Encode RSA public keys in RFC 3110 DNSKEY format

src/libstrongswan/credentials/cred_encoding.h

@@ -85,6 +85,8 @@ enum cred_encoding_type_t {
 	/** PGP key encoding */
 	PUBKEY_PGP,
 	PRIVKEY_PGP,
+	/** DNSKEY encoding */
+	PUBKEY_DNSKEY,
 
 	/** ASN.1 DER encoded certificate */
 	CERT_ASN1_DER,

src/libstrongswan/plugins/dnskey/Makefile.am

@@ -11,6 +11,7 @@ endif
 
 libstrongswan_dnskey_la_SOURCES = \
 	dnskey_plugin.h dnskey_plugin.c \
-	dnskey_builder.h dnskey_builder.c
+	dnskey_builder.h dnskey_builder.c \
+	dnskey_encoder.h dnskey_encoder.c
 
 libstrongswan_dnskey_la_LDFLAGS = -module -avoid-version

src/libstrongswan/plugins/dnskey/dnskey_builder.c

@@ -39,8 +39,14 @@ enum dnskey_algorithm_t {
 	DNSKEY_ALG_RSA_MD5 = 1,
 	DNSKEY_ALG_DH = 2,
 	DNSKEY_ALG_DSA = 3,
-	DNSKEY_ALG_ECC = 4,
 	DNSKEY_ALG_RSA_SHA1 = 5,
+	DNSKEY_ALG_DSA_NSEC3_SHA1 = 6,
+	DNSKEY_ALG_RSA_SHA1_NSEC3_SHA1 = 7,
+	DNSKEY_ALG_RSA_SHA256 = 8,
+	DNSKEY_ALG_RSA_SHA512 = 10,
+	DNSKEY_ALG_ECC_GOST = 12,
+	DNSKEY_ALG_ECDSA_P256_SHA256 = 13,
+	DNSKEY_ALG_ECDSA_P384_SHA384 = 14
 };
 
 /**
@@ -59,7 +65,11 @@ static dnskey_public_key_t *parse_public_key(chunk_t blob)
 
 	switch (rr->algorithm)
 	{
+		case DNSKEY_ALG_RSA_MD5:
 		case DNSKEY_ALG_RSA_SHA1:
+		case DNSKEY_ALG_RSA_SHA1_NSEC3_SHA1:
+		case DNSKEY_ALG_RSA_SHA256:
+		case DNSKEY_ALG_RSA_SHA512:
 			return lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_RSA,
 									  BUILD_BLOB_DNSKEY, blob, BUILD_END);
 		default:

src/libstrongswan/plugins/dnskey/dnskey_encoder.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2013 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "dnskey_encoder.h"
+
+#include <utils/debug.h>
+
+/**
+ * Encode an RSA public key in DNSKEY format (RFC 3110)
+ */
+bool build_pub(chunk_t *encoding, va_list args)
+{
+	chunk_t n, e, pubkey;
+	size_t exp_len;
+	u_char *pos;
+
+	if (cred_encoding_args(args, CRED_PART_RSA_MODULUS, &n,
+						   CRED_PART_RSA_PUB_EXP, &e, CRED_PART_END))
+	{
+		/* remove leading zeros in exponent and modulus */
+		while (*e.ptr == 0)
+		{
+			e = chunk_skip(e, 1);
+		}
+		while (*n.ptr == 0)
+		{
+			n = chunk_skip(n, 1);
+		}
+
+		if (e.len < 256)
+		{
+			/* exponent length fits into a single octet */
+			exp_len = 1;
+			pubkey = chunk_alloc(exp_len + e.len + n.len);
+			pubkey.ptr[0] = (char)e.len;
+		}
+		else if (e.len < 65536)
+		{
+			/* exponent length fits into two octets preceded by zero octet */
+			exp_len = 3;
+			pubkey = chunk_alloc(exp_len + e.len + n.len);
+			pubkey.ptr[0] = 0x00;
+			htoun16(pubkey.ptr + 1, e.len);
+		}			
+		else
+		{
+			/* exponent length is too large */
+			return FALSE;
+		}
+
+		/* copy exponent and modulus and convert to base64 format */
+		pos = pubkey.ptr + exp_len;
+		memcpy(pos, e.ptr, e.len);
+		pos += e.len;
+		memcpy(pos, n.ptr, n.len);
+		*encoding = chunk_to_base64(pubkey, NULL);
+		chunk_free(&pubkey);
+
+		return TRUE;
+	}
+	return FALSE;
+}
+
+/**
+ * See header.
+ */
+bool dnskey_encoder_encode(cred_encoding_type_t type, chunk_t *encoding,
+						   va_list args)
+{
+	switch (type)
+	{
+		case PUBKEY_DNSKEY:
+			return build_pub(encoding, args);
+		default:
+			return FALSE;
+	}
+}
+
+

src/libstrongswan/plugins/dnskey/dnskey_encoder.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2013 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup dnskey_encoder dnskey_encoder
+ * @{ @ingroup dnskey
+ */
+
+#ifndef DNSKEY_ENCODER_H_
+#define DNSKEY_ENCODER_H_
+
+#include <credentials/cred_encoding.h>
+
+/**
+ * Encoding function for DNSKEY (RFC 3110) public key format.
+ */
+bool dnskey_encoder_encode(cred_encoding_type_t type, chunk_t *encoding,
+						  va_list args);
+
+#endif /** DNSKEY_ENCODER_H_ @}*/

src/libstrongswan/plugins/dnskey/dnskey_plugin.c

@@ -17,6 +17,7 @@
 
 #include <library.h>
 #include "dnskey_builder.h"
+#include "dnskey_encoder.h"
 
 typedef struct private_dnskey_plugin_t private_dnskey_plugin_t;
 
@@ -53,6 +54,8 @@ METHOD(plugin_t, get_features, int,
 METHOD(plugin_t, destroy, void,
 	private_dnskey_plugin_t *this)
 {
+	lib->encoding->remove_encoder(lib->encoding, dnskey_encoder_encode);
+
 	free(this);
 }
 
@@ -73,6 +76,8 @@ plugin_t *dnskey_plugin_create()
 		},
 	);
 
+	lib->encoding->add_encoder(lib->encoding, dnskey_encoder_encode);
+
 	return &this->public.plugin;
 }
 

src/pki/commands/pub.c

@@ -158,7 +158,7 @@ static void __attribute__ ((constructor))reg()
 		pub, 'p', "pub",
 		"extract the public key from a private key/certificate",
 		{"[--in file|--keyid hex] [--type rsa|ecdsa|pkcs10|x509]",
-		 "[--outform der|pem|pgp]"},
+		 "[--outform der|pem|pgp|dnskey]"},
 		{
 			{"help",	'h', 0, "show usage information"},
 			{"in",		'i', 1, "input file, default: stdin"},

src/pki/pki.c

@@ -76,6 +76,17 @@ bool get_form(char *form, cred_encoding_type_t *enc, credential_type_t type)
 				return FALSE;
 		}
 	}
+	else if (streq(form, "dnskey"))
+	{
+		switch (type)
+		{
+			case CRED_PUBLIC_KEY:
+				*enc =PUBKEY_DNSKEY;
+				return TRUE;
+			default:
+				return FALSE;
+		}
+	}
 	return FALSE;
 }