From 6d76fe12067e2e60952213610ad2c0eb6491e71b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20Hohnst=C3=A4dt?= <christian@hohnstaedt.de>
Date: Mon, 15 Feb 2021 07:46:48 +0100
Subject: [PATCH] Close #142: Support Ed25519 Export private SSH2 key

Currently "PEM private" will export the key in SSH2
for PEM export into the clipboard
---
 lib/pki_key.cpp | 57 +++++++++++++++++++++++++++++++++++++++++++------
 lib/pki_key.h   |  6 ++++++
 2 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/lib/pki_key.cpp b/lib/pki_key.cpp
index bfbf22ad..37a85479 100644
--- a/lib/pki_key.cpp
+++ b/lib/pki_key.cpp
@@ -92,6 +92,34 @@ QByteArray pki_key::i2d() const
         return i2d_bytearray(I2D_VOID(i2d_PUBKEY), key);
 }
 
+void pki_key::write_SSH2_ed25519_private(BioByteArray &b,
+			 const EVP_PKEY *pkey, const EVP_CIPHER *enc) const
+{
+	static const char data0001[] = { 0, 0, 0, 1};
+	char buf_nonce[8];
+	QByteArray data, priv, pubfull;
+	(void)enc;
+
+	pubfull = SSH2publicQByteArray(true);
+	RAND_bytes((unsigned char*)buf_nonce, sizeof buf_nonce);
+	priv.append(buf_nonce, sizeof buf_nonce);
+	priv += pubfull;
+	ssh_key_QBA2data(ed25519PrivKey(pkey) + ed25519PubKey(), &priv);
+
+	data = "openssh-key-v1";
+	data.append('\0');
+	ssh_key_QBA2data("none", &data); // enc-alg
+	ssh_key_QBA2data("none", &data); // KDF name
+	ssh_key_QBA2data("", &data); // KDF data
+	data.append(data0001, sizeof data0001);
+	ssh_key_QBA2data(pubfull, &data);
+	ssh_key_QBA2data(priv, &data);
+
+	PEM_write_bio(b, PEM_STRING_OPENSSH_KEY, (char*)"",
+		(unsigned char*)(data.data()), data.size());
+	pki_openssl_error();
+}
+
 bool pki_key::pem(BioByteArray &b, int format)
 {
 	EVP_PKEY *pkey;
@@ -122,6 +150,11 @@ bool pki_key::pem(BioByteArray &b, int format)
 				EVP_PKEY_get0_EC_KEY(pkey),
 				NULL, NULL, 0, NULL, NULL);
 			break;
+#ifdef EVP_PKEY_ED25519
+		case EVP_PKEY_ED25519:
+			write_SSH2_ed25519_private(b, pkey, NULL);
+			break;
+#endif
 #endif
 		}
 		EVP_PKEY_free(pkey);
@@ -322,18 +355,30 @@ QString pki_key::ecPubKey() const
 	return pub;
 }
 
-QByteArray pki_key::ed25519PubKey() const
+static QByteArray ed25519Key(int(*EVP_PKEY_get_raw)
+			(const EVP_PKEY*, unsigned char *, size_t *),
+			const EVP_PKEY *pkey)
 {
 #ifdef EVP_PKEY_ED25519
-	unsigned char pub[ED25519_KEYLEN];
-	size_t len = sizeof pub;
+	unsigned char k[ED25519_KEYLEN];
+	size_t len = sizeof k;
 
-	if (getKeyType() == EVP_PKEY_ED25519 &&
-	    EVP_PKEY_get_raw_public_key(key, pub, &len))
-		return QByteArray((char*)pub, len);
+	if (EVP_PKEY_id(pkey) == EVP_PKEY_ED25519 &&
+	    EVP_PKEY_get_raw(pkey, k, &len))
+		return QByteArray((char*)k, len);
 #endif
 	return QByteArray();
 }
+
+QByteArray pki_key::ed25519PubKey() const
+{
+	return ed25519Key(EVP_PKEY_get_raw_public_key, key);
+}
+
+QByteArray pki_key::ed25519PrivKey(const EVP_PKEY *pkey) const
+{
+	return ed25519Key(EVP_PKEY_get_raw_private_key, pkey);
+}
 #endif
 
 QList<int> pki_key::possibleHashNids()
diff --git a/lib/pki_key.h b/lib/pki_key.h
index bac20221..f465b28e 100644
--- a/lib/pki_key.h
+++ b/lib/pki_key.h
@@ -223,10 +223,14 @@ class pki_key: public pki_base
 		QString pubEx() const;
 		QString subprime() const;
 		QString pubkey() const;
+
+#ifndef OPENSSL_NO_EC
 		int ecParamNid() const;
 		QString ecPubKey() const;
 		QByteArray ed25519PubKey() const;
+		QByteArray ed25519PrivKey(const EVP_PKEY *pkey) const;
 		BIGNUM *ecPubKeyBN() const;
+#endif
 		void d2i(QByteArray &ba);
 		void d2i_old(QByteArray &ba, int type);
 		QByteArray i2d() const;
@@ -234,6 +238,8 @@ class pki_key: public pki_base
 		void writeSSH2public(XFile &file) const;
 		QString fingerprint(const QString &format) const;
 		bool SSH2_compatible() const;
+		void write_SSH2_ed25519_private(BioByteArray &b,
+			const EVP_PKEY *pkey, const EVP_CIPHER *enc) const;
 		void print(BioByteArray &b, enum print_opt opt) const;
 		void resetUcount()
 		{