Linux "ecparam" Command Line Options and Examples
EC parameter manipulation and generation

This command is used to manipulate or generate EC parameter files..


openssl ecparam [-help] [-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]

Command Line Options:

Print out a usage message.
ecparam -help ...
This specifies the input format. The DER option uses an ASN.1 DER encoded form compatible with RFC 3279 EcpkParameters. The PEMform is the default format: it consists of the DER format base64 encoded with additional header and footer lines.
ecparam -inform ...
This specifies the output format, the options have the same meaning as the -inform option.
ecparam -outform ...
This specifies the input filename to read parameters from or standard input if this option is not specified.
ecparam -in ...
This specifies the output filename parameters to. Standard output is used if this option is not present. The output filenameshould not be the same as the input filename.
ecparam -out ...
This option inhibits the output of the encoded version of the parameters.
ecparam -noout ...
This option prints out the EC parameters in human readable form.
ecparam -text ...
This option converts the EC parameters into C code. The parameters can then be loaded by calling the get_ec_group_XXX() function.
ecparam -C ...
Validate the elliptic curve parameters.
ecparam -check ...
Use the EC parameters with the specified 'short' name. Use -list_curves to get a list of all currently implemented EC parameters.
ecparam -name ...
If this options is specified ecparam will print out a list of all currently implemented EC parameters names and exit.
ecparam -list_curves ...
This specifies how the points on the elliptic curve are converted into octet strings. Possible values are: compressed (thedefault value), uncompressed and hybrid. For more information regarding the point conversion forms please read the X9.62standard. Note Due to patent issues the compressed option is disabled by default for binary curves and can be enabled bydefining the preprocessor macro OPENSSL_EC_BIN_PT_COMP at compile time.
ecparam -conv_form ...
This specifies how the elliptic curve parameters are encoded. Possible value are: named_curve, i.e. the ec parameters arespecified by an OID, or explicit where the ec parameters are explicitly given (see RFC 3279 for the definition of the ECparameters structures). The default value is named_curve. Note the implicitlyCA alternative, as specified in RFC 3279, iscurrently not implemented in OpenSSL.
ecparam -param_enc ...
This option inhibits that the 'seed' for the parameter generation is included in the ECParameters structure (see RFC 3279).
ecparam -no_seed ...
This option will generate an EC private key using the specified parameters.
ecparam -genkey ...
a file or files containing random data used to seed the random number generator, or an EGD socket (see RAND_egd(3)). Multiplefiles can be specified separated by an OS-dependent character. The separator is ; for MS-Windows, , for OpenVMS, and : for allothers.
ecparam -rand ...
specifying an engine (by its unique id string) will cause ecparam to attempt to obtain a functional reference to the specifiedengine, thus initialising it if needed. The engine will then be set as the default for all available algorithms.NOTESPEM format EC parameters use the header and footer lines:
ecparam -engine ...