refactor key generation

1 files changed, 126 insertions, 0 deletions

diff --git a/key/generate.go b/key/generate.go
new file mode 100644
index 0000000..d7480c9
--- /dev/null
+++ b/key/generate.go
@@ -0,0 +1,126 @@
+package key
+
+import (
+	crypto_rand "crypto/rand"
+	"encoding/hex"
+	"fmt"
+	"golang.org/x/crypto/nacl/box"
+	"golang.org/x/crypto/nacl/sign"
+	"io"
+
+	"git.samanthony.xyz/hose/util"
+)
+
+// A keyGenerator generates a new keypair from a random bitstream.
+type keyGenerator func(rand io.Reader) (publicKey, privateKey []byte, err error)
+
+// generateKeypair uses a key generator function to create a new public/private keypair.
+// The public key is saved to the public file, and the private key is saved to the private file.
+// If either of the files already exist, an error is returned.
+func generateKeypair(generate keyGenerator, pubFileName, privFileName string) error {
+	// Create public key file.
+	pubFile, err := createFileIfNotExist(pubFileName, pubFileMode)
+	if err != nil {
+		return err
+	}
+	defer pubFile.Close()
+
+	// Create private key file.
+	privFile, err := createFileIfNotExist(privFileName, privFileMode)
+	if err != nil {
+		return err
+	}
+	defer privFile.Close()
+
+	// Generate keypair.
+	pubkey, privkey, err := generate(crypto_rand.Reader)
+	if err != nil {
+		return err
+	}
+
+	// Write keypair to files.
+	buf := make([]byte, hex.EncodedLen(len(pubkey)))
+	hex.Encode(buf, pubkey)
+	if _, err := pubFile.Write(buf); err != nil {
+		return err
+	}
+	buf = make([]byte, hex.EncodedLen(len(privkey)))
+	hex.Encode(buf, privkey)
+	if _, err := privFile.Write(buf); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// If neither the public file nor private file exist, generateKeypair uses the key generator
+// function to create a new keypair. The public key is saved to the public key file,
+// and the private key is saved to the private key file.
+func generateKeypairIfNotExist(generate keyGenerator, pubFile, privFile string) error {
+	pubExists, err := fileExists(pubFile)
+	if err != nil {
+		return err
+	}
+	privExists, err := fileExists(privFile)
+	if err != nil {
+		return err
+	}
+
+	if pubExists && privExists {
+		// Keypair already exists.
+		return nil
+	} else if pubExists && !privExists {
+		return fmt.Errorf("found public key file but not private key file")
+	} else if privExists && !pubExists {
+		return fmt.Errorf("found private key file but not public key file")
+	}
+	// Neither public nor private key file exists; generate new keypair.
+	return generateKeypair(generate, pubFile, privFile)
+}
+
+// generateBoxKeypair generates a new public/private keypair for NaCl box
+// (encryption/decryption) operations.  It stores the private key in the private box
+// key file and the public box key in the public key file.  If either of the key files
+// already exist, they will not be overwritten; instead an error will be returned.
+func generateBoxKeypair() error {
+	return generateKeypair(boxKeyGenerator, boxPubKeyFile, boxPrivKeyFile)
+}
+
+// generateBoxKeypairIfNotExist generates a NaCal box keypair if it doesn't already exist.
+func generateBoxKeypairIfNotExist() error {
+	return generateKeypairIfNotExist(boxKeyGenerator, boxPubKeyFile, boxPrivKeyFile)
+}
+
+// NaCl box (encrypt/decrypt) keypair generator for use with generateKeypair().
+func boxKeyGenerator(rand io.Reader) (publicKey, privateKey []byte, err error) {
+	util.Logf("generating new encryption/decryption keypair...")
+	pub, priv, err := box.GenerateKey(rand)
+	if err != nil {
+		return []byte{}, []byte{}, err
+	}
+	return (*pub)[:], (*priv)[:], nil
+}
+
+// generateSigKeypair generates a new NaCl sign/verify keypair.
+// It stores the private signing key in the private signing key file
+// and the public verification key in the public verification key file.
+// If either of the key files already exist, they will not be overwritten;
+// instead an error will be returned.
+func generateSigKeypair() error {
+	util.Logf("generating new sign/verify keypair...")
+	return generateKeypair(sigKeyGenerator, sigPubKeyFile, sigPrivKeyFile)
+}
+
+// generateSigKeypairIfNotExist generates a NaCl sign/verify keypair if it doesn't already exist.
+func generateSigKeypairIfNotExist() error {
+	return generateKeypairIfNotExist(sigKeyGenerator, sigPubKeyFile, sigPrivKeyFile)
+}
+
+// NaCl sign/verify keypair generator for use with generateKeypair().
+func sigKeyGenerator(rand io.Reader) (publicKey, privateKey []byte, err error) {
+	pub, priv, err := sign.GenerateKey(rand)
+	if err != nil {
+		return []byte{}, []byte{}, err
+	}
+	return (*pub)[:], (*priv)[:], nil
+}