stjohn_piano 2020-09-12 no Parts - Description - Assets - Notes - Recipe - Examples Description This recipe describes a method of looking up the unspent outputs associated with a Bitcoin address. The unspent outputs can be used: - to calculate the balance of the address. - as inputs to a new Bitcoin transaction. This version of the recipe relies on a feature of a particular block explorer that automates most of the previous version. Previous version of this recipe: article Recipe_for_looking_up_the_unspent_outputs_in_a_Bitcoin_address edgecase 175 Recipe for looking up the unspent outputs in a Bitcoin address Assets Asset: A tool that queries blockchain.info for the list of unspent outputs in an address and re-formats the result. asset get_unspent_outputs_in_address.py get_unspent_outputs_in_address.py 181364f7ac734b5aef7b1554993543e2fed108d789a2ff2c208ab86a68f53175 Notes Bitcoin is stored in a Bitcoin address. An address holds "unspent outputs", which have been created by previous Bitcoin transactions. (The sum of the values in the unspent outputs) = (the amount of bitcoin that is held in the address). Any unspent output used as an input in a transaction becomes "spent". Recipe Block explorers usually: - allow a user to look up an address and see a list of all related transactions. - look up a transaction and get information about its inputs and outputs. These two features can be used to derive the list of unspent outputs in an address. In the article Recipe_for_looking_up_the_unspent_outputs_in_a_Bitcoin_address edgecase 175 previous version of this recipe , this process was manual. In this version, we rely on a feature of the block explorer hyperlink http://blockchain.info blockchain.info . This block explorer tracks the unspent outputs stored in each address and makes them available for querying at this URL: http://blockchain.info/unspent?active={ADDRESS} 1) Prerequisite: Python 2.7.x. The code in this recipe has been run successfully under Python 2.7.12. 2) Scroll to the Assets section of this recipe. Download get_unspent_outputs_in_address.py. 3) Commands: Guidance: python get_unspent_outputs_in_address.py --help Use: python get_unspent_outputs_in_address.py --address {ADDRESS} Example: python get_unspent_outputs_in_address.py --address 12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP Examples This recipe was written during the previous project article Creating_and_signing_a_standard_Bitcoin_transaction_with_two_inputs_and_two_outputs edgecase 173 Creating and signing a standard Bitcoin transaction with two inputs and two outputs , so I was able to test it while some of the test addresses contained unspent outputs. Look up the unspent outputs in address A1: 1BB66Gx4833uKx8Lo2k8Mt4TRk42WTr7cZ Browse to: hyperlink http://blockchain.info/unspent?active=1BB66Gx4833uKx8Lo2k8Mt4TRk42WTr7cZ blockchain.info/unspent?active=1BB66Gx4833uKx8Lo2k8Mt4TRk42WTr7cZ Result: No free outputs to spend Look up the unspent outputs in address A2: 12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP Browse to: hyperlink http://blockchain.info/unspent?active=12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP blockchain.info/unspent?active=12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP Result: {"notice":"","unspent_outputs":[{"tx_hash":"ea1b9db39c6fd5df377e381a896ddb47da4c3c23faf80fe2da9b13014c055f58","tx_hash_big_endian":"585f054c01139bdae20ff8fa233c4cda47db6d891a387e37dfd56f9cb39d1bea","tx_output_n":0,"script":"76a91410de69df99d4b834ee6f2bd1466edab556beb7d688ac","value":474300,"value_hex":"073cbc","confirmations":395,"tx_index":0}]} This is the information we want, but to be useful it needs to be reformatted a bit. This block explorer uses these terms: - "tx_hash_big_endian" (txid) - "tx_output_n" (previous_output_index) - "value" (satoshi_value) The tool get_unspent_outputs_in_address.py queries the URL for a specified address and re-formats the result to be more readable. stjohn@judgement:work$ python get_unspent_outputs_in_address.py --help usage: get_unspent_outputs_in_address.py [-h] -a ADDRESS A command-line tool that looks up the Unspent Transaction Outputs (UTXOs) in a particular Bitcoin address. It queries blockchain.info. It ignores unspent outputs that have less than 6 confirmations. optional arguments: -h, --help show this help message and exit -a ADDRESS, --address ADDRESS Address to look up stjohn@judgement:work$ python get_unspent_outputs_in_address.py --address 1BB66Gx4833uKx8Lo2k8Mt4TRk42WTr7cZ This address has 0 unspent outputs. Its balance is therefore 0 satoshi (0.00000000 bitcoin). stjohn@judgement:work$ python get_unspent_outputs_in_address.py --address 12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP address: 12YCFdpsRDvEHNcj5rsmvJ5G2XXkW1icJP balance (satoshi): 474300 balance (bitcoin): 0.00474300 - unspent output 0: -- txid: 585f054c01139bdae20ff8fa233c4cda47db6d891a387e37dfd56f9cb39d1bea -- previous_output_index: 0 -- satoshi_value: 474300 -- bitcoin_value: 0.00474300 At this point in these examples, the previous project has ended. I've made a few tweaks in the code. I'll test the tool on the final address from the previous project. stjohn@judgement:work$ python get_unspent_outputs_in_address.py -a 1NBXXLc7443x5KFw7k5jbnHBwM1CNGw6ka address: 1NBXXLc7443x5KFw7k5jbnHBwM1CNGw6ka balance (satoshi): 6385539 balance (bitcoin): 0.06385539 - unspent output 0: -- txid: 961be73009cba0e361f8dd41c82aeb584167134f63bec08d54f77aca5d284de2 -- previous_output_index: 10 -- satoshi_value: 210000 -- bitcoin_value: 0.00210000 - unspent output 1: -- txid: cf0789ccbd8234cbfd522e11f4552363e2e928323b6f41ccf0f58a3a796f42e9 -- previous_output_index: 27 -- satoshi_value: 5307339 -- bitcoin_value: 0.05307339 - unspent output 2: -- txid: aad6d03ab13203ee7bdfb7e747c5aaef5a60f23c46b87e744176ad7955bd8bb6 -- previous_output_index: 0 -- satoshi_value: 868200 -- bitcoin_value: 0.00868200 Let's test that the bitcoin values in the outputs all add up to the balance: stjohn@judgement:work$ python Python 2.7.12 (default, Jul 21 2020, 15:19:50) [GCC 5.4.0 20160609] on linux2 Type "help", "copyright", "credits" or "license" for more information. \>\>\> values = ['0.00210000', '0.05307339', '0.00868200'] \>\>\> from decimal import Decimal \>\>\> values = [Decimal(v) for v in values] \>\>\> balance = Decimal('0.06385539') \>\>\> sum(values) == balance True \>\>\> sum(values) Decimal('0.06385539') Yup, works. On a block explorer, the balance is confirmed to be: 0.06385539 bitcoin Good. That's the end of this project.