Public private key encryption. OpenSSL provides two command line tools for working with keys suitable for Elliptic Curve (EC) algorithms:

1. Generate Ec Key Pair Java
2. Java Generate Ecc Key Pair

The only Elliptic Curve algorithms that OpenSSL currently supports are Elliptic Curve Diffie Hellman (ECDH) for key agreement and Elliptic Curve Digital Signature Algorithm (ECDSA) for signing/verifying.

x25519, ed25519 and ed448 aren't standard EC curves so you can't use ecparams or ec subcommands to work with them. If you need to generate x25519 or ed25519 keys then see the genpkey subcommand.

• Generate an ed25519 SSH keypair- this is a new algorithm added in OpenSSH. Ssh-keygen -t ed25519 Extracting the public key from an RSA keypair. Openssl rsa -pubout -in privatekey.pem -out publickey.pem Extracting the public key from an DSA keypair. Openssl dsa -pubout -in privatekey.pem -out publickey.pem Copy the public key to the server.
• The JOSE standard recommends a minimum RSA key size of 2048 bits. To generate a 2048-bit RSA private + public key pair for use in RSxxx and PSxxx signatures: openssl genrsa 2048 -out rsa-2048bit-key-pair.pem Elliptic Curve keys. To generate an EC key pair the curve designation must be specified.
• Mar 03, 2020 openssl ecparam -genkey -name prime256v1 -noout -out ecprivate.pem openssl ec -in ecprivate.pem -pubout -out ecpublic.pem These commands create the following public/private key pair: ecprivate.pem: The private key that must be securely stored on the device and used to sign the authentication JWT.

You must specify a key pair when you launch an EC2 instance and then specify the private key of the key pair when you connect to the instance. You can create a key pair or use an existing key pair that you’ve used when launching other instances. Oracle Java documentation is a little sparse on the topic, but it does look like with the SunJCE, a key generated asEC can be used with either ECDH or ECDSA. (I'm not an Elliptic curve expert, but) Theoretically, I believe that the domain parameters for ECDH and ECDSA have the same form, that is the equation of the curve and a base point G.

EC Private Key File Formats[edit]

By default OpenSSL will work with PEM files for storing EC private keys. These are text files containing base-64 encoded data. A typical traditional format private key file in PEM format will look something like the following, in a file with a '.pem' extension:

Or, in an encrypted form like this:

You may also encounter PKCS8 format private keys in PEM files. These look like this:

Or, in an encrypted form like this:

PKCS8 private key files, like the above, are capable of holding many different types of private key - not just EC keys.

You can convert between these formats if you like. All of the conversion commands can read either the encrypted or unencrypted forms of the files however you must specify whether you want the output to be encrypted or not. To convert a PKCS8 file to a traditional encrypted EC format use:

You can replace the first argument 'aes-128-cbc' with any other valid openssl cipher name (see Manual:enc(1) for a list of valid cipher names). To convert a PKCS8 file to a traditional unencrypted EC format, just drop the first argument:

Or to convert from a traditional EC format to an encrypted PKCS8 format use:

Or to a non-encrypted PKCS8 format use:

Note that by default in the above traditional format EC Private Key files are not encrypted (you have to explicitly state that the file should be encrypted, and what cipher to use), whilst for PKCS8 files the opposite is true. The default is to encrypt - you have to explicitly state that you do not want encryption applied if appropriate using the '-nocrypt' option.

As well as PEM format all of the above types of key file can also be stored in DER format. This is a binary format and so is not directly human readable - unlike a PEM file. A PEM file is essentially just DER data encoded using base 64 encoding rules with a header and footer added. Often it is more convenient to work with PEM files for this reason.

The openssl commands typically have options '-inform DER' or '-outform DER' to specify that the input or output file is DER respectively. So for example the command to convert a PKCS8 file to a traditional encrypted EC format in DER is the same as above, but with the addition of '-outform DER':

Note that you cannot encrypt a traditional format EC Private Key in DER format (and in fact if you attempt to do so the argument is silently ignored!). The same is not true for PKCS8 files - these can still be encrypted even in DER format. So for example the following will convert a traditional format key file to an ecrypted PKCS8 format DER encoded key:

EC Public Key File Formats[edit]

EC Public Keys are also stored in PEM files. A typical EC public key looks as follows:

This format is used to store all types of public keys in OpenSSL not just EC keys.

It is possible to create a public key file from a private key file (although obviously not the other way around!):

As above a DER encoded version can be created using '-outform DER':

Generating EC Keys and Parameters[edit]

An EC Parameters file contains all of the information necessary to define an Elliptic Curve that can then be used for cryptographic operations (for OpenSSL this means ECDH and ECDSA). OpenSSL contains a large set of pre-defined curves that can be used. The full list of built-in curves can be obtained through the following command:

An EC parameters file can then be generated for any of the built-in named curves as follows:

Replace secp256k1 in the above with whichever curve you are interested in.

Keys can be generated from the ecparam command, either through a pre-existing parameters file or directly by selecting the name of the curve. To generate a private/public key pair from a pre-eixsting parameters file use the following:

Or to do the equivalent operation without a parameters file use the following:

Information on the parameters that have been used to generate the key are embedded in the key file itself.

By default, when creating a parameters file, or generating a key, openssl will only store the name of the curve in the generated parameters or key file, not the full set of explicit parameters associated with that name. For example:

This will simply confirm the name of the curve in the parameters file by printing out the following:

If you wish to examine the specific details of the parameters associated with a particular named curve then this can be achieved as follows:

The above command shows the details for a built-in named curve from a file, but this can also be done directly using the '-name' argument instead of '-in'. The output will look similar to the following:

The meaning of each of these parameters is discussed further on this page.

Parameters and key files can be generated to include the full explicit parameters instead of just the name of the curve if desired. This might be important if, for example, not all the target systems know the details of the named curve. In OpenSSL version 1.0.2 new named curves have been added such as brainpool512t1. Attempting to use a parameters file or key file in versions of OpenSSL less than 1.0.2 with this curve will result in an error:

This problem can be avoided if explicit parameters are used instead. So under OpenSSL 1.0.2 you could create a parameters file like this:

Looking at the parameters file you will notice that it is now much longer:

The full parameters are included rather than just the name. This can now be processed by versions of OpenSSL less than 1.0.2. So under 1.0.1:

This will correctly display the parameters, even though this version of OpenSSL does not know about this curve.

The same is true of key files. So to generate a key with explicit parameters:

This key file can now be processed by versions of openssl that do not know about the brainpool curve.

It should be noted however that once the parameters have been converted from the curve name format into explicit parameters it is not possible to change them back again, i.e. there is no utility to take a set of explicit parameters and work out which named curve they are associated with.

See also[edit]

In this chapter we will introduce the rather new Elliptic Curve Cryptography (ECC or EC for short) OpenPGP keys.

1. What are Elliptic Curve OpenPGP keys?
2. Example code
3. Compatibility Notes
4. Async code

What are Elliptic Curve OpenPGP keys?

ECC keys are rather new to the OpenPGP standard. They were first defined in RFC 6637. This extension of the OpenPGP standard defines only three NIST approved curves. Later the open source GnuPG software added three Brainpool curves (defined in RFC 5639).

Encryption with EC keys is based on the Elliptic Curve Diffie-Hellman (ECDH) key agreement protocol. Signing with EC keys is based on the Elliptic Curve DSA (ECDSA) algorithm.

Generate Ec Key Pair Java

The encryption with EC OpenPGP keys is considered to be much more secure compared to the current RSA and Elgamal (DH/DSS) keys.

Supported EC curves

Currently, DidiSoft OpenPGP library for .NET supports ECC keys based on these elliptic curves:

• NIST P-256 (DidiSoft.Pgp.EcCurve.P256)
• NIST-384 (DidiSoft.Pgp.EcCurve.P384)
• NIST-521 (DidiSoft.Pgp.EcCurve.P521)
• Brainpool 256 bit (DidiSoft.Pgp.EcCurve.Brainpool256)
• Brainpool 384 bit (DidiSoft.Pgp.EcCurve.Brainpool384)
• Brainpool 512 bit (DidiSoft.Pgp.EcCurve.Brainpool512)

Key generation speed

The key generation of EC keys is much faster compared to the traditional RSA and DH/DSS keys.

Example Code

The key generation is invoked by the methods GenerateEccKeyPair defined in the KeyStore and PGPKeyPair classes.

Below is a short example that illustrates how to generate EC OpenPGP keys with the library.

C# example

VB.NET example

The example code above will generate keys with no expiration date and predefined preferred algorithms for compression, hash function, and symmetric encryption. If you wish to specify manually those algorithms, please check one of the overloaded versions of the method GenerateEccKeyPair.

Java Generate Ecc Key Pair

After the key generation, the keys can be exported from the KeyStore or you can directly generate a key in a PGPKeyPair object and export them from there.

Compatibility Issues

ECC OpenPGP keys were first introduced in version 1.7.7 of DidiSoft OpenPGP Library for .NET

Elliptic curves OpenPGP keys are supported only by newer OpenPGP implementations like is Symantec (r) PGP Command line v. 10.2. and upper versions and GnuPGversion 2.1 and above. Attempts to use ECC OpenPGP keys with older software usually fails with error messages. For example, if you try to use such keys with older versions of our library you will receive exceptions with the message: “unknown PGP public key algorithm encountered“.

Async support

In order to create a key pair asynchronously, we have to use the DidiSoft.Pgp.KeyStoreAsync class which provides the same key creation methods with Async suffixes.

Summary

In this chapter, we have introduced the Elliptic Curve (EC) OpenPGP keys. The EC OpenPGP keys are still not adopted by the major OpenPGP software implementations but they will hopefully get traction soon.

They are considered superior by terms of cryptography security to the currently widespread RSA and DH/DSS keys.