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4 votes
Accepted

How do I find the order of the subgroup in a Diffie-Hellman key exchange?

But I can't find what the value of q should be. For that group, the size of the subgroup is $q = (p-1)/2$. However, I do have these comments: That's a MODP group ...
poncho's user avatar
  • 148k
2 votes

DH Encrypt by XOR

Some observations: Curve25519 is only 255 bits effective. The top bit is always 0, so you leak 1 bit of secret. Elliptic-curve point coordinate is not uniformly distributed, which means there's bias ...
DannyNiu's user avatar
  • 9,490

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