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/*
authfile.c
Author: Tatu Ylonen <ylo@cs.hut.fi>
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
All rights reserved
Created: Mon Mar 27 03:52:05 1995 ylo
This file contains functions for reading and writing identity files, and
for reading the passphrase from the user.
*/
#include "config.h"
#include "includes.h"
RCSID("$Id: authfile.c,v 1.2 1999/10/28 03:25:17 damien Exp $");
#ifdef HAVE_OPENSSL
#include <openssl/bn.h>
#endif
#ifdef HAVE_SSL
#include <ssl/bn.h>
#endif
#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "cipher.h"
#include "ssh.h"
/* Version identification string for identity files. */
#define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
/* Saves the authentication (private) key in a file, encrypting it with
passphrase. The identification of the file (lowest 64 bits of n)
will precede the key to provide identification of the key without
needing a passphrase. */
int
save_private_key(const char *filename, const char *passphrase,
RSA *key, const char *comment)
{
Buffer buffer, encrypted;
char buf[100], *cp;
int f, i;
CipherContext cipher;
int cipher_type;
u_int32_t rand;
/* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting to
another cipher; otherwise use SSH_AUTHFILE_CIPHER. */
if (strcmp(passphrase, "") == 0)
cipher_type = SSH_CIPHER_NONE;
else
cipher_type = SSH_AUTHFILE_CIPHER;
/* This buffer is used to built the secret part of the private key. */
buffer_init(&buffer);
/* Put checkbytes for checking passphrase validity. */
rand = arc4random();
buf[0] = rand & 0xff;
buf[1] = (rand >> 8) & 0xff;
buf[2] = buf[0];
buf[3] = buf[1];
buffer_append(&buffer, buf, 4);
/* Store the private key (n and e will not be stored because they will
be stored in plain text, and storing them also in encrypted format
would just give known plaintext). */
buffer_put_bignum(&buffer, key->d);
buffer_put_bignum(&buffer, key->iqmp);
buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */
/* Pad the part to be encrypted until its size is a multiple of 8. */
while (buffer_len(&buffer) % 8 != 0)
buffer_put_char(&buffer, 0);
/* This buffer will be used to contain the data in the file. */
buffer_init(&encrypted);
/* First store keyfile id string. */
cp = AUTHFILE_ID_STRING;
for (i = 0; cp[i]; i++)
buffer_put_char(&encrypted, cp[i]);
buffer_put_char(&encrypted, 0);
/* Store cipher type. */
buffer_put_char(&encrypted, cipher_type);
buffer_put_int(&encrypted, 0); /* For future extension */
/* Store public key. This will be in plain text. */
buffer_put_int(&encrypted, BN_num_bits(key->n));
buffer_put_bignum(&encrypted, key->n);
buffer_put_bignum(&encrypted, key->e);
buffer_put_string(&encrypted, comment, strlen(comment));
/* Allocate space for the private part of the key in the buffer. */
buffer_append_space(&encrypted, &cp, buffer_len(&buffer));
cipher_set_key_string(&cipher, cipher_type, passphrase, 1);
cipher_encrypt(&cipher, (unsigned char *)cp,
(unsigned char *)buffer_ptr(&buffer),
buffer_len(&buffer));
memset(&cipher, 0, sizeof(cipher));
/* Destroy temporary data. */
memset(buf, 0, sizeof(buf));
buffer_free(&buffer);
/* Write to a file. */
f = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0600);
if (f < 0)
return 0;
if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
buffer_len(&encrypted))
{
debug("Write to key file %.200s failed: %.100s", filename,
strerror(errno));
buffer_free(&encrypted);
close(f);
remove(filename);
return 0;
}
close(f);
buffer_free(&encrypted);
return 1;
}
/* Loads the public part of the key file. Returns 0 if an error
was encountered (the file does not exist or is not readable), and
non-zero otherwise. */
int
load_public_key(const char *filename, RSA *pub,
char **comment_return)
{
int f, i;
off_t len;
Buffer buffer;
char *cp;
/* Read data from the file into the buffer. */
f = open(filename, O_RDONLY);
if (f < 0)
return 0;
len = lseek(f, (off_t)0, SEEK_END);
lseek(f, (off_t)0, SEEK_SET);
buffer_init(&buffer);
buffer_append_space(&buffer, &cp, len);
if (read(f, cp, (size_t)len) != (size_t)len)
{
debug("Read from key file %.200s failed: %.100s", filename,
strerror(errno));
buffer_free(&buffer);
close(f);
return 0;
}
close(f);
/* Check that it is at least big enought to contain the ID string. */
if (len < strlen(AUTHFILE_ID_STRING) + 1)
{
debug("Bad key file %.200s.", filename);
buffer_free(&buffer);
return 0;
}
/* Make sure it begins with the id string. Consume the id string from
the buffer. */
for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
{
debug("Bad key file %.200s.", filename);
buffer_free(&buffer);
return 0;
}
/* Skip cipher type and reserved data. */
(void)buffer_get_char(&buffer); /* cipher type */
(void)buffer_get_int(&buffer); /* reserved */
/* Read the public key from the buffer. */
buffer_get_int(&buffer);
pub->n = BN_new();
buffer_get_bignum(&buffer, pub->n);
pub->e = BN_new();
buffer_get_bignum(&buffer, pub->e);
if (comment_return)
*comment_return = buffer_get_string(&buffer, NULL);
/* The encrypted private part is not parsed by this function. */
buffer_free(&buffer);
return 1;
}
/* Loads the private key from the file. Returns 0 if an error is encountered
(file does not exist or is not readable, or passphrase is bad).
This initializes the private key. */
int
load_private_key(const char *filename, const char *passphrase,
RSA *prv, char **comment_return)
{
int f, i, check1, check2, cipher_type;
off_t len;
Buffer buffer, decrypted;
char *cp;
CipherContext cipher;
BN_CTX *ctx;
BIGNUM *aux;
struct stat st;
/* Read the file into the buffer. */
f = open(filename, O_RDONLY);
if (f < 0)
return 0;
/* We assume we are called under uid of the owner of the file */
if (fstat(f, &st) < 0 ||
(st.st_uid != 0 && st.st_uid != getuid()) ||
(st.st_mode & 077) != 0) {
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("Bad ownership or mode(0%3.3o) for '%s'.",
st.st_mode & 0777, filename);
error("It is recommended that your private key files are NOT accessible by others.");
return 0;
}
len = lseek(f, (off_t)0, SEEK_END);
lseek(f, (off_t)0, SEEK_SET);
buffer_init(&buffer);
buffer_append_space(&buffer, &cp, len);
if (read(f, cp, (size_t)len) != (size_t)len)
{
debug("Read from key file %.200s failed: %.100s", filename,
strerror(errno));
buffer_free(&buffer);
close(f);
return 0;
}
close(f);
/* Check that it is at least big enought to contain the ID string. */
if (len < strlen(AUTHFILE_ID_STRING) + 1)
{
debug("Bad key file %.200s.", filename);
buffer_free(&buffer);
return 0;
}
/* Make sure it begins with the id string. Consume the id string from
the buffe
|