So, usually you generate wallets, not keypairs directly, to avoid exposing the ultrasensitive private key directly. But if you just want to get a keypair, here's an easy way with some of the tooling I'm working on.
Prerequisite: Java 8 installed on your machine.
Caveats: No warranties, if anybody gets or sees the private key any value associated with the keypair
may be stolen, the entropy behind the generation of these keys is the default implementation and seeding
of java.security.SecureRandom, which may or may not be adequate. This is a SNAPSHOT version that references
lots of other SNAPSHOT libraries, which may not be stable and will be redownloaded with annoying frequency
until (hopefully soon) it is upgraded to a release version.
The "eth-command-line" project is really just a customized sbt interactive shell. If you are familiar with sbt, all your tricks will work.
Without further ado...
$ git clone git@github.com:swaldman/eth-command-line.git
Cloning into 'eth-command-line'...
remote: Counting objects: 55, done.
remote: Total 55 (delta 0), reused 0 (delta 0), pack-reused 55
Receiving objects: 100% (55/55), 16.00 KiB | 0 bytes/s, done.
Resolving deltas: 100% (29/29), done.
$ cd eth-command-line/
$ ./eth-command-line
The first time you execute this, it will download lots and lots of libraries. Most of these will be downloaded just once, but several of the libraries are "snapshot" releases, and these will be annoyingly rechecked with great frequency and downloaded whenever they have been updated. (This will stop happening when things stabilize to a release.)
At the end of a lot of ceremony, you'll see a prompt:
eth-command-line ~>
To get a keypair printed on the console:
eth-command-line ~> show xethGenKeyPair
[info] Generated keypair for address '0xc0feaca0c57676f69317f351b14a1dc7aeb5a6ee'
[info] EthKeyPair(EthPrivateKey(ByteSeqExact32(0x83303b5fb489061cb0c283d4765723362387692b47d69a40e68bcd0954b2af4e)),EthPublicKey(ByteSeqExact64(0xf8edca00c4def093927c21d5855a24f15a2780bf8ad4100a3ad681ce940c25e56c421b29c61d762392a68809eee6f53e7006d68be6e919c064fb32f7e741883c)))
That's it!