Bitcoin Forum

When one sign a text with private key, he can prove, that he had a text
If one will add a timestamp from some block
one can prove that he have that text before any other.

Oh yea? 

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

When one sign a text with private key, he can prove, that he had a text
If one will add a timestamp from some block
one can prove that he have that text before any other.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

iEYEARECAAYFAk7cTRwACgkQrIWTYrBBO/oc1gCfRV8cDcCPLhhAWcuCgD0MZUk9
/3QAoMF1Bdd+3iPSsu+FNMJEV7U9svWx
=auev
-----END PGP SIGNATURE-----


See. I had said it first. Proven.

Even back-dated about 6 hours. Nice.

Edit: Nevermind. The forum is using UTC for the time-stamp on posts.
Edit2: See, I was really first:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

When one sign a text with private key, he can prove, that he had a text
If one will add a timestamp from some block
one can prove that he have that text before any other.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQFN6rhFPPYMXhz9onsRAk6lAJ9KROC1FpJMHAqABzhe4uHKIWttsgCdFEWj
PN8OQlvYN8uCM7Qq3COEfNo=
=k+Qs
-----END PGP SIGNATURE-----

To go back any further, I would have had to back-date my signing key as well. Then there are archaeological considerations like: should I use the Debian "Weak keys" just for extra detail?

You mean this:
http://btcmsg.staticloud.com/

Sometimes a summary can help. I stopped reading at the Python interpreter written in JavaScript (http://btcmsg.staticloud.com/btcmsg.mozilla.cache.html) that took gedit about 60 seconds 4 minutes of CPU time to prettify. (Edit: the module 'msg' starts at line 22588) Edit2: It appears to use the MD5 hash function which is no longer considered cryptographically secure.

If you mean encoding short, human readable messages in the block-chain; I don't think that is what the OP was referring to. You can be a lot more subtle (https://bitcointalk.org/index.php?topic=28877.0) while proving you have access to a certain text with the block-chain. Simply take the SHA-2 hash, convert it into a public/private address pair, send a token amount to that address, then (optionally) spend the coins back to yourself.

That's so horrible... I opened that site and it made my computer sound like a jet engine.

Try etchablock.com (http://etchablock.com)!

etchablock.com (http://etchablock.com) is very inexpensive and will notify you the moment the transaction is sent and the moment it gets into a block.

You can leave tributes, write poems, or send love letters...How better to show someone your love is eternal! And your text can be read at blockexplorer.com or any other block chain viewer site.

Here is an example:

http://blockchain.info/tx-index/12752243/8f64d2b7a762767e3870c4aee95f8c7b5439cf02cf7d7e5d99b6e39967ecada8

Excellent idea, but I'm not sure whether a cryptographic hash (instead of the full text) would stand up in court. Are there any precedents for this?

I don't know the caselaw, but it is a variation on the old "mail yourself the transcript" (which can be cheated by mailing an unsealed envelope for later use).

The correct way to prove authorship is to register the work with the copyright office in your jurisdiction. Such registration still has the problem that registration only proves access to the transcript, not authorship. Cryptographic hashes do not improve on the process.

Nice!