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 +1,445 @@
+/*
+ * 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_private_key.h"
+#include "openssl_ec_public_key.h"
+#include "openssl_util.h"
+
+#include <debug.h>
+
+#include <openssl/evp.h>
+#include <openssl/ecdsa.h>
+
+typedef struct private_openssl_ec_private_key_t private_openssl_ec_private_key_t;
+
+/**
+ * Private data of a openssl_ec_private_key_t object.
+ */
+struct private_openssl_ec_private_key_t {
+	/**
+	 * Public interface for this signer.
+	 */
+	openssl_ec_private_key_t public;
+	
+	/**
+	 * EC key object
+	 */
+	EC_KEY *ec;
+
+	/**
+	 * Keyid formed as a SHA-1 hash of a privateKey object
+	 */
+	identification_t* keyid;
+
+	/**
+	 * Keyid formed as a SHA-1 hash of a privateKeyInfo object
+	 */
+	identification_t* keyid_info;
+	
+	/**
+	 * reference count
+	 */
+	refcount_t ref;	
+};
+
+/**
+ * Mapping from the signature scheme defined in (RFC 4754) to the elliptic
+ * curve and the hash algorithm
+ */
+typedef struct {
+	/**
+	 * Scheme specified in RFC 4754
+	 */
+	int scheme;
+	
+	/**
+	 * NID of the hash
+	 */
+	int hash;
+	
+	/**
+	 * NID of the curve
+	 */
+	int curve;
+} openssl_ecdsa_scheme_t;
+
+#define END_OF_LIST -1
+
+/**
+ * Signature schemes
+ */
+static openssl_ecdsa_scheme_t ecdsa_schemes[] = {
+	{SIGN_ECDSA_256, NID_sha256, NID_X9_62_prime256v1},
+	{SIGN_ECDSA_384, NID_sha384, NID_secp384r1},
+	{SIGN_ECDSA_521, NID_sha512, NID_secp521r1},
+	{END_OF_LIST,    0,          0},
+};
+
+/**
+ * Look up the hash and curve of a signature scheme
+ */
+static bool lookup_scheme(int scheme, int *hash, int *curve)
+{
+	openssl_ecdsa_scheme_t *ecdsa_scheme = ecdsa_schemes;
+	while (ecdsa_scheme->scheme != END_OF_LIST)
+	{
+		if (scheme == ecdsa_scheme->scheme)
+		{
+			*hash = ecdsa_scheme->hash;
+			*curve = ecdsa_scheme->curve;
+			return TRUE;
+		}
+		ecdsa_scheme++;
+	}
+	return FALSE;
+}
+
+/**
+ * shared functions, implemented in openssl_ec_public_key.c
+ */
+bool openssl_ec_public_key_build_id(EC_KEY *ec, identification_t **keyid,
+								 identification_t **keyid_info);
+
+openssl_ec_public_key_t *openssl_ec_public_key_create_from_private_key(EC_KEY *ec);
+
+
+/**
+ * Convert an ECDSA_SIG to a chunk by concatenating r and s.
+ * This function allocates memory for the chunk.
+ */
+static bool sig2chunk(const EC_GROUP *group, ECDSA_SIG *sig, chunk_t *chunk)
+{
+	return openssl_bn_cat(EC_FIELD_ELEMENT_LEN(group), sig->r, sig->s, chunk);
+}
+
+/**
+ * Build the signature
+ */
+static bool build_signature(private_openssl_ec_private_key_t *this,
+							int hash_type, chunk_t data, chunk_t *signature)
+{
+	chunk_t hash = chunk_empty;
+	ECDSA_SIG *sig;
+	bool ret = FALSE;
+	
+	if (!openssl_hash_chunk(hash_type, data, &hash))
+	{
+		return FALSE;
+	}
+	
+	sig = ECDSA_do_sign(hash.ptr, hash.len, this->ec);
+	if (!sig)
+	{
+		goto error;
+	}
+	
+	if (!sig2chunk(EC_KEY_get0_group(this->ec), sig, signature))
+	{
+		goto error;
+	}
+	
+	ret = TRUE;
+error:
+	chunk_free(&hash);
+	if (sig)
+	{
+		ECDSA_SIG_free(sig);
+	}
+	return ret;
+}
+
+/**
+ * Implementation of private_key_t.get_type.
+ */
+static key_type_t get_type(private_openssl_ec_private_key_t *this)
+{
+	return KEY_ECDSA;
+}
+
+/**
+ * Implementation of private_key_t.sign.
+ */
+static bool sign(private_openssl_ec_private_key_t *this, signature_scheme_t scheme, 
+				 chunk_t data, chunk_t *signature)
+{
+	EC_GROUP *req_group;
+	const EC_GROUP *my_group;
+	int hash, curve;
+	
+	if (!lookup_scheme(scheme, &hash, &curve))
+	{
+		DBG1("signature scheme %N not supported in EC",
+				 signature_scheme_names, scheme);
+		return FALSE;
+	}
+	
+	req_group = EC_GROUP_new_by_curve_name(curve);
+	if (!req_group)
+	{
+		DBG1("signature scheme %N not supported in EC (required curve not supported)",
+				 signature_scheme_names, scheme);
+		return FALSE;
+	}
+	
+	my_group = EC_KEY_get0_group(this->ec);
+	if (EC_GROUP_cmp(my_group, req_group, NULL) != 0)
+	{
+		DBG1("signature scheme %N not supported by private key",
+				 signature_scheme_names, scheme);
+		return FALSE;
+	}
+	
+	EC_GROUP_free(req_group);
+	
+	return build_signature(this, hash, data, signature);
+}
+
+/**
+ * Implementation of private_key_t.destroy.
+ */
+static bool decrypt(private_openssl_ec_private_key_t *this,
+					chunk_t crypto, chunk_t *plain)
+{
+	DBG1("EC private key decryption not implemented");
+	return FALSE;
+}
+
+/**
+ * Implementation of private_key_t.get_keysize.
+ */
+static size_t get_keysize(private_openssl_ec_private_key_t *this)
+{
+	return EC_FIELD_ELEMENT_LEN(EC_KEY_get0_group(this->ec));
+}
+
+/**
+ * Implementation of private_key_t.get_id.
+ */
+static identification_t* get_id(private_openssl_ec_private_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;
+	}
+}
+
+/**
+ * Implementation of private_key_t.get_public_key.
+ */
+static openssl_ec_public_key_t* get_public_key(private_openssl_ec_private_key_t *this)
+{
+	return openssl_ec_public_key_create_from_private_key(this->ec);
+}
+
+/**
+ * Implementation of private_key_t.belongs_to.
+ */
+static bool belongs_to(private_openssl_ec_private_key_t *this, public_key_t *public)
+{
+	identification_t *keyid;
+
+	if (public->get_type(public) != KEY_ECDSA)
+	{
+		return FALSE;
+	}
+	keyid = public->get_id(public, ID_PUBKEY_SHA1);
+	if (keyid && keyid->equals(keyid, this->keyid))
+	{
+		return TRUE;
+	}
+	keyid = public->get_id(public, ID_PUBKEY_INFO_SHA1);
+	if (keyid && keyid->equals(keyid, this->keyid_info))
+	{
+		return TRUE;
+	}
+	return FALSE;
+}
+
+/**
+ * Implementation of private_key_t.get_encoding.
+ */
+static chunk_t get_encoding(private_openssl_ec_private_key_t *this)
+{
+	chunk_t enc = chunk_alloc(i2d_ECPrivateKey(this->ec, NULL));
+	u_char *p = enc.ptr;
+	i2d_ECPrivateKey(this->ec, &p);
+	return enc;
+}
+
+/**
+ * Implementation of private_key_t.get_ref.
+ */
+static private_openssl_ec_private_key_t* get_ref(private_openssl_ec_private_key_t *this)
+{
+	ref_get(&this->ref);
+	return this;
+
+}
+
+/**
+ * Implementation of private_key_t.destroy.
+ */
+static void destroy(private_openssl_ec_private_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);
+	}
+}
+
+/**
+ * Internal generic constructor
+ */
+static private_openssl_ec_private_key_t *openssl_ec_private_key_create_empty(void)
+{
+	private_openssl_ec_private_key_t *this = malloc_thing(private_openssl_ec_private_key_t);
+	
+	this->public.interface.get_type = (key_type_t (*)(private_key_t *this))get_type;
+	this->public.interface.sign = (bool (*)(private_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t *signature))sign;
+	this->public.interface.decrypt = (bool (*)(private_key_t *this, chunk_t crypto, chunk_t *plain))decrypt;
+	this->public.interface.get_keysize = (size_t (*) (private_key_t *this))get_keysize;
+	this->public.interface.get_id = (identification_t* (*) (private_key_t *this,id_type_t))get_id;
+	this->public.interface.get_public_key = (public_key_t* (*)(private_key_t *this))get_public_key;
+	this->public.interface.belongs_to = (bool (*) (private_key_t *this, public_key_t *public))belongs_to;
+	this->public.interface.get_encoding = (chunk_t(*)(private_key_t*))get_encoding;
+	this->public.interface.get_ref = (private_key_t* (*)(private_key_t *this))get_ref;
+	this->public.interface.destroy = (void (*)(private_key_t *this))destroy;
+	
+	this->ec = NULL;
+	this->keyid = NULL;
+	this->keyid_info = NULL;
+	this->ref = 1;
+	
+	return this;
+}
+
+/**
+ * load private key from an ASN1 encoded blob
+ */
+static openssl_ec_private_key_t *load(chunk_t blob)
+{
+	u_char *p = blob.ptr;
+	private_openssl_ec_private_key_t *this = openssl_ec_private_key_create_empty();
+	
+	this->ec = d2i_ECPrivateKey(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;
+	}
+	
+	if (!EC_KEY_check_key(this->ec))
+	{
+		destroy(this);
+		return NULL;
+	}
+	
+	return &this->public;
+}
+
+typedef struct private_builder_t private_builder_t;
+/**
+ * Builder implementation for key loading/generation
+ */
+struct private_builder_t {
+	/** implements the builder interface */
+	builder_t public;
+	/** loaded/generated private key */
+	openssl_ec_private_key_t *key;
+};
+
+/**
+ * Implementation of builder_t.build
+ */
+static openssl_ec_private_key_t *build(private_builder_t *this)
+{
+	openssl_ec_private_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_private_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;
+}
+