Linux "ec" Command Line Options and Examples
EC key processing

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.


openssl ec [-help] [-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] [-no_public] [-check] [-engine id]

Command Line Options:

Print out a usage message.
ec -help ...
This specifies the input format. The DER option with a private key uses an ASN.1 DER encoded SEC1 private key. When used with apublic key it uses the SubjectPublicKeyInfo structure as specified in RFC 3280. The PEM form is the default format: it consistsof the DER format base64 encoded with additional header and footer lines. In the case of a private key PKCS#8 format is alsoaccepted.
ec -inform ...
This specifies the output format, the options have the same meaning as the -inform option.
ec -outform ...
This specifies the input filename to read a key from or standard input if this option is not specified. If the key is encrypted apass phrase will be prompted for.
ec -in ...
the input file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
ec -passin ...
This specifies the output filename to write a key to or standard output by is not specified. If any encryption options are setthen a pass phrase will be prompted for. The output filename should not be the same as the input filename.
ec -out ...
the output file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section inopenssl(1).
ec -passout ...
These options encrypt the private key with the DES, triple DES, IDEA or any other cipher supported by OpenSSL before outputtingit. A pass phrase is prompted for. If none of these options is specified the key is written in plain text. This means that usingthe ec utility to read in an encrypted key with no encryption option can be used to remove the pass phrase from a key, or bysetting the encryption options it can be use to add or change the pass phrase. These options can only be used with PEM formatoutput files.
ec -des|-des3|-idea ...
prints out the public, private key components and parameters.
ec -text ...
this option prevents output of the encoded version of the key.
ec -noout ...
this option prints out the value of the public key component of the key.
ec -modulus ...
by default a private key is read from the input file: with this option a public key is read instead.
ec -pubin ...
by default a private key is output. With this option a public key will be output instead. This option is automatically set if theinput is a public key.
ec -pubout ...
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.
ec -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.
ec -param_enc ...
This option omits the public key components from the private key output.
ec -no_public ...
this option checks the consistency of an EC private or public key.
ec -check ...
specifying an engine (by its unique id string) will cause ec 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.NOTESThe PEM private key format uses the header and footer lines:
ec -engine ...