Python 中使用 SHA256withRSA 的数字签名验证失败

Question

我正在尝试使用给定的证书文件验证离线 aadhaar KYC 验证应用程序的数字签名。

此说明在文档中给出以供验证。

Aadhaar 无纸化离线 e-KYC 下载后具有以下内容XML：

<OKY v=""n=""r=""i=""d=""e=""m=""g=""a=""s="" />

XSD 为上述 xml

<?xml version="1.0" encoding="UTF-8"?>
<xs:schemaxmlns:xs="http: www.w3.org="" 2001="" xmlschema"="" attributeformdefault="unqualified" elementformdefault="qualified" targetnamespace="http://www.uidai.gov.in/offlinePaperlesseKYC/1.0">
<xs:element name="OKY">
<xs:complextype>
<xs:attribute name="v" type="xs:string"/>
<xs:attribute name="n" type="xs:string"/>
<xs:attribute name="i" type="xs:string"/>
<xs:attribute name="d" type="xs:string"/>
<xs:attribute name="e" type="xs:string"/>
<xs:attribute name="m" type="xs:string"/>
<xs:attribute name="g" type="xs:string"/>
<xs:attribute name="a" type="xs:string"/>
<xs:attribute name="r" type="xs:string"/>
<xs:attribute name="s" type="xs:string"/>
</xs:complextype>
</xs:element>
</xs:schema>

Read the entire XML and separate the s=”xxxx” tag from it.

Use a signature validation algorithm leveraging “SHA256withRSA” based hashing and encryption technique

Signature value present in “s” tag, remaining XML (without "s" tag) and UIDAI public key (available here.) is to be fed to the algorithm to validate the digital signature.

组织提供的示例 C# 代码片段。 (PS :这也不起作用)

using System;
using System.Security.Cryptography.X509Certificates;
using System.Xml;

namespace test
{
class MainClass
{
    public static void Main(string[] args)
    {
        // link -> https://drive.google.com/file/d/1aSv3HJUFf5_42Z-FqpdVHEk5b3VA3T3D/view


        string XMLFilePath = "offlineaadhaar.xml"; //Get the XML file

// link -> https://drive.google.com/file/d/1FW4ciIhZqJuelOcGF2x6VaBCSDO9J-gM/view


string KeyFilePath = "okyc-publickey.cer"; //Get the public key certificate file

        XmlDocument ObjXmlDocument = new XmlDocument();
        ObjXmlDocument.Load(XMLFilePath); //Load the XML
        XmlAttributeCollection SignatureElement = ObjXmlDocument.DocumentElement.Attributes; //Get the all XML attribute
        string SignatureValue = SignatureElement.GetNamedItem("s").InnerXml; // Get Signature value

        SignatureElement.RemoveNamedItem("s");//Remove the signature "s" attribute from XML and get the new XML to validate

        /*----------------Read and parse the public key as string-----------------------*/
        X509Certificate2 ObjX509Certificate2 = new X509Certificate2(KeyFilePath, "public"); //Initialize the public ket certificate file

        Org.BouncyCastle.X509.X509Certificate objX509Certificate;
        Org.BouncyCastle.X509.X509CertificateParser objX509CertificateParser = new Org.BouncyCastle.X509.X509CertificateParser();

        objX509Certificate = objX509CertificateParser.ReadCertificate(ObjX509Certificate2.GetRawCertData());
        /*----------------End-----------------------*/

        /* Init alg */
        Org.BouncyCastle.Crypto.ISigner signer = Org.BouncyCastle.Security.SignerUtilities.GetSigner("SHA256withRSA");

        /* Populate key */
        signer.Init(false, objX509Certificate.GetPublicKey());

        /* Get the signature into bytes */
        var expectedSig = Convert.FromBase64String(SignatureValue);

        /* Get the bytes to be signed from the string */
        var msgBytes = System.Text.Encoding.UTF8.GetBytes(ObjXmlDocument.InnerXml);


        /* Calculate the signature and see if it matches */
        signer.BlockUpdate(msgBytes, 0, msgBytes.Length);
        bool Flag = signer.VerifySignature(expectedSig);            
        if (Flag)
        {
            Console.WriteLine("XML Validate Successfully");
        }
        else
        {
            Console.WriteLine("XML Validation Failed");
        }
    }
}
}

我正在尝试在 Python 中实施，但 XML 验证失败。我不确定是证书文件有误还是我的代码有问题。

这是我的 Python 代码：

import xml
import xml.etree.cElementTree as etree
from xml.etree import ElementTree
import OpenSSL
from cryptography import x509
from cryptography.hazmat.backends import default_backend
from Crypto.PublicKey import RSA
from base64 import b64encode, b64decode
from M2Crypto import BIO, RSA, EVP

xmlDoc = open('adhar.xml', 'r').read()
Tr = etree.XML(xmlDoc)
Tr.keys()
# ['s', 'r', 'a', 'g', 'm', 'e', 'd', 'i', 'n', 'v']

sign = Tr.get('s')
len(sign)
# 344

del Tr.attrib['s']

from M2Crypto import X509

x509 =X509.load_cert('ekyc_public_key.cer')
#x509 =X509.load_cert(cert4)
rsa = x509.get_pubkey().get_rsa()
pubkey = EVP.PKey()
pubkey.assign_rsa(rsa)

xmlstr = etree.tostring(Tr, encoding='utf8', method='xml')
#rstr=str(xmlstr)[45:][:-1]
#rstr = rstr.encode(encoding='utf-8')


# if you need a different digest than the default 'sha1':
pubkey.reset_context(md='sha256')
pubkey.verify_init()

# hashlib.sha256(message_without_sign).digest()
pubkey.verify_update(xmlstr)
if(pubkey.verify_final(b64decode(sign)) != 1):
    print('Digital Signeture not validated')
else: 
    print('Digital Signeture validated')

Answer 1

问题中的描述不足以完全指定签名生成/验证。当然需要对协议进行澄清；最好请求正式的描述。指定 XML digsig 并非毫无意义；您需要标准化的规范化、字符集等。最后，签名是按字节计算的，而不是 XML / 文本。

"SHA256withRSA"不是签名算法；这是 PKCS#1 v1.5 签名方案的（相当糟糕的）Java 名称。

这些都不是好兆头；你应该问一下协议是否已经过专家验证。

Python 中使用 SHA256withRSA 的数字签名验证失败

Digital Signature Verification failed using SHA256withRSA in Python

hash

cryptography

public-key

xml-signature

rsa-sha256