signature-params: Add functions to parse/build ASN.1 RSASSA-PSS params

2017-11-08 16:48:10 +01:00
parent c2b878cd61
commit a22316520b
7 changed files with 421 additions and 1 deletions
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2017 Tobias Brunner
+ * 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 "signature_params.h"
+
+#include <asn1/oid.h>
+#include <asn1/asn1_parser.h>
+
+/**
+ * ASN.1 definition of RSASSA-PSS-params
+ */
+static const asn1Object_t RSASSAPSSParamsObjects[] = {
+	{ 0, "RSASSA-PSS-params",	ASN1_SEQUENCE,		ASN1_NONE			}, /* 0 */
+	{ 1,   "DEFAULT SHA-1",		ASN1_CONTEXT_C_0,	ASN1_DEF			}, /* 1 */
+	{ 2,     "hashAlgorithm",	ASN1_EOC,			ASN1_RAW			}, /* 2 */
+	{ 1,   "DEFAULT MGF1SHA1",	ASN1_CONTEXT_C_1,	ASN1_DEF			}, /* 3 */
+	{ 2,     "maskGenAlgorithm",ASN1_EOC,			ASN1_RAW			}, /* 4 */
+	{ 1,   "DEFAULT 20",		ASN1_CONTEXT_C_2,	ASN1_DEF			}, /* 5 */
+	{ 2,     "saltLength",		ASN1_INTEGER,		ASN1_BODY			}, /* 6 */
+	{ 1,   "DEFAULT 1",			ASN1_CONTEXT_C_3,	ASN1_DEF			}, /* 7 */
+	{ 2,     "trailerField",	ASN1_INTEGER,		ASN1_BODY			}, /* 8 */
+	{ 0, "exit",				ASN1_EOC,			ASN1_EXIT			}
+};
+#define RSASSA_PSS_PARAMS_HASH_ALG		2
+#define RSASSA_PSS_PARAMS_MGF_ALG		4
+#define RSASSA_PSS_PARAMS_SALT_LEN		6
+#define RSASSA_PSS_PARAMS_TRAILER		8
+
+/*
+ * Described in header
+ */
+bool rsa_pss_params_parse(chunk_t asn1, int level0, rsa_pss_params_t *params)
+{
+	asn1_parser_t *parser;
+	chunk_t object;
+	int objectID, alg;
+	bool success = FALSE;
+
+	params->hash = HASH_SHA1;
+	params->mgf1_hash = HASH_SHA1;
+	params->salt_len = HASH_SIZE_SHA1;
+
+	parser = asn1_parser_create(RSASSAPSSParamsObjects, asn1);
+	parser->set_top_level(parser, level0);
+
+	while (parser->iterate(parser, &objectID, &object))
+	{
+		u_int level = parser->get_level(parser)+1;
+
+		switch (objectID)
+		{
+			case RSASSA_PSS_PARAMS_HASH_ALG:
+				if (object.len)
+				{
+					alg = asn1_parse_algorithmIdentifier(object, level, NULL);
+					params->hash = hasher_algorithm_from_oid(alg);
+					if (params->hash == HASH_UNKNOWN)
+					{
+						goto end;
+					}
+				}
+				break;
+			case RSASSA_PSS_PARAMS_MGF_ALG:
+				if (object.len)
+				{
+					chunk_t hash;
+
+					alg = asn1_parse_algorithmIdentifier(object, level, &hash);
+					if (alg != OID_MGF1)
+					{
+						goto end;
+					}
+					alg = asn1_parse_algorithmIdentifier(hash, level+1, NULL);
+					params->mgf1_hash = hasher_algorithm_from_oid(alg);
+					if (params->mgf1_hash == HASH_UNKNOWN)
+					{
+						goto end;
+					}
+				}
+				break;
+			case RSASSA_PSS_PARAMS_SALT_LEN:
+				if (object.len)
+				{
+					params->salt_len = (size_t)asn1_parse_integer_uint64(object);
+				}
+				break;
+			case RSASSA_PSS_PARAMS_TRAILER:
+				if (object.len && (object.len != 1 || *object.ptr != 1))
+				{
+					goto end;
+				}
+				break;
+			default:
+				break;
+		}
+	}
+	success = parser->success(parser);
+
+end:
+	parser->destroy(parser);
+	return success;
+}
+
+/*
+ * Described in header
+ */
+bool rsa_pss_params_build(rsa_pss_params_t *params, chunk_t *asn1)
+{
+	chunk_t hash = chunk_empty, mgf = chunk_empty, slen = chunk_empty;
+	int alg;
+
+	if (params->hash != HASH_SHA1)
+	{	/* with SHA-1 we MUST omit the field */
+		alg = hasher_algorithm_to_oid(params->hash);
+		if (alg == OID_UNKNOWN)
+		{
+			return FALSE;
+		}
+		hash = asn1_algorithmIdentifier(alg);
+	}
+	if (params->mgf1_hash != HASH_SHA1)
+	{	/* with MGF1-SHA1 we MUST omit the field */
+		alg = hasher_algorithm_to_oid(params->mgf1_hash);
+		if (alg == OID_UNKNOWN)
+		{
+			chunk_free(&hash);
+			return FALSE;
+		}
+		mgf = asn1_wrap(ASN1_SEQUENCE, "mm", asn1_build_known_oid(OID_MGF1),
+						asn1_algorithmIdentifier(alg));
+	}
+	if (params->salt_len > RSA_PSS_SALT_LEN_DEFAULT)
+	{
+		if (params->salt_len != HASH_SIZE_SHA1)
+		{
+			slen = asn1_integer("m", asn1_integer_from_uint64(params->salt_len));
+		}
+	}
+	else if (params->hash != HASH_SHA1)
+	{
+		size_t hlen = hasher_hash_size(params->hash);
+		if (!hlen)
+		{
+			chunk_free(&hash);
+			chunk_free(&mgf);
+			return FALSE;
+		}
+		slen = asn1_integer("m", asn1_integer_from_uint64(hlen));
+	}
+	*asn1 = asn1_wrap(ASN1_SEQUENCE, "mmm",
+				hash.len ? asn1_wrap(ASN1_CONTEXT_C_0, "m", hash) : chunk_empty,
+				mgf.len ? asn1_wrap(ASN1_CONTEXT_C_1, "m", mgf) : chunk_empty,
+				slen.len ? asn1_wrap(ASN1_CONTEXT_C_2, "m", slen) : chunk_empty);
+	return TRUE;
+}
@@ -38,4 +38,23 @@ struct rsa_pss_params_t {
 #define RSA_PSS_SALT_LEN_DEFAULT -1
 };

+/**
+ * Parse the given ASN.1 algorithm identifier params
+ *
+ * @param asn1		ASN.1 encoded RSASSA-PSS-params
+ * @param level0	current level of the ASN.1 parser
+ * @param params	parsed parameters
+ * @return			TRUE if successfully parsed
+ */
+bool rsa_pss_params_parse(chunk_t asn1, int level0, rsa_pss_params_t *params);
+
+/**
+ * Build ASN.1 algorithm identifier params
+ *
+ * @param params	parameters to encode
+ * @param asn1		ASN.1 encoded RSASSA-PSS-params (allocated)
+ * @return			TRUE if successfully built
+ */
+bool rsa_pss_params_build(rsa_pss_params_t *params, chunk_t *asn1);
+
 #endif /** SIGNATURE_PARAMS_H_ @}*/