<p>Interesting find! </p>

<blockquote>
  <p>when it happen?</p>
</blockquote>

<p>2012-03-09 19:20:14, according to blockchain.info.</p>

<blockquote>
  <p>why it happen?</p>
</blockquote>

<p>It seems that someone was using a faulty signing process. The R value will only be the same if the same <code>k</code> value is chosen during the <a href="http://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm" rel="nofollow noreferrer">ECDSA</a> signing process. </p>

<blockquote>
  <p>how it Happen?</p>
</blockquote>

<p>Hard to say, as the person who made that transaction is probably hard to find. It could have been done by faulty software, or it could have been done intentionally to see if anyone would recognize it and steal the coins (since <a href="https://bitcoin.stackexchange.com/questions/35848/recovering-private-key-when-someone-uses-the-same-k-twice-in-ecdsa-signatures">using the same k value twice on different signatures leaks the private key</a>).</p>

CC BY-SA 3.0
2015-05-27T16:56:10.000Z
There have been a few cases of Bitcoin wallets using flawed random number generators...
Nate Eldredge
CC BY-SA 3.0
2015-05-28T10:18:34.777Z
@NateEldredge The Android *bouncycastle* (Java library)  flaw surfaced in Aug 2013. Nils Schneider first IDd the issue. This Tx is actually mine. It was made using the Blockchain.Info app on Android. The funds weren't stolen, luckily
Wizard Of Ozzie
CC BY-SA 3.0
2015-05-27T16:09:25.253Z
2015-05-27T16:09:25.253Z
2017-04-13T12:47:36.647Z
morsecoder
<p><a href="https://blockchain.info/tx/9ec4bc49e828d924af1d1029cacf709431abbde46d59554b62bc270e3b29c4b1" rel="nofollow">Blockchain transaction id</a></p>

<pre><code>30440220d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad1022044e1ff2dfd8102cf7a47c21d5c9fd5701610d04953c6836596b4fe9dd2f53e3e01 04dbd0c61532279cf72981c3584fc32216e0127699635c2789f549e0730c059b81ae133016a69c21e23f1859a95f06d52b7bf149a8f2fe4e8535c8a829b449c5ff

30440220d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad102209a5f1c75e461d7ceb1cf3cab9013eb2dc85b6d0da8c3c6e27e3a5a5b3faa5bab01 04dbd0c61532279cf72981c3584fc32216e0127699635c2789f549e0730c059b81ae133016a69c21e23f1859a95f06d52b7bf149a8f2fe4e8535c8a829b449c5ff
</code></pre>

<p>Identical R value d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad1</p>

<p>When did it happen?</p>

<p>Why did it happen?</p>

<p>How did it happen?</p>

<transactions><signature><hash><ecdsa>
bitcoin two identical R
Prabu r
# bitcoin two identical R

(Asked by: username_0 on 2015-05-27)

[Blockchain transaction id](https://blockchain.info/tx/9ec4bc49e828d924af1d1029cacf709431abbde46d59554b62bc270e3b29c4b1)

```
30440220d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad1022044e1ff2dfd8102cf7a47c21d5c9fd5701610d04953c6836596b4fe9dd2f53e3e01 04dbd0c61532279cf72981c3584fc32216e0127699635c2789f549e0730c059b81ae133016a69c21e23f1859a95f06d52b7bf149a8f2fe4e8535c8a829b449c5ff

30440220d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad102209a5f1c75e461d7ceb1cf3cab9013eb2dc85b6d0da8c3c6e27e3a5a5b3faa5bab01 04dbd0c61532279cf72981c3584fc32216e0127699635c2789f549e0730c059b81ae133016a69c21e23f1859a95f06d52b7bf149a8f2fe4e8535c8a829b449c5ff

```

Identical R value d47ce4c025c35ec440bc81d99834a624875161a26bf56ef7fdc0f5d52f843ad1

When did it happen?

Why did it happen?

How did it happen?

**Tags:** transactions, signature, hash, ecdsa


---

## 1 answers

### Answer by username_1 on 2015-05-27. Score: 2

Interesting find!

> when it happen?

2012-03-09 19:20:14, according to blockchain.info.

> why it happen?

It seems that someone was using a faulty signing process. The R value will only be the same if the same `k` value is chosen during the [ECDSA](http://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm) signing process.

> how it Happen?

Hard to say, as the person who made that transaction is probably hard to find. It could have been done by faulty software, or it could have been done intentionally to see if anyone would recognize it and steal the coins (since [using the same k value twice on different signatures leaks the private key](https://bitcoin.stackexchange.com/questions/35848/recovering-private-key-when-someone-uses-the-same-k-twice-in-ecdsa-signatures)).

> **Comments:**
> **username_2**: There have been a few cases of Bitcoin wallets using flawed random number generators...  
> **username_3**: @username_2 The Android *bouncycastle* (Java library)  flaw surfaced in Aug 2013. Nils Schneider first IDd the issue. This Tx is actually mine. It was made using the Blockchain.Info app on Android. The funds weren't stolen, luckily  

---

