17 votes

What information is leaked if I reuse an address?

Fragments of the private key of that reused address are leaked. An attacker could find a bundle hash (via brute-forcing) that can be signed with the leaked fragments. Luckily for the user, the window ...
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15 votes
Accepted

What information is leaked if I reuse an address?

To expand on CFB's answer, because IOTA uses Lamport signatures, half of the private key is leaked each time. This halves the security level of the address (from 54 trytes of security to 27 trytes for ...
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  • 1,358
12 votes
Accepted

Address re-use and snapshot

You should never send iota to an address that was already spent. This will make it possible for an attacker to steal your iotas. This rule is uninfluenced by any snapshot. The problem after a ...
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11 votes
Accepted

From which address money is being sent if I have money on more than 1 address?

First of all, there seems to be a misconception in your question. If you spend 2 iotas from an address with 10 iotas, that address will not then contain 8 iotas, the address will actually be empty and ...
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  • 1,358
8 votes
Accepted

A receive address is made public for donations, how do I safely withdraw funds?

How can I safely withdraw the funds a second time ? Second withdraw will be less secure. The security decrease exponential with every withdraw. There is nothing you can do against that. How can I ...
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  • 5,344
8 votes
Accepted

How to provide an IOTA based service, considering the receiving address has to change on every withdrawal?

M2M Payments 2 Machines: Alice and Bob Alice wants to give 5 IOTAs to Bob Alice sends an address request to Bob: Depending on the kind of machines this can be achieved in various ways via http GET: ...
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  • 4,459
8 votes
Accepted

What is the difference between "double-spending" and "address-reuse"?

Every double-spending is an address reuse but not every address-reuse is a double-spending. Let's say you have an address with a balance of 100i Double Spend You send 100i from the address to ...
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  • 4,459
7 votes
Accepted

Does reattaching a transaction compromise my private key for the source address?

No. The data signed in a transaction don't include parent and branch transaction hash. So when you reattach a transaction the signature is unchanged. It means that the portion of the private key ...
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  • 5,344
7 votes

Can I be forced to reuse an address by confirming a transaction that is part of a double-spend attempt?

According to this answer to another question, I can just reattach my transaction again without signing it, so the answer is no. I cannot be forced to reuse my address for spending this way.
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  • 1,087
6 votes

Why are there no safeguards in place to prevent sending a transaction to a used-up address?

The "problem" is, anyone is free to send funds to any address they want, even if this address has been emptied before (the protocol is agnostic to the source & destination address). A partial ...
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  • 1,663
6 votes
Accepted

Does attaching an address reveal its private key?

No, because when you attach an address, a zero-value transaction is done to the address. I.e. it's an incoming transaction to the target address and doesn't reveal the private key.
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  • 5,344
5 votes
Accepted

Exchange Winternitz one-time signatures

Post-quantum cryptography is a fairly young field, and while there may be post-quantum signature schemes that are not one-time signatures, I don't know of any (feel free to correct me here). A method ...
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  • 7,254
5 votes

What information is leaked if I reuse an address?

With every spend a random 50% of the private key is exposed. The reason that it is a one-time signature follows from what a second spend can reveal: The overlap of the 2 random 50% reveals can be ...
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5 votes

What happens if I receive IOTAs at an address I've already spent from?

You should send as soon as possible all the IOTA from that specific address (say ADDRESS9X) to another address of yours from which you never sent (say ADDRESS9Y). If this transaction succeeds in being ...
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4 votes

A receive address is made public for donations, how do I safely withdraw funds?

As far as I know Lets say you were receiving donations on Address X, my recommendation is to not use this address till you REALLY need to withdraw from it. After you withdraw from address X, make ...
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4 votes

On average, what % of my private key is compromised on the first address re-use, and what exponential effect does it have on security?

Disclaimer: I'm still learning Iota specifications, so take this answer with a grain of salt We assume that you re-use your key for a transaction that is new and different from the previous (aka hash(...
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  • 241
4 votes
Accepted

Are all your iotas moved to the new address when pressing "generate new address" in the light wallet?

When you press the button "Generate new address", this is what happens: generate new private key from the seed generate address from the new private key send a 0-value transaction to the address ...
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  • 4,459
4 votes
Accepted

Mechanism used to Claim at risk addresses

The foundation has used snapshots in order to move at risk funds from vulnerable addresses to new addresses. A snapshot, currently, is completely manual, and is basically a database of addresses and ...
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  • 3,135
4 votes
Accepted

How is address reuse prevented in the current wallet implementation?

In iri 1.4.2 an API call wereAddressesSpentFrom was introduced. This (and later) iri versions come with a list of previously spent addresses bundled. When the API function is called, both the current ...
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  • 7,254
3 votes
Accepted

New transaction if the last transaction is still pending

When sending a transaction, and another transaction of the wallet is still pending, you will usually have to wait. In case your first transaction does not exactly use up the amount of your first few ...
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  • 7,254
3 votes
Accepted

How to properly move funds from Wallet A to Wallet B without being exposed to security risks?

Sergey, there should be no serious risk. Here is a step by step process: 1) On Wallet B, generate a new address. 2) Once it is generated, send that address to the computer with Wallet A, via email ...
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  • 3,135
3 votes

How to provide an IOTA based service, considering the receiving address has to change on every withdrawal?

Client ask to the service provider for a valid address. Service provider decide according it's own internal policy the address where this particular client can send funds (it can be a new one). The ...
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  • 5,344
3 votes
Accepted

Multi seeds or multi addresses for sensors

As https://iotasupport.com/how-addresses-are-used-in-IOTA.shtml explains: The generated addresses are part of a sequence of one time(!) keys generated from a single seed. Using multiple addresses of ...
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  • 146
3 votes
Accepted

Coordinator Address is Hard-Coded - Secure?

The coordinator uses Merkle tree based signature scheme which allows to sign multiple messages with the same public/private key pair. This Merkle tree contains 2^20 keys. That means that the ...
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  • 498
2 votes

A receive address is made public for donations, how do I safely withdraw funds?

For now, you need to make sure that you consider an address a temporary place to receive funds for the exact reason you bring up: You will be compromising your security by withdrawing from a static ...
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  • 3,135
2 votes

Multi seeds or multi addresses for sensors

Obviously, there are a lot of solutions to your problem but I think best practice would be to give each device it's own seed and additionally store all the seeds in a local database in your company so ...
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  • 4,459
2 votes

How does address reuse prevention affect scalability?

This is meant to be a temporary measure, until a better wallet comes along. Once everyone is using a "stateful" wallet that remembers the addresses used in the past and avoids their reuse, there will ...
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  • 435
2 votes
Accepted

Is part of the address private key revealed when the user reattaches a failed transaction?

You cannot get parts of the private key using reattachments. To understand why, let's see how signing works. First of all, there is an unsigned bundle consisting out of several transactins. To sign ...
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2 votes
Accepted

Adress reuse with zero value transactions

Zero value transactions don't need to be signed but you can sign them, either by mistake or by using a buggy library and in this case: it is unsafe to re-use the same address. I can't find the ...
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  • 5,344

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