implemented a pgp plugin providing PGP key parsing builders

2009-08-26 11:23:50 +02:00
parent 4e3d1e804e
commit 9493dd2ce0
7 changed files with 610 additions and 0 deletions
@@ -0,0 +1,347 @@
+/*
+ * Copyright (C) 2009 Martin Willi
+ * Copyright (C) 2002-2009 Andreas Steffen
+ * 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 "pgp_builder.h"
+
+#include <debug.h>
+#include <credentials/keys/private_key.h>
+
+
+ENUM_BEGIN(pgp_packet_tag_names, PGP_PKT_RESERVED, PGP_PKT_PUBLIC_SUBKEY,
+	"Reserved",
+	"Public-Key Encrypted Session Key Packet",
+	"Signature Packet",
+	"Symmetric-Key Encrypted Session Key Packet",
+	"One-Pass Signature Packet",
+	"Secret Key Packet",
+	"Public Key Packet",
+	"Secret Subkey Packet",
+	"Compressed Data Packet",
+	"Symmetrically Encrypted Data Packet",
+	"Marker Packet",
+	"Literal Data Packet",
+	"Trust Packet",
+	"User ID Packet",
+	"Public Subkey Packet"
+);
+ENUM_NEXT(pgp_packet_tag_names, PGP_PKT_USER_ATTRIBUTE, PGP_PKT_MOD_DETECT_CODE, PGP_PKT_PUBLIC_SUBKEY,
+	"User Attribute Packet",
+	"Sym. Encrypted and Integrity Protected Data Packet",
+	"Modification Detection Code Packet"
+);
+ENUM_END(pgp_packet_tag_names, PGP_PKT_MOD_DETECT_CODE);
+
+ENUM_BEGIN(pgp_pubkey_alg_names, PGP_PUBKEY_ALG_RSA, PGP_PUBKEY_ALG_RSA_SIGN_ONLY,
+	"RSA",
+	"RSA_ENC_ONLY",
+	"RSA_SIGN_ONLY"
+);
+ENUM_NEXT(pgp_pubkey_alg_names, PGP_PUBKEY_ALG_ELGAMAL_ENC_ONLY, PGP_PUBKEY_ALG_DIFFIE_HELLMAN, PGP_PUBKEY_ALG_RSA_SIGN_ONLY,
+	"ELGAMAL_ENC_ONLY",
+	"DSA",
+	"ECC",
+	"ECDSA",
+	"ELGAMAL",
+	"DIFFIE_HELLMAN"
+);
+ENUM_END(pgp_pubkey_alg_names, PGP_PUBKEY_ALG_DIFFIE_HELLMAN);
+
+ENUM(pgp_sym_alg_names, PGP_SYM_ALG_PLAIN, PGP_SYM_ALG_TWOFISH,
+	"PLAINTEXT",
+	"IDEA",
+	"3DES",
+	"CAST5",
+	"BLOWFISH",
+	"SAFER",
+	"DES",
+	"AES_128",
+	"AES_192",
+	"AES_256",
+	"TWOFISH"
+);
+
+/**
+ * Read a PGP scalar of bytes length, advance blob
+ */
+static bool read_scalar(chunk_t *blob, size_t bytes, u_int32_t *scalar)
+{
+	u_int32_t res = 0;
+	
+	if (bytes > blob->len)
+	{
+		DBG1("PGP data too short to read %d byte scalar", bytes);
+		return FALSE;
+	}
+	while (bytes-- > 0)
+	{
+		res = 256 * res + blob->ptr[0];
+		*blob = chunk_skip(*blob, 1);
+	}
+	*scalar = res;
+	return TRUE;
+}
+
+/**
+ * Read a PGP MPI, advance blob
+ */
+static bool read_mpi(chunk_t *blob, chunk_t *mpi)
+{
+	u_int32_t bits, bytes;
+	
+	if (!read_scalar(blob, 2, &bits))
+	{
+		DBG1("PGP data too short to read MPI length");
+		return FALSE;
+	}
+	bytes = (bits + 7) / 8;
+	if (bytes > blob->len)
+	{
+		DBG1("PGP data too short to %d byte MPI", bytes);
+		return FALSE;
+	}
+	*mpi = chunk_create(blob->ptr, bytes);
+	*blob = chunk_skip(*blob, bytes);
+	return TRUE;
+}
+
+/**
+ * Load a generic public key from a PGP packet
+ */
+static public_key_t *parse_public_key(chunk_t blob)
+{
+	u_int32_t alg;
+	public_key_t *key;
+	
+	if (!read_scalar(&blob, 1, &alg))
+	{
+		return NULL;
+	}
+	switch (alg)
+	{
+		case PGP_PUBKEY_ALG_RSA:
+		case PGP_PUBKEY_ALG_RSA_SIGN_ONLY:
+			key = lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_RSA,
+									 BUILD_BLOB_PGP, blob, BUILD_END);
+			break;
+		default:
+			DBG1("PGP public key algorithm %N not supported",
+				 pgp_pubkey_alg_names, alg);
+			return NULL;
+	}
+	return key;
+}
+
+/**
+ * Load a RSA public key from a PGP packet
+ */
+static public_key_t *parse_rsa_public_key(chunk_t blob)
+{
+	chunk_t mpi[2];
+	int i;
+	
+	for (i = 0; i < 2; i++)
+	{
+		if (!read_mpi(&blob, &mpi[i]))
+		{
+			return NULL;
+		}
+	}
+	return lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_RSA,
+						BUILD_RSA_MODULUS, mpi[0], BUILD_RSA_PUB_EXP, mpi[1],
+						BUILD_END);
+}
+
+/**
+ * Load a RSA private key from a PGP packet
+ */
+static private_key_t *parse_rsa_private_key(chunk_t blob)
+{
+	chunk_t mpi[6];
+	u_int32_t s2k;
+	int i;
+	
+	for (i = 0; i < 2; i++)
+	{
+		if (!read_mpi(&blob, &mpi[i]))
+		{
+			return NULL;
+		}
+	}
+	if (!read_scalar(&blob, 1, &s2k))
+	{
+		return NULL;
+	}
+	if (s2k == 255 || s2k == 254)
+	{
+		DBG1("string-to-key specifiers not supported");
+		return NULL;
+	}
+	if (s2k != PGP_SYM_ALG_PLAIN)
+	{
+		DBG1("%N private key encryption not supported", pgp_sym_alg_names, s2k);
+		return NULL;
+	}
+	
+	for (i = 2; i < 6; i++)
+	{
+		if (!read_mpi(&blob, &mpi[i]))
+		{
+			return NULL;
+		}
+	}
+	return lib->creds->create(lib->creds, CRED_PRIVATE_KEY, KEY_RSA, 
+						BUILD_RSA_MODULUS, mpi[0], BUILD_RSA_PUB_EXP, mpi[1],
+						BUILD_RSA_PRIV_EXP, mpi[2], BUILD_RSA_PRIME1, mpi[3],
+						BUILD_RSA_PRIME2, mpi[4], BUILD_RSA_COEFF, mpi[5],
+						BUILD_END);
+}
+
+typedef struct private_builder_t private_builder_t;
+
+/**
+ * Builder implementation for private/public key loading
+ */
+struct private_builder_t {
+	/** implements the builder interface */
+	builder_t public;
+	/** PGP packet data */
+	chunk_t blob;
+	/** type of key to build */
+	key_type_t type;
+};
+
+/**
+ * Implementation of builder_t.build for public keys
+ */
+static public_key_t *build_public(private_builder_t *this)
+{
+	public_key_t *key = NULL;
+	
+	switch (this->type)
+	{
+		case KEY_ANY:
+			key = parse_public_key(this->blob);
+			break;
+		case KEY_RSA:
+			key = parse_rsa_public_key(this->blob);
+			break;
+		default:
+			break;
+	}
+	free(this);
+	return key;
+}
+
+/**
+ * Implementation of builder_t.add for public keys
+ */
+static void add_public(private_builder_t *this, builder_part_t part, ...)
+{
+	va_list args;
+	
+	switch (part)
+	{
+		case BUILD_BLOB_PEM:
+		{
+			va_start(args, part);
+			this->blob = va_arg(args, chunk_t);
+			va_end(args);
+			break;
+		}
+		default:
+			builder_cancel(&this->public);
+			break;
+	}
+}
+
+/**
+ * Builder construction function for public keys
+ */
+builder_t *pgp_public_key_builder(key_type_t type)
+{
+	private_builder_t *this;
+	
+	if (type != KEY_ANY && type != KEY_RSA)
+	{
+		return NULL;
+	}
+	
+	this = malloc_thing(private_builder_t);
+	
+	this->blob = chunk_empty;
+	this->type = type;
+	this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add_public;
+	this->public.build = (void*(*)(builder_t *this))build_public;
+	
+	return &this->public;
+}
+
+/**
+ * Implementation of builder_t.build for private keys
+ */
+static private_key_t *build_private(private_builder_t *this)
+{
+	private_key_t *key;
+	
+	key = parse_rsa_private_key(this->blob);
+	free(this);
+	return key;
+}
+
+/**
+ * Implementation of builder_t.add for private keys
+ */
+static void add_private(private_builder_t *this, builder_part_t part, ...)
+{
+	va_list args;
+	
+	switch (part)
+	{
+		case BUILD_BLOB_PGP:
+		{
+			va_start(args, part);
+			this->blob = va_arg(args, chunk_t);
+			va_end(args);
+			break;
+		}
+		default:
+			builder_cancel(&this->public);
+			break;
+	}
+}
+
+/**
+ * Builder construction function for private keys
+ */
+builder_t *pgp_private_key_builder(key_type_t type)
+{
+	private_builder_t *this;
+	
+	if (type != KEY_RSA)
+	{
+		return NULL;
+	}
+	
+	this = malloc_thing(private_builder_t);
+	
+	this->blob = chunk_empty;
+	this->type = type;
+	this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add_private;
+	this->public.build = (void*(*)(builder_t *this))build_private;
+	
+	return &this->public;
+}
+