EC(1) OpenSSL EC(1)NAMEec - 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 structur 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 for‐
mat 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 speci‐
fied 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. Pos‐
sible 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 alterna‐
tive ,as specified in RFC 3279, is currently not implemented in
OpenSSL.
-engine id
specifying an engine (by it's unique id string) will cause req 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 ALSOecparam(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).
0.9.8k 2009-05-20 EC(1)
