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openssh-key.c
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openssh-key.c
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/*
* This file is governed by Licenses which are listed in
* the LICENSE file, which shall be included in all copies
* and redistributions of this project.
*/
#include "openssh-key.h"
/* opaque EC_KEY + ECDSA NIDs to make it compile for now .. */
typedef struct EC_KEY EC_KEY;
enum ecdsa_nids { NID_X9_62_prime256v1, NID_secp384r1, NID_secp521r1 };
/* +-------------------+ */
/* | structs and types | */
/* +-------------------+ */
/* openssh key struct */
struct opensshkey {
int type;
/* ecdsa nist curves */
int ecdsa_nid;
EC_KEY *ecdsa_key;
/* ed25519 curve */
unsigned char *ed25519_sk;
unsigned char *ed25519_pk;
};
/* supported key types */
static const struct {
const char *name;
const char *shortname;
int type;
int nid;
int iscert;
} supported_keytypes[] = {
/* name shortname type ecdsa_nid cert */
{ "ssh-ed25519", "ED25519", KEY_ED25519, -1, 0 },
{ "[email protected]", "ED25519-CERT", KEY_ED25519_CERT, -1, 1 },
{ "ecdsa-sha2-nistp256", "ECDSA", KEY_ECDSA, NID_X9_62_prime256v1, 0 },
{ "[email protected]", "ECDSA-CERT", KEY_ECDSA_CERT, NID_X9_62_prime256v1, 1 },
{ "ecdsa-sha2-nistp384", "ECDSA", KEY_ECDSA, NID_secp384r1, 0 },
{ "[email protected]", "ECDSA-CERT", KEY_ECDSA_CERT, NID_secp384r1, 1 },
{ "ecdsa-sha2-nistp521", "ECDSA", KEY_ECDSA, NID_secp521r1, 0 },
{ "[email protected]", "ECDSA-CERT", KEY_ECDSA_CERT, NID_secp521r1, 1 },
{ "unknown", "UNKNOWN", KEY_UNKNOWN, -1, 0 },
};
#define n_supported_keytypes sizeof supported_keytypes / sizeof *supported_keytypes
/* +--------------------------------+ */
/* | newly allocate or cleanly free | */
/* +--------------------------------+ */
/* allocate new*/
struct opensshkey *newopensshkey (int type)
{
struct opensshkey *newkey;
if (type > KEY_UNKNOWN)
return NULL;
if ((newkey = zalloc(sizeof *newkey)) == NULL)
return NULL;
newkey->type = type;
newkey->ecdsa_key = NULL;
newkey->ecdsa_nid = -1;
newkey->ed25519_sk = NULL;
newkey->ed25519_pk = NULL;
return newkey;
}
/* free with explicit zeroing */
void freeopensshkey (struct opensshkey *key)
{
if (key == NULL)
return;
switch (key->type) {
case KEY_ED25519:
case KEY_ED25519_CERT:
/* memzero() pointers and free */
nullpointer(key->ed25519_pk, ED25519_PUBLICKEY_SIZE);
nullpointer(key->ed25519_sk, ED25519_SECRETKEY_SIZE);
break;
case KEY_ECDSA:
case KEY_ECDSA_CERT:
/* requires openssl or libressl ..
if (key->ecdsa_key != NULL)
EC_KEY_free(key->ecdsa_key);
key->ecdsa_key = NULL;
break; */
case KEY_UNKNOWN:
default:
break;
}
/* free struct itself */
nullpointer(key, sizeof *key);
return;
}
/* +--------------------+ */
/* | keytype operations | */
/* +--------------------+ */
/* detect key type from given string */
int opensshkey_detect_type (const unsigned char *name)
{
for (int i = 0; i < n_supported_keytypes; i++) {
/* the supported keytype has invalid names */
if (supported_keytypes[i].name == NULL || supported_keytypes[i].shortname == NULL)
continue;
/* match long name */
if (strcmp(name, supported_keytypes[i].name) == 0 ||
/* or match short name */
strcasecmp(name, supported_keytypes[i].shortname) == 0)
return supported_keytypes[i].type;
}
return KEY_UNKNOWN;
}
int opensshkey_get_type (const struct opensshkey *key)
{
if (key == NULL)
return KEY_UNSPECIFIED;
return key->type;
}
const unsigned char *opensshkey_get_typename (const struct opensshkey *key)
{
if (key == NULL)
return NULL;
for (int i = 0; i < n_supported_keytypes; i++) {
/* the supported keytype has invalid names */
if (supported_keytypes[i].name == NULL || supported_keytypes[i].shortname == NULL)
continue;
/* match keytype */
if (key->type == supported_keytypes[i].type &&
/* and match nid */
key->ecdsa_nid == supported_keytypes[i].nid)
return supported_keytypes[i].name;
}
return NULL;
}
/* +----------------------------+ */
/* | operations on key material | */
/* +----------------------------+ */
/* set pk and sk on ed25519 key */
int opensshkey_set_ed25519_keys (struct opensshkey *key, unsigned char *pk, unsigned char *sk)
{
if (key == NULL)
return ERR_NULLPTR;
/* key must be ed25519 key */
if ( !(key->type == KEY_ED25519 || key->type == KEY_ED25519_CERT) )
return OPENSSH_KEY_INCOMPATIBLE;
/* set new public key */
if (pk != NULL)
key->ed25519_pk = pk;
/* set new privatekey */
if (sk != NULL)
key->ed25519_sk = sk;
return SUCCESS;
}
/* return public and private part of elliptic curve keys */
int opensshkey_save_to_tinyssh (const struct opensshkey *key, const unsigned char *dir)
{
if (key == NULL)
return ERR_NULLPTR;
int e = FAILURE;
/* pointers to data to be written */
unsigned char *seckey = NULL, *pubkey = NULL;
size_t seckey_len = 0, pubkey_len = 0;
/* strings to construct the filenames in */
unsigned char pubkey_file[1024 + 64] = "", seckey_file[1024 + 64] = "";
strncat(pubkey_file, dir, 1023);
strncat(seckey_file, dir, 1023);
/* if last character is not a slash, append it */
if (strncmp(seckey_file + strlen(seckey_file) - 1, "/", 1) != 0) {
strncat(pubkey_file, "/", 2);
strncat(seckey_file, "/", 2);
}
/* decide by key type */
switch (key->type) {
case KEY_ED25519:
case KEY_ED25519_CERT:
/* we need a private key but could use
the embedded public key there. use public
key anyway, as it is easier pointer math */
if (key->ed25519_sk == NULL || key->ed25519_pk == NULL)
cleanreturn(ERR_NULLPTR);
/* set pointers and lengths */
seckey = key->ed25519_sk;
seckey_len = ED25519_SECRETKEY_SIZE;
pubkey = key->ed25519_pk;
pubkey_len = ED25519_PUBLICKEY_SIZE;
/* construct the filenames */
strncat(pubkey_file, ED25519_PUBLIC_TINYSSH_NAME, sizeof ED25519_PUBLIC_TINYSSH_NAME);
strncat(seckey_file, ED25519_SECRET_TINYSSH_NAME, sizeof ED25519_SECRET_TINYSSH_NAME);
break;
case KEY_ECDSA:
case KEY_ECDSA_CERT:
/* not supported yet, requires ssl library */
case KEY_UNKNOWN:
case KEY_UNSPECIFIED:
default:
return OPENSSH_KEY_UNKNOWN_KEYTYPE;
}
/* write keys */
if (seckey != NULL && pubkey != NULL) {
/* secret key */
printf("writing seckey to: %s ...\n", seckey_file);
if ((e = savestring(seckey_file, seckey, seckey_len)) != SUCCESS)
cleanreturn(e);
/* public key */
printf("writing pubkey to: %s ...\n", pubkey_file);
if ((e = savestring(pubkey_file, pubkey, pubkey_len)) != SUCCESS)
cleanreturn(e);
}
/* housekeeping .. */
cleanup:
seckey = NULL;
pubkey = NULL;
return e;
}
/* +-----------+ */
/* | debugging | */
/* +-----------+ */
void opensshkey_dump (const struct opensshkey *key)
{
if (key == NULL) {
printf("Passed key pointer is NULL!\n");
return;
}
printf("Dumping opensshkey ...\n");
switch (key->type) {
case KEY_ECDSA:
case KEY_ECDSA_CERT:
printf("Keytype is: ECDSA (unsupported)\n");
break;
case KEY_ED25519:
case KEY_ED25519_CERT:
printf("Keytype is: ed25519\n");
debugbuf("ed25519 public key", key->ed25519_pk, ED25519_PUBLICKEY_SIZE);
debugbuf("ed25519 secret key", key->ed25519_sk, ED25519_SECRETKEY_SIZE);
break;
case KEY_UNKNOWN:
default:
printf("Keytype is UNKNOWN!\n");
break;
}
}