vc6.0rsa的数字签名C++

实现数字签名的方式有很多种，下面是使用 VC6.0 实现 RSA 数字签名的示例代码：

#include <windows.h>
#include <wincrypt.h>
#include <stdio.h>
#include <string.h>

#pragma comment(lib, "Crypt32.lib")

DWORD MyHandleError(char *s);

int main()
{
    HCRYPTPROV hProv = NULL;
    HCRYPTHASH hHash = NULL;
    HCRYPTKEY hKey = NULL;
    DWORD dwSigLen = 0;
    DWORD dwHashLen = 0;
    BYTE pbHash[1024] = { 0 };
    BYTE pbSignature[1024] = { 0 };
    CHAR szContainerName[] = "MyContainer";
    CHAR szProviderName[] = "Microsoft Enhanced Cryptographic Provider v1.0";
    CHAR szData[] = "This is a test data for signing";

    // acquire a handle to the default key container
    if (!CryptAcquireContext(&hProv, szContainerName, szProviderName, PROV_RSA_FULL, 0))
    {
        if (GetLastError() == NTE_BAD_KEYSET)
        {
            // create a new key container
            if (!CryptAcquireContext(&hProv, szContainerName, szProviderName, PROV_RSA_FULL, CRYPT_NEWKEYSET))
                MyHandleError("Error in acquiring context");
        }
        else
        {
            MyHandleError("Error in acquiring context");
        }
    }

    // create a hash object
    if (!CryptCreateHash(hProv, CALG_SHA1, 0, 0, &hHash))
        MyHandleError("Error in creating hash object");

    // hash the data
    if (!CryptHashData(hHash, (BYTE*)szData, strlen(szData), 0))
        MyHandleError("Error in hashing data");

    // determine the size of the signature
    if (!CryptSignHash(hHash, AT_SIGNATURE, NULL, 0, NULL, &dwSigLen))
        MyHandleError("Error in determining signature length");

    // allocate memory for the signature
    if (!CryptSignHash(hHash, AT_SIGNATURE, NULL, 0, pbSignature, &dwSigLen))
        MyHandleError("Error in signing hash");

    // verify the signature
    if (!CryptGetUserKey(hProv, AT_SIGNATURE, &hKey))
        MyHandleError("Error in getting user key");

    if (!CryptVerifySignature(hHash, pbSignature, dwSigLen, hKey, NULL, 0))
        MyHandleError("Error in verifying signature");

    printf("Signature verified successfully\n");

    // release resources
    if (hKey)
        CryptDestroyKey(hKey);

    if (hHash)
        CryptDestroyHash(hHash);

    if (hProv)
        CryptReleaseContext(hProv, 0);

    return 0;
}

DWORD MyHandleError(char *s)
{
    fprintf(stderr, "%s\n", s);
    exit(EXIT_FAILURE);
}

这段代码会创建一个 RSA 密钥对，使用 SHA1 哈希算法对数据进行哈希，然后对哈希值进行数字签名，并验证签名的正确性。在实际使用中，可以根据需要修改哈希算法和签名算法，以及相关的参数。