Mark Karpelès(@MagicalTux):SecondFi security issue wasn't a nonce reuse, or a weak key, but a public nonce used to sign keys. The Ed25519 standard defines how you are supposed to generate nonces, using a secret prefix. SecondFi didn't have a secret prefix at all, meaning anyone could derive the nonce by just seeing a signed transaction. Rolling your own crypto code is dangerous, I'm guessing the wallet wasn't audited, resulting in this problem going undetected. Read more at Tibane:

Mark Karpelès

@MagicalTux

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Mark Karpelès@MagicalTux

2026.06.25 16:18

SecondFi security issue wasn't a nonce reuse, or a weak key, but a public nonce used to sign keys. The Ed25519 standard defines how you are supposed to generate nonces, using a secret prefix. SecondFi didn't have a secret prefix at all, meaning anyone could derive the nonce by just seeing a signed transaction. Rolling your own crypto code is dangerous, I'm guessing the wallet wasn't audited, resulting in this problem going undetected. Read more at Tibane: