I've read the white paper of Monero(CryptoNote v2.0) and a problem confuses me.

This paper says that when Alice sends coin to Bob, she uses P = Hs(rA)G + B as a destination key and packs value R = rG "somewhere" into the Tx.

Since Bob needs R for checking whether this transaction goes to himself. Where can I find this R = rG in the public Monero blockchain data?

Or maybe the payment ID is actually this R?

up vote 3 down vote accepted

The transaction public key, R, is in the tx_extra part of the transaction data structure. If you look at a block explorer, you'll see the transaction public key listed, e.g. it is e90bea66d774232033ef86684f17e756641dc7ba11bd23b7c3605d8387f2cf3c for this transaction: https://xmrchain.net/tx/a1ebbf1c50665e8ccf26d920b1df9e81ab7ffd8edec52c83709b4582656daa2b

The tx_extra data structure is defined here: https://cryptonote.org/cns/cns005.txt

The payment ID also happens to be communicated in the tx_extra, but is entirely unrelated and is optional for each transaction.

  • Thank you so much! The data showed in the blockchain is already clear enough. – manich Apr 18 at 14:29

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