Does the application of Shor's algorithm in any way relate/affect the schnorr signature in ed25519?
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$\begingroup$ Your question is a bit unclear. Are you asking whether Shor's algorithm breaks the Schnorr signatures over Curve25519? Ed25519 signatures are btw related but distinct from Schnorr signatures. $\endgroup$ – Maeher Mar 6 '18 at 1:21
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$\begingroup$ Hi Maeher, the answer from Squeamish is exactly on point. thanks. $\endgroup$ – Nathan Aw Mar 6 '18 at 7:10
Shor's algorithm can compute discrete logs in elliptic curves and thereby recover the secret scalar from a public Ed25519 key, which you can use to forge signatures of your choice.
So, yes, it affects Ed25519—it completely breaks Ed25519, or it would if you could engineer a quantum computer capable of executing it.
It can also compute discrete logs in finite fields, which you can use to forge traditional finite-field Schnorr signatures.