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/*
* Copyright (C) 2013 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.
*/
#include "sshkey_builder.h"
#include <asn1/oid.h>
#include <asn1/asn1.h>
#include <bio/bio_reader.h>
#include <utils/debug.h>
#define ECDSA_PREFIX "ecdsa-sha2-"
/**
* Parse an EC domain parameter identifier as defined in RFC 5656
*/
static chunk_t parse_ec_identifier(chunk_t identifier)
{
chunk_t oid = chunk_empty;
if (chunk_equals(identifier, chunk_from_str("nistp256")))
{
oid = asn1_build_known_oid(OID_PRIME256V1);
}
else if (chunk_equals(identifier, chunk_from_str("nistp384")))
{
oid = asn1_build_known_oid(OID_SECT384R1);
}
else if (chunk_equals(identifier, chunk_from_str("nistp521")))
{
oid = asn1_build_known_oid(OID_SECT521R1);
}
else
{
char ascii[64];
if (snprintf(ascii, sizeof(ascii), "%.*s", (int)identifier.len,
identifier.ptr) < sizeof(ascii))
{
oid = asn1_wrap(ASN1_OID, "m", asn1_oid_from_string(ascii));
}
}
return oid;
}
/**
* Load a generic public key from an SSH key blob
*/
static sshkey_public_key_t *parse_public_key(chunk_t blob)
{
bio_reader_t *reader;
chunk_t format;
reader = bio_reader_create(blob);
if (!reader->read_data32(reader, &format))
{
DBG1(DBG_LIB, "invalid key format in SSH key");
reader->destroy(reader);
return NULL;
}
if (chunk_equals(format, chunk_from_str("ssh-rsa")))
{
chunk_t n, e;
if (!reader->read_data32(reader, &e) ||
!reader->read_data32(reader, &n))
{
DBG1(DBG_LIB, "invalid RSA key in SSH key");
reader->destroy(reader);
return NULL;
}
reader->destroy(reader);
return lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_RSA,
BUILD_RSA_MODULUS, n, BUILD_RSA_PUB_EXP, e, BUILD_END);
}
else if (format.len > strlen(ECDSA_PREFIX) &&
strpfx(format.ptr, ECDSA_PREFIX))
{
chunk_t ec_blob, identifier, q, oid, encoded;
sshkey_public_key_t *key;
ec_blob = reader->peek(reader);
reader->destroy(reader);
reader = bio_reader_create(ec_blob);
if (!reader->read_data32(reader, &identifier) ||
!reader->read_data32(reader, &q))
{
DBG1(DBG_LIB, "invalid ECDSA key in SSH key");
reader->destroy(reader);
return NULL;
}
oid = parse_ec_identifier(identifier);
if (!oid.ptr)
{
DBG1(DBG_LIB, "invalid ECDSA key identifier in SSH key");
reader->destroy(reader);
return NULL;
}
reader->destroy(reader);
/* build key from subjectPublicKeyInfo */
encoded = asn1_wrap(ASN1_SEQUENCE, "mm",
asn1_wrap(ASN1_SEQUENCE, "mm",
asn1_build_known_oid(OID_EC_PUBLICKEY), oid),
asn1_bitstring("c", q));
key = lib->creds->create(lib->creds, CRED_PUBLIC_KEY,
KEY_ECDSA, BUILD_BLOB_ASN1_DER, encoded, BUILD_END);
chunk_free(&encoded);
return key;
}
DBG1(DBG_LIB, "unsupported SSH key format %.*s", (int)format.len,
format.ptr);
reader->destroy(reader);
return NULL;
}
/**
* See header.
*/
sshkey_public_key_t *sshkey_public_key_load(key_type_t type, va_list args)
{
chunk_t blob = chunk_empty;
while (TRUE)
{
switch (va_arg(args, builder_part_t))
{
case BUILD_BLOB_SSHKEY:
blob = va_arg(args, chunk_t);
continue;
case BUILD_END:
break;
default:
return NULL;
}
break;
}
if (blob.ptr && type == KEY_ANY)
{
return parse_public_key(blob);
}
return NULL;
}
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