Edgecase | Edgecase Bitcoin Storage Toolset version 2

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Brief Summary

This article contains the assets for Edgecase Bitcoin Storage Toolset (EBST) version 2. See the Downloadable Assets section.

Capabilities:
- Designed for offline use
- Address generation
- Creation of signed transactions with multiple inputs and multiple outputs
- Can send bitcoin to nonstandard P2SH addresses

Contents

- Brief Summary
- Contents
- Summary
- Downloadable Assets
- Dependency Trees

Summary

Let "EBST" = Edgecase Bitcoin Storage Toolset.

EBST version 1 consists of the set of assets listed in the article Recipe for storing bitcoin on paper using a Raspberry Pi.
- Capabilities: Designed for offline use, address generation, creation of signed transactions, can use a non-standard P2SH address as its destination.
- Limitations: Transactions must have exactly one input and one output.

EBST version 2 is an expansion of version 1 that handles multiple inputs and multiple outputs.

This expansion was developed in these articles:
- Creating a Bitcoin transaction with two outputs
- Creating a Bitcoin transaction with two inputs

In this article, I have gathered together the set of assets that comprise EBST version 2. I've made some additional changes (e.g. removing default values, updating import statements, changing comments).

I've also made the adjustment described in Bitcoin transaction test set, in the Notes section, in the part "Adjustment to transaction_2.py".

I have tested EBST version 2 against:
- the addresses in Bitcoin address test set
- the transactions in Bitcoin transaction test set
- the transactions in Bitcoin nonstandard transaction test set
All tests were successful.

Downloadable Assets

Assets of this article:

List:

- convert_dice_rolls_to_hex_bytes_3.py
- create_nonstandard_transaction_3.py
- create_transaction_3.py
- generate_bitcoin_address_4.py
- nonstandard_bitcoin_functions_2.py
- nonstandard_transaction_3.py
- transaction_3.py

Asset: A script that converts dice roll results into bytes.
convert_dice_rolls_to_hex_bytes_3.py

Asset: A script that creates and signs a nonstandard Bitcoin transaction with one or more standard P2PKH inputs and one or more outputs. Outputs can be standard P2PKH outputs or nonstandard P2SH outputs.
create_nonstandard_transaction_3.py

Asset: A script that creates and signs a standard Bitcoin transaction with one or more inputs and one or more outputs.
create_transaction_3.py

Asset: A script that generates a standard Bitcoin address from a private key.
generate_bitcoin_address_4.py

Asset: A library of functions for handling nonstandard Bitcoin data types.
nonstandard_bitcoin_functions_2.py

Asset: A library of classes for nonstandard Bitcoin transactions.
nonstandard_transaction_3.py

Asset: A library of classes for standard Bitcoin transactions.
transaction_3.py

Assets of other articles:

List:

- bitcoin_functions_2.py
- bjorn_edstrom_ripemd160.py
- ecdsa-0.10.tar.gz
- pypy_sha256.py

Asset: A library of functions for handling standard Bitcoin data types.
bitcoin_functions_2.py [paywalled]

Asset: An implementation of RIPEMD-160, written by Björn Edström.
bjorn_edstrom_ripemd160.py [paywalled]

Asset: A Python implementation of ECDSA cryptography, written by Peter Pearson.
ecdsa-0.10.tar.gz [paywalled]

Asset: A Python implementation of SHA256. Author unknown.
pypy_sha256.py [paywalled]

Dependency Trees

Address generation assets (standard addresses) dependency tree:

- convert_dice_rolls_to_hex_bytes_3.py
- generate_bitcoin_address_4.py
-- bitcoin_functions_2.py
--- bjorn_edstrom_ripemd160.py
--- ecdsa-0.10.tar.gz
--- pypy_sha256.py

Transaction creation assets (standard transactions) dependency tree:

- create_transaction_3.py
-- bitcoin_functions_2.py
--- bjorn_edstrom_ripemd160.py
--- ecdsa-0.10.tar.gz
--- pypy_sha256.py
-- transaction_3.py
--- bitcoin_functions_2.py
[...]
--- ecdsa-0.10.tar.gz

Transaction creation assets (nonstandard transactions) dependency tree:

- create_nonstandard_transaction_3.py
-- bitcoin_functions_2.py
--- bjorn_edstrom_ripemd160.py
--- ecdsa-0.10.tar.gz
--- pypy_sha256.py
-- nonstandard_bitcoin_functions_2.py
--- bitcoin_functions_2.py
[...]
-- nonstandard_transaction_3.py
--- bitcoin_functions_2.py
[...]
--- ecdsa-0.10.tar.gz
--- nonstandard_bitcoin_functions_2.py
[...]
-- transaction_3.py
--- bitcoin_functions_2.py
[...]
--- ecdsa-0.10.tar.gz

Combined list of assets:

- bitcoin_functions_2.py
- bjorn_edstrom_ripemd160.py
- convert_dice_rolls_to_hex_bytes_3.py
- create_nonstandard_transaction_3.py
- create_transaction_3.py
- ecdsa-0.10.tar.gz
- generate_bitcoin_address_4.py
- nonstandard_bitcoin_functions_2.py
- nonstandard_transaction_3.py
- pypy_sha256.py
- transaction_3.py

This article has been linked from:

How to write a Bitcoin private key on paper

How to write a Bitcoin address on paper

Recipe for creating and signing a standard Bitcoin transaction #2

Recipe for creating and signing a nonstandard Bitcoin transaction #2

Creating and signing a standard Bitcoin transaction with two inputs and two outputs

Recipe for storing bitcoin on paper using an offline Raspberry Pi #2

Recipe for storing bitcoin on an online Windows 10 laptop

Creating and signing a standard Bitcoin transaction with three inputs and three outputs

Generating a standard Bitcoin address #2

Validating a standard Bitcoin address

Bitcoin transaction test set #2

Creating a Bitcoin transaction

StJohn Piano | 2020-08-29 | Comment 0

Correction:

The asset create_nonstandard_transaction_3.py is missing a line containing:

{

Lines 57-58 are currently:

	},
	"txid": "",

Instead, they should be:

	},
	{
	"txid": "",

StJohn Piano | 2021-01-02 | Comment 1

Note:

In the file

bitcoin_functions_2.py

, the functions

- validate_hex_length()
- validate_hex_length_domain()

both contain this line:

n = len(input) / 2 # number of hex bytes

which won't handle non-even numbers of hex bytes properly (it will round down).

However, the validate_hex() function, called first in both cases, uses this line:

if len(input) % 2 == 0:

to check the evenness, and this will catch an odd number of hex bytes and raise an error.

StJohn Piano | 2021-01-06 | Comment 2

Problems in bitcoin_functions_2.py:

1) The function

validate_bitcoin_amount

doesn't reject inputs with too many decimal places.

Example: The value

0.002000010

is not rejected for having 9 decimal places.

This leads to a bug: The function

bitcoin_to_satoshi

produces an incorrect result if it receives an input with too many decimal places. This function is used in the Input and Output creation methods in transaction_3.py.

Example: The value

0.002000010

will be converted to 2000010 satoshi (instead of 200001 satoshi), and later back to 0.02000010 bitcoin i.e. it's been multiplied by 10.

This bug will not raise an error during operation. If an input amount is incorrect, the resulting transaction will be invalid. However, an incorrect output amount could redirect a large amount of bitcoin from the change address to an external address.

A solution:

	# Check whether the amount has too many decimal places.

	if '.' in amount:

		decimalPlaces = len(amount.split('.')[1])

		if decimalPlaces > 8:

			raise ValueError("Bitcoin amount ({a}) has {d} decimal places.".format(a=amount, d=decimalPlaces))

^ This can be added just after the "apart from the period, input can contain only digits." check in

validate_bitcoin_amount

.

2) The function

validate_bitcoin_amount

has error messages that don't correctly display Bitcoin amounts.

Example:

ERROR: The minimum input amount is 0.000000. Input: 0.000000001

The minimum input amount is rounded to 6 decimal places. It should be

0.00000001

.

A solution: Replace

%f

in the error messages with

%.8f

.

3) On reflection, the function

validate_bitcoin_private_key_hex

should only accept values that are exactly 32 bytes. A convenience option to not include leading zeros can be implemented at a higher level. The internal library code should only handle private keys of 32 bytes.

A solution: Replace the

validate_hex

and

validate_hex_length_domain

checks with a single

validate_hex_length(input, 32)

check.

This function is also used to validate the random values supplied to the

sign

method of the Transaction class in transaction_3.py. Changing it would cause this method to require 32-byte random values. This is ok. The internal library code should also only handle random values that are exactly 32 bytes.

Note: In transaction_3.py, the

create_from_txid

method in the Input class accepts a less-than-32-byte private key and pads it to 32 bytes. Later it confirms that the length is 32 bytes. These two steps can be replaced with a single use of the new version of

validate_bitcoin_private_key_hex

.