C++用CNG从模和指数导入RSA公钥

ztmd8pv5  于 2023-04-01  发布在  其他
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我尝试使用CNG加密一些数据,并将公钥作为参数提供。当调用NCryptImportKey函数时,我得到NTE_BAD_DATA错误which isn't listed in the msdn page.
我的代码:

#include <iostream>
#include <Windows.h>
#include <Bcrypt.h>
#include <Ntstatus.h>
#include <string>
#include <vector>
#include "base64.h"

using std::string;
using std::vector;

struct MyRSAPublicBlob {
    BCRYPT_RSAKEY_BLOB blob;
    BYTE exponent[3];
    BYTE modulus[128];
    MyRSAPublicBlob(const vector<BYTE>& mod, const vector<BYTE>& exp)
    {
        blob.BitLength = (128 + 3) * 8;
        blob.Magic = BCRYPT_RSAPUBLIC_MAGIC;
        blob.cbModulus = 128;
        blob.cbPublicExp = 3;
        for (size_t i = 0; i < mod.size(); ++i) //copy BigEndian
            modulus[i] = mod[mod.size() - 1 - i];
        for (size_t i = 0; i < exp.size(); ++i) //copy BigEndian
            exponent[i] = exp[exp.size() - 1 - i];
    }
    MyRSAPublicBlob() { ; }

};

MyRSAPublicBlob b;

bool RSA_encrypt() {
    SECURITY_STATUS stat;
    NCRYPT_PROV_HANDLE hProv;
    NCRYPT_KEY_HANDLE hKey;

    stat = NCryptOpenStorageProvider(&hProv, MS_KEY_STORAGE_PROVIDER, 0);
    if (ERROR_SUCCESS != stat) {
        std::cout << "failed in NCryptOpenStorageProvider: " << GetLastError() << std::endl;
        return false;
    }
    stat = NCryptImportKey(hProv,
        NULL,
        BCRYPT_RSAPUBLIC_BLOB,
        NULL,
        &hKey,
        (PBYTE)&b.blob,
        sizeof(b),
        0);

    if (ERROR_SUCCESS != stat) {
        std::cout << "failed in NCryptImportKey: " << GetLastError() << std::endl;
        return false;
    }

我如何构建MyRSAPublicBlob的示例:

string PubKeyModulus = "yVUndgQFuB5Z5FgC0/WgWCg6Y8VuB582avGjQDdeoJDa1+RBKCyXo700sAMSGjM/bVakOlFqvCsVFNBysx1CH731CDb2DR1a0bsmYmDQ9d0ZHX+AOohVDIx9mc7bkDQZoEFpe9NqFsu95Y9yktpl1JKPmKyLOFgufGJYYvQyoOM=";
string PubKeyExp = "AQAB";

vector<BYTE> PubKeyModulus_bin = base64_decode(PubKeyModulus);
vector<BYTE> PubKeyExp_bin = base64_decode(PubKeyExp);
struct MyRSAPublicBlob c(PubKeyModulus_bin, PubKeyExp_bin);
b = c;

我做错什么了吗?

slsn1g29

slsn1g291#

RSA公钥BLOB(BCRYPT_RSAPUBLIC_BLOB)在连续内存中具有以下格式。请尝试使用#pragma pack以避免任何填充问题。例如,

#pragma pack(push, 1)
struct MyRSAPublicBlob {
    BCRYPT_RSAKEY_BLOB blob;
    BYTE exponent[3];
    BYTE modulus[128];
...};
#pragma pack(pop)
uz75evzq

uz75evzq2#

BitLength值是“密钥的大小”,对于RSA来说,这意味着“模值的大小”。所以它与cbModulus有点冗余,但这就是生活。
如果你在计算BitLength时删除+ 3,它可能会开始工作。与.NET为RSACng.ImportParameters构建blob相比:http://source.dot.net/#System.Security.Cryptography.Cng/Common/System/Security/Cryptography/RSACng.ImportExport.cs,79

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