how to know if btc address is compressed or uncompressed ?

Mrhowie

newbie

Activity: 2

Merit: 0

Quote from: HCP on October 12, 2017, 11:54:56 PM

As far as I know, you can't start from the Address and work out if it is compressed/uncompressed. The address is the result of a one way hash, so you can't tell if it was created from a compressed or uncompressed public key.

You'd need to start with the private key and go from there... Have a play with https://www.bitaddress.org/ Generate a new private key and then put it into the "Wallet Details" tab... you'll see every private key generates a compressed and an uncompressed address.

You might be able to tell by looking at previous transactions involving those addresses on the blockchain and inspecting the input sizes... ~148 bytes = compressed... ~180 bytes = uncompressed

Thank you for the help Cheesy

DannyHamilton

legendary

Activity: 3472

Merit: 4801

Quote from: HCP on October 12, 2017, 11:54:56 PM

You'd need to start with the private key and go from there...

You don't need the private key to determine if the address is compressed or not. You only need the public key. Hash both the compressed and uncompressed versions of the public key (it is easy to convert between them) and see which one matches.

Quote from: HCP on October 12, 2017, 11:54:56 PM

You might be able to tell by looking at previous transactions involving those addresses on the blockchain and inspecting the input sizes... ~148 bytes = compressed... ~180 bytes = uncompressed

That method would work, however, the input scripts contain the public key. As long as bitcoins that had previously been received with that address have been spent, you could just look at the public key and see if it is compressed or not.

btctousd81

sr. member

Activity: 434

Merit: 270

Quote from: HCP on October 12, 2017, 11:54:56 PM

As far as I know, you can't start from the Address and work out if it is compressed/uncompressed. The address is the result of a one way hash, so you can't tell if it was created from a compressed or uncompressed public key.

You'd need to start with the private key and go from there... Have a play with https://www.bitaddress.org/ Generate a new private key and then put it into the "Wallet Details" tab... you'll see every private key generates a compressed and an uncompressed address.

You might be able to tell by looking at previous transactions involving those addresses on the blockchain and inspecting the input sizes... ~148 bytes = compressed... ~180 bytes = uncompressed

okie., thats one way to do it.,

so practically its a dead end. thanks for your input.

HCP

legendary

Activity: 2086

Merit: 4363

As far as I know, you can't start from the Address and work out if it is compressed/uncompressed. The address is the result of a one way hash, so you can't tell if it was created from a compressed or uncompressed public key.

You'd need to start with the private key and go from there... Have a play with https://www.bitaddress.org/ Generate a new private key and then put it into the "Wallet Details" tab... you'll see every private key generates a compressed and an uncompressed address.

You might be able to tell by looking at previous transactions involving those addresses on the blockchain and inspecting the input sizes... ~148 bytes = compressed... ~180 bytes = uncompressed

btctousd81

sr. member

Activity: 434

Merit: 270

lets say i have these addresses

1Az2dypSbg7oNv37mqao1T8vYJgQG1p7Be
1Esg276vGGT6LGxY7dEHvYLsp2efw6DgdX
1CS5EVQztBXuoiq9xgD3CkANngFePeWNnN

how can i check which one is compresed and which are uncompressed ?

thanks

Topic: how to know if btc address is compressed or uncompressed ? (Read 650 times)