eprint.iacr.org/2025/692.pdfAn interactive aggregate signature scheme allows n signers, each with their own
secret/public key pair (ski, pki
) and message mi, to jointly produce a short signature that
simultaneously witnesses that mi has been signed under pki
for every i ∈ {1, . . . , n}. Despite
the large potential for savings in terms of space and verification time, which constitute the
two main bottlenecks for large blockchain systems such as Bitcoin, aggregate signatures have
received much less attention than the other members of the multi-party signature family,
namely multi-signatures such as MuSig2 and threshold signatures such as FROST.
In this paper, we propose DahLIAS, the first aggregate signature scheme with constant-size
signatures—a signature has the same shape as a standard Schnorr signature—directly based
on discrete logarithms in pairing-free groups. The signing protocol of DahLIAS consists of two
rounds, the first of which can be preprocessed without the message, and verification (for a
signature created by n signers) is dominated by one multi-exponentiation of size n + 1, which
is asymptotically twice as fast as batch verification of n individual Schnorr signatures.
DahLIAS is designed with real-world applications in mind. Besides the aforementioned benefits
of space savings and verification speedups, DahLIAS offers key tweaking, a technique commonly
used in Bitcoin to derive keys in hierarchical deterministic wallets and to save space as well as
enhance privacy on the blockchain. We prove DahLIAS secure in the concurrent setting with
key tweaking under the (algebraic) one-more discrete logarithm assumption in the random
oracle model.