What is a Compressed and Uncompressed Bitcoin Address?
We can assume that most of us are already familiar with crypto, bitcoin, bitcoin wallets, bitcoin addresses, sending and receiving bitcoins into our wallets.
We know that for us to have control over our crypto wallet, we must have the private key to that wallet which we must store privately and in secret. From this private key, a public key is generated from which we derive our bitcoin wallet address.
A private key is used to derive a public key, and from that public key, the public address is derived. A private key when is used for derivation, gives out two outputs in the form of public-key which are x and y. Both are 32 bits, which is the same as the private key.
These outputs later can derive themselves into two outputs again, which are “Compressed public key” and “Uncompressed public key”.
For the compressed public key, it is of 33 bits, which is +1 with the 32 bits of x public key output. For the Uncompressed public key, it is 65 bits because it is calculated with the combination of both the former x and y public keys +1.
Now, from the compressed public key, a compressed public address is derived. While an uncompressed public address is derived from the uncompressed public key.
Both of these addresses are of 17 bits.
What’s The Difference?
Both of the addresses be compressed or uncompressed is derived from the same private key. Both are referred to the same wallet and hence any amount that is sent to either of the address gets sent to the same wallet. Except for smaller bits in the public key for compressed one, there is not much difference between them.
Which Is Better?
In terms of speed, transaction fees, definitely, the compressed address is much preferred because of its less number of value in bits, and hence transactions can get broadcasted and completed quicker. However, Bitcoin clients can only work with compressed addresses as long as they can support compressed public keys since the compressed public key is a new addition. The standard Bitcoin client 0.6 has started implementing the compressed public key.
We can see that the most advanced and recent wallets used by us can support compressed public keys and hence we can use compressed addresses for our transactions. This is an added advantage and there are practically not many disadvantages of using it over uncompressed public keys. However, apart from transaction speeds and fees, there isn’t much of an edge, while using an uncompressed address gives us more freedom since even the oldest of wallets and bitcoin clients support it!