[英]adding elements to array of structs in C
So for a crypto class, we are implementing Mental Poker with the SRA protocol. 因此,对于加密课程,我们正在使用SRA协议实施精神扑克。 We are using the openSSL library for BIGNUM http://www.openssl.org/docs/crypto/bn.html and I am having an issue when adding encrypted cards to an array of BIGNUM structs.
我们正在使用BIGNUM http://www.openssl.org/docs/crypto/bn.html的openSSL库,并且在将加密卡添加到BIGNUM结构数组时遇到问题。
#include <openssl/bn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
BIGNUM* encryptedDeck[52];
BIGNUM* bobHand[5];
BIGNUM* aliceHand[5];
int main(int argc, char* argv[]){
int lcv = 0;
BIGNUM *P,*Q,*N,*alpha,*alphaPrime,*beta,*betaPrime,*temp,*Pminus;
BN_CTX *ctx = BN_CTX_new();
P = BN_new(); //same for all BIGNUM pointers
BN_generate_prime(P,512,1,NULL,NULL,NULL,NULL);
BN_generate_prime(Q,512,1,NULL,NULL,NULL,NULL);
BN_generate_prime(alpha,128,1,NULL,NULL,NULL,NULL); //Alice's key [ gcd(alpha,P) = 1 ]
BN_generate_prime(beta,128,1,NULL,NULL,NULL,NULL); //Bob's key. Same rule as alice's
BN_one(temp); //set temp to be a BIGNUM equivalent to integer 1
BN_sub(Pminus,P,temp);
BN_mul(N,P,Q,ctx);
temp = BN_new();
BIGNUM *encryptedCard = BN_new();
for(lcv; lcv < 52; lcv++){
BN_bin2bn(deck[lcv],strlen(deck[lcv]),temp);
BN_mod_exp(encryptedCard,temp,beta,P,ctx); //encrypt temp, store in encryptedCard
printf("ec: %s\n\n",BN_bn2dec(encryptedCard)); //prints *correct numbers
encryptedDeck[lcv] = encryptedCard; //store cards in the array of encrypted cards
}
printf("00: %s\n\n",BN_bn2dec(encryptedDeck[0]));
printf("01: %s\n\n",BN_bn2dec(encryptedDeck[1]));
//...
printf("40: %s\n\n",BN_bn2dec(encryptedDeck[40]));
}
The print statement in the forloop prints 52 different values (1 for each card.) forloop中的print语句打印52个不同的值(每张卡1个)。
I intended for each of those values to simply be added to the array encryptedDeck, but when I check the values after exiting the loop, they are all equivalent to the 52nd card. 我打算将每个值简单地添加到数组encryptedDeck中,但是当我在退出循环后检查值时,它们都等同于第52张卡。 So for some reason, each index in the array is being overwritten for every new card?
所以出于某种原因,每个新卡都会覆盖数组中的每个索引? Or something weird like that.
或者类似的东西。
Is there some obvious thing that I am missing when dealing with arrays of structs? 在处理结构数组时,是否有一些显而易见的事情? The only thing that I would think of right off the bat is something about the array not being initialized with enough space or something.
我唯一能想到的就是没有用足够的空间或其他东西来初始化阵列。
I think that it is possible to convert the BIGNUM values into char* and store them in an array that way, but I tried to avoid this because I don't know how big the pointers need to be, or even have a guess of their range. 我认为可以将BIGNUM值转换为char *并将它们存储在数组中,但我试图避免这种情况,因为我不知道指针需要多大,甚至猜测它们范围。 something like
就像是
char encryptedDeck[52][something ridiculous];
I omitted some code, but I believe this should still compile (provided you have the openssl library, and link it when compiling) and fill in the BN_new() for all the other BIGNUM pointers that I didn't initialize. 我省略了一些代码,但我相信这仍然应该编译(假设您有openssl库,并在编译时链接它)并为我没有初始化的所有其他BIGNUM指针填充BN_new()。
Just above your for-loop: 就在你的for循环之上:
BIGNUM *encryptedCard = BN_new();
You never change what this points to. 你永远不会改变这指向的东西。 You just keep dropping new data into the same card, then save that card into the current slot of the for-loop.
您只需将新数据放入同一张卡中,然后将该卡保存到for循环的当前插槽中。
My surmise is to move the card inside the loop. 我的猜测是将卡内循环。
for(lcv; lcv < 52; lcv++){
BIGNUM *encryptedCard = BN_new();
BN_bin2bn(deck[lcv],strlen(deck[lcv]),temp);
BN_mod_exp(encryptedCard,temp,beta,P,ctx);
printf("ec: %p: %s\n\n",encryptedCard, BN_bn2dec(encryptedCard));
encryptedDeck[lcv] = encryptedCard;
}
Noted: I don't use this crypto library, so I can't tell you if temp
needs the same locality in the loop, but seems like where your problem may be. 注意:我没有使用这个加密库,所以我不能告诉你
temp
需要循环中的相同位置,但似乎你的问题可能在哪里。
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