<p>The term is used specifically in Monero's ring signature based spending scheme.</p>

<p>Monero transactions do not exactly specify which previous outputs are being spent. Instead, a list of alternative inputs is provided (consisting of the real one, and a number of chaff coins). A ring signature is then used to prove authority to spend from the real one, without revealing which one that is.</p>

<p>This has the advantage of obscuring the transaction graph significantly. It also comes at a very high price - as it means validation cannot use a UTXO set based approach, and must instead maintain an ever-growing database of spent coins to prevent double spending.</p>

CC BY-SA 3.0
2017-10-02T16:48:18.683Z
2017-10-02T16:48:18.683Z
Pieter Wuille
<p>I read in several paper about "chaff coins" but I could not find a clear definition for this phenomenon. Does it refer to a specific coin? Is there any "formal" definition for that ? </p>

<p>Reference: <a href="https://arxiv.org/abs/1704.04299" rel="nofollow noreferrer">https://arxiv.org/abs/1704.04299</a></p>

CC BY-SA 3.0
2017-10-01T14:50:12.050Z
It refers to the altcoins that no one uses.
MCCCS
CC BY-SA 3.0
2017-10-01T14:55:03.697Z
@MCCCS: Please don't use comments to answer the question. :)
Murch
CC BY-SA 3.0
2017-10-01T15:35:21.533Z
@MCCCS, Would you explain more about that ? e.g. which altcoin called as a chaff coin ?
Questioner
CC BY-SA 3.0
2017-10-01T16:04:44.033Z
There are over 900 altcoins in this list (https://coinmarketcap.com), and only less than 100 of them are serious money. Others are junk.
MCCCS
CC BY-SA 3.0
2017-10-01T20:50:20.687Z
Are you talking about this paper? https://arxiv.org/abs/1704.04299
Nick ODell
CC BY-SA 3.0
2017-10-02T12:03:29.437Z
@ Nick ODell, Yes, of course, Do you know what does it mean exactly?
Questioner
<terminology><monero><confidential-transactions>
what are chaff coins in cryptocurrency?
Questioner
# what are chaff coins in cryptocurrency?

(Asked by: username_0 on 2017-10-01)

I read in several paper about "chaff coins" but I could not find a clear definition for this phenomenon. Does it refer to a specific coin? Is there any "formal" definition for that ?

Reference: <https://arxiv.org/abs/1704.04299>

**Tags:** terminology, monero, confidential-transactions

> **Comments:**
> **username_1**: It refers to the altcoins that no one uses.  
> **username_2**: @username_1: Please don't use comments to answer the question. :)  
> **username_0**: @username_1, Would you explain more about that ? e.g. which altcoin called as a chaff coin ?  
> **username_1**: There are over 900 altcoins in this list (https://coinmarketcap.com), and only less than 100 of them are serious money. Others are junk.  
> **username_3**: Are you talking about this paper? https://arxiv.org/abs/1704.04299  
> **username_0**: @ username_3 username_3, Yes, of course, Do you know what does it mean exactly?  

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## 1 answers

### Answer by username_4 on 2017-10-02. Score: 3

The term is used specifically in Monero's ring signature based spending scheme.

Monero transactions do not exactly specify which previous outputs are being spent. Instead, a list of alternative inputs is provided (consisting of the real one, and a number of chaff coins). A ring signature is then used to prove authority to spend from the real one, without revealing which one that is.

This has the advantage of obscuring the transaction graph significantly. It also comes at a very high price - as it means validation cannot use a UTXO set based approach, and must instead maintain an ever-growing database of spent coins to prevent double spending.


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