PKCS file type

ASN.1 introduction

pem, cer, crt, der, p7b, p7c, p12, pfx

Certificate filename extensions

What are the differences between PEM, DER, P7B/PKCS#7, PFX/PKCS#12 certificates

证书

.pem – 证书 (Privacy-enhanced Electronic Mail) Base64 encoded DER certificate, enclosed between “—–BEGIN CERTIFICATE—–” and “—–END CERTIFICATE—–”

.cer, .crt, .der – binary DER编码的证书，或者Base64 DER编码(pem兼容)

.p7b, .p7c – PKCS#7 SignedData structure without data, just certificate(s) or CRL(s)

信息交换

.p12 – PKCS#12, may contain certificate(s) (public) and private keys (password protected)

.pfx – PFX personal information exchange, predecessor of PKCS#12 (usually contains data in PKCS#12 format, e.g., with PFX files generated in IIS)

openssl operation

The Most Common OpenSSL Commands

openssl command

How to Convert certificates between PEM, DER, P7B/PKCS#7, PFX/PKCS#12