On the left side of the transaction, the blockchain explorer shows Alice's bitcoin address as the "sender." In fact, this information is not in the transaction itself. When the blockchain explorer references the transaction it also references the previous transaction associated with the input and extracted the first output from that older transaction. Within that output is a locking script that locks the UTXO to Alice's public key hash (a P2PKH script). The blockchain explorer extracted the public key hash and encoded it using Base58Check encoding to produce and display the bitcoin address that represents that public key.
On the left side of the transaction, the blockchain explorer shows Alice's bitcoin address as the "sender." In fact, this information is not in the transaction itself. When the blockchain explorer references the transaction it also references the previous transaction associated with the input and extracts the first output from that older transaction. Within that output is a locking script that locks the UTXO to Alice's public key hash (a P2PKH script). The blockchain explorer extracted the public key hash and encoded it using Base58Check encoding to produce and display the bitcoin address that represents that public key.
Similarly, on the right side, the blockchain explorer shows the two outputs; the first to Bob's bitcoin address and the second to Alice's bitcoin address (as change). Once again, to create these bitcoin addresses, the blockchain explorer extracted the locking script from each output, recognized it as a P2PKH script, and extracted the public-key-hash from within. Finally, the blockchain explorer reencoded each public key hash with Base58Check to produce and display the bitcoin addresses.
Will Binns
3 years ago
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