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_curve] [
-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)