Because the legacy on-chain redemption mechanism was insecure once Attain closed, the team "swept" the unredeemed vouchers off-chain, re-verifying claimants through local counsel and exchange partners.
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Cardano Founder Reflects On Betrayal, Plans To Step Back
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Charles Hoskinson explained that after Attain Corporation’s closure, IOG deemed the legacy redemption process insecure and conducted an off-chain sweep of unclaimed ADA, revalidating eligible buyers through legal and exchange partners as a consumer protection step
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