In the previous article, we looked at different methods to generate a private key. Whatever method you choose, you’ll end up with 32 bytes of data. Here’s the one that we got at the end of that article:
Mar 28, 2019 An address is derived from the public key through the use of a one-way cryptographic hash function. With Bitcoin, the algorithms that are used to make a bitcoin address from the public key are the Secure Hash Algorithm 256 ( SHA-256) and the RACE Integrity Primitives Evaluation Message Digest 160 ( RIPEMD-160 ). I'm paranoid that I've been sending bitcoins to the paper bitcoin addresses where somehow at sometime my saved private keys got corrupted. So from time to time I want to run a script, python or whatever, to check if my private keys do correspond to the public address that I've been sending bitcoins to. It generates valid address from ECKey and i send transaction to that address via electrum. But wallet didn't receive money. Don't know where the money gone. What should i do to convert master private key into BigInteger or bytes PS: I'm beginner in cryptocurrency.
60cf347dbc59d31c1358c8e5cf5e45b822ab85b79cb32a9f3d98184779a9efc2
We’ll use this private key throughout the article to derive both a public key and the address for the Bitcoin wallet.
What we want to do is to apply a series of conversions to the private key to get a public key and then a wallet address. Most of these conversions are called hash functions. These hash functions are one-way conversions that can’t be reversed. We won’t go to the mechanics of the functions themselves — there are plenty of great articles that cover that. Instead, we will look at how using these functions in the correct order can lead you to the Bitcoin wallet address that you can use.
Elliptic Curve Cryptography
The first thing we need to do is to apply the ECDSA or Elliptic Curve Digital Signature Algorithm to our private key. An elliptic curve is a curve defined by the equation
y² = x³ + ax + b with a chosen a and b . There is a whole family of such curves that are widely known and used. Bitcoin uses the secp256k1 curve. If you want to learn more about Elliptic Curve Cryptography, I’ll refer you to this article.
By applying the ECDSA to the private key, we get a 64-byte integer. This consists of two 32-byte integers that represent the X and Y of the point on the elliptic curve, concatenated together.
For our example, we got:
1e7bcc70c72770dbb72fea022e8a6d07f814d2ebe4de9ae3f7af75bf706902a7b73ff919898c836396a6b0c96812c3213b99372050853bd1678da0ead14487d7 .
In Python, it would look like this:
Note: as you can see from the code, before I used a method from the
ecdsa module, I decoded the private key using codecs . This is relevant more to the Python and less to the algorithm itself, but I will explain what are we doing here to remove possible confusion.
In Python, there are at least two classes that can keep the private and public keys: “str” and “bytes”. The first is a string and the second is a byte array. Cryptographic methods in Python work with a “bytes” class, taking it as input and returning it as the result.
Now, there’s a little catch: a string, say,
4f3c does not equal the byte array 4f3c , it equals the byte array with two elements, O& lt;. And that’s what codecs.dec ode method does: it converts a string into a byte array. That will be the same for all cryptographic manipulations that we’ll do in this article.
Encryption Keying External Key Loader, OTAR Synchronization CFB-Cipher Feedback OFB-Output Feedback Vector Generator National Institute of Standards and Technology (NIST) Approved random number generator Encryption Type Digital Key Erasure Keyboard Command Code Key Initialization Internal Pseudorandom Generator Standards FIPS 46-3, FIPS 81. Apr 26, 2014 I scored a UHF 380-470 EF Johnson 5100 the other day and would love to get it up and running. I've been told they do NOT need to affiliate to monitor a 9600 system. I would appear they use a proprietary type of system key. Does anyone have any insight? May 20, 2012 The EF Johnson system keys are 64 Bit Key Files. And are Made the Same way as the OPT Files Are Made. How Ever you can Enter a Trunked system without the syskey. You can do the Motorola Radios the same way also with out the Key File or Key Dongle. It's not all that Hard. Motorola system key generator.
Public key
Once we’re done with the ECDSA, all we need to do is to add the bytes
0x04 at the start of our public key. The result is a Bitcoin full public key, which is equal to: 041e7bcc70c72770dbb72fea022e8a6d07f814d2ebe4de9ae3f7af75bf706902a7b73ff919898c836396a6b0c96812c3213b99372050853bd1678da0ead14487d7 for us.
Compressed public key
But we can do better. As you might remember, the public key is some point (X, Y) on the curve. We know the curve, and for each X there are only two Ys that define the point which lies on that curve. So why keep Y? Instead, let’s keep X and the sign of Y. Later, we can derive Y from that if needed.
The specifics are as follows: we take X from the ECDSA public key. Now, we add the
0x02 if the last byte of Y is even, and the byte 0x03 if the last byte is odd.
In our case, the last byte is odd, so we add
0x03 to get the compressed public key: 031e7bcc70c72770dbb72fea022e8a6d07f814d2ebe4de9ae3f7af75bf706902a7 . This key contains the same information, but it’s almost twice as short as the uncompressed key. Cool!
Previously, wallet software used long, full versions of public keys, but now most of it has switched to compressed keys.
Encrypting the public key
From now on, we need to make a wallet address. Whatever method of getting the public key you choose, it goes through the same procedure. Obviously, the addresses will differ. In this article, we will go with the compressed version.
What we need to do here is to apply SHA-256 to the public key, and then apply RIPEMD-160 to the result. The order is important.
SHA-256 and RIPEMD-160 are two hash functions, and again, we won’t go into the details of how they work. What matters is that now we have 160-bit integer, which will be used for further modifications. Let’s call that an encrypted public key. For our example, the encrypted public key is
453233600a96384bb8d73d400984117ac84d7e8b .
Here’s how we encrypt the public key in Python:
Adding the network byte
The Bitcoin has two networks, main and test. The main network is the network that all people use to transfer the coins. The test network was created — you guessed it — to test new features and software.
![]()
We want to generate an address to use it on the mainnet, so we need to add
0x00 bytes to the encrypted public key. The result is 00453233600a96384bb8d73d400984117ac84d7e8b . For the testnet, that would be 0x6f bytes.
Checksum
Now we need to calculate the checksum of our mainnet key. The idea of checksum is to make sure that the data (in our case, the key) wasn’t corrupted during transmission. The wallet software should look at the checksum and mark the address as invalid if the checksum mismatches.
To calculate the checksum of the key, we need to apply SHA-256 twice and then take first 4 bytes of the result. For our example, the double SHA-256 is
512f43c48517a75e58a7ec4c554ecd1a8f9603c891b46325006abf39c5c6b995 and therefore the checksum is 512f43c4 (note that 4 bytes is 8 hex digits).
The code to calculate an address checksum is the following:
Getting the address
Finally, to make an address, we just concatenate the mainnet key and the checksum. That makes it
00453233600a96384bb8d73d400984117ac84d7e8b512f43c4 for our example.
That’s it! That’s the wallet address for the private key at the start of the article.
But you may notice that something is off. You’ve probably seen a handful of Bitcoin addresses and they didn’t look like that. Well, the reason is that they are encoded with Base58. It’s a little bit odd.
Here’s the algorithm to convert a hex address to the Base58 address:
What we get is
17JsmEygbbEUEpvt4PFtYaTeSqfb9ki1F1 , a compressed Bitcoin wallet address.
Conclusion
The wallet key generation process can be split into four steps:
Depending on the form of public key (full or compressed), we get different addresses, but both are perfectly valid.
Here’s the full algorithm for the uncompressed public key:
If you want to play with the code, I published it to the Github repository.
I am making a course on cryptocurrencies here on freeCodeCamp News. The first part is a detailed description of the blockchain.
I also post random thoughts about crypto on Twitter, so you might want to check it out.
Addressgen is a utility to generate private keys and their correspondingaddresses for cryptocurrencies based on secp256k1. Currently, only Bitcoin,Dogecoin, and Litecoin are supported, but in the future I will add support formore.
Addressgen is tested on Linux and Windows, requires Python 3.3 and a copy oflibeay32.dll (Windows, obtained from OpensSL packages) or libssl.so (linux,openssl package).
Public Private Key Encryption
Run 'python3 genaddress.py'
Generate Private Key From Bitcoin AddressArgumentsExamples
$ python3 genaddress.py
$ python3 genaddress.py -p 'correct horse battery staple'
$ python3 genaddress.py -t -c
Generate Private Key From Address Free
$ python3 genaddress.py -n doge
Comments are closed.
|
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |