XMSS: Extended Hash-Based Signatures

Document Type Replaced Internet-Draft (individual)
Authors Andreas Huelsing  , Denis Butin  , Stefan-Lukas Gazdag  , Aziz Mohaisen 
Last updated 2015-09-22 (latest revision 2015-03-23)
Replaces draft-xmss
Replaced by RFC 8391, RFC 8391
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IESG IESG state Replaced by draft-irtf-cfrg-xmss-hash-based-signatures, draft-irtf-cfrg-xmss-hash-based-signatures
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This note describes the eXtended Merkle Signature Scheme (XMSS), a hash-based digital signature system. It follows existing descriptions in scientific literature. The note specifies the WOTS+ one-time signature scheme, a single-tree (XMSS) and a multi-tree variant (XMSS^MT) of XMSS. Both variants use WOTS+ as a main building block. XMSS provides cryptographic digital signatures without relying on the conjectured hardness of mathematical problems. Instead, it is proven that it only relies on the properties of cryptographic hash functions. XMSS provides strong security guarantees and, besides some special instantiations, is even secure when the collision resistance of the underlying hash function is broken. It is suitable for compact implementations, relatively simple to implement, and naturally resists side-channel attacks. Unlike most other signature systems, hash-based signatures withstand attacks using quantum computers.


Andreas Huelsing (a.t.huelsing@tue.nl)
Denis Butin (dbutin@cdc.informatik.tu-darmstadt.de)
Stefan-Lukas Gazdag (stefan-lukas_gazdag@genua.eu)
Aziz Mohaisen (amohaisen@verisign.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)