Add ed25519 support

Makefile.in

@@ -31,13 +31,13 @@ OPTION_HEADERS += localoptions.h
 endif
 
 COMMONOBJS=dbutil.o buffer.o dbhelpers.o \
-		dss.o bignum.o \
+		dss.o ed25519.o ed25519_crypto.o bignum.o \
 		signkey.o rsa.o dbrandom.o \
 		queue.o \
 		atomicio.o compat.o fake-rfc2553.o \
 		ltc_prng.o ecc.o ecdsa.o crypto_desc.o \
 		dbmalloc.o \
-		gensignkey.o gendss.o genrsa.o
+		gensignkey.o gendss.o gened25519.o genrsa.o
 
 SVROBJS=svr-kex.o svr-auth.o sshpty.o \
 		svr-authpasswd.o svr-authpubkey.o svr-authpubkeyoptions.o svr-session.o svr-service.o \

common-algo.c

@@ -238,6 +238,9 @@ algo_type sshhostkey[] = {
 #endif
 #if DROPBEAR_DSS
 	{"ssh-dss", DROPBEAR_SIGNKEY_DSS, NULL, 1, NULL},
+#endif
+#ifdef DROPBEAR_ED25519
+	{"ssh-ed25519", DROPBEAR_SIGNKEY_ED25519, NULL, 1, NULL},
 #endif
 	{NULL, 0, NULL, 0, NULL}
 };

common-session.c

@@ -28,7 +28,6 @@
 #include "packet.h"
 #include "algo.h"
 #include "buffer.h"
-#include "dss.h"
 #include "ssh.h"
 #include "dbrandom.h"
 #include "kex.h"

default_options.h

@@ -116,6 +116,7 @@ IMPORTANT: Some options will require "make clean" after changes */
  * code (either ECDSA or ECDH) increases binary size - around 30kB
  * on x86-64 */
 #define DROPBEAR_ECDSA 1
+#define DROPBEAR_ED25519 1
 
 /* RSA must be >=1024 */
 #define DROPBEAR_DEFAULT_RSA_SIZE 2048

dropbearkey.c

@@ -43,6 +43,14 @@
  * mp_int	y
  * mp_int	x
  *
+ * ECDSA:
+ * string	"ecdsa-sha2-nistp256" or "ecdsa-sha2-nistp384" or "ecdsa-sha2-nistp521"
+ * (not discribed here further)
+ *
+ * ed25519:
+ * string	"ssh-ed25519"
+ * string       64 bytes: private_key (32 bytes) + public_key (32 bytes)
+ *
  */
 #include "includes.h"
 #include "signkey.h"
@@ -75,6 +83,9 @@ static void printhelp(char * progname) {
 #endif
 #if DROPBEAR_ECDSA
 					"		ecdsa\n"
+#endif
+#ifdef DROPBEAR_ED25519
+					"		ed25519\n"
 #endif
 					"-f filename    Use filename for the secret key.\n"
 					"               ~/.ssh/id_dropbear is recommended for client keys.\n"
@@ -94,6 +105,9 @@ static void printhelp(char * progname) {
 					"521 "
 #endif
 					"\n"
+#endif
+#ifdef DROPBEAR_ED25519
+					"           ed25519 has a fixed size of 256 bits\n"
 #endif
 					"-y		Just print the publickey and fingerprint for the\n		private key in <filename>.\n"
 #if DEBUG_TRACE
@@ -224,6 +238,12 @@ int main(int argc, char ** argv) {
 		keytype = DROPBEAR_SIGNKEY_ECDSA_KEYGEN;
 	}
 #endif
+#ifdef DROPBEAR_ED25519
+	if (strcmp(typetext, "ed25519") == 0)
+	{
+		keytype = DROPBEAR_SIGNKEY_ED25519;
+	}
+#endif
 
 	if (keytype == DROPBEAR_SIGNKEY_NONE) {
 		fprintf(stderr, "Unknown key type '%s'\n", typetext);

ed25519.c

@@ -0,0 +1,130 @@
+/*
+ * Dropbear - a SSH2 server
+ *
+ * Copyright (c) 2002,2003 Matt Johnston
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#include "includes.h"
+#include "dbutil.h"
+#include "ed25519.h"
+#include "ed25519_crypto.h"
+#include "buffer.h"
+#include "ssh.h"
+
+/* Handle ed25519 (Edwards 25519 elliptic curve)
+ * operations, such as key reading, signing, verification. Key generation
+ * will be in gened25519.c, since it isn't required in the server itself.
+ */
+
+#ifdef DROPBEAR_ED25519
+
+/* Load a ed25519 key from a buffer, initialising the values.
+ * The key will have the same format as buf_put_ed25519_key.
+ * These should be freed with ed25519_key_free.
+ * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
+int buf_get_ed25519_pub_key(buffer* buf, dropbear_ed25519_key *key) {
+	/* Format (same as the base64-encoded 2nd word in each line of
+	 * ~/.ssh/authorized_keys used by dropbear and OpenSSH):
+	 *
+	 * "\0\0\0\x0bssh-ed25519\0\0\0 " + pk,
+	 * where pk is 32 bytes of public key.
+	 * It's 51 bytes in total.
+	 */
+	if (buf->pos + 51 > buf->len ||
+	    0 != memcmp(buf->data + buf->pos, "\0\0\0\x0bssh-ed25519\0\0\0 ", 19)
+	   ) return DROPBEAR_FAILURE;
+	memset(key->spk, '\0', 32);  /* Secret key not known. */
+	memcpy(key->spk + 32, buf->data + buf->pos + 19, 32);
+	buf->pos += 51;
+	return DROPBEAR_SUCCESS;
+}
+
+/* Loads a private ed25519 key from a buffer
+ * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
+int buf_get_ed25519_priv_key(buffer* buf, dropbear_ed25519_key *key) {
+	/* Format (not shared with OpenSSH):
+	 *
+	 * "\0\0\0\x0bssh-ed25519\0\0\0@" + sk + pk,
+	 * where sk is 32 bytes of secret key (private key).
+	 * where pk is 32 bytes of public key.
+	 * It's 83 bytes in total.
+	 */
+	if (buf->pos + 83 > buf->len ||
+	    0 != memcmp(buf->data + buf->pos, "\0\0\0\x0bssh-ed25519\0\0\0@", 19)
+	   ) return DROPBEAR_FAILURE;
+	memcpy(key->spk, buf->data + buf->pos + 19, 64);
+	buf->pos += 83;
+	return DROPBEAR_SUCCESS;
+}
+
+
+/* Clear and free the memory used by a public or private key */
+void ed25519_key_free(dropbear_ed25519_key *key) {
+	(void)key;
+}
+
+/* put the ed25519 public key into the buffer in the required format. */
+void buf_put_ed25519_pub_key(buffer* buf, dropbear_ed25519_key *key) {
+	dropbear_assert(key != NULL);
+	buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
+	buf_putstring(buf, key->spk + 32, 32);
+}
+
+/* put the ed25519 private key into the buffer in the required format. */
+void buf_put_ed25519_priv_key(buffer* buf, dropbear_ed25519_key *key) {
+	dropbear_assert(key != NULL);
+	buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
+	buf_putstring(buf, key->spk, 64);
+}
+
+#ifdef DROPBEAR_SIGNKEY_VERIFY
+/* Verify a ed25519 signature (in buf) made on data by the key given.
+ * returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
+int buf_ed25519_verify(buffer* buf, dropbear_ed25519_key *key, buffer *data_buf) {
+	char sm[512];
+	int res;
+	/* Typical data_size is 148 bytes for ssh. */
+	unsigned data_size;
+	if (buf_getint(buf) != 64 ||
+	    buf->len - buf->pos != 64 ||
+	    (data_size = data_buf->len) > sizeof(sm) - 64) {
+		return DROPBEAR_FAILURE;
+	}
+	memcpy(sm, buf->data + buf->pos, 64);
+	memcpy(sm + 64, data_buf->data, data_size);
+	res = ed25519_crypto_verify(sm, data_size, key->spk + 32);
+	return res ? DROPBEAR_FAILURE : DROPBEAR_SUCCESS;
+}
+#endif /* DROPBEAR_SIGNKEY_VERIFY */
+
+/* Sign the data presented with key, writing the signature contents
+ * to buf */
+void buf_put_ed25519_sign(buffer* buf, dropbear_ed25519_key *key, buffer *data_buf) {
+	char sm[512];
+	/* Typical data_size is 32 bytes for ssh. */
+	unsigned data_size = data_buf->len;
+	if (data_size > sizeof(sm) - 64) dropbear_exit("ed25519 message to sign too long");
+	ed25519_crypto_sign(sm, data_buf->data, data_size, key->spk);
+	buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
+	buf_putstring(buf, sm, 64);
+}
+
+#endif /* DROPBEAR_ED25519 */

ed25519.h

@@ -0,0 +1,49 @@
+/*
+ * Dropbear - a SSH2 server
+ * 
+ * Copyright (c) 2002,2003 Matt Johnston
+ * All rights reserved.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#ifndef DROPBEAR_ED25519_H_
+#define DROPBEAR_ED25519_H_
+
+#include "includes.h"
+#include "buffer.h"
+
+#ifdef DROPBEAR_ED25519 
+
+typedef struct {
+	char spk[64];  /* The first 32 bytes is th private part. */
+} dropbear_ed25519_key;
+
+void buf_put_ed25519_sign(buffer* buf, dropbear_ed25519_key *key, buffer *data_buf);
+#ifdef DROPBEAR_SIGNKEY_VERIFY
+int buf_ed25519_verify(buffer* buf, dropbear_ed25519_key *key, buffer *data_buf);
+#endif
+int buf_get_ed25519_pub_key(buffer* buf, dropbear_ed25519_key *key);
+int buf_get_ed25519_priv_key(buffer* buf, dropbear_ed25519_key *key);
+void buf_put_ed25519_pub_key(buffer* buf, dropbear_ed25519_key *key);
+void buf_put_ed25519_priv_key(buffer* buf, dropbear_ed25519_key *key);
+void ed25519_key_free(dropbear_ed25519_key *key);
+
+#endif /* DROPBEAR_ED25519 */
+
+#endif /* DROPBEAR_ED25519_H_ */