To convert a PKCS #7 (.p7b) to PEM (Privacy Enhanced Mail) certificate format using OpenSSL, perform the following steps.
Note: In order for OpenSSL software successfully installed on a computer system. You must have local system administrator privilege on the computer.
Convert PKCS #7 (.p7b) to PEM using OpenSSL
Run the following OpenSSL command:
openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer