ECPARAM
Section: OpenSSL (1)
Updated: 2017-05-25
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NAME
ecparam - EC parameter manipulation and generation
SYNOPSIS
openssl ecparam
[
-inform DER|PEM]
[
-outform DER|PEM]
[
-in filename]
[
-out filename]
[
-noout]
[
-text]
[
-C]
[
-check]
[
-name arg]
[
-list_curves]
[
-conv_form arg]
[
-param_enc arg]
[
-no_seed]
[
-rand file(s)]
[
-genkey]
[
-engine id]
DESCRIPTION
This command is used to manipulate or generate
EC parameter files.
OPTIONS
- -inform DER|PEM
-
This specifies the input format. The DER option uses an ASN.1 DER encoded
form compatible with RFC 3279 EcpkParameters. The PEM form is the default
format: it consists of the DER format base64 encoded with additional
header and footer lines.
- -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 parameters from or standard input if
this option is not specified.
- -out filename
-
This specifies the output filename parameters to. Standard output is used
if this option is not present. The output filename should not be the same
as the input filename.
- -noout
-
This option inhibits the output of the encoded version of the parameters.
- -text
-
This option prints out the EC parameters in human readable form.
- -C
-
This option converts the EC parameters into C code. The parameters can then
be loaded by calling the get_ec_group_XXX() function.
- -check
-
Validate the elliptic curve parameters.
- -name arg
-
Use the EC parameters with the specified 'short' name. Use -list_curves
to get a list of all currently implemented EC parameters.
- -list_curves
-
If this options is specified ecparam will print out a list of all
currently implemented EC parameters names and exit.
- -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.
- -no_seed
-
This option inhibits that the 'seed' for the parameter generation
is included in the ECParameters structure (see RFC 3279).
- -genkey
-
This option will generate a EC private key using the specified parameters.
- -rand file(s)
-
a file or files containing random data used to seed the random number
generator, or an EGD socket (see RAND_egd(3)).
Multiple files can be specified separated by a OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for
all others.
- -engine id
-
specifying an engine (by its unique id string) will cause ecparam
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
PEM format
EC parameters use the header and footer lines:
-----BEGIN EC PARAMETERS-----
-----END EC PARAMETERS-----
OpenSSL is currently not able to generate new groups and therefore
ecparam can only create EC parameters from known (named) curves.
EXAMPLES
To create
EC parameters with the group 'prime192v1':
openssl ecparam -out ec_param.pem -name prime192v1
To create EC parameters with explicit parameters:
openssl ecparam -out ec_param.pem -name prime192v1 -param_enc explicit
To validate given EC parameters:
openssl ecparam -in ec_param.pem -check
To create EC parameters and a private key:
openssl ecparam -out ec_key.pem -name prime192v1 -genkey
To change the point encoding to 'compressed':
openssl ecparam -in ec_in.pem -out ec_out.pem -conv_form compressed
To print out the EC parameters to standard output:
openssl ecparam -in ec_param.pem -noout -text
SEE ALSO
ec(1),
dsaparam(1)
HISTORY
The ecparam command was first introduced in OpenSSL 0.9.8.
AUTHOR
Nils Larsch for the OpenSSL project (
http://www.openssl.org)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- NOTES
-
- EXAMPLES
-
- SEE ALSO
-
- HISTORY
-
- AUTHOR
-
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