openssl-ec, ec - EC key processing
openssl ec [-help] [-inform PEM|DER]
[-outform PEM|DER] [-in filename] [-passin arg]
[-out filename] [-passout arg] [-des] [-des3]
[-idea] [-text] [-noout] [-param_out]
[-pubin] [-pubout] [-conv_form arg] [-param_enc
arg] [-no_public] [-check] [-engine id]
The ec command processes EC keys. They can be converted
between various forms and their components printed out. Note OpenSSL
uses the private key format specified in 'SEC 1: Elliptic Curve
Cryptography' (http://www.secg.org/). To convert an OpenSSL EC private key
into the PKCS#8 private key format use the pkcs8 command.
- -help
- Print out a usage message.
- -inform
DER|PEM
- This specifies the input format. The DER option with a private key
uses an ASN.1 DER encoded SEC1 private key. When used with a public key it
uses the SubjectPublicKeyInfo structure as specified in RFC 3280. The
PEM form is the default format: it consists of the DER
format base64 encoded with additional header and footer lines. In the case
of a private key PKCS#8 format is also accepted.
- -outform
DER|PEM
- This specifies the output format, the options have the same meaning and
default as the -inform option.
- -in filename
- This specifies the input filename to read a key from or standard input if
this option is not specified. If the key is encrypted a pass phrase will
be prompted for.
- -passin
arg
- The input file password source. For more information about the format of
arg see "Pass Phrase Options" in openssl(1).
- -out filename
- This specifies the output filename to write a key to or standard output by
is not specified. If any encryption options are set then a pass phrase
will be prompted for. The output filename should not be the same as
the input filename.
- -passout
arg
- The output file password source. For more information about the format of
arg see "Pass Phrase Options" in openssl(1).
- -des|-des3|-idea
- These options encrypt the private key with the DES, triple DES, IDEA or
any other cipher supported by OpenSSL before outputting it. A pass phrase
is prompted for. If none of these options is specified the key is written
in plain text. This means that using the ec utility to read in an
encrypted key with no encryption option can be used to remove the pass
phrase from a key, or by setting the encryption options it can be use to
add or change the pass phrase. These options can only be used with PEM
format output files.
- -text
- Prints out the public, private key components and parameters.
- -noout
- This option prevents output of the encoded version of the key.
- -pubin
- By default, a private key is read from the input file. With this option a
public key is read instead.
- -pubout
- By default a private key is output. With this option a public key will be
output instead. This option is automatically set if the input is a public
key.
- -conv_form
- This specifies how the points on the elliptic curve are converted into
octet strings. Possible values are: compressed (the default value),
uncompressed and hybrid. For more information regarding the
point conversion forms please read the X9.62 standard. Note Due to
patent issues the compressed option is disabled by default for
binary curves and can be enabled by defining the preprocessor macro
OPENSSL_EC_BIN_PT_COMP at compile time.
- -param_enc
arg
- This specifies how the elliptic curve parameters are encoded. Possible
value are: named_curve, i.e. the ec parameters are specified by an
OID, or explicit where the ec parameters are explicitly given (see
RFC 3279 for the definition of the EC parameters structures). The default
value is named_curve. Note the implicitlyCA
alternative, as specified in RFC 3279, is currently not implemented in
OpenSSL.
- -no_public
- This option omits the public key components from the private key
output.
- -check
- This option checks the consistency of an EC private or public key.
- -engine id
- Specifying an engine (by its unique id string) will cause ec
to attempt to obtain a functional reference to the specified engine, thus
initialising it if needed. The engine will then be set as the default for
all available algorithms.
The PEM private key format uses the header and footer lines:
-----BEGIN EC PRIVATE KEY-----
-----END EC PRIVATE KEY-----
The PEM public key format uses the header and footer lines:
-----BEGIN PUBLIC KEY-----
-----END PUBLIC KEY-----
To encrypt a private key using triple DES:
openssl ec -in key.pem -des3 -out keyout.pem
To convert a private key from PEM to DER format:
openssl ec -in key.pem -outform DER -out keyout.der
To print out the components of a private key to standard
output:
openssl ec -in key.pem -text -noout
To just output the public part of a private key:
openssl ec -in key.pem -pubout -out pubkey.pem
To change the parameters encoding to explicit:
openssl ec -in key.pem -param_enc explicit -out keyout.pem
To change the point conversion form to compressed:
openssl ec -in key.pem -conv_form compressed -out keyout.pem
Copyright 2003-2021 The OpenSSL Project Authors. All Rights
Reserved.
Licensed under the OpenSSL license (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>.