[ZIP 307] Light Client Protocol for Payment Detection #226

str4d · 2019-04-11T22:08:15Z

Client operations

Client updates

rex4539 · 2019-04-12T04:36:17Z

zip-XXX-light-payment-detection.rst

+==========
+
+Currently a client that wishes to send or receive shielded payments must be a full node
+participanting in the Zcash network. This requires an amount of available bandwidth,


Suggested change

participanting in the Zcash network. This requires an amount of available bandwidth,

participating in the Zcash network. This requires an amount of available bandwidth,

rex4539 · 2019-04-12T04:37:12Z

zip-XXX-light-payment-detection.rst

+is, the proxy should not learn which transactions (received from the blockchain) are
+addressed to a given light wallet. If we further assume network privacy (via Tor or
+similar), the proxy should not be able to link different connections or queries as
+deriving from the the same wallet.


Suggested change

deriving from the the same wallet.

deriving from the same wallet.

rex4539 · 2019-04-12T04:38:17Z

zip-XXX-light-payment-detection.rst

+
+A key observation in this protocol is that the current zcashd encrypted field is several
+hundred bytes long, due to the inclusion of a transaction “memo”. The need to download
+this entire field imposes a substantial bandwidth cost on each light wallets, which may be


Typo: "on each light wallets"

Suggested change

this entire field imposes a substantial bandwidth cost on each light wallets, which may be

this entire field imposes a substantial bandwidth cost on each light wallet instance, which may be

rex4539 · 2019-04-12T04:38:40Z

zip-XXX-light-payment-detection.rst

+this entire field imposes a substantial bandwidth cost on each light wallets, which may be
+a limited mobile device on a restricted-bandwidth plan. While more efficient techniques
+can be developed in the future, for the moment we propose ignoring the memo field during
+payment detection. Futhermore, we can also ignore any information that is not directly


Suggested change

payment detection. Futhermore, we can also ignore any information that is not directly

payment detection. Furthermore, we can also ignore any information that is not directly

rex4539 · 2019-04-12T04:42:05Z

zip-XXX-light-payment-detection.rst

+========================
+
+This proposal is supported by a set of libraries and reference code made available by the
+Zcash Company.


Zcash Company -> Electric Coin Company

Suggested change

Zcash Company.

Electric Coin Company.

rex4539 · 2019-04-12T04:44:57Z

zip-XXX-light-payment-detection.rst

@@ -0,0 +1,612 @@
+::
+
+  ZIP: XXX


ZIP: XXX -> ZIP: 307

Suggested change

ZIP: XXX

ZIP: 307

acityinohio · 2019-04-30T14:46:00Z

Concept ACK

daira · 2019-05-20T09:54:54Z

Concept ACK. This looks like it's not ready for merge yet (missing references, TODOs that should be resolved).

daira · 2019-06-04T11:54:04Z

zip-XXX-light-payment-detection.rst

+
+- let sharedSecret = KA\ :sup:`Sapling`\ .Agree(*ivk*, *epk*)
+- let K\ :sup:`enc` = KDF\ :sup:`Sapling`\ (sharedSecret, *epk*)
+- let P\ :sup:`enc` = ChaCha20.Decrypt\ :sub:`K^enc`\ (*ciphertext*)


This is not specified precisely enough. The intent is to perform the decryption as it would be performed by IETF_AEAD_CHACHA20_POLY1305, but this involves decrypting with the block counter starting from 1. Since ChaCha20 is not defined at all, it's not clear that the block counter should start with 1.

I suggest adding a definition like this:

Let ChaCha20.Decrypt\ :sub:`K^enc`\ (*initialCounter*, *ciphertext*) be the decryption of *ciphertext* with key K^enc, initial counter value *initialCounter*, and all-zero nonce, as specified in section 2.4 of [#RFC7539]_.

and then use ChaCha20.Decrypt_K^enc(1, ciphertext).

daira · 2020-06-29T16:16:29Z

Published at https://zips.z.cash/zip-0307 .

gtank and others added 10 commits October 2, 2018 16:54

zipWIP: light payment draft

a1ab41d

zipWIP: add diagrams and tables

abf1619

zipXXX: add description of API

f5ae360

Client operations

2241345

Merge pull request #1 from str4d/light_payment_detection

fb4c871

Client operations

Reformat client-server interaction and block privacy sections

271037a

Describe interaction changes when importing a seed

9aeec8c

Expand note witness handling

2f0da1b

Block header validation

52f165c

Merge pull request #2 from str4d/client-updates

996cdd9

Client updates

str4d added the ZIP number assigned label Apr 11, 2019

rex4539 suggested changes Apr 12, 2019

View reviewed changes

rex4539 reviewed Apr 12, 2019

View reviewed changes

acityinohio added the review needed label Apr 16, 2019

acityinohio removed the review needed label Apr 30, 2019

daira mentioned this pull request May 20, 2019

Faster light client protocol by making few bytes of shielded addresses public #233

Open

daira assigned gtank May 20, 2019

daira reviewed Jun 4, 2019

View reviewed changes

daira force-pushed the master branch 10 times, most recently from fff4d5c to f5af3a3 Compare August 6, 2019 00:56

daira force-pushed the master branch 5 times, most recently from 4864dde to c333fe2 Compare August 6, 2019 18:58

daira force-pushed the master branch from 0aef8ce to 2815bee Compare August 24, 2019 13:29

daira force-pushed the master branch from 4d44dfa to 95240be Compare April 27, 2020 14:57

daira force-pushed the master branch from bfb932c to 03932d2 Compare June 26, 2020 20:25

daira closed this Jun 29, 2020

r3ld3v added this to the Core Sprint 2020-25 milestone Jun 29, 2020

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[ZIP 307] Light Client Protocol for Payment Detection #226

[ZIP 307] Light Client Protocol for Payment Detection #226

str4d commented Apr 11, 2019 •

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rex4539 Apr 12, 2019 •

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daira commented May 20, 2019

daira Jun 4, 2019

daira commented Jun 29, 2020 •

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	participanting in the Zcash network. This requires an amount of available bandwidth,
	participating in the Zcash network. This requires an amount of available bandwidth,

	deriving from the the same wallet.
	deriving from the same wallet.

	this entire field imposes a substantial bandwidth cost on each light wallets, which may be
	this entire field imposes a substantial bandwidth cost on each light wallet instance, which may be

	payment detection. Futhermore, we can also ignore any information that is not directly
	payment detection. Furthermore, we can also ignore any information that is not directly

[ZIP 307] Light Client Protocol for Payment Detection #226

[ZIP 307] Light Client Protocol for Payment Detection #226

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