From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1X6xfi-0000Ax-CZ for bitcoin-development@lists.sourceforge.net; Tue, 15 Jul 2014 08:01:10 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of bitpay.com designates 74.125.82.50 as permitted sender) client-ip=74.125.82.50; envelope-from=jgarzik@bitpay.com; helo=mail-wg0-f50.google.com; Received: from mail-wg0-f50.google.com ([74.125.82.50]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1X6xfg-0007ZQ-BZ for bitcoin-development@lists.sourceforge.net; Tue, 15 Jul 2014 08:01:10 +0000 Received: by mail-wg0-f50.google.com with SMTP id n12so5105493wgh.33 for ; Tue, 15 Jul 2014 01:01:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:from:date:message-id:subject:to :content-type; bh=pvY6GkYRCzvG6tcUGN5KwOofpFHSd4Pw+dWZRVGAxho=; b=igvnR0z2Y7KFmtIQt/FT1x7Sw3pIR6ArHH9W6BqpdXccffd9oBmq7IExuaijOA9eMK bmUETMS/ecE8HyDD9m7coDZHBTm6OYMU45q1Rn7Am8RbOk64SZs3bNWiVZqUkQGe8kUl ex9gLrw0eo4hNzbNigH7RcCS+ZDi3u3Qn+xsny4dG8v/nze4fHpOSOkFNX350xn7v1Ok 6Kfsj1E9+eH9NRMGxngblyMy1ZMycmfmGsJ2qH6JKQ9WFOpXfjaTIb+LXpKNzxfemf19 f+JN/Dch0DtGlXTey4cIaWu5aUi7uTwha9+ukVXNue0bXIiQaY0PWcYl4BXH1QKkLoB9 nODA== X-Gm-Message-State: ALoCoQniSXX6ZAnD1CJr0gLmmUHHmdgR5EK80NScHXOJkYdt3/zP6o8mrwtrU6YeKVRnKrYcSTTk X-Received: by 10.194.205.65 with SMTP id le1mr25315487wjc.67.1405411261836; Tue, 15 Jul 2014 01:01:01 -0700 (PDT) MIME-Version: 1.0 Received: by 10.194.5.67 with HTTP; Tue, 15 Jul 2014 01:00:41 -0700 (PDT) From: Jeff Garzik Date: Tue, 15 Jul 2014 04:00:41 -0400 Message-ID: To: Bitcoin Dev Content-Type: text/plain; charset=UTF-8 X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1X6xfg-0007ZQ-BZ Subject: [Bitcoin-development] Bitcoin address TTL & key expiration? X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Jul 2014 08:01:10 -0000 Proxying another's idea, from CoinSummit. The request: It would be useful to limit the lifetime of a bitcoin address. Intentionally prevent (somehow) bitcoins being sent to a pubkey/pkh after the key expires. You could append "don't ["permit"|confirm] after X [time|block]" to the address I suppose. The metadata would not be digitally signed, but it would be hash-sealed. As "address" is a client-side notion, wallet clients would be the ones enforcing such a rule. Bitcoin protocol of course knows about keys, and key expiration is a well known and useful concept in public key cryptography. The best insertion point in the protocol for key expiration is an open question, if it's even a good idea at that level at all. Some flag "no more TxOuts exactly like this [after X block?]"? I readily admit I don't have good answers, but it does seem valuable IMO to * Prevent users from accidentally sending to an "expired" TxOut/pkh. This happens in the field. * Discourage address reuse * Enable sites that generate lots of keys to rotate ancient keys off their core systems. (HD wallets mitigate this) -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/