从文件读公钥私钥进行rsa加解密

int test_rsa_crypt_from_file()
{
    char msg[]="i, i have no data to enc";
    char msg2[256];
    int r;

    //读公匙

    RSA *key;
    FILE *fp = fopen("publickey.pem", "r");
    //FILE *fp = fopen("public.txt", "r");//ok

    if(fp == NULL)
        printf("fp error!");
    key = PEM_read_RSAPublicKey(fp, NULL, NULL, NULL);

    r = RSA_public_encrypt(strlen(msg), (unsigned char *)msg, (unsigned char *)msg2, key, RSA_PKCS1_PADDING); // or RSA_PKCS1_OAEP_PADDING

    
    FILE *fp1 = fopen("msg2.txt", "w");
    fwrite(msg2,sizeof(unsigned char),r, fp1);
    fflush(fp1);


    printf("\nmsg2:\n");
    
    for(int i=0; i<r; i++)
    {
        printf("%02x", (unsigned char)msg2[i]);
    }
     printf("\n");

    return 1;
}

//解密

// ok

int test_rsa_decrypt_from_file()
{

    OpenSSL_add_all_algorithms(); //gengpeng-重要，有些算法必须这样初始化。



    //-------------------------------------------------------

    //需要openssl/applink.c文件

    //读私钥

    RSA *key;
    FILE *fp = fopen("private.txt", "r");
    if(fp == NULL)
        printf("fp error!");
    key = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);

    RSA_print_fp(stdout,key,11);
    //--------------------------------------------------------



    ///////////////////////////////////////////////////////////////

    //bio 读私匙

    BIO * bp = NULL;
    RSA * r = NULL;
    bp = BIO_new(BIO_s_file());
    BIO_read_filename(bp, "private.txt" );
    r = PEM_read_bio_RSAPrivateKey(bp, NULL, NULL, NULL);
    BIO_free_all(bp);
    
    RSA_print_fp(stdout,r,11);

    //读要解密的文件。

    unsigned char msg2[1000], msg3[100];
    int msg2len, msg3len;
    FILE *fpmsg = fopen("msg2.txt", "rb");
    msg2len = fread( msg2, sizeof(unsigned char), 1000, fpmsg );



    msg3len = RSA_private_decrypt(msg2len, (unsigned char *)msg2, (unsigned char *)msg3,
        key, RSA_PKCS1_PADDING);

    msg3[msg3len] = 0;
    printf("解密后的明文：\n%s\n", msg3);

    return 1;

}