No. of confirmation through API

[upal]

May I know the no. of confirmations through API ? I was reading this and did not find no. of confirmations...

https://blockchain.info/rawtx/83c1172ce6c6ec998fc4f1b010a1335ce6516928fb9142d3046f9444cbdf2356

[upal]

any help ?

[DeathAndTaxes]

It is a little more complex than that using the low level API.

1) The API call you referenced includes block height & block hash.
2) You can then check if the block (by block hash) is in the MAIN CHAIN by checking the block.
3) Getting the most recent block would give you the # of confirmations (recent_block_height - tx_block_height = #confirmations).

Step #2 is important as the chain can fork and your tx can be in a block which is orphaned off the main chain.  In most cases an orphaned tx (a tx confirmed in an orphaned block) will also be confirmed in a block in the main chain but in the event of a double spend it won't.

Still honestly I would use bitcoind directly rather than add a trusted third party into a network which is trustless.  With bitcoind you can use waletnotify & blocknotify to create callback functions which will fire whenever there is a new tx or new block.

[upal]

Thank u so much for the explanation. Would u mind to say how do I accomplish Point 2 using API ? I mean I have got my tx block hash, but how do I check if it is part of the main chain ?

[DeathAndTaxes]

Thank u so much for the explanation. Would u mind to say how do I accomplish Point 2 using API ? I mean I have got my tx block hash, but how do I check if it is part of the main chain ?

Using blockchain.info API?
By looking for "mainchain" value in the rawblock RPC using the blockhash from step 1.

https://blockchain.info/rawblock/00000000000007d0f98d9edca880a6c124e25095712df8952e0439ac7409738a

{
   "hash":"00000000000007d0f98d9edca880a6c124e25095712df8952e0439ac7409738a",
   "ver":1,   
   "prev_block":"0000000000000a5d8e40fb83ef468e6d83d1bf5365a8dfad36c4271c4a68c7b5",
   "mrkl_root":"4850536df3c620972a07df5bd4896c61212776059ad6be4f6b583f9186bc98e9",
   "time":1322130562,
   "bits":437129626,
    "fee":2150000,
    "nonce":2984497136,
   "n_tx":99,
   "size":26700,
   "block_index":169706,
   "main_chain":true,
   "height":154594,
   "received_time":1322130562,
   "relayed_by":"127.0.0.1",
...

With blockchain.info the internals of their API are a blackbox so I wouldn't want to assume that however you can explicitly confirm that by
a) getting the blockhash of the tx (rawtx)
b) checking that block is still in the main chain (rawblock)
c) computing the confirmations as latestblock_height - txblock_height  (latestblock)

Combined that allows you to verify that the tx is in a block, that the block is in the main chain and has the required number of confirmations.

If you have the ability to run bitcoind (can be run without server knowing the decryption passphrase or even better with a watching wallet copy) you can get the same information easier and without having to trust a third party.   You can use the transaction and block callback to be notified when a tx is included in a block and when a block has found.  By checking the status of the tx you can confirm it is in the main chain (orphaned tx will show 0 confirms).

If you want an easier option and can't run bitcoind, blockchain.info also has a receive payments API.  Understand this isn't zero-trust as payments will be sent to an address which blockchain.info has the private key for and then forwarded on to an address you designate.  This means in theory funds could be stolen if blockchain.info is hacked or "hacked".  It does however provide an easier higher level API and the potential loss is limited to payments that haven't yet been forwarded to you.  Depending on your transaction value and risk tolerance this might be acceptable.  Do your own due diligence I haven't used or researched this API.
https://blockchain.info/api/api_receive

[upal]

But, in step 1, when I make a call to rawtx, I only get the block_height ...is not it ? Which one is the block_hash in this call ? e.g.

https://blockchain.info/rawtx/5bc9ed31d4cf09d31cf935cc9e2e4062a9f4cfc6fe48fec6d3961dcfc6e08515

{"block_height":154594,"time":1322130562,"inputs":[{}],"vout_sz":1,"relayed_by":"0.0.0.0","hash":"5bc9ed31d4cf09d31cf935cc9e2e4062a9f4cfc6fe48fec6d3961dcfc6e08515","vin_sz":1,"tx_index":2091476,"ver":1,"out":[{"n":0,"value":5002150000,"addr":"1AvVCRXzuBNTBR3UKjZNKGsGWjPqZnhX7H","tx_index":2091476,"spent":true,"type":0}],"size":135}

"block_height":154594

Which one is block hash ?


Thanks again for your response...

[DeathAndTaxes]

Sorry I looked quickly and assumed the rawtx call provided the block hash as well as the block height.

[upal]

Sorry I looked quickly and assumed the rawtx call provided the block hash as well as the block height.

Its OK. Would u mind to tell me if this "main_chain":true happens to the block as soon as the tx is created ? Once I have "main_chain":true, can it be converted to "main_chain":false at a later state when I have got a few confirmations ?