c调用openssl从pem文件获取公钥私钥加解密

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define PUBLICKEY "public.pem"
#define OPENSSLKEY "private.pem"
#define BUFFSIZE 1024
char *my_encrypt(char *str, char *path_key); //加密
char *my_decrypt(char *str, char *path_key); //解密
int main(void)
{
	char *source = "i like dancing !!!";
	char *ptf_en, *ptf_de;
	printf("source is :%s\n", source);
	//1.加密
	ptf_en = my_encrypt(source, PUBLICKEY);
	if (ptf_en == NULL){
		return 0;
	}else{
		printf("ptf_en is :%s\n", ptf_en);
	}
	//2.解密
	ptf_de = my_decrypt(ptf_en, OPENSSLKEY);
	if (ptf_de == NULL){
		return 0;
	}else{
		printf("ptf_de is :%s\n", ptf_de);
	}
	if(ptf_en) free(ptf_en);
	if(ptf_de) free(ptf_de);
	return 0;
}
//加密
char *my_encrypt(char *str, char *path_key)
{
	char *p_en = NULL;
	RSA *p_rsa = NULL;
	FILE *file = NULL;
	int length = 0; //flen为源文件长度， rsa_len为秘钥长度
	//1.打开秘钥文件
	if((file = fopen(path_key, "rb")) == NULL)
	{
		perror("fopen() error 111111111 ");
		goto End;
	}
	//2.从公钥中获取 加密的秘钥
	if((p_rsa = PEM_read_RSAPublicKey(file, NULL,NULL,NULL )) == NULL)
	{
		ERR_print_errors_fp(stdout);
		goto End;
	}

	length = strlen(str);
	p_en = (char *)malloc(256);
	if(!p_en)
	{
		perror("malloc() error 2222222222");
		goto End;
	}
	memset(p_en, 0, 256);
	//5.对内容进行加密
	if(RSA_public_encrypt(length, (unsigned char*)str, (unsigned char*)p_en, p_rsa, RSA_PKCS1_PADDING) < 0)
	{
		perror("RSA_public_encrypt() error 2222222222");
		goto End;
	}
End:
	//6.释放秘钥空间， 关闭文件
	if(p_rsa) RSA_free(p_rsa);
	if(file) fclose(file);
	return p_en;
}
//解密
char *my_decrypt(char *str, char *path_key)
{
	char *p_de = NULL;
	RSA *p_rsa = NULL;
	FILE *file = NULL;
	//1.打开秘钥文件
	file = fopen(path_key, "rb");
	if(!file)
	{
		perror("fopen() error 22222222222");
		goto End;
	}
	//2.从私钥中获取 解密的秘钥
	if((p_rsa = PEM_read_RSAPrivateKey(file, NULL,NULL,NULL )) == NULL)
	{
		ERR_print_errors_fp(stdout);
		goto End;
	}

	p_de = (char *)malloc(245);
	if(!p_de)
	{
		perror("malloc() error ");
		goto End;
	}
	memset(p_de, 0, 245);
	//5.对内容进行解密
	if(RSA_private_decrypt(RSA_size(p_rsa), (unsigned char*)str, (unsigned char*)p_de, p_rsa, RSA_PKCS1_PADDING) < 0)
	{
		perror("RSA_public_encrypt() error ");
		goto End;
	}
End:
	//6.释放秘钥空间， 关闭文件
	if(p_rsa) RSA_free(p_rsa);
	if(file) fclose(file);
	return p_de;
}

编译：gcc sslrsa.c -o sslrsa.o -lcrypto