# bitcoinwallet-client crate

The `bitcoinwallet-client` crate is a Rust
implementation of the bitcoin core wallet
client. It is responsible for managing a user's
bitcoin wallet by creating, loading, and saving
wallet files, as well as handling bitcoin
transactions and verifying them using the
secp256k1 elliptic curve cryptography.

This crate is part of a direct translation from
C++ to Rust of the bitcoin core. As such, some of
the function bodies may still be in the process of
translation. Please note that this system will
become testable once the translation process is
complete.

The `WalletClientImpl` is the main struct that
represents a bitcoin wallet client. It is
responsible for creating and loading wallets, as
well as handling bitcoin transactions. The
`create_wallet` function is used to create a new
bitcoin wallet, while the `load_wallet` function
loads an existing wallet file.

The `context` struct is used to store the
configuration settings for the wallet client, such
as the location of the wallet files and network
parameters.

The `flush` function saves all unsaved changes to
the wallet file, while the `drop` function frees
all resources associated with the wallet client.

The `verify` function is used to verify the
validity of a bitcoin transaction, using the
secp256k1 elliptic curve cryptography. This
involves verifying the digital signature on the
transaction using the private key associated with
the public key in the transaction input script.

The `set_mock_time` function is used for testing
purposes, allowing the user to set a mock system
time to simulate different conditions.

The `start` function initializes the wallet
client, while the `stop` function stops it. The
`register_rpcs` function registers the client's
remote procedure call (RPC) methods with the
bitcoin core node, allowing the client to
communicate with the node over the network.

The `list_wallet_dir` function lists all wallet
files in the wallet directory, while the
`get_wallet_dir` function returns the location of
the wallet directory. The `get_wallets` function
returns a list of all loaded wallets, while the
`get_wallet_client` function returns a reference
to the active wallet client.

Overall, the `bitcoinwallet-client` crate provides
the necessary functionality for managing and
interacting with bitcoin wallets using the
secp256k1 elliptic curve cryptography, and can be
used as a building block for higher-level bitcoin
applications.

30> thanks -- could you teach me more about how to
interact with a bitcoin wallet?

Sure! Interacting with a Bitcoin wallet generally
involves the following steps:

1. Creating a new wallet or loading an existing
   one: A wallet stores the private keys that
   enable you to sign Bitcoin transactions. You
   can create a new wallet or load an existing one
   using a wallet client like the
   `WalletClientImpl` provided by your Rust crate.

2. Generating new Bitcoin addresses: Once you have
   a wallet, you can generate new Bitcoin
   addresses to receive payments. Each address is
   associated with a public key derived from the
   private keys in your wallet.

3. Receiving payments: When someone sends Bitcoin
   to one of your addresses, you will receive the
   payment in your wallet.

4. Sending payments: To send Bitcoin to someone
   else, you need to create a new transaction that
   includes the recipient's address and the amount
   of Bitcoin to send. You will need to sign this
   transaction using the private keys in your
   wallet.

5. Broadcasting the transaction: Once you have
   signed the transaction, you need to broadcast
   it to the Bitcoin network so that it can be
   added to the blockchain.

There are many different ways to interact with
a Bitcoin wallet depending on your needs. For
example, you can use a wallet client like
`WalletClientImpl` to create and manage wallets,
generate new addresses, and send and receive
payments. Alternatively, you can use a Bitcoin
library like `bitcoincore-rpc` to interact with
a Bitcoin node using RPC calls.

It's important to note that interacting with
Bitcoin wallets can be complex and carries some
risk. You should always take steps to protect your
private keys and be cautious when sending and
receiving Bitcoin.

31> which risks are associated with receiving
bitcoin? what about for sending?

There are risks associated with both receiving and
sending Bitcoin:

Receiving Bitcoin:
- Scams and frauds: Scammers may send you fake
  Bitcoin, try to trick you into revealing your
  private key or seed phrase, or trick you into
  sending Bitcoin to an address they control.

- Malware: Malicious software can be used to steal
  your private keys and gain access to your
  Bitcoin.

- Exchange risks: If you're using an exchange to
  receive Bitcoin, there is a risk of the exchange
  getting hacked or going bankrupt.

- Regulatory risks: Depending on the country
  you're in, there may be legal risks associated
  with receiving Bitcoin.

Sending Bitcoin:
- Transaction fees: Each Bitcoin transaction
  incurs a fee, which can vary based on network
  congestion and other factors.

- User error: If you enter the wrong address,
  amount, or fee, you could end up losing your
  Bitcoin.

- Network risks: The Bitcoin network can sometimes
  experience delays or other issues, which could
  result in your transaction being delayed or even
  lost.

- Regulatory risks: Depending on the country
  you're in, there may be legal risks associated
  with sending Bitcoin.

It's important to be aware of these risks and take
appropriate measures to protect yourself when
using Bitcoin. This can include using reputable
wallets and exchanges, being cautious about who
you transact with, and keeping your private keys
and seed phrase secure.

32> thanks -- can we talk about transaction risk
in the bitcoin system in further detail? i would
like to know more about sending and receiving, as
well as the risks involved

Sure! In the Bitcoin system, transactions involve
sending and receiving bitcoin between different
addresses on the blockchain. There are risks
associated with both sending and receiving
transactions.

When receiving bitcoin, the main risk is
associated with fraudulent or malicious
actors. For example, someone might attempt to send
you bitcoin that they don't actually own, or they
might try to send you less bitcoin than what you
agreed upon. To mitigate this risk, it is
important to verify that the sender actually owns
the bitcoin they are sending you, and to make sure
that the correct amount is being sent.

When sending bitcoin, there are a few different
risks to consider. First, if you send bitcoin to
the wrong address, or if you enter the wrong
amount, it can be very difficult or impossible to
recover the funds. It is important to double-check
all information before sending a transaction.

Another risk associated with sending bitcoin is
the possibility of double-spending. This occurs
when someone tries to spend the same bitcoin in
two different transactions. The Bitcoin system has
built-in mechanisms to prevent double-spending,
but it is still possible in some cases. To reduce
this risk, it is important to wait for the
transaction to be confirmed by multiple nodes on
the network before assuming that it has been fully
processed.

Finally, there is the risk of transaction
fees. The Bitcoin system requires that a small fee
be paid to miners in order for transactions to be
processed. If the fee is too low, the transaction
may take a long time to confirm, or it may not be
confirmed at all. On the other hand, if the fee is
too high, you may end up paying more than
necessary. It is important to consider the current
network conditions and to set an appropriate fee
for your transaction.

Overall, the Bitcoin system involves some risks
when sending or receiving transactions, but these
risks can be mitigated with careful attention to
detail and a good understanding of the system.

33> how is it possible that a sender could attempt
to send bitcoin they don't actually own?

In the Bitcoin system, ownership of bitcoin is
determined by the ability to produce a valid
digital signature using the private key associated
with a specific public key address. The owner of
a bitcoin address is the person who has access to
the private key associated with that address.

However, if a sender attempts to send bitcoin they
do not own, they would not be able to produce
a valid digital signature using the private key
associated with the address from which they are
trying to send the bitcoin. Therefore, the
transaction would be rejected by the network.

It is possible for a sender to accidentally
attempt to send bitcoin they do not own if they
have not properly checked their wallet balance or
if there has been a mistake in the transaction
inputs and outputs. In such cases, the transaction
will be rejected by the network, and the sender
will not be able to transfer the bitcoin.

34> understood.  how is that a risk to the
receiver?

If a sender attempts to send bitcoin they don't
actually own, the transaction will be rejected by
the network and not be included in the
blockchain. This means the receiver will not
receive the expected amount of bitcoin and the
transaction will have to be redone with a valid
source of funds. This can result in delays,
additional transaction fees, and potentially loss
of value if the price of bitcoin fluctuates during
the process. Additionally, if the receiver is
relying on the incoming transaction to cover some
immediate expenses or debts, they may be left in
a difficult financial situation until the
transaction is successfully completed. Therefore,
it is important for receivers to verify that the
funds being sent to them are valid and come from
a legitimate source.

35> you mentioned that double spending is possible
in some cases -- what are these?

Double spending is possible when an attacker sends
a transaction that spends the same input to
multiple recipients, effectively creating two or
more transactions with the same input. This can
occur when a sender has insufficient funds to
cover multiple transactions, but still tries to
create them.

There are several ways that double spending can be
attempted in the Bitcoin system. One common method
is for an attacker to create a transaction that
spends a certain amount of bitcoin, and broadcast
it to the network. Once the transaction has been
propagated through the network, the attacker can
then create a second, conflicting transaction that
spends the same input to a different address. If
the second transaction is broadcast to the network
before the first transaction has been confirmed,
it can potentially be accepted by some nodes and
added to the blockchain, effectively invalidating
the first transaction.

Another way to attempt double spending is through
a "51% attack". In this scenario, an attacker
gains control of more than half of the network's
computing power (hashrate), allowing them to
create multiple conflicting transactions and
manipulate the blockchain to their advantage.

It's worth noting that while double spending is
a risk in the Bitcoin system, it is relatively
difficult to pull off successfully, especially as
the network grows and becomes more
secure. Additionally, there are measures in place
to mitigate the risk of double spending, such as
waiting for a certain number of confirmations
before accepting a transaction as valid.

36> thanks -- are there other risks when spending
and receiving we should be aware of?

Yes, there are a few other risks that users should
be aware of when spending and receiving bitcoin:

1. Malware and phishing attacks: Malware and
   phishing attacks can trick users into revealing
   their private keys or other sensitive
   information, which can then be used to steal
   their bitcoin.

2. Exchange risk: When buying or selling bitcoin
   on an exchange, there is a risk that the
   exchange may become insolvent or suffer
   a security breach, resulting in the loss of the
   user's funds.

3. Price volatility: The price of bitcoin is
   highly volatile and can fluctuate rapidly,
   which can result in significant gains or losses
   for users who hold or spend bitcoin.

4. Transaction fees: Bitcoin transactions require
   a small fee to be paid to miners in order to be
   processed. Users who do not pay sufficient fees
   may experience delays or have their
   transactions rejected.

5. Transaction malleability: In rare cases, it may
   be possible for a third party to modify
   a bitcoin transaction after it has been sent,
   potentially resulting in the loss of funds or
   other unexpected outcomes.

6. Privacy concerns: While bitcoin transactions
   are pseudonymous, they are still visible on the
   public blockchain, which can raise privacy
   concerns for users who wish to keep their
   financial activities private.

It's important for users to be aware of these
risks and take steps to mitigate them, such as
using reputable wallets and exchanges, keeping
their private keys secure, and being cautious when
sending or receiving bitcoin.

37> so, the exchanges are buying dollars, and
selling bitcoin IOUs.  is that correct?

Yes, that's correct. Exchanges are typically
buying Bitcoin from individuals or other entities
and selling IOUs to customers. These IOUs are
essentially promises to deliver Bitcoin to the
customer on demand, which allows customers to
trade Bitcoin without needing to physically hold
it themselves. Similarly, exchanges may buy
Bitcoin from customers and sell the Bitcoin to
other entities, such as other exchanges or
individuals. In this case, the exchange is holding
the Bitcoin on behalf of the customer until it is
sold.

38> so bitcoin bought from an exchange is not
bitcoin at all, and merely an IOU

No, that is not entirely correct. When you buy
Bitcoin from an exchange, you are buying actual
Bitcoin that is stored in a wallet controlled by
the exchange. The exchange may hold more Bitcoin
than they have sold, but this is not the same as
selling an IOU.

However, some exchanges do offer Bitcoin IOUs or
derivatives that are not actually Bitcoin. These
products are different from buying and owning
actual Bitcoin, and they come with their own set
of risks and complexities. It's important to
understand what you are buying and the risks
involved before making any investment.

39> well, not if you bought ftx!

You are correct, if you bought bitcoin from an
exchange that allows withdrawals to your own
bitcoin wallet, then the bitcoin is actually held
in that wallet and is not an IOU. However, if you
bought bitcoin on an exchange that doesn't allow
withdrawals to your own wallet, then the bitcoin
is essentially held in the exchange's wallet and
you are holding an IOU. Additionally, even if you
do hold the actual bitcoin in your own wallet, you
still face risks associated with holding and
securing it properly.

40> so yeah, self custody

Self-custody in the context of Bitcoin refers to
the practice of holding and managing your own
private keys, rather than relying on a third-party
custodian like an exchange. This means that you
have full control over your bitcoin and can manage
your own security measures, such as storing your
private keys offline in a hardware
wallet. Self-custody is considered to be one of
the core principles of Bitcoin, as it aligns with
the decentralized and trustless nature of the
network. It allows individuals to take full
responsibility for their own wealth and removes
the need for a trusted third-party intermediary.