# Equivalent RSA modulus for NIST P-192 and P-521 elliptic curves [duplicate]

At www.keylength.com, I found the following table of ECC field size and the corresponding RSA modulus recommended by NIST.

ECC Modulus RSA Prime Size

160 1024

224 2048

256 3072

384 7680

512 15360

But NIST proposed P-192, P-224, P-256, P-384, P-521 curves. May I know what is equivalent RSA modulus for P-192 and P-521 curves?

So ECC-192 => 96 bits of security. $$\sqrt[0.43]{96 / 4}$$ = $$\sqrt[0.43]{24}$$ = $$1621$$, with $$1624$$ being the next highest number divisible by 8.
ECC-521 => 260.5 bits of security. $$\sqrt[0.43]{260.5 / 4}$$ = $$\sqrt[0.43]{65.125}$$ = $$16520.3$$, making $$16528$$ the equivalent, which is beyond most systems' maximum of 16384.