjustment calculations during clearing are now based on a new Volume Weighted Average Price, which should resolve the problem.
Target Fix Date: TBC

3. Forced closure of "winning" contract positions.  

Because ICBIT does not assume the counterparty risk for futures contracts being traded, gains must come directly from counterparty contract holders.  So if you buy a contract, and BTC rises, your profit must come from the loss of a corresponding seller.  In extreme market scenarios, those on the negative side of a contract will decide not to replenish a heavily depleted margin (and are perfectly entitled to do so).  Under normal conditions such contracts will then be forced back onto the market and transferred to a new seller at the best offered market price, however in the event that no other sellers exist, there is no way to continue maintain the contract obligation to pay profit to the gaining party, so contracts are force-closed at the "optimal" price (which essentially means the best possible price for the "gaining" side).

Because market price gaps can cause a contract loss to exceed both available margin, and the entire available account balance (if low enough), it is possible that already "realised" profit against an open contract can be reversed at the point of closure.
13  Bitcoin / Development & Technical Discussion / Forking scenario - when border connections are closed on: March 29, 2013, 10:26:00 PM
Scenario:  Bitcoin has been widely and globally adopted as the primary trade currency.  But it didn't solve everything, and somewhere a country in the midst of some tumultuous situation is either voluntarily or forcibly severed from the wider internet (easier said than done, but let's assume it is possible).

Does this result in a forked blockchain within which all coins can effectively be spent twice (once in each zone)?

Assuming forks could eventually be re-merged with the larger overriding the smaller, am I correct that double-spent coins on the smaller fork would be invalidated, with recipients incurring the losses as received coins disappear?

How would/will such a scenario be managed?  

I'm sure this scenario will have already been raised so apologies if duplicating.
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