RSASSAPSS

Overview

License: MIT

library RSASSAPSS

Cryptography module

This library provides functionality to verify RSASSA-PSS signatures with MGF1 mask generation function.

Users may provide custom hash functions via Parameters struct. However, the usage of sha256 is recommended. The RSASSA-PSS signature verification costs ~340k gas.

Learn more about the algorithm here.

Structs info

Parameters

struct Parameters {
    uint256 hashLength;
    uint256 saltLength;
    function (bytes) pure returns (bytes) hasher;
}

The RSASSA-PSS parameters.

Parameters:

Name	Type	Description
hashLength	uint256	the hash function output length in bytes.
saltLength	uint256	the pss encoding salt length in bytes.
hasher	function (bytes) pure returns (bytes)	the function-pointer to a custom hash function.

Functions info

verifySha256

function verifySha256(
    bytes memory message_,
    bytes memory s_,
    bytes memory e_,
    bytes memory n_
) internal view returns (bool)

Same as verify but with sha256 hash function preconfiguration.

verify

function verify(
    RSASSAPSS.Parameters memory params_,
    bytes memory message_,
    bytes memory s_,
    bytes memory e_,
    bytes memory n_
) internal view returns (bool)

Verifies RSAPSS-SSA signature with custom parameters.

Parameters:

Name	Type	Description
params_	struct RSASSAPSS.Parameters	The parameters to specify the hash length, salt length, and hash function of choice.
message_	bytes	The arbitrary message to be verified.
s_	bytes	The "encrypted" signature
e_	bytes	The public key exponent. 65537 is a recommended value.
n_	bytes	The modulus of a public key.