Quote from: BusyBeaverHP on April 17, 2015, 07:34:57 AM

Quote from: Amph on April 16, 2015, 01:53:57 PM

now, public key are 128 bit

I'm still learning ECC, but considering that the X and Y coordinate of a bitcoin public key are both 256 bits resulting from point addition of 256-bit Generator Point, isn't a bitcoin public key technically 256 bit?

Reference: http://www.royalforkblog.com/2014/07/31/address-gen/

The only caveat I remember, is that even though a given ECC operates in 256-bit space, it has only the equivalent of 128-bits symmetric (e.g. AES) security.

The caveat explained by DeathAndTaxes here: https://bitcointalk.org/index.php?topic=1007619.msg10936084#msg10936084

it seems that it depend also on some wallet, for example on some client private key start from 128 key

here the reference https://en.bitcoin.it/wiki/Private_key

In Bitcoin, a private key is usually a 256-bit number (some newer wallets may use between 128 and 512 bits)

maybe it's the same for public keys