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Bitcoin / Wallet software / Re: [ANN] Bither - simple&secure Bitcoin wallet.(Desktop v1.3.5 released)
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on: July 20, 2015, 03:02:16 AM
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Currently, we can not copy private key. Can you fix it? Also, dropped transactions are being re-broadcasted indefinitely. Please don't re-broadcast transaction, instead, show a warning when transaction is dropped.
Sorry for reply later. Clipboard is an public area for other app on your phone, so there is may be some bad app can stolen your private key when you copy it, so we think it is not safe enough. Drop transaction is only remove the transaction on your phone, it can not stop other peer to broadcast this transaction. So it may receive again from other peer, but this time it will not re-broadcast again. We will think about record the transaction is dropped, so when you receive the transaction it will show a mark. |
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3
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Bitcoin / Bitcoin Discussion / Re: Apple lists Bither among apps for Apple Watch on WWDC2015
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on: June 09, 2015, 06:33:42 AM
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Apple still not allow Bitcoin app in China, although China government say Bitcoin can trade as virtual product. So we need have a USA region account or HongKong account to download Bitcoin app. T_T
That is interesting to know. Edit: 1) Put app on http://allcydia.com/ 2) crack DRM 3) app will work. iOS has sandbox to protect security of app data. If your jailbreak it, the protection is gone, although Bither is always encrypt your private key, but it still is not safe. So we suggest our user not to jailbreak, and we will not provider jailbreak version too. But thank you for your advice.  |
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9
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Bitcoin / Development & Technical Discussion / Re: Did satoshi not know that public key is recoverable from ECDSA signature?
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on: January 30, 2015, 06:59:49 AM
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I believe it wasn't known to him or he didn't understand it enough to trust it. PubKey recovery was certainly known prior to 2009. There are a number of other "nuts and bolts" decisions (oversights?) which make me thing Satoshi's background was not cryptography. He probably had exposure to and experience working with cryptography but wasn't a cryptographer.
In addition to PubKey recovery here are just a few other "quirks":
* Transaction Malleability (Bitcoin Specific). It is cumbersome to fix to fix today but with a different txn structure it would be impossible.
* Signature Malleability (ECDSA). ECDSA can have multiple signatures for the same digest the solution is to either not make the signature part of the txn hash or limit Bitcoin to a single form.
* DER encoding serves no purpose. Even if OpenSSL was used the DER bits could be striped.
* Lack of Compressed Keys. Optimally the only valid key would be a compressed key and thus not only is key size reduced but there is only one format to consider.
* Unusual choice of double hashing. Normally done to prevent length extension attacks which don't exist in Bitcoin.
This isn't to say Satoshi wasn't a genius, the magic in Bitcoin isn't the cryptographic primitives used. It is in the way he elegantly used existing systems (digital signatures & hashing algorithms) to create a timestamp and consensus finding system that is very simple and yet very difficult to attack.
Totally agree |
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12
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Bitcoin / Development & Technical Discussion / Re: Is it possible to trim the public key in bitcoin transaction's script?
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on: January 19, 2015, 08:57:25 AM
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For a decentralized system like Bitcoin, the IO is much more expensive than the CPU. One byte of extra data means transferring to and storing on all nodes. So saving the data storage is very important to Bitcoin.
In the transaction structure of Bitcoin, if removing the public key part in the transaction data, we may save nearly 30% of storage. The cost is we have to check the previous output to check the signature. But still it is worth to do the trim, cause the 30% data saving. (the blockchain data may be decreased from 30GB to 20GB)
Is it possible to do that?
It is technically possible with a fork, but that will cause a much bigger problem. In current design, a node can forget all spent outputs. Also, a node can forget scriptSig after verification, and store the UTXO only. If a new transaction may refer to the information in the historical blockchain, nodes have to store the whole blockchain forever. Satoshi has already addressed this problem in the section 7 of his white paper: https://bitcoin.org/bitcoin.pdf . Please read before you propose a new "solution". -------------------- Alternatively, it is possible to calculate the public key with only the signature and the signed message. The trade-off is spending more CPU time. Read more: https://bitcointalk.org/index.php?topic=6430.0http://www.secg.org/sec1-v2.pdf section 4.1.6 I think we are talking about the full node implementatioin, not SPV And for full nodes, the storage is much more expensive than CPU. Thanks  The section 7 of Satoshi's paper is NOT about SPV "Reclaiming Disk Space". OK. |
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13
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Bitcoin / Development & Technical Discussion / Re: Is it possible to trim the public key in bitcoin transaction's script?
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on: January 19, 2015, 08:49:35 AM
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For a decentralized system like Bitcoin, the IO is much more expensive than the CPU. One byte of extra data means transferring to and storing on all nodes. So saving the data storage is very important to Bitcoin.
In the transaction structure of Bitcoin, if removing the public key part in the transaction data, we may save nearly 30% of storage. The cost is we have to check the previous output to check the signature. But still it is worth to do the trim, cause the 30% data saving. (the blockchain data may be decreased from 30GB to 20GB)
Is it possible to do that?
It is technically possible with a fork, but that will cause a much bigger problem. In current design, a node can forget all spent outputs. Also, a node can forget scriptSig after verification, and store the UTXO only. If a new transaction may refer to the information in the historical blockchain, nodes have to store the whole blockchain forever. Satoshi has already addressed this problem in the section 7 of his white paper: https://bitcoin.org/bitcoin.pdf . Please read before you propose a new "solution". -------------------- Alternatively, it is possible to calculate the public key with only the signature and the signed message. The trade-off is spending more CPU time. Read more: https://bitcointalk.org/index.php?topic=6430.0http://www.secg.org/sec1-v2.pdf section 4.1.6 I think we are talking about the full node implementatioin, not SPV And for full nodes, the storage is much more expensive than CPU. Thanks |
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Bitcoin / Development & Technical Discussion / Re: Is it possible to trim the public key in bitcoin transaction's script?
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on: January 19, 2015, 08:48:47 AM
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Is it possible to do that? Yes and no. Yes: it is possible to 1) create hard-fork or alt-coin with another protocol 2) use P2PK outputs instead of P2PKH outputs. This saves some space 3) use compression while storing tx data on hard disk No: it is almost impossible to 1) change the current consensus protocol 2) use P2PK outputs instead of P2PKH outputs because all software works with addresses, not public keys 3) use realtime compression of blockchain because it is economically unreasonable OK, everything is possible. but this is not reasonable. The question is not about P2PK and P2PKH. We can recover the public key from r+s with rec_id, and verifying this with previous output address will be enough. Thanks |
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15
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Bitcoin / Development & Technical Discussion / Is it possible to trim the public key in bitcoin transaction's script?
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on: January 19, 2015, 07:34:23 AM
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For a decentralized system like Bitcoin, the IO is much more expensive than the CPU. One byte of extra data means transferring to and storing on all nodes. So saving the data storage is very important to Bitcoin.
In the transaction structure of Bitcoin, if removing the public key part in the transaction data, we may save nearly 30% of storage. The cost is we have to check the previous output to check the signature. But still it is worth to do the trim, cause the 30% data saving. (the blockchain data may be decreased from 30GB to 20GB)
Is it possible to do that?
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20
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Local / 中文 (Chinese) / Re: 比特币离我们实际生活到底有多远！
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on: October 16, 2014, 06:07:27 AM
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比特币离实际生活还有一段距离，如何保管和使用比特币就是第一个需要普及的问题。不要小看这个问题，现在很多圈内人都没搞明白。上次东叔说的朋友丢了2000多个币；几天前8btc上丢的600多个币。这些还是大额的，大家因为自己不小心丢的小额币可能就更多了。
但这些终将解决掉，你们可以回想下20年前怎么上网的么？有浏览器么？
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