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2026-03-01
Crypto
Hard
DEADROP Crypto 4 - DSA Again?
Two DSA signatures from the same key share an identical r value, a dead giveaway of nonce reuse. Recover the private key, forge a signature over the target authorization message, and submit it to the server.
dsa
nonce-reuse
private-key-recovery
signature-forgery
2026-02-24
Crypto
Hard
WHAMazon! Crypto 5 - Signature Residue
Exploiting a weak (low) DSA nonce k to brute-force the signing secret, recover the private key x, and derive the flag via SHA-256.
dsa
low-nonce
private-key-recovery
signature