Re: [CFRG] Questions for the group from the HPKE presentation

Richard Barnes <> Fri, 06 August 2021 22:49 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 47DA93A1C01 for <>; Fri, 6 Aug 2021 15:49:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.896
X-Spam-Status: No, score=-1.896 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id ZgPM7IOuYyGn for <>; Fri, 6 Aug 2021 15:49:35 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:4864:20::82c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 566BA3A1BFE for <>; Fri, 6 Aug 2021 15:49:35 -0700 (PDT)
Received: by with SMTP id c6so3381783qtv.5 for <>; Fri, 06 Aug 2021 15:49:35 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MCWzPzjRlt2VlppGG4FL8gWZgmjk8lXCs+fFUQreg0E=; b=zbnRgBVYRf4cdWQ0dTeq8ftpTwyFLAlIqCGSqNWjsZlojr4tMweJwobDkqHnJL7hoi qDFctmhnqEW1cZGwyXi9ldJfoWvdiJcad57xeK3dRokDvYNaM1Wy5iQuqLODisF/kVoo Ein+zAlQY019Jk6/YxFQad59oqIo1Lnqy0uWZnlTLLoTwybHIhM6sMIB1Bdaf+ArBm3V mJNsB5LxX9DpaRnDTeahfGbsXx277DTrX+QNf1Dhdc89SPfIU5pmX5BukxPH+Jp3lMuT LrwODfK9rJxxBJ3BXqfsG6dZXvZkVt1N03fBQfO5cEZu+3up64ze/BE/Li6+hTrhzUbe Exew==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MCWzPzjRlt2VlppGG4FL8gWZgmjk8lXCs+fFUQreg0E=; b=cm2WpfWByfcaJBj9xus6lzKjT7Kkfg4NCPVQl1yAZNROSKiCt8J3y1S8H2UneES6HW 8vkDzTIvCUs0yw5PVCfEJ3RDaZGCVsNo7I3iP0udhKYpiQBAKezYpc5lVglOBnepAFnp DsQL9TFE6EvhcYuPDJwD6doweVN/g6Zv/TkeE56BWD8CtaVYcnbUZA7WSs65FABiTzsj IGiN5aF9jfCwjjJwHV3YsjbVBQuIqqLpSlncK7Cvz/RZp+rpGVVoz/4izCyBh7d0Ngf1 bXiF4D+ZkgHK3GJayzxpk7pJvsO1y+/lpp5mDutaIG5jyPxdlAECijx/DySXwxrWg3GJ /NwQ==
X-Gm-Message-State: AOAM532YeVuAl2swGf29HIeBf3LA+z66P/b2yK2+wPuesp4HRIiammot ppPj+JLz8sY06UHaQ+Llktfojs5+vab2jipRVaV65Q==
X-Google-Smtp-Source: ABdhPJz9QRYcTjtDlUbqgxLjDXrgt26jiPnxaF3tjtGXo1icUJR+Rg9//ZL1tL4hzOP8QR/Qn0/NOQn5H18ibfMdBXs=
X-Received: by 2002:ac8:7c44:: with SMTP id o4mr11129627qtv.191.1628290173580; Fri, 06 Aug 2021 15:49:33 -0700 (PDT)
MIME-Version: 1.0
References: <>
In-Reply-To: <>
From: Richard Barnes <>
Date: Fri, 6 Aug 2021 12:49:21 -1000
Message-ID: <>
To: Nick Sullivan <>
Cc: CFRG <>, Dan Harkins <>
Content-Type: multipart/alternative; boundary="00000000000063506a05c8ebd99d"
Archived-At: <>
Subject: Re: [CFRG] Questions for the group from the HPKE presentation
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Crypto Forum Research Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 06 Aug 2021 22:49:40 -0000

1. I don't think this question is well-formed.  HPKE isn't an API, it is a
construction.  In fact, the "API considerations" section of the HPKE spec
is there precisely because there might be different APIs to an HPKE
implementation.  Given all that, I would be in favor of no action here.
There are several existing ways for an HPKE-based protocol to deal with
out-of-order delivery.

2. Personally, I don't have a use case for either of these.

On Fri, Aug 6, 2021 at 12:31 PM Nick Sullivan <nick=> wrote:

> Dear CFRG participants,
> At IETF 111, Dan Harkins made a presentation
> <>
> with two proposals:
> - a proposal to define new codepoints for HPKE representing new KEMs for
> compressed NIST points
> - a proposal to define new codepoints to support deterministic
> authenticated encryption schemes that don't use a nonce. This is in service
> of the use case of out-of-order delivery of ciphertexts. *In the
> discussion, it was noted that HPKE uses a nonce to ensure that it never
> leaks whether the same plaintext was encrypted twice and that this proposal
> does not provide this security property.*
> Also during the discussion, an alternative proposal was made to solve the
> out-of-order use case: modify the API for HPKE to enable the user to reset
> the nonce counter. This API would enable out-of-order delivery of
> ciphertexts with existing HPKE AEADs.
> The chairs would like to ask the group a few questions:
> 1) Does the research group support adding an API to HPKE for resetting the
> nonce counter?
> 2) Is there interest in pursuing a work item to explore defining either of
> the following:
> - new codepoints for compressed curve points in HPKE?
> - new codepoints for deterministic authenticated encryption in HPKE (given the
> answer to (1) was no)?
> Regards,
> Nick (for the chairs)
> _______________________________________________
> CFRG mailing list