demo_rsaenc.c

使用OPENSSL进行 RSA加密解密例子

// demo how to enc a piece of data using RSA
//  by Linden 0:23 2003-11-15

#include <openssl/md5.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <string.h>

main()
{
	#define RSA_KEY_FILE "rsakey.txt"
		// > openssl genrsa -out rsakey.txt 1024
	RSA* key;
	char msg[]="i, i have no data to enc";
	char msg2[256];
	char msg3[256];
	int r;
	
	//SSL_library_init();
	//SSL_load_error_strings();
	//OpenSSL_add_all_algorithms();
	
	//key = RSA_new();

#if 1	// gen 
	puts("genrsa...(maybe a few seconds)");
	key = RSA_generate_key(1024, 65537, NULL, NULL);
	puts("ok");
#else	// read in
	{	 
#if 0  // 曾经ok过吗？忘了
		FILE *fp = fopen(RSA_KEY_FILE, "r");
		key = PEM_read_RSAPrivateKey(fp, &key, NULL, NULL);
#else
		int i;
		EVP_PKEY* k;
		BIO *in = BIO_new(BIO_s_file_internal());
		i = BIO_read_filename(in, RSA_KEY_FILE);
		if (i<=0) puts("read key file err");
		else
			k = PEM_read_bio_PrivateKey(in, NULL, NULL, NULL);	
		key = RSAPrivateKey_dup(k->pkey.rsa);
		EVP_PKEY_free(k);
		BIO_free(in);
#endif
	}
#endif

#if 0	// display.  there's err
	{
	//BIO *o = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
	 BIO *o = BIO_new(BIO_s_file());
	 RSA_print(o, key, 0);
	 BIO_free(o);
	}
#endif

	r = RSA_public_encrypt(strlen(msg), msg, msg2, 
		key, RSA_PKCS1_PADDING); //  or RSA_PKCS1_OAEP_PADDING
	if (!r)
		puts("error in enc");

#if 0
	sig[0]++; // 假想的错误
#endif

	r = RSA_private_decrypt(r, msg2, msg3, 
		key, RSA_PKCS1_PADDING);
	if (!r)
		puts("error in dec");

	if (memcmp(msg, msg3, strlen(msg)))
		puts("ERROR! text2 != text");
	else
	{
		msg3[strlen(msg)] = 0;
		printf("解密后的明文：%s", msg3);
	}

	puts("is there errs? no? ok!");

	RSA_free(key);

	return 0;
}