RSA键是对称的,您可以使用任何一个作为私钥或公钥,只是您选择的一个问题(但DSA键不对称).下面的程序生成两个2048位长的RSA密钥,然后将它们保存到文件中并将它们读回到内存中.这应该给你的想法如何做到这一点.
#include
#include
#include
#include
#include
#include
#include
#include
#include
const char* pcszPassphrase = "open sezamee";
static void gen_callback(int iWhat, int inPrime, void* pParam);
static void init_openssl(void);
static void cleanup_openssl(void);
static int passwd_callback(char *pcszBuff,int size,int rwflag, void *pPass);
static EVP_PKEY* create_rsa_key(void);
static void handle_openssl_error(void);
int main(int argc, char **argv)
{
int iRet = EXIT_SUCCESS;
EVP_PKEY* pPrivKey = NULL;
EVP_PKEY* pPubKey = NULL;
FILE* pFile = NULL;
const EVP_CIPHER* pCipher = NULL;
init_openssl();
pPrivKey = create_rsa_key();
pPubKey = create_rsa_key();
if(pPrivKey && pPubKey)
{/* Save the keys */
if((pFile = fopen("privkey.pem","wt")) && (pCipher = EVP_aes_256_cbc()))
{
if(!PEM_write_PrivateKey(pFile,pPrivKey,pCipher,
(unsigned char*)pcszPassphrase,
(int)strlen(pcszPassphrase),NULL,NULL))
{
fprintf(stderr,"PEM_write_PrivateKey failed.\n");
handle_openssl_error();
iRet = EXIT_FAILURE;
}
fclose(pFile);
pFile = NULL;
if(iRet == EXIT_SUCCESS)
{
if((pFile = fopen("pubkey.pem","wt")) && PEM_write_PUBKEY(pFile,pPubKey))
fprintf(stderr,"Both keys saved.\n");
else
{
handle_openssl_error();
iRet = EXIT_FAILURE;
}
if(pFile)
{
fclose(pFile);
pFile = NULL;
}
}
}
else
{
fprintf(stderr,"Cannot create \"privkey.pem\".\n");
handle_openssl_error();
iRet = EXIT_FAILURE;
if(pFile)
{
fclose(pFile);
pFile = NULL;
}
}
if(iRet == EXIT_SUCCESS)
{/* Read the keys */
EVP_PKEY_free(pPrivKey);
pPrivKey = NULL;
EVP_PKEY_free(pPubKey);
pPubKey = NULL;
if((pFile = fopen("privkey.pem","rt")) &&
(pPrivKey = PEM_read_PrivateKey(pFile,NULL,passwd_callback,(void*)pcszPassphrase)))
{
fprintf(stderr,"Private key read.\n");
}
else
{
fprintf(stderr,"Cannot read \"privkey.pem\".\n");
handle_openssl_error();
iRet = EXIT_FAILURE;
}
if(pFile)
{
fclose(pFile);
pFile = NULL;
}
if((pFile = fopen("pubkey.pem","rt")) &&
(pPubKey = PEM_read_PUBKEY(pFile,NULL,NULL,NULL)))
{
fprintf(stderr,"Public key read.\n");
}
else
{
fprintf(stderr,"Cannot read \"pubkey.pem\".\n");
handle_openssl_error();
iRet = EXIT_FAILURE;
}
}
}
if(pPrivKey)
{
EVP_PKEY_free(pPrivKey);
pPrivKey = NULL;
}
if(pPubKey)
{
EVP_PKEY_free(pPubKey);
pPubKey = NULL;
}
cleanup_openssl();
return iRet;
}
EVP_PKEY* create_rsa_key(void)
{
RSA *pRSA = NULL;
EVP_PKEY* pKey = NULL;
pRSA = RSA_generate_key(2048,RSA_3,gen_callback,NULL);
pKey = EVP_PKEY_new();
if(pRSA && pKey && EVP_PKEY_assign_RSA(pKey,pRSA))
{
/* pKey owns pRSA from now */
if(RSA_check_key(pRSA) <= 0)
{
fprintf(stderr,"RSA_check_key failed.\n");
handle_openssl_error();
EVP_PKEY_free(pKey);
pKey = NULL;
}
}
else
{
handle_openssl_error();
if(pRSA)
{
RSA_free(pRSA);
pRSA = NULL;
}
if(pKey)
{
EVP_PKEY_free(pKey);
pKey = NULL;
}
}
return pKey;
}
void gen_callback(int iWhat, int inPrime, void* pParam)
{
char c='*';
switch(iWhat)
{
case 0: c = '.'; break;
case 1: c = '+'; break;
case 2: c = '*'; break;
case 3: c = '\n'; break;
}
fprintf(stderr,"%c",c);
}
int passwd_callback(char *pcszBuff,int size,int rwflag, void *pPass)
{
size_t unPass = strlen((char*)pPass);
if(unPass > (size_t)size)
unPass = (size_t)size;
memcpy(pcszBuff, pPass, unPass);
return (int)unPass;
}
void init_openssl(void)
{
if(SSL_library_init())
{
SSL_load_error_strings();
OpenSSL_add_all_algorithms();
RAND_load_file("/dev/urandom", 1024);
}
else
exit(EXIT_FAILURE);
}
void cleanup_openssl(void)
{
CRYPTO_cleanup_all_ex_data();
ERR_free_strings();
ERR_remove_thread_state(0);
EVP_cleanup();
}
void handle_openssl_error(void)
{
ERR_print_errors_fp(stderr);
}