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 (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 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
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)