[英]how to decrypt ASN.1 DER encoded CMS file using the openssl API?
我有一個DER編碼的CMS文件,我想使用openssl API解密。
我發現了用於解密的API :
CMS_decrypt(cms_content, pkey, cert, NULL, out, NULL);
我已經找到了讀取pkey和cert PEM文件以及設置輸出BIO的示例,但是我找不到如何讀取cms文件的示例。
問 :我怎樣才能讀取ASN.1 DER編碼文件到cms_content
具有類型變量CMS_ContentInfo
?
編輯:感謝Camille的回答 ,我設法使其與以下產品一起使用:
#include <stdio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/cms.h>
int main (int argc, char **argv)
{
char pkeypath[] = "recipient_prvkey.pem";
char certpath[] = "sender_cert.pem";
char cmspath[] = "encrypted.der";
char decpath[] = "decrypted.zip";
BIO *in = NULL, *out = NULL, *tbio = NULL;
CMS_ContentInfo *cms = NULL;
EVP_PKEY *pkey;
X509 *cert;
OpenSSL_add_all_algorithms();
ERR_load_crypto_strings();
tbio = BIO_new_file(pkeypath, "r");
pkey = PEM_read_bio_PrivateKey(tbio, NULL, 0, NULL);
if (pkey == NULL) {
printf("error reading private key");
return EXIT_FAILURE;
}
BIO_free(tbio);
tbio = BIO_new_file(certpath, "r");
cert = PEM_read_bio_X509(tbio, NULL, 0, NULL);
if (cert == NULL) {
printf("error reading private key");
return EXIT_FAILURE;
}
in = BIO_new_file(cmspath, "r");
cms = d2i_CMS_bio(in, NULL);
BIO_free(in);
out = BIO_new_file(decpath, "w");
if (!CMS_decrypt_set1_pkey(cms, pkey, cert))
{
fprintf(stderr, "set1_pkey error\n");
return EXIT_FAILURE;
}
if (!CMS_decrypt(cms, NULL, NULL, NULL, out, CMS_BINARY))
{
int error = ERR_get_error();
fprintf(stderr, "error: %s :: %s :: %s\n",
ERR_reason_error_string(error),
ERR_func_error_string(error),
ERR_lib_error_string(error)
);
}
BIO_free(out);
return 0;
}
我只是復制了可與PEM一起使用的OpenSSL cms_dec示例,並將其改編為DER編碼的CMS文件
BIO *in = NULL, *out = NULL, *tbio = NULL;
X509 *cert= NULL;
EVP_PKEY *rkey = NULL;
CMS_ContentInfo *cms = NULL;
int ret = 1;
OpenSSL_add_all_algorithms();
ERR_load_crypto_strings();
/* Read in recipient certificate and private key */
tbio = BIO_new_file("yourCMS.der", "r");
rcert = i2d_x509_bio(tbio, NULL);
BIO_reset(tbio);
i2d_PrivateKey_bio(tbio, rkey);
/* Open S/MIME message to decrypt */
in = BIO_new_file("smencr.txt", "r");
/* Parse message */
cms = SMIME_read_CMS(in, NULL);
out = BIO_new_file("decout.txt", "w");
/* Decrypt S/MIME message */
CMS_decrypt(cms, rkey, rcert, out, NULL, CMS_BINARY) //Edit : Added Flags for DER.
...
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