EC
Section: OpenSSL (1)
Updated: 2017-05-25
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NAME
ec - EC key processing
SYNOPSIS
openssl ec
[
-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]
[
-engine id]
DESCRIPTION
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 a OpenSSL
EC private key into the
PKCS#8 private key format use the
pkcs8 command.
COMMAND OPTIONS
- -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 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 the PASS PHRASE ARGUMENTS section 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 the PASS PHRASE ARGUMENTS section 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.
- -modulus
-
this option prints out the value of the public key component 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 a 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.
- -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.
NOTES
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-----
EXAMPLES
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
SEE ALSO
ecparam(1),
dsa(1),
rsa(1)
HISTORY
The ec command was first introduced in OpenSSL 0.9.8.
AUTHOR
Nils Larsch for the OpenSSL project (
http://www.openssl.org).
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- COMMAND OPTIONS
-
- NOTES
-
- EXAMPLES
-
- SEE ALSO
-
- HISTORY
-
- AUTHOR
-
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