国密SM2算法的加密签名消息语法封装解析p7格式signedData

前文可参考：SM2算法的加密签名消息语法规范（三）如何构造signedData_天对地，雨对风的博客-CSDN博客系列。

这里直接讲openssl asn1解析和封装的部分代码。

国密 p7格式标准，参考：GMT0010-2012

1、p7 签名结构：

编写结构体GMTSignedData.h

#ifndef _GMTSignedData_H
#define _GMTSignedData_H

#include <openssl\asn1.h>
#include <openssl\asn1t.h>
#include <openssl\safestack.h>
#include <openssl\evp.h>
#include <openssl\pkcs7.h>
#include <openssl\x509.h>

# ifdef __cplusplus
extern "C" {
# endif

/*oid refer to GM/T 0006*/
#define OID_SM2_1 "1.2.156.10197.1.301.1"           /*sm2-1 数字签名算法 */
#define OID_SM2_3 "1.2.156.10197.1.301.3"           /*sm2-3 公钥加密算法*/
#define OID_SM3 "1.2.156.10197.1.401"               /*SM3密码杂凑算法*/
#define OID_SM4 "1.2.156.10197.1.104"               /*SM4分组密码算法*/

/*oid refer to GM/T 0010*/
#define OID_SM2_Data               "1.2.156.10197.6.1.4.2.1"    //SM2算法消息语法规范- 数据类型
#define OID_SM2_Signed             "1.2.156.10197.6.1.4.2.2"    //SM2算法消息语法规范- 签名数据类型
#define OID_SM2_Enveloped          "1.2.156.10197.6.1.4.2.3"    //SM2算法消息语法规范- 数字信封数据类型  
#define OID_SM2_SignedAndEnveloped "1.2.156.10197.6.1.4.2.4"    //SM2算法消息语法规范- 签名及数字信封数据类型
#define OID_SM2_Encrypted          "1.2.156.10197.6.1.4.2.5"    //SM2算法消息语法规范- 加密数据类型
#define OID_SM2_KeyAgreementInfo   "1.2.156.10197.6.1.4.2.6"    //SM2算法消息语法规范- 密钥协商数据类型

typedef struct sm2_signed_st {
    ASN1_INTEGER *version;      /* version 1 */
    STACK_OF(X509_ALGOR) *md_algs; /* md used */
    struct SM2ContentInfo_st *contents;
    STACK_OF(X509) *cert;       /* [ 0 ] */
    STACK_OF(X509_CRL) *crl;    /* [ 1 ] */
    STACK_OF(PKCS7_SIGNER_INFO) *signer_info;
} SM2_SIGNED;

typedef struct SM2_SignedData_st {
    int type;
    union {
        /* NID_pkcs7_data */
        ASN1_OCTET_STRING *data;
        /* sm2_signed */
        SM2_SIGNED *sign;
        /* NID_pkcs7_enveloped */
        PKCS7_ENVELOPE *enveloped;
        /* NID_pkcs7_signedAndEnveloped */
        PKCS7_SIGN_ENVELOPE *signed_and_enveloped;
        /* NID_pkcs7_digest */
        PKCS7_DIGEST *digest;
        /* NID_pkcs7_encrypted */
        PKCS7_ENCRYPT *encrypted;
        /* Anything else */
        ASN1_TYPE *other;
    } d;
} SM2_SignedData;

DECLARE_ASN1_FUNCTIONS(SM2_SignedData)

typedef    struct SM2ContentInfo_st
{
    ASN1_OBJECT *type;
    SM2_SignedData* sd;
} SM2ContentInfo;

DECLARE_ASN1_FUNCTIONS(SM2ContentInfo)

#  ifdef  __cplusplus
}
#  endif

#endif    //_GMTSignedData_H

注意：SM2_SignedData_st结构中的sign类型修改为SM2_SIGNED，sm2_signed_st结构中的contents 类型修改为SM2_ContentInfo_st。

GMTSignedData.cpp

#pragma once

#include "stdafx.h"    
#include "GMTSignedData.h"

ASN1_NDEF_SEQUENCE(SM2_SIGNED) = {
        ASN1_SIMPLE(SM2_SIGNED, version, ASN1_INTEGER),
        ASN1_SET_OF(SM2_SIGNED, md_algs, X509_ALGOR),
        ASN1_SIMPLE(SM2_SIGNED, contents, SM2ContentInfo),
        ASN1_IMP_SEQUENCE_OF_OPT(SM2_SIGNED, cert, X509, 0),
        ASN1_IMP_SET_OF_OPT(SM2_SIGNED, crl, X509_CRL, 1),
        ASN1_SET_OF(SM2_SIGNED, signer_info, PKCS7_SIGNER_INFO)
} ASN1_NDEF_SEQUENCE_END(SM2_SIGNED)

IMPLEMENT_ASN1_FUNCTIONS(SM2_SIGNED)

ASN1_CHOICE(SM2_SignedData) =
{
    ASN1_SIMPLE(SM2_SignedData, d.data, ASN1_OCTET_STRING),
    ASN1_OPT(SM2_SignedData, d.sign, SM2_SIGNED),
    ASN1_OPT(SM2_SignedData, d.enveloped, PKCS7_ENVELOPE),
    ASN1_OPT(SM2_SignedData, d.signed_and_enveloped, PKCS7_SIGN_ENVELOPE),
    ASN1_OPT(SM2_SignedData, d.digest, PKCS7_DIGEST),
    ASN1_OPT(SM2_SignedData, d.encrypted, PKCS7_ENCRYPT),
    ASN1_OPT(SM2_SignedData, d.other, ASN1_ANY)
}ASN1_CHOICE_END(SM2_SignedData)
IMPLEMENT_ASN1_FUNCTIONS(SM2_SignedData)

ASN1_SEQUENCE(SM2ContentInfo) =
{
    ASN1_SIMPLE(SM2ContentInfo, type, ASN1_OBJECT),
    ASN1_EXP(SM2ContentInfo, sd, SM2_SignedData, 0)
}ASN1_SEQUENCE_END(SM2ContentInfo)
IMPLEMENT_ASN1_FUNCTIONS(SM2ContentInfo)

解码测试：

void test()
{
    //puchData为数据内容，nDataLen为数据长度。自行定义。
    SM2ContentInfo* p7 = NULL;

    p7 = d2i_SM2ContentInfo(&p7, &puchData, nDataLen);

    char oid1[255] = { 0 };
    OBJ_obj2txt(oid1, 255, p7->type, 0);
}

至此可以解码成功，编码参考其他文章。