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[1] XMSS: Extended Hash-Based Signatures,
draft-itrf-cfrg-xmss-hash-based-signatures-06
Release: July 2016.
https://datatracker.ietf.org/doc/
draft-irtf-cfrg-xmss-hash-based-signatures/?include_text=1
Provides XMSS_PublicKey and XMSS_PrivateKey classes as well as implementations
for the Botan interfaces PK_Ops::Signature and PK_Ops::Verification. XMSS has
been integrated into the Botan test bench, signature generation and verification
can be tested independently by invoking "botan-test xmss_sign" and
"botan-test xmss_verify"
- Some headers that are not required to be exposed to users of the library have
to be declared as public in `info.txt`. Declaring those headers private will
cause the amalgamation build to fail. The following headers have been
declared public inside `info.txt`, even though they are only intended for
internal use:
* atomic.h
* xmss_hash.h
* xmss_index_registry.h
* xmss_address.h
* xmss_common_ops.h
* xmss_tools.h
* xmss_wots_parameters.h
* xmss_wots_privatekey.h
* xmss_wots_publickey.h
- XMSS_Verification_Operation Requires the "randomness" parameter out of the
XMSS signature. "Randomness" is part of the prefix that is hashed *before*
the message. Since the signature is unknown till sign() is called, all
message content has to be buffered. For large messages this can be
inconvenient or impossible.
**Possible solution**: Change PK_Ops::Verification interface to take
the signature as constructor argument, and provide a setter method to be able
to update reuse the instance on multiple signatures. Make sign a parameterless
member call. This solution requires interface changes in botan.
**Suggested workaround** for signing large messages is to not sign the message
itself, but to precompute the message hash manually using Botan::HashFunctio
and sign the message hash instead of the message itself.
- Some of the available test vectors for the XMSS signature verification have
been commented out in order to reduce testbench runtime.
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