No. Kaspa’s ordinary transaction signatures are not quantum-safe. Its wallets use Schnorr or ECDSA signatures, which rely on elliptic-curve mathematics. A sufficiently powerful quantum computer could break that protection when the public key is known, and an ordinary Kaspa address contains the public key itself, so it is visible as soon as the address is shared. [1][2] Kaspa has research experiments using post-quantum signatures, but these are not the same as making the whole network quantum-safe. [1]
What the risk means
A private key authorizes spending. A public key lets others check that authorization. The quantum threat is a computer powerful enough to defeat the mathematics that protects the private key. The kaspa-xmss research documentation describes this threat specifically for coins whose public keys are known. [1]
“Quantum-safe” therefore needs a clear scope. Replacing the signature that authorizes a payment addresses one problem. It does not, by itself, establish that every other part of a blockchain is protected.
What has actually been demonstrated
Maxim Biryukov developed a research experiment that implements XMSS^MT, a hash-based signature scheme, as a Kaspa spending condition. Its documentation identifies it as a NIST-standardized scheme under SP 800-208. Instead of relying on elliptic-curve mathematics, its security relies on properties of hash functions. [1]
The project documents a worked example on testnet 10, Kaspa’s testing network. In the documentation snapshot of 3 July 2026, the author reports that a payment signed with this post-quantum signature was accepted and confirmed on testnet 10, after a setup transaction created the coins the experiment uses. This is a research demonstration, not a standard wallet feature. [3]
There is an important complication: XMSS^MT is stateful. The signer must keep track of which one-time signing keys have been used. Signing twice with the same one-time key can leak it. The experiment uses two cooperating scripts and covenant rules to enforce that discipline. A covenant is a spending rule that also constrains what comes next. [1]
That is a useful detail behind the headline: choosing a post-quantum signature is only part of the work. Preventing unsafe reuse is also part of the design. [1]
Would hiding public keys solve it?
Hiding a public key behind a hash can reduce its exposure, but it is not the same as replacing a quantum-vulnerable signature.
In a discussion on 21 July 2025, Ori Newman argued that existing script-hash addresses, which show only a fingerprint of the spending rules until the coins are spent, could provide the public-key-hiding effect being proposed. Maxim Biryukov also described a new address format pointing to such a fingerprint without requiring a hard fork, a rule change every node must adopt. These were design discussions, not an announcement of a completed wallet rollout. [2]
How the founder described the upgrade approach
In his 21 August 2025 Bitcoin Takeover interview, Yonatan Sompolinsky said he was not a post-quantum cryptography expert. He described Kaspa as deliberately less conservative than Bitcoin about upgrades and argued that suitable changes should not need to take years. That was an explanation of his approach, not a promised activation date or a claim that Kaspa was already quantum-safe. [4]
Watch his answer in “S16 E41: Yonatan Sompolinsky on Bitcoin, Kaspa & Proof of Work,” from 5:10:30. [4]