How difficult is it to break the OpenPGP 40 character long fingerprint?

Daniel Kahn Gillmor dkg at
Mon Jun 3 19:20:43 CEST 2013

On 06/03/2013 08:04 AM, Melvin Carvalho wrote:

> Bitcoin is essentially a ledger where you have an array of fingerprints
> (160 bit hashes of a public key) and a value (number of coins in wallet).

i thought that bitcoin didn't hash the public keys at all, but rather
used the full elliptic curve public key, since it is smaller than
comparably-strong RSA or DSA keys.  I don't know much about bitcoin
though so i could be mistaken here.

> Unfortunately bitcoin only supports ECDSA and not RSA.  But I wonder if a
> fingerprint of your GPG key could be used as the basis of a payment ledger?

The OpenPGP standard supports elliptic curve keys directly:

GnuPG will add support for these keys in version 2.1 (now in beta).  If
you wanted to make an assertion about your ownership of a given bitcoin
purse it seems like you might be able to do that.

however, the specific curves used seem to differ:

According to,

   For ECDSA the secp256k1 curve from is used. refers to NIST curve
P-256, which i think is different :/

Still, it seems like it wouldn't be difficult to use your OpenPGP
identity make assertions about your possession of any given bitcoin
wallet, they just wouldn't be digested into the global bitcoin
transaction log.

Does this address what you were asking about?  if not, what problem are
you trying to solve specifically?


PS your MUA seems to think that this list is named "Jay Litwyn on
GnuPG-Users <gnupg-users at>" -- you probably want to update your
addressbook :)

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