Hi,
I have problem in RSA encrypt and decrypt using EVP methods.
My below program is some times working fine and some times it fails to
decrypt the message.
That means when i executing the below code 2 times working fine 3rd time it
fails to decrypt.
Please point out the error.
Code:
#include <iostream>
#include <string>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/engine.h>
EVP_PKEY *pkey = EVP_PKEY_new();
EVP_PKEY_CTX *ctx2;
unsigned char *out1;
size_t outlen1;
EVP_PKEY_CTX *ctx;
ENGINE *eng;
RSA *rsakey =RSA_new();
bool GenerateRsaKeyPair()
{
BIGNUM *bnexp = NULL;
unsigned long exp = RSA_F4;
bnexp = BN_new();
if(!BN_set_word(bnexp,exp))
{
std::cout <<"Failed to set exponent word in BIO."<<std::endl;
return false;
}
// generate rsa key with length of KEY_LENGTH bits
RSA_generate_key_ex(rsakey, 1024, bnexp, NULL);
if(!rsakey)
return false;
if(RSA_check_key(rsakey) <= 0)
{
std::cout <<"Generated RSA asymmetric key is
invalid."<<std::endl;
return false;
}
std::cout<<rsakey<<std::endl;
return true;
}
bool encrypt(const std::string& inMsg, std::string& outMsg, EVP_PKEY
*evpkey)
{
char *in = (char*)malloc(inMsg.size()+1);
size_t inlen = (size_t)inMsg.size();
strcpy(in, inMsg.c_str());
unsigned char *out;
size_t outlen;
ctx = EVP_PKEY_CTX_new(evpkey,NULL);
if (!ctx)
{
std::cout<<"error in pkey assign"<<std::endl;
}
if (EVP_PKEY_encrypt_init(ctx) <= 0)
{
std::cout<<"EVP_PKEY_encrypt_init failure "<<std::endl;
}
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
{
std::cout<<"error in padding"<<std::endl;
}
/* Determine buffer length */
if (EVP_PKEY_encrypt(ctx, NULL, &outlen, (const unsigned char*)in, inlen)
<= 0)
{
std::cout<<"error in encrypt length"<<std::endl;
}
out = (unsigned char*)OPENSSL_malloc(outlen);
if (!out)
{
std::cout<<" malloc failure "<<std::endl;
}
if (EVP_PKEY_encrypt(ctx, out, &outlen, (const unsigned char*)in, inlen) <=
0)
{
std::cout<<"error in encrypt"<<std::endl;
}
std::cout<<"output length: "<<outlen<<std::endl;
std::cout<<"output: "<<out<<std::endl;
outMsg.assign((const char*)out, outlen);
}
bool decrypt(const std::string& inMsg, EVP_PKEY *evpkey)
{
char *out = (char*)malloc(inMsg.size()+1);
size_t outlen = (size_t)inMsg.size();
strcpy(out, inMsg.c_str());
ctx2 = EVP_PKEY_CTX_new(evpkey,NULL);
if (!ctx2)
{}
if (EVP_PKEY_decrypt_init(ctx2) <= 0)
{}
if (EVP_PKEY_CTX_set_rsa_padding(ctx2, RSA_PKCS1_PADDING) <= 0)
{}
/* Determine buffer length */
if (EVP_PKEY_decrypt(ctx2, NULL, &outlen1, (const unsigned char*)out,
outlen) <= 0)
{}
std::cout<<"dec output length: "<<outlen1<<std::endl;
out1 = (unsigned char*)OPENSSL_malloc(outlen1);
if (!out)
{} /* malloc failure */
if (EVP_PKEY_decrypt(ctx2, out1, &outlen1, (const unsigned char*)out,
outlen) <= 0)
{}
out1[outlen1] = '\0';
std::cout<<"dec output length: "<<outlen1<<std::endl;
std::cout<<"dec output: "<<out1<<std::endl;
}
int main()
{
RSA* rsamainkey = RSA_new();
EVP_PKEY *key= EVP_PKEY_new();
std::string in = "Hello encrypt this message test from main.";
std::string ctext;
GenerateRsaKeyPair();
rsamainkey = rsakey;
std::cout<<"main rsa key: "<<rsamainkey<<std::endl;
if(!EVP_PKEY_assign_RSA(key, rsamainkey))
std::cout<<"error in assign rsa."<<std::endl;
std::cout<<"key: "<<key<<std::endl;
encrypt(in, ctext, key);
std::cout<<"ctext: "<<ctext<<std::endl;
decrypt(ctext, key);
}
--
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