After EIP 198 introduction, how much gas is required for RSA signature verification in solidity?

Question

Thanks to the introduction of EIP 198, RSA signature verification is now feasible in Ethereum.

How much gas is required for such a verification?

Answer 1

You can read about it here: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-198.md

A 4096-bit RSA exponentiation would cost mult_complexity(512) * 4095 / 100 = 22853376 gas in the worst case, though RSA verification in practice usually uses an exponent of 3 or 65537, which would reduce the gas consumption to 5580 or89292, respectively.

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According with the first example of the EIP, the function modExp() implemented here and the inputs:

0x03
0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2e
0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f

the execution cost was 14248 gas.