c - OpenSSL 1.1.0 中的 EVP_get_cipherbyname 和 "undefined struct/union evp_cipher_st"

Question

我正在尝试将 openssl 与 visual studio c 项目一起使用。

我使用 visual studio nmake 命令编译了 openssl，然后使用以下命令将所有内容安装到预定义的文件夹 (C:\openssl):

nmake install

文件夹结构如下:

• bin

• include/openssl

• 库

在include/openssl里面有.h头文件。

在我的 Visual Studio 2012 中，我创建了一个空的通用 C++ 项目并包含 C:\openssl\include

[Project properties -> C/C++ -> General -> Additional Include Directories]

我还添加了 lib 目录和 .lib 文件。

但是当我编译代码时，我得到了

left of 'key_len' specifies undefined struct/union 'evp_cipher_st'

在我的代码中有这些行

const EVP_CIPHER *cipher = EVP_get_cipherbyname("aes-256-cbc");
//some other code
return cipher->key_len;

查看 ossl_typ.h 文件中的 evp_cipher_st 定义，它被声明为

typedef struct evp_cipher_st EVP_CIPHER;

并且结构体没有定义!

进一步深入源代码树，evp_cipher_st 定义在 crypto\include\internal\evp_int.h 中，它不包含在 openssl 安装文件夹的 include 文件夹中。

我还尝试开箱即用地包含 crypto\include\internal\evp_int.h，但它会导致更多问题。

知道如何解决这个问题吗？

更新:

这是完整的函数和我的主要包括所有包含:

#include <winsock2.h>
#include <Ws2tcpip.h>
#include <mswsock.h>
#include <windows.h>
#include <minwindef.h>
#include <malloc.h>
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
typedef int socklen_t;
#include "wingetopt.h"
#include <Wincrypt.h>
#include <iphlpapi.h>
#include "Shlwapi.h"
#include <Bcrypt.h>

#define inline __inline
#define STATUS_SUCCESS 0

#pragma comment(lib, "iphlpapi.lib")
#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "Shlwapi.lib")

#include <sys/stat.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdarg.h>
#include <fcntl.h>
#include <time.h>

int generate_aes_key(const unsigned char *input_key, uint16_t input_key_size,
            unsigned char *output_key, uint16_t *outputkey_size) {

        const EVP_MD *dgst = NULL;
        unsigned char iv[EVP_MAX_IV_LENGTH];
        const EVP_CIPHER *cipher = EVP_get_cipherbyname("aes-256-cbc");

        if(!cipher) {

            return -1;
        }

        dgst = EVP_get_digestbyname("sha256");

        if(!dgst) {

            fprintf(stderr, "no such digest\n");
            return -2;
        }

        if(!EVP_BytesToKey(cipher, dgst, NULL, input_key, input_key_size, 1, output_key, iv)) {

            return -3;
        }

        *outputkey_size = (uint16_t)cipher->key_len;

        return 0;
}

int main(int argc, char *argv[]) {

    char secret[] = "MIIFBTCCAu2gAwIBAgICEAAwDQYJKoZIhvcNAQELBQAwTjELMAkGA1UEBhMCR0Ix";

    unsigned char shared_secret[500];
    uint16_t aes_keylen = 0;

    //bunch of codes 

    if(generate_aes_key((unsigned char *)secret, strlen(secret), shared_secret, &aes_keylen) < 0) {

        fprintf(stderr, "Could not get initial shared secret\n");
        return 0;
    }

    //other codes
}

Openssl 版本是:

OpenSSL_1_1_0-pre6-1266-g487d3a726

以上版本是git最新的标签名，我认为是目前为止最新鲜的。最新提交版本和日期如下:

487d3a726a1970e84853434561d88cb4ac212d15

Author: EasySec Date: Tue Jan 17 17:21:55 2017 +0100

最后是 Visual Studio 2012 编译输出:

Build started 1/28/2017 8:23:02 PM.
 1>Project "C:\CODE\mycode.vcxproj" on node 2 (Build target(s)).
 1>ClCompile:
     C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\bin\CL.exe /c /I"c:\openssl\include" /ZI /nologo /W3 /WX- /Od /Oy- /D _MBCS /Gm /EHsc /RTC1 /MDd /GS /fp:precise /Zc:wchar_t /Zc:forScope /Fo"Debug\\" /Fd"Debug\vc110.pdb" /Gd /TC /analyze- /errorReport:prompt src\main.c ... 

     wingetopt.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     crypto.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
 1>c:\CODE\src\crypto.c(517): error C2037: left of 'key_len' specifies undefined struct/union 'evp_cipher_st'
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     client.c
 1>c:\openssl\include\openssl\lhash.h(198): warning C4090: 'function' : different 'const' qualifiers
     Generating Code...
 1>Done Building Project "C:\CODE\mycode.vcxproj" (Build target(s)) -- FAILED.

Build FAILED.

Time Elapsed 00:00:08.55

Answer 1

您可以使用以下方式获取 key 长度:

*outputkey_size = EVP_CIPHER_key_length(cipher);

将下一行放在代码的末尾:

printf("Key-size: %d\n", aes_keylen);
printf("Key: "); for (int i = 0; i<aes_keylen; ++i) { printf("%02x", shared_secret[i]); } printf("\n");

它打印出正确的输出，接下来是:

Key-size: 32
Key: 51ae3ac4721439302cc5f90313f440bd9ca714c9a80b2213d034c87c00a700a0

我不确定 key_len 在以前的版本中是否可用，但在 openssl-1.10 release notes 中你可以阅读:

• Most libcrypto and libssl public structures were made opaque, including: BIGNUM and associated types, EC_KEY and EC_KEY_METHOD, DH and DH_METHOD, DSA and DSA_METHOD, RSA and RSA_METHOD, BIO and BIO_METHOD, EVP_MD_CTX, EVP_MD, EVP_CIPHER_CTX, EVP_CIPHER, EVP_PKEY and associated types, HMAC_CTX, X509, X509_CRL, X509_OBJECT, X509_STORE_CTX, X509_STORE, X509_LOOKUP, X509_LOOKUP_METHOD
• libssl internal structures made opaque

这意味着不再允许应用程序查看结构变量内部。这就是 _key_len(和其他)显示未定义的原因。