From e7801b268c97c6b72bfcd76549ce5fd50ab0b1b5 Mon Sep 17 00:00:00 2001
From: Rasmus Dahlberg <rasmus.dahlberg@kau.se>
Date: Tue, 27 Oct 2020 19:16:10 +0100
Subject: added ed25519 signing and SDIs

---
 x509.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

(limited to 'x509.go')

diff --git a/x509.go b/x509.go
index 4e5a4d6..1e443a1 100644
--- a/x509.go
+++ b/x509.go
@@ -3,6 +3,9 @@ package stfe
 import (
 	"fmt"
 
+	"crypto"
+	"crypto/rand"
+	"crypto/ed25519"
 	"crypto/ecdsa"
 	"crypto/rsa"
 	"crypto/x509"
@@ -44,6 +47,38 @@ func LoadTrustAnchors(path string) ([]*x509.Certificate, *x509.CertPool, error)
 	return anchors, pool, nil
 }
 
+
+func LoadEd25519SigningKey(path string) (ed25519.PrivateKey, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed reading private key: %v", err)
+	}
+
+	var block *pem.Block
+	block, data = pem.Decode(data)
+	if block == nil {
+		return nil, fmt.Errorf("private key not loaded")
+	}
+	if block.Type != "PRIVATE KEY" {
+		return nil, fmt.Errorf("unexpected PEM block type: %s", block.Type)
+	}
+	if len(data) != 0 {
+		return nil, fmt.Errorf("trailing data found after key: %v", data)
+	}
+
+	key, err := x509.ParsePKCS8PrivateKey(block.Bytes)
+	if err != nil {
+		return nil, fmt.Errorf("failed parsing signing key: %v", err)
+	}
+
+	switch t := key.(type) {
+	case ed25519.PrivateKey:
+		return key.(ed25519.PrivateKey), nil
+	default:
+		return nil, fmt.Errorf("unexpected signing key type: %v", t)
+	}
+}
+
 func VerifyChain(ld *LogParameters, certificate *x509.Certificate) ([]*x509.Certificate, error) {
 	opts := x509.VerifyOptions{
 		Roots:     ld.AnchorPool,
@@ -76,3 +111,13 @@ func VerifySignature(leaf, signature []byte, certificate *x509.Certificate) erro
 	}
 	return nil
 }
+
+
+func GenV1SDI(ld *LogParameters, leaf []byte) (StItem, error) {
+	// Note that ed25519 does not use the passed io.Reader
+	sig, err := ld.Signer.Sign(rand.Reader, leaf, crypto.Hash(0))
+	if err != nil {
+		return StItem{}, fmt.Errorf("ed25519 signature failed: %v", err)
+	}
+	return NewSignedDebugInfoV1(ld.LogId, []byte("reserved"), sig), nil
+}
-- 
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