签名使用的hash算法为SHA256，填充规则用RSA-PSS

首先使用composer安装phpseclib/phpseclib指定版本1.0.19：

composer require phpseclib/phpseclib  1.0.19

php部分签名和验签 

    /**
     * 根据原文生成签名内容
     *
     * @param array $data 原文内容
     * @return string
     */
    public function sign($data = [])
    {
        $rsa = new Crypt_RSA();
        $rsa->loadKey($this->private_key);
        $rsa->setHash('sha256');
        $rsa->setMGFHash('sha256');
        $rsa->setSaltLength(32);  // CRYPT_RSA_SIGNATURE_PSS 需要设置 Salt 长度为32
        //设置签名模式 CRYPT_RSA_SIGNATURE_PKCS1 CRYPT_RSA_SIGNATURE_PSS
        $rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PSS); 
        $encrypted = $rsa->sign($data);
        //$encrypted = pack("H*",$encrypted);
        //$encrypted = bin2hex($encrypted);
        $signature = base64_encode($encrypted);
      
        return $signature;
    }

    /**
     * 验证签名是否正确
     *
     * @param string $data 签名的原文
     * @param string $signature 签名
     *
     * @return bool
     */
    function verifySign($data = '', $signature = '')
    {
        $rsa = new Crypt_RSA();
        $rsa->loadKey($this->public_key);
        $rsa->setHash('sha256');
        $rsa->setMGFHash('sha256');
        $rsa->setSaltLength(32);
        //设置签名模式 CRYPT_RSA_SIGNATURE_PKCS1 CRYPT_RSA_SIGNATURE_PSS
        $rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PSS); 
       
        $signature = base64_decode($signature);
        return $rsa->verify($data, $signature);
    }

python部分rsa签名与验签

import Crypto.PublicKey.RSA as RSA
import Crypto.Random
import Crypto.Hash.SHA256 as SHA256
from Crypto.Signature import PKCS1_PSS
from Crypto.Signature import PKCS1_v1_5
import base64
import json

PRIVATE_KEY = '-----BEGIN PRIVATE KEY-----\n' \
             '\n' \
             '-----END PRIVATE KEY-----'

PUBLIC_KEY = '-----BEGIN PUBLIC KEY-----\n' \
            '\n' \
            '-----END PUBLIC KEY-----'

# 签名
def sign(message, private_key):
    key = RSA.importKey(private_key)
    sha256 = SHA256.new()
    sha256.update(message)
    signer = PKCS1_PSS.new(key)
    # signer = PKCS1_v1_5.new(key)
    signature = signer.sign(sha256)

    return base64.b64encode(signature)


data = 'test'
# 字符串encode将获得一个bytes对象
data = str.encode(data)
a = sign(data, PRIVATE_KEY)
a = bytes.decode(a)
print(a)

# 验签
def verify(message, signature, public_key):
    signs = base64.b64decode(signature)
    key = RSA.importKey(public_key)
    sha256 = SHA256.new()
    sha256.update(message)
    verifier = PKCS1_PSS.new(key)
    return verifier.verify(sha256, signs)

b = verify(data, a, PUBLIC_KEY)
print(b)