QuoVadis provides a PKI Widget to help convert certificates between the DER, PEM, and PKCS#7 /P7B formats.
For more information, please see https://pkiwidgets.quovadisglobal.com/pkiwidgets/convertCert.aspx
PEM Format
PEM files are Base64 encoded ASCII and contain "-----BEGIN
CERTIFICATE-----" and "-----END CERTIFICATE-----" statements. Both
digital certificates and private keys can be in PEM format. PEM files
usually end with .pem, .crt, .cer, or .key. Multiple PEM certificates
and private keys, may be included in one file, one below the other.
However, many platforms, such as Apache, require the certificates and
private key to be in separate files.
DER Format
DER files are in binary format. They usually end with .der or .cer, so
to differentiate between DER.cer and PEM.cer files, you may need to use a
text editor to look at the BEGIN/END statements. Both digital
certificates and private keys can be encoded in DER format. DER is
typically used with Java platforms. The QuoVadis tool can only convert
certificates to DER format. You should use OpenSSL if you need to
convert a private key to DER.
PKCS#7/P7B Format
The PKCS#7 or P7B format is usually stored in Base64 ASCII format using
the .p7b or .p7c file extensions. P7B certificates contain "-----BEGIN
PKCS7-----" and "-----END PKCS7-----" statements. P7B files only contain
certificates, not the private key. Several platforms support P7B files
including Microsoft Windows and Java Tomcat.
