/usr/man/cat.1/openssl-ec.1
EC(1) OpenSSL EC(1)
NAME
openssl-ec, 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
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EC(1) OpenSSL EC(1)
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
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EC(1) OpenSSL EC(1)
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)
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HISTORY
The ec command was first introduced in OpenSSL 0.9.8.
AUTHOR
Nils Larsch for the OpenSSL project
(http://www.openssl.org).
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See also ec(1)
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