如何從PKCS7.p7b證書文件中讀取證書文件usind openssl？

Question

我正在獲取PKCS7文件（p7b）。我想讀取文件的內容並在X509結構中提取證書。

如何使用openssl庫從PKCS容器訪問單個證書？

Answer 1

我用下面的程序：

#include <stdio.h> 
#include <openssl/pkcs7.h> 
#include <openssl/x509.h> 
#include <openssl/bio.h> 
#include <openssl/pem.h> 

int main(int argc, char **argv) 
{ 
    PKCS7 *p7 = NULL; 
    BIO *in = BIO_new(BIO_s_file()); 
    BIO *out = BIO_new(BIO_s_file()); 
    int der = 0; /* Input from DER or PEM ? */ 
    int text = 0; /* Dump text or output PEM ? */ 
    STACK_OF(X509) *certs = NULL; 
    int i; 

    CRYPTO_malloc_init();            \ 
    ERR_load_crypto_strings(); 
    OpenSSL_add_all_algorithms(); 

    BIO_set_fp(out, stdout, BIO_NOCLOSE); 
    BIO_read_filename(in, argv[1]); 
    p7 = der ? 
     d2i_PKCS7_bio(in, NULL) : 
     PEM_read_bio_PKCS7(in, NULL, NULL, NULL); 

    i = OBJ_obj2nid(p7->type); 
    if(i == NID_pkcs7_signed) { 
     certs = p7->d.sign->cert; 
    } else if(i == NID_pkcs7_signedAndEnveloped) { 
     certs = p7->d.signed_and_enveloped->cert; 
    } 

    for (i = 0; certs && i < sk_X509_num(certs); i++) { 
     X509 *x = sk_X509_value(certs,i); 
     if(text) { 
      X509_print(out, x); 
     } else { 
      PEM_write_bio_X509(out,x); 
     } 
    } 
} 

它基於openssl-1.0.0d/apps/pkcs7.c和它很容易編譯（在Linux或Mac OS X）使用（只要你將它保存爲readp7.c）：

gcc -o readp7 readp7.c -lcrypto 

您可以使用OpenSSL創建文件和這樣的閱讀：

openssl crl2pkcs7 -nocrl -certfile a.crt -certfile b.crt -out test.p7b 
./readp7 test.p7b