1 files changed, 104 insertions, 0 deletions
diff --git a/ed25519.go b/ed25519.go
new file mode 100644
index 0000000..602ac52
--- /dev/null
+++ b/ed25519.go
@@ -0,0 +1,104 @@
+package pki
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/rand"
+	"encoding/pem"
+	"errors"
+	"io"
+
+	"github.com/agl/ed25519"
+)
+
+const (
+	PemLabelEd25519 = "ED25519 PRIVATE KEY" // TODO find correct label
+)
+
+type (
+	Ed25519PrivateKey struct {
+		private_key [ed25519.PrivateKeySize]byte
+	}
+
+	Ed25519PublicKey struct {
+		public_key [ed25519.PublicKeySize]byte
+	}
+)
+
+// Create a new private key of type ed25519.
+func NewPrivateKeyEd25519() (*Ed25519PrivateKey, error) {
+	_, pr_raw, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		return nil, err
+	}
+	return &Ed25519PrivateKey{*pr_raw}, nil
+}
+
+// Restore an ed25519 private key from a raw byte stream.
+// TODO does this have to be asn1? all other functions expect asn1
+func LoadPrivateKeyEd25519(raw []byte) (*Ed25519PrivateKey, error) {
+	var pr_loaded [ed25519.PrivateKeySize]byte
+	length := copy(pr_loaded[:], raw)
+	if length != ed25519.PrivateKeySize {
+		return nil, errors.New("private key length incorrect")
+	}
+	return &Ed25519PrivateKey{pr_loaded}, nil
+}
+
+// TODO implement the raw API for the private key
+func (pr *Ed25519PrivateKey) PrivateKey() crypto.PrivateKey {
+	return nil
+}
+
+// Return the public key for this private key.
+func (pr *Ed25519PrivateKey) Public() PublicKey {
+	buf := bytes.NewBufferString(string(pr.private_key[:])) // create a bytes buffer to read the private key
+	pu_raw, _, err := ed25519.GenerateKey(buf)              // use the already built private key again
+	if err != nil {
+		return nil
+	}
+	return &Ed25519PublicKey{*pu_raw}
+}
+
+// Hash the message given the hash algorythm and sign the hash using the private key.
+func (pr *Ed25519PrivateKey) Sign(message []byte, hash crypto.Hash) ([]byte, error) {
+	hashed_message := hash.New()
+	hashed_message.Write(message)
+	result := ed25519.Sign(&pr.private_key, hashed_message.Sum(nil))[:]
+	return result, nil
+}
+
+// Export the private key into the Pem format.
+func (pr Ed25519PrivateKey) MarshalPem() (io.WriterTo, error) {
+	pem_block := pem.Block{Type: PemLabelEd25519, Bytes: pr.private_key[:]}
+	return marshalledPemBlock(pem.EncodeToMemory(&pem_block)), nil
+}
+
+// Load the public key from a raw byte stream.
+// TODO should this be read from ASN.1? All other functions do that.
+func LoadPublicKeyEd25519(raw []byte) (*Ed25519PublicKey, error) {
+	var pu_loaded [ed25519.PublicKeySize]byte
+	length := copy(pu_loaded[:], raw)
+	if length != ed25519.PublicKeySize {
+		return nil, errors.New("public key length incorrect")
+	}
+	return &Ed25519PublicKey{pu_loaded}, nil
+}
+
+// Export the public key into the pem format.
+func (pu Ed25519PublicKey) MarshalPem() (io.WriterTo, error) {
+	pem_block := pem.Block{Type: PemLabelPublic, Bytes: pu.public_key[:]}
+	return marshalledPemBlock(pem.EncodeToMemory(&pem_block)), nil
+}
+
+// Hash the message with the hash algorythm and check the signature against the result.
+func (pu Ed25519PublicKey) Verify(message []byte, signature []byte, hash crypto.Hash) (bool, error) {
+	var sig [ed25519.SignatureSize]byte
+	length := copy(sig[:], signature)
+	if length != ed25519.SignatureSize {
+		return false, errors.New("signature does not fit length")
+	}
+	hashed_message := hash.New()
+	hashed_message.Write(message)
+	return ed25519.Verify(&pu.public_key, hashed_message.Sum(nil), &sig), nil
+}