Understanding the Basics

Before diving into the conversion process, it is essential to understand the difference between PEM and PKCS7 formats. PEM, or Privacy Enhanced Mail, is a base64 encoded format used for storing SSL certificates. PKCS7, on the other hand, is a binary format used for encrypting and signing data.

Why Convert PEM to PKCS7?

Converting PEM to PKCS7 is necessary when working with certain applications and systems that require PKCS7 format. For example, Microsoft Exchange servers require PKCS7 format for SSL certificates.

Using OpenSSL for Conversion

OpenSSL is a widely used command-line tool for working with SSL certificates and encryption. It is available on most Linux and Unix-based systems.

Step-by-Step Guide to Convert PEM to PKCS7

Follow these simple steps to convert PEM to PKCS7 using OpenSSL:

Step 1: Install OpenSSL

If OpenSSL is not already installed on your system, install it using the appropriate command for your distribution. For example, on Ubuntu, use:


Step 2: Create a PEM File

Create a PEM file containing the SSL certificate you want to convert. This can be done by copying the certificate text to a file with a .pem extension. For example:

Step 3: Convert PEM to PKCS7

Use the OpenSSL command to convert the PEM file to PKCS7 format. For example:

This command will create a new file called certificate.p7b containing the SSL certificate in PKCS7 format.

FAQs for converting pem to pkcs7 openssl

What is the difference between PEM and PKCS7 formats?

PEM (Privacy Enhanced Mail) and PKCS7 (Public Key Cryptography Standards #7) are both formats used for storing certificates and keys. PEM files generally contain a private key, certificate, and CA certificate. PKCS7 files, on the other hand, store a certificate chain without any private key. In other words, PEM files are used for private keys and their corresponding certificates, while PKCS7 files belong to public certificates.

Why would I want to convert PEM to PKCS7?

There are several situations where you might need to convert PEM to PKCS7. For example, if you need to install a certificate chain in HTTP servers like Apache, Nginx, or IIS, these servers may need the certificate to be in PKCS7 format. PKCS7 format is also used for certificate signing requests (CSR) and for digital signature verification.

How can I convert a PEM file to PKCS7 using OpenSSL?

To convert a PEM file to PKCS7 format in OpenSSL, you can use the following command:

openssl crl2pkcs7 -nocrl -certfile certificate.pem -out certificate.p7b -certfile CA.pem

Where certificate.pem is the certificate file in PEM format, certificate.p7b is the output file in PKCS7 format, and CA.pem is the CA bundle file.

Are there any other commands that can be used for PEM to PKCS7 conversion?

Yes, there is another OpenSSL command that can be used for this purpose:

openssl pkcs7 -in certificate.pem -print_certs -out certificate.p7b

This command will convert the certificate.pem file to PKCS7 format and save it as certificate.p7b. It accomplishes the same conversion as the previous command.

Can I convert PKCS7 back to PEM format?

Yes, you can convert PKCS7 files back to PEM format using OpenSSL. To do this, execute the following OpenSSL command:

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.pem

Where certificate.p7b is the input file in PKCS7 format and certificate.pem is the output file in PEM format.

Is there any difference between the content of the certificate in PEM and PKCS7 formats?

No, there is no difference between the content of the certificate in both formats. The only difference is in the file format and the way it is encoded. The certificate contains the same information regardless of whether it is stored in PEM or PKCS7 format.