diff options
Diffstat (limited to 'bip-0047.mediawiki')
| -rw-r--r-- | bip-0047.mediawiki | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/bip-0047.mediawiki b/bip-0047.mediawiki index bdac681..0720eb4 100644 --- a/bip-0047.mediawiki +++ b/bip-0047.mediawiki @@ -1,7 +1,7 @@ RECENT CHANGES: +* (17 Apr 2016) Clarify usage of outpoints in notification transactions * (18 Dec 2015) Update explanations to resolve FAQs * (12 Oct 2015) Revise blinding method for notification transactions -* (21 Sep 2015) Correct base58check version byte <pre> BIP: 47 @@ -119,6 +119,9 @@ It is assumed that Alice can easily obtain Bob's payment code via a suitable met * Payment code: an extended public key and associated metadata which is associated with a particular identity/account * Notification address: the P2PKH address associated with the 0<sup>th</sup> public key derived from a payment code * Notification transaction: a transaction which sends an output to a notification address which includes an embedded payment code +* Designated input: the first input in the notification transaction which exposes an secp256k1 pubkey in either its signature script, or in the redeem script or pubkey script of the output being spent +* Designated pubkey: the first secp256k1 pubkey pushed to the stack during script execution for the designated input +* Outpoint: the specific output of a previous transaction which is being spent. See the Reference section for the binary serialization ====Notification Transaction==== @@ -127,12 +130,12 @@ Prior to the first time Alice initiates a transaction to Bob, Alice MUST inform # Alice constructs a transaction which sends a small quantity of bitcoins to Bob's notification address (notification transaction) ## The inputs selected for this transaction MUST NOT be easily associated with Alice's notification address # Alice derives a unique shared secret using ECDH: -## Alice selects the private key corresponding to the first exposed public key, of the first pubkey-exposing input, of the transaction: <pre>a</pre> +## Alice selects the private key corresponding to the designated pubkey: <pre>a</pre> ## Alice selects the public key associated with Bob's notification address: <pre>B, where B = bG</pre> ## Alice calculates a secret point: <pre>S = aB</pre> ## Alice calculates a 64 byte blinding factor: <pre>s = HMAC-SHA512(x, o)</pre> ### "x" is the x value of the secret point -### "o" is the outpoint being spent by the first pubkey-exposing input of the transaction. +### "o" is the outpoint being spent by the designated input # Alice serializes her payment code in binary form. # Alice renders her payment code (P) unreadable to anyone except Bob: ## Replace the x value with x': <pre>x' = x XOR (first 32 bytes of s)</pre> @@ -143,12 +146,12 @@ Prior to the first time Alice initiates a transaction to Bob, Alice MUST inform # Bob watches for any transactions which create an output at his notification address. # When a transaction is received, the client examines it to determine if it contains a standard OP_RETURN output with an 80 byte payload (notification transactions). # If the first byte of the payload in a notification transaction is 0x01: -## Bob selects the first exposed public key, of the first pubkey-exposing input, of the transaction: <pre>A, where A = aG</pre> +## Bob selects the designated pubkey: <pre>A, where A = aG</pre> ## Bob selects the private key associated with his notification address: <pre>b</pre> ## Bob calculates a secret point: <pre>S = bA</pre> ## Bob calculates the binding factor: <pre>s = HMAC-SHA512(x, o)</pre> ### "x" is the x value of the secret point -### "o" is the outpoint being spent by the first pubkey-exposing input of the transaction. +### "o" is the outpoint being spent by the designated input. ## Bob interprets the 80 byte payload as a payment code, except: ### Replace the x value with x': <pre>x' = x XOR (first 32 bytes of s)</pre> ### Replace the chain code with c': <pre>c' = c XOR (last 32 bytes of s)</pre> @@ -300,7 +303,7 @@ In order to use Bitmessage notification, the recipient must have a Bitmessage cl * [[bip-0032.mediawiki|BIP32 - Hierarchical Deterministic Wallets]] * [[bip-0043.mediawiki|BIP43 - Purpose Field for Deterministic Wallets]] * [[bip-0044.mediawiki|BIP44 - Multi-Account Hierarchy for Deterministic Wallets]] -* [[https://bitcoin.org/en/glossary/outpoint|Outpoint]] +* [[https://bitcoin.org/en/developer-reference#outpoint|Outpoint]] * [[https://github.com/petertodd/dust-b-gone|dust-b-gone]] * [[https://en.bitcoin.it/wiki/Base58Check_encoding|Base58Check encoding]] * [[https://bitmessage.org/bitmessage.pdf|Bitmessage]] |