Is this a transaction?

Question

I found an old wallet.dat but i dont know what is this. Is it a transaction that is not signed? If yes please help. I dont have a clue about cryptography. I have read and seen some tutorials but i dont get it.

Answer 1

I don't have a clue about cryptography.

That's OK, The Bitcoin protocol doesn't encrypt anything. Although implementations like Bitcoin core can use a wallet password to encrypt private keys stored in a wallet file. Anyway the text shown doesn't include any encrypted data.

So if the wallet isn't encrypted, you don't need to know anything about encryption.

Cryptography or crypto-graphy literally means secret writing. Cryptography is the study and use of methods of writing secret (encrypted) messages that can't be understood by an enemy. Many forms of encryption use an encryption key - a set of letters or a number that can be used with an encryption method to turn readable plain text into unreadable ciphertext. Or vice versa.

In the late 20th century, new forms of cryptography were invented that used mathematically related pairs of numbers as private and public keys such that the public key could be used to decrypt a ciphertext that had been encrypted using a private key (and usually, vice versa). At the same time, the idea of a digital signature was created. By checking the signature a general could be sure that the order to "nuke Baltimore" came from the president and not from the enemy.

The Bitcoin network doesn't use encryption but it does take from cryptography the idea and methods of digital signatures - and hence it uses the mathematical methods of creating and using public and private keys that are required for digital signatures.

Is this a transaction?

No.

Your image shows a data structure in JSON text format.

That JSON text isn't what I would expect to find in a wallet.dat file produced by Bitcoin core. It might be something produced by a wallet reading tool of some sort.

That JSON appears to show data relating to an address. Some of that sort of address data can be found as part of a transaction but what you show isn't a description of a transaction.

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(later comment by question author mentioned the use of decodescript in Bitcoin-core)

Decodescript

decodescript takes a hex-encoded script and produces a JSON "decoding" of it. Note that the "decoding" is not "decryption", it isn't anything to do with encryption. It is trying to make a more easily understood description of the Bitcoin script that you gave it in Hexadecimal form.

A Bitcoin script is the part of a transaction that specifies how someone can prove they are entitled to spend one of the output amounts of a transaction.

A script consists of operators (instructions) and data items. Things like OP_DUP are an operator that says to duplicate the top item on the stack. There are a small number of operators. There are standard scripts that use those operators in specific ways.

When you spend the bitcoin amount (the unspent transaction output or UTXO amount), you create an unconfirmed transaction that includes the input data needed by that script. Typically that input data includes a digital signature. Your wallet software will take care of this for you. See signrawtransactionwithkey

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Wallet contents

A good source of information about the contents of a wallet.dat produced by Bitcoin-core is an answer to dumpwallet output documentation & explanation?

I summarise that as

• Extended Master Private Key
• List of derived Private Keys
  • List of Addresses

To fully understand wallet.dat, you'd also need to understand the storage format used - which is a kind of database structure. This Q&A website has answers to other questions that cover this.

Bitcoin Addresses

Bitcoin addresses are a presentation abstract of a bitcoin script. However the addresses themselves don't really appear in Bitcoin transactions as transmitted, only the bitcoin script they represent. So strictly speaking, we could say that addresses are not present in Bitcoin transactions. Saying that transactions contain addresses is a sort of convenient shorthand to try to make things easier for beginners to understand what they are doing.

For a particular type of Bitcoin script, popularly used over many years, such as P2SH, the Bitcoin address is formed from information including the public-key of a key-pair.

For some other types of Bitcoin script present in transactions in the blockchain, there is no standard way to form a Bitcoin address.

Since an HD wallet like Bitcoin core creates a large number of key-pairs in advance, its wallet.dat will contain many unused key-pairs and hence contain many unused addresses.