準備工作

命令列加密解密，用與比對程式碼中的演算法和命令列的演算法是否一致

C:\openssl_test>openssl rsautl -encrypt -in data.txt -inkey public.pem -pubin -out data.en
C:\openssl_test>openssl rsautl -decrypt -in data.en -inkey private.pem -out data.de

-pubin表示使用純公鑰加密

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>

#include <openssl/applink.c>
#pragma comment(lib, "libeay32.lib")
#pragma comment(lib, "ssleay32.lib")


int main()
{
	RSA *rsaKey;

	char fData[]="j23ur2jfsf-=20r034ujf";
	char tData[128];
	
	
	FILE *fp;
	fp = fopen("C:\\openssl_test\\public.pem", "r");

	int strLen = strlen(fData);
	
    rsaKey = PEM_read_RSA_PUBKEY(fp, NULL, NULL, NULL);
	int ret = RSA_public_encrypt(strLen, (unsigned char *)fData, (unsigned char*)tData, rsaKey, RSA_PKCS1_PADDING);
	//每次加密出來的tData都不一樣，因為填充了隨機數
	RSA_free(rsaKey);
	fclose(fp);

	//此段程式碼使用者比對，校驗命令列的加密
	//將結果寫入檔案，生成的檔案用命令列解密
	//openssl rsautl -decrypt -in pdata.en -inkey private.pem -out pdata.de
	fp = fopen("C:\\openssl_test\\pdata.en", "wb");
	fwrite(tData , ret, 1 , fp );
	fclose(fp);




	fp = fopen("C:\\openssl_test\\private.pem", "r");
	rsaKey = PEM_read_RSAPrivateKey(fp,NULL,NULL,NULL);
	ret = RSA_private_decrypt(128, (unsigned char *)tData, (unsigned char *)fData, rsaKey, RSA_PKCS1_PADDING);  

	
	fclose(fp);
	
	//此段程式碼用於比對，校驗命令列的解密
	//將命令列生成的加密檔案讀入記憶體，然後解密
	//openssl rsautl -encrypt -in data.txt -inkey public.pem -pubin -out data.en
	fp = fopen("C:\\openssl_test\\data.en", "rb");
	fread(tData , 128, 1 , fp );

	ret = RSA_private_decrypt(128, (unsigned char *)tData, (unsigned char *)fData, rsaKey, RSA_PKCS1_PADDING);  
	fclose(fp);
	

	RSA_free(rsaKey);
	return 0;   
}