The Legitcoin ICO/token sales windows have opened and will end on February 14. The Legitcard Mastercard also known as Legitcard will be distributed only to users who purchase and hold at least 200 LEGIT in their account.
http://legtm.me/152971
Share Legitcoin with your friends and trustees using your referral link. Each time someone signs up via this link, you will be rewarded with $20 equivalent of Legitcoin as well as 7% of their Legitcoin purchases. Your referals get $10 (5 LEGIT) worth of Legitcoin for signup.

There are some Bitcoiners declaring on social media that they have already started to open Lightning channels and started to send Bitcoins with them.

Should this be encouraged by the Lightning developers? I believe it is irresponsible because it has not been fully tested in the testnet. People might lose their coins.

Achow, Carlton, what are your opinions on this?

As you may know, Intel has been exposed heavily in the past few hours with 2 different exploits that can deliver pretty scare results if used maliciously:

Quote
Meltdown and Spectre

Bugs in modern computers leak passwords and sensitive data.

Meltdown and Spectre exploit critical vulnerabilities in modern processors. These hardware bugs allow programs to steal data which is currently processed on the computer. While programs are typically not permitted to read data from other programs, a malicious program can exploit Meltdown and Spectre to get hold of secrets stored in the memory of other running programs. This might include your passwords stored in a password manager or browser, your personal photos, emails, instant messages and even business-critical documents.

Meltdown and Spectre work on personal computers, mobile devices, and in the cloud. Depending on the cloud provider's infrastructure, it might be possible to steal data from other customers.

https://meltdownattack.com/

On the site you can see them in action:





What do you think about this when it comes to bitcoin?

Even if I moved all of my private keys into an airgapped laptop which has never seen the internet after being formatted, when I wanted to sign an offline transaction into the online node... the node is still connected to the internet, could somehow a exploit happen in the process?

News: August 2014
My boring professional life made me stay away from bitcoin for far too long but I'm now back in business
Pywallet won't be fixed anymore except for critical bugs
Instead I'll finish its successor (that still has no name)


News: September 2013
I'm rebuilding pywallet from scratch:

    I need a new name for this project, propose one if you want
    See the progress here: https://bitcointalk.org/index.php?topic=294439



This thread
First of all, I'd like to thank Joric for the first version of pywallet he made, this thread is about my fork.
Pywallet is a python script that deals with wallet.dat. It allows you to do plenty of things inside it.
You can post here whatever you want about pywallet: critics, asking for improvements/changes, telling me it helped you, pointing out errors/bugs, etc.


Pywallet 2: 22nd March 2013
Pywallet has been discontinued for around a year but is now actively developed again.
Look at the end of the 7th page for updates: encrypted wallet support, exporting/importing to/from files, merging wallets, etc.


Instructions (see also here)
Currently you can:

    Dump your wallet, see your pubkeys, privkeys, their labels, etc
        Under "Dump your wallet:"
        Fill version with 0 for bitcoin, 52 for namecoin, 111 for testnets

    Dump your transactions to a json file
        Under "Dump your transactions to a file:"
        Fill Output file with the full path to the file where you want the transactions to be written, this file must not exist

    Import a key/address into your wallet, with a label, or as a reserve key
        Under "Import a key into your wallet:"
        Key is the private key to import, in base58 or in hexadecimal chars
        Label is the name you want to see in the Address Book of the client
        Check Reserve if you want your address NOT to show in the Address Book
        Version = 0 for bitcoin, 52 for namecoin, 111 for testnets
        Format of the private key: Hexadecimal if you see only digits, a, b, c, d, e and f, otherwise chose Regular

    Import a transaction into your wallet
        Under "Import a transaction into your wallet:"
        Txk is the tx_k value you see in the wallet dump
        Txv is the tx_v value you see in the wallet dump

    Import transactions from a json file
        Under "Import a transaction into your wallet:"
        Txk = "file" (without quotes)
        Txv = full path to the transactions dump file

    Delete addresses from your wallet
        Under "Delete a key from your wallet:"
        Key is a Bitcoin address, not a priv key
        Type: Bitcoin Address

    Delete transactions from your wallet
        Under "Delete a key from your wallet:"
        Key is the hash of the transaction you want to delete (type "all" to delete them all)
        Type: Transaction

    Get info about a privkey, i.e. see address, base58 privkey, hexprivkey, pubkey and hash160, using the network you want
        Under "Get some info about one key[and sign/verify messages]:"
        Key is a private key
        Leave Msg, Sig and Pubkey empty
        Version = 0 for bitcoin, 52 for namecoin, 111 for testnets
        Format of the private key: Hexadecimal if you see only digits, a, b, c, d, e and f, otherwise chose Regular

    Sign and verify string, files, and binary string
        Under "Get some info about one key and sign/verify messages:"
        Key is the private key you want to sign the message/file with (only for signing)
        Message is the message you want to sign/verify
            If it is a string, just type it
            If it is a binary string, type "Hex:" just before its hexadecimal representation
            If it is a file, type "File:" just before its full path

        Signature is the signature of your message (only for verifying)
        Pubkey is the pubkey used to sign the message (only for verifying)

    Read a device to find deleted keys (CLI only)
        Assuming that:
            The device you want to read is /dev/sda3
            The size of /dev/sda3 is 30.1Gio
            You want pywallet to write the new wallet containing the found keys in /home/jackjack/recovered_wallets
        Run "sudo ./pywallet.py --recover --recov_device /dev/sda3 --recov_size 30.1Gio --recov_outputdir /home/jackjack/recovered_wallets"
        Then replace your wallet (back it up before) with the recovered wallet and run "bitcoin -rescan"

    Print the balance of a bitcoin address, read from blockexplorer



Installation:

    Linux/OSX: See README file
    Windows:
        Download https://github.com/downloads/jackjack-jj/pywallet/PWI_0.0.3.exe (SHA256: 645a4d092733ad6685de730a38b210c6594e44a15690a87a231859477deca316)
        Run it
        Click about a thousand times on Yes/Next/I Agree/OK
        Go to the directory where you extracted it and run pywallet.bat
        http://localhost:8989


How to run it:
 Download it there: https://github.com/jackjack-jj/pywallet
 Run './pywallet.py --web' then open 'http://localhost:8989' in your brower

Requirements:
 Python 2.5-2.7, with bsddb package
 ÃƒÆ’ƒÆ’Æ’Æ’Æ’ÃÆ’¢â‚¬Å¡ twisted package is necessary if you want to use the web interface
 ÃƒÆ’ƒÆ’Æ’Æ’Æ’ÃÆ’¢â‚¬Å¡ ecdsa package is necessary if you want to sign and verify messages

Confirmed to work on:
 Ubuntu 32bit(me)
 Windows 32bit(me), 64bit(ctoon6)
 OSX(defxor)

Pywallet can be used to:
 Import Vanitygen keys
 Delete 0/unconfirmed transactions
 Recover Namecoins (and testnetcoins) sent to Bitcoin addresses
 Create a deterministic wallet (using a passphrase)
 Create a deterministic wallet (using a file)
 Broadcast offline transactions
 Create a Bitcoin/*coin address from scratch
 Recover a wallet/deleted keys

Quote from: Stedsm on November 04, 2017, 08:45:49 AM
What about the old P2PKH addresses? I mean will they be included in the Bech32 (native segwit) format?

No, BIP173 (though it is still draft) specifies Bech32 only to P2WPKH and P2WSH. It may be extended to include older formats but I think it won't because it will only confuse people.

Quote
Is there any difference in using the old addresses? Shall I stop using the P2PKH and/or P2PSH addresses?

Old P2PKH and P2SH addresses are going to work. It is the only way to ensure that old coins are spendablle so I guess it will be supported as long as Bitcoin exists.

Quote
The addresses that blockchain.info provides nowadays, do they all come under the SegWit Protocol?

Segwit protocol is a broad and complicated thing. All the blocks mined are already under segwit protocol. In theory, there can be a non-segwit block mined with only non-segwit transactions but I think all the miners upgraded software so it does not happen.

BIP141 defines 4 segwit payment methods:

    P2WPKH
    P2WPKH nested in P2SH (P2SH-P2WPKH)
    P2WSH
    P2WSH nested in P2SH (P2SH-P2WSH)


P2WPKH and P2WSH are native segwit. Both spending and receiving requires segwit-aware wallets. The addresses are bech32 encoded.  For P2SH-P2WPKH and P2SH-P2WSH only spending requires segwit-aware wallets (but relaying and block validation can happen also on non-segwit aware node). Anybody (with BIP9 P2SH-aware wallet) can send to these addresses because they look (and the output behaves) the same as non-segwit P2SH. They are provided to ease the transition to segwit. The nesting in P2SH induces an overhead so native segwit transactions are smaller. Only at input it is revealed if the address is P2SH only or P2SH with witness. Both look the same (starting with 3)

Currently, very few of the native segwit transactions are happening. But it is slowly growing. If you don't care about receiving (say, a wallet for sending with occasional top-up, many exchanges have such wallets), you can use it right away and save on fees. P2SH-P2WPKH is more universal but the transactions have higher size (and fees), though still lower than non-segwit P2PKH or P2SH.

I'm trying to fully understand how P2SH (BIP16) works, and I thought I did.  For fun and to check my understanding, I disabled BIP16 in Bitcoin Core (setting BIP16Height in chainparams to a high value) and tried to "sign" a transaction spending a P2SH output by just providing the redeem script.  According to my understanding, this should be enough pre-BIP16, since it will make the "OP_HASH160 <hash> OP_EQUAL" script of the P2SH output succeed, right?  But that seems to be not the case.

In regtest mode, I created the following P2SH address:

Code:

$ addmultisigaddress 1 '["03c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e", "0221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad570"]'
2MwCrk6S9UEeFujacKe7m4uDCzu25F3VAeM

$ validateaddress 2MwCrk6S9UEeFujacKe7m4uDCzu25F3VAeM
{
  "isvalid": true,
  "address": "2MwCrk6S9UEeFujacKe7m4uDCzu25F3VAeM",
  "scriptPubKey": "a9142b6defe41aa3aa47795b702c893c73e716d485ab87",
  "ismine": false,
  "iswatchonly": false,
  "isscript": true,
  "script": "multisig",
  "hex": "512103c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e210221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad57052ae",
  "addresses": [
    "mg41i3DBptiWbQ9PQ59ykdbc8T85gEqWdK",
    "muC6tdGQrYXSqghPZziyvZwu1KSwL49ioy"
  ],
  "sigsrequired": 1,
  "account": ""
}


And funded it:

Code:

$ sendtoaddress 2MwCrk6S9UEeFujacKe7m4uDCzu25F3VAeM 10
14e8f61534b9a0b6110655dc153d41cc90f64b8104b820e1f4534fd14a732df0

$ generate 1

$ gettxout 14e8f61534b9a0b6110655dc153d41cc90f64b8104b820e1f4534fd14a732df0 0
{
  "bestblock": "40d573ebb78bdab760d6659b8ad9d91c46633144d25084eaf3de1f7411040305",
  "confirmations": 1,
  "value": 10.00000000,
  "scriptPubKey": {
    "asm": "OP_HASH160 2b6defe41aa3aa47795b702c893c73e716d485ab OP_EQUAL",
    "hex": "a9142b6defe41aa3aa47795b702c893c73e716d485ab87",
    "reqSigs": 1,
    "type": "scripthash",
    "addresses": [
      "2MwCrk6S9UEeFujacKe7m4uDCzu25F3VAeM"
    ]
  },
  "coinbase": false
}


Then, I tried to spend it by providing just the serialised redeem script as scriptSig, but this fails:

Code:

$ decoderawtransaction 0100000001f02d734ad14f53f4e120b804814bf690cc413d15dc550611b6a0b93415f6e814000000004847512103c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e210221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad57052aeffffffff0100e1f505000000001976a914cf112b41997697caa3eee9e308ad9b2b917b4e4c88ac00000000
{
  "txid": "1971750cd655c7f93627354c380595e3e3434b69c3b6e788eecfb9c685eba703",
  "hash": "1971750cd655c7f93627354c380595e3e3434b69c3b6e788eecfb9c685eba703",
  "version": 1,
  "size": 157,
  "vsize": 157,
  "locktime": 0,
  "vin": [
    {
      "txid": "14e8f61534b9a0b6110655dc153d41cc90f64b8104b820e1f4534fd14a732df0",
      "vout": 0,
      "scriptSig": {
        "asm": "512103c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e210221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad57052ae",
        "hex": "47512103c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e210221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad57052ae"
      },
      "sequence": 4294967295
    }
  ],
  "vout": [
    {
      "value": 1.00000000,
      "n": 0,
      "scriptPubKey": {
        "asm": "OP_DUP OP_HASH160 cf112b41997697caa3eee9e308ad9b2b917b4e4c OP_EQUALVERIFY OP_CHECKSIG",
        "hex": "76a914cf112b41997697caa3eee9e308ad9b2b917b4e4c88ac",
        "reqSigs": 1,
        "type": "pubkeyhash",
        "addresses": [
          "mzPpjgciTo6DMGpE3Lkb4ZLBSn8A239aDZ"
        ]
      }
    }
  ]
}

$ sendrawtransaction 0100000001f02d734ad14f53f4e120b804814bf690cc413d15dc550611b6a0b93415f6e814000000004847512103c278d06b977e67b8ea45ef24e3c96a9258c47bc4cce3d0b497b690d672497b6e210221ac9dc97fe12a98374344d08b458a9c2c1df9afb29dd6089b94a3b4dc9ad57052aeffffffff0100e1f505000000001976a914cf112b41997697caa3eee9e308ad9b2b917b4e4c88ac00000000 true
error code: -26
error message:
16: mandatory-script-verify-flag-failed (Operation not valid with the current stack size)


As you can see, the scriptSig of the raw transaction I try to send matches the hex of the P2SH address.  (A very similar script is sent for a correctly signed spending of the P2SH output, except prepended by the actual signatures as mandated by BIP16.)  From my understanding of how P2SH works, this should be a valid script pre-fork.  Can someone please explain to me what I'm missing here?

Android wallet Coinomi supports many coins. But, it's closed source, and keeping all your coins in a hot wallet for long term is bad practice.

For secure storage, you shouldn't rely on just one wallet that covers all, you should research all coins individually, and choose the best wallet for each coin. I prefer to keep each wallet in it's own VM.
Research, installation, backup and funding is quite a lot of work per coin. But, it also prevents you from just buying 100 random coins without having any idea what you're getting into.
You could make it a goal to buy 2 coins per week. That also means you'll have to research more than that, as you shouldn't just buy any random coin. This way, you'll buy 100 coins over the course of this year. If you're seriously going to do this, I would be very interested if you keep track of all your coins in a (self moderated) topic on this forum.

Hi Folks,
 
I made a movie about Bitcoin's underlying technique.
Since English is not my native language, I would be glad if you watch the movie and give me some advice if necessary.
Currently the film is accompanied by an automatic voice. I'll change that later as soon as I know that the text is somehow understandable.

So, its still a draft:


Thanks for any feedback.