ECDSA with OpenSSL

2008-06-10 09:08:27 +00:00
parent 2904403e96
commit ea0823dffd
28 changed files with 1456 additions and 101 deletions
@@ -0,0 +1,447 @@
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * 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.
+ *
+ * $Id$
+ */
+
+#include "openssl_ec_public_key.h"
+#include "openssl_util.h"
+
+#include <debug.h>
+
+#include <openssl/evp.h>
+#include <openssl/ecdsa.h>
+#include <openssl/x509.h>
+
+typedef struct private_openssl_ec_public_key_t private_openssl_ec_public_key_t;
+
+/**
+ * Private data structure with signing context.
+ */
+struct private_openssl_ec_public_key_t {
+	/**
+	 * Public interface for this signer.
+	 */
+	openssl_ec_public_key_t public;
+	
+	/**
+	 * EC key object
+	 */
+	EC_KEY *ec;
+	
+	/**
+	 * Keyid formed as a SHA-1 hash of a publicKeyInfo object
+	 */
+	identification_t *keyid_info;
+	
+	/**
+	 * Keyid formed as a SHA-1 hash of a publicKey object
+	 */
+	identification_t *keyid;
+	
+	/**
+	 * reference counter
+	 */
+	refcount_t ref;
+};
+
+/**
+ * Convert a chunk to an ECDSA_SIG (which must already exist). r and s
+ * of the signature have to be concatenated in the chunk.
+ */
+static bool chunk2sig(const EC_GROUP *group, chunk_t chunk, ECDSA_SIG *sig)
+{
+	return openssl_bn_split(chunk, sig->r, sig->s);
+}
+
+/**
+ * Verification of a signature as in RFC 4754
+ */
+static bool verify_signature(private_openssl_ec_public_key_t *this,
+								int hash_type, chunk_t data, chunk_t signature)
+{
+	chunk_t hash = chunk_empty;
+	ECDSA_SIG *sig;
+	bool valid = FALSE;
+	
+	if (!openssl_hash_chunk(hash_type, data, &hash))
+	{
+		return FALSE;
+	}
+	
+	sig = ECDSA_SIG_new();
+	if (!sig)
+	{
+		goto error;
+	}
+	
+	if (!chunk2sig(EC_KEY_get0_group(this->ec), signature, sig))
+	{
+		goto error;
+	}
+	
+	valid = (ECDSA_do_verify(hash.ptr, hash.len, sig, this->ec) == 1);
+	
+error:
+	if (sig)
+	{
+		ECDSA_SIG_free(sig);
+	}
+	chunk_free(&hash);
+	return valid;
+}
+
+
+/**
+ * Verification of the default signature using SHA-1
+ */
+static bool verify_default_signature(private_openssl_ec_public_key_t *this,
+								chunk_t data, chunk_t signature)
+{
+	bool valid = FALSE;
+	chunk_t hash = chunk_empty;
+	u_char *p;
+	ECDSA_SIG *sig;
+	
+	/* remove any preceding 0-bytes from signature */
+	while (signature.len && *(signature.ptr) == 0x00)
+	{
+		signature.len -= 1;
+		signature.ptr++;
+	}
+	
+	p = signature.ptr;
+	sig = d2i_ECDSA_SIG(NULL, (const u_char**)&p, signature.len);
+	if (!sig)
+	{
+		return FALSE;
+	}
+	
+	if (!openssl_hash_chunk(NID_sha1, data, &hash))
+	{
+		goto error;
+	}
+	
+	valid = (ECDSA_do_verify(hash.ptr, hash.len, sig, this->ec) == 1);
+
+error:
+	if (sig)
+	{
+		ECDSA_SIG_free(sig);
+	}
+	chunk_free(&hash);
+	return valid;
+}
+
+/**
+ * Implementation of public_key_t.get_type.
+ */
+static key_type_t get_type(private_openssl_ec_public_key_t *this)
+{
+	return KEY_ECDSA;
+}
+
+/**
+ * Implementation of public_key_t.verify.
+ */
+static bool verify(private_openssl_ec_public_key_t *this, signature_scheme_t scheme, 
+				   chunk_t data, chunk_t signature)
+{
+	switch (scheme)
+	{
+		case SIGN_ECDSA_WITH_SHA1:
+			return verify_default_signature(this, data, signature);
+		case SIGN_ECDSA_256:
+			return verify_signature(this, NID_sha256, data, signature);
+		case SIGN_ECDSA_384:
+			return verify_signature(this, NID_sha384, data, signature);
+		case SIGN_ECDSA_521:
+			return verify_signature(this, NID_sha512, data, signature);
+		default:
+			DBG1("signature scheme %N not supported in EC",
+				 signature_scheme_names, scheme);
+			return FALSE;
+	}
+}
+
+/**
+ * Implementation of public_key_t.get_keysize.
+ */
+static bool encrypt(private_openssl_ec_public_key_t *this, chunk_t crypto, chunk_t *plain)
+{
+	DBG1("EC public key encryption not implemented");
+	return FALSE;
+}
+
+/**
+ * Implementation of public_key_t.get_keysize.
+ */
+static size_t get_keysize(private_openssl_ec_public_key_t *this)
+{
+	return EC_FIELD_ELEMENT_LEN(EC_KEY_get0_group(this->ec));
+}
+
+/**
+ * Implementation of public_key_t.get_id.
+ */
+static identification_t *get_id(private_openssl_ec_public_key_t *this,
+								id_type_t type)
+{
+	switch (type)
+	{
+		case ID_PUBKEY_INFO_SHA1:
+			return this->keyid_info;
+		case ID_PUBKEY_SHA1:
+			return this->keyid;
+		default:
+			return NULL;
+	}
+}
+
+/**
+ * Encodes the public key
+ */ 
+static chunk_t get_encoding_raw(EC_KEY *ec)
+{
+	/* since the points can be stored in three different forms this may not
+	 * be correct for all cases */
+	const EC_GROUP *group = EC_KEY_get0_group(ec);
+	const EC_POINT *pub = EC_KEY_get0_public_key(ec);
+	chunk_t enc = chunk_alloc(EC_POINT_point2oct(group, pub,
+						POINT_CONVERSION_UNCOMPRESSED, NULL, 0, NULL));
+	EC_POINT_point2oct(group, pub, POINT_CONVERSION_UNCOMPRESSED,
+						enc.ptr, enc.len, NULL);
+	return enc;	
+}
+
+/**
+ * Encodes the public key info (public key with ec parameters)
+ */ 
+static chunk_t get_encoding_full(EC_KEY *ec)
+{
+	chunk_t enc = chunk_alloc(i2d_EC_PUBKEY(ec, NULL));
+	u_char *p = enc.ptr;
+	i2d_EC_PUBKEY(ec, &p);
+	return enc;
+}
+
+/*
+ * Implementation of public_key_t.get_encoding.
+ */
+static chunk_t get_encoding(private_openssl_ec_public_key_t *this)
+{
+	return get_encoding_full(this->ec);
+}
+
+/**
+ * Implementation of public_key_t.get_ref.
+ */
+static private_openssl_ec_public_key_t* get_ref(private_openssl_ec_public_key_t *this)
+{
+	ref_get(&this->ref);
+	return this;
+}
+
+/**
+ * Implementation of openssl_ec_public_key.destroy.
+ */
+static void destroy(private_openssl_ec_public_key_t *this)
+{
+	if (ref_put(&this->ref))
+	{
+		if (this->ec)
+		{
+			EC_KEY_free(this->ec);
+		}
+		DESTROY_IF(this->keyid);
+		DESTROY_IF(this->keyid_info);
+		free(this);
+	}
+}
+
+/**
+ * Generic private constructor
+ */
+static private_openssl_ec_public_key_t *openssl_ec_public_key_create_empty()
+{
+	private_openssl_ec_public_key_t *this = malloc_thing(private_openssl_ec_public_key_t);
+	
+	this->public.interface.get_type = (key_type_t (*)(public_key_t *this))get_type;
+	this->public.interface.verify = (bool (*)(public_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t signature))verify;
+	this->public.interface.encrypt = (bool (*)(public_key_t *this, chunk_t crypto, chunk_t *plain))encrypt;
+	this->public.interface.get_keysize = (size_t (*) (public_key_t *this))get_keysize;
+	this->public.interface.get_id = (identification_t* (*) (public_key_t *this,id_type_t))get_id;
+	this->public.interface.get_encoding = (chunk_t(*)(public_key_t*))get_encoding;
+	this->public.interface.get_ref = (public_key_t* (*)(public_key_t *this))get_ref;
+	this->public.interface.destroy = (void (*)(public_key_t *this))destroy;
+	
+	this->ec = NULL;
+	this->keyid = NULL;
+	this->keyid_info = NULL;
+	this->ref = 1;
+	
+	return this;
+}
+
+/**
+ * Build key identifier from the public key using SHA1 hashed publicKey(Info).
+ * Also used in openssl_ec_private_key.c.
+ */
+bool openssl_ec_public_key_build_id(EC_KEY *ec, identification_t **keyid,
+								 identification_t **keyid_info)
+{
+	chunk_t publicKeyInfo, publicKey, hash;
+	hasher_t *hasher;
+	
+	hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
+	if (hasher == NULL)
+	{
+		DBG1("SHA1 hash algorithm not supported, unable to use EC");
+		return FALSE;
+	}
+	
+	publicKey = get_encoding_raw(ec);
+	
+	hasher->allocate_hash(hasher, publicKey, &hash);
+	*keyid = identification_create_from_encoding(ID_PUBKEY_SHA1, hash);
+	chunk_free(&hash);
+	
+	publicKeyInfo = get_encoding_full(ec);
+	
+	hasher->allocate_hash(hasher, publicKeyInfo, &hash);
+	*keyid_info = identification_create_from_encoding(ID_PUBKEY_INFO_SHA1, hash);
+	chunk_free(&hash);
+	
+	hasher->destroy(hasher);
+	chunk_free(&publicKeyInfo);
+	chunk_free(&publicKey);
+	
+	return TRUE;
+}
+
+/**
+ * Create a public key from BIGNUM values, used in openssl_ec_private_key.c
+ */
+openssl_ec_public_key_t *openssl_ec_public_key_create_from_private_key(EC_KEY *ec)
+{
+	private_openssl_ec_public_key_t *this = openssl_ec_public_key_create_empty();
+	
+	this->ec = EC_KEY_new();
+	EC_KEY_set_public_key(this->ec, EC_KEY_get0_public_key(ec));
+	
+	if (!openssl_ec_public_key_build_id(this->ec, &this->keyid, &this->keyid_info))
+	{
+		destroy(this);
+		return NULL;
+	}
+	return &this->public;
+}
+
+/**
+ * Load a public key from an ASN1 encoded blob
+ */
+static openssl_ec_public_key_t *load(chunk_t blob)
+{
+	u_char *p = blob.ptr;
+	private_openssl_ec_public_key_t *this = openssl_ec_public_key_create_empty();
+	
+	this->ec = d2i_EC_PUBKEY(NULL, (const u_char**)&p, blob.len);
+	
+	chunk_clear(&blob);
+	
+	if (!this->ec)
+	{
+		destroy(this);
+		return NULL;
+	}
+	
+	if (!openssl_ec_public_key_build_id(this->ec, &this->keyid, &this->keyid_info))
+	{
+		destroy(this);
+		return NULL;
+	}
+	return &this->public;
+}
+
+typedef struct private_builder_t private_builder_t;
+/**
+ * Builder implementation for key loading
+ */
+struct private_builder_t {
+	/** implements the builder interface */
+	builder_t public;
+	/** loaded public key */
+	openssl_ec_public_key_t *key;
+};
+
+/**
+ * Implementation of builder_t.build
+ */
+static openssl_ec_public_key_t *build(private_builder_t *this)
+{
+	openssl_ec_public_key_t *key = this->key;
+	
+	free(this);
+	return key;
+}
+
+/**
+ * Implementation of builder_t.add
+ */
+static void add(private_builder_t *this, builder_part_t part, ...)
+{
+	va_list args;
+	
+	if (this->key)
+	{
+		DBG1("ignoring surplus build part %N", builder_part_names, part);
+		return;
+	}
+	
+	switch (part)
+	{
+		case BUILD_BLOB_ASN1_DER:
+		{
+			va_start(args, part);
+			this->key = load(va_arg(args, chunk_t));
+			va_end(args);
+			break;
+		}
+		default:
+			DBG1("ignoring unsupported build part %N", builder_part_names, part);
+			break;
+	}
+}
+
+/**
+ * Builder construction function
+ */
+builder_t *openssl_ec_public_key_builder(key_type_t type)
+{
+	private_builder_t *this;
+	
+	if (type != KEY_ECDSA)
+	{
+		return NULL;
+	}
+	
+	this = malloc_thing(private_builder_t);
+	
+	this->key = NULL;
+	this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
+	this->public.build = (void*(*)(builder_t *this))build;
+	
+	return &this->public;
+}
+