OPENSSL-FORMAT-OPTIONS(1)

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>.