- NAME
- SYNOPSIS
- DESCRIPTION
- OPTIONS
  - Format Options
  - Format Option Arguments
- COPYRIGHT

# NAME

openssl-format-options - OpenSSL command input and output format options

# SYNOPSIS

openssl command [ options ... ] [ parameters ... ]

# DESCRIPTION

Several OpenSSL commands can take input or generate output in a variety of formats.

Since OpenSSL 3.0 keys, single certificates, and CRLs can be read from files in any of the DER, PEM or P12 formats. Specifying their input format is no more needed and the openssl commands will automatically try all the possible formats. However if the DER or PEM input format is specified it will be enforced.

# OPTIONS

## Format Options

The options to specify the format are as follows. Refer to the individual man page to see which options are accepted.

-inform format, -outform format

  The format of the input or output streams.

-keyform format

  Format of a private key input source.

-CRLform format

  Format of a CRL input source.

## Format Option Arguments

The possible format arguments are described below. Both uppercase and lowercase are accepted.

The list of acceptable format arguments, and the default, is described in each command documentation.

DER

  A binary format, encoded or parsed according to Distinguished Encoding Rules (DER) of the ASN.1 data language.

P12

  A DER-encoded file containing a PKCS#12 object. It might be necessary to provide a decryption password to retrieve the private key or certificate.

PEM

  A text format defined in IETF RFC 1421 and IETF RFC 7468. Briefly, this is a block of base-64 encoding (defined in IETF RFC 4648), with specific lines used to mark the start and end:

      Text before the BEGIN line is ignored.
      ----- BEGIN object-type -----
      OT43gQKBgQC/2OHZoko6iRlNOAQ/tMVFNq7fL81GivoQ9F1U0Qr+DH3ZfaH8eIkX
      xT0ToMPJUzWAn8pZv0snA0um6SIgvkCuxO84OkANCVbttzXImIsL7pFzfcwV/ERK
      UM6j0ZuSMFOCr/lGPAoOQU0fskidGEHi1/kW+suSr28TqsyYZpwBDQ==
      ----- END object-type -----
      Text after the END line is also ignored

  The object-type must match the type of object that is expected. For example a `BEGIN X509 CERTIFICATE` will not match if the command is trying to read a private key. The types supported include:

      ANY PRIVATE KEY
      CERTIFICATE
      CERTIFICATE REQUEST
      CMS
      DH PARAMETERS
      DSA PARAMETERS
      DSA PUBLIC KEY
      EC PARAMETERS
      EC PRIVATE KEY
      ECDSA PUBLIC KEY
      ENCRYPTED PRIVATE KEY
      PARAMETERS
      PKCS #7 SIGNED DATA
      PKCS7
      PRIVATE KEY
      PUBLIC KEY
      RSA PRIVATE KEY
      SSL SESSION PARAMETERS
      TRUSTED CERTIFICATE
      X509 CRL
      X9.42 DH PARAMETERS

  The following legacy object-type's are also supported for compatibility with earlier releases:

      DSA PRIVATE KEY
      NEW CERTIFICATE REQUEST
      RSA PUBLIC KEY
      X509 CERTIFICATE

SMIME

  An S/MIME object as described in IETF RFC 8551. Earlier versions were known as CMS and are compatible. Note that the parsing is simple and might fail to parse some legal data.

# COPYRIGHT

Copyright 2000-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.