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dropbear/keyimport.c
Matt Johnston 1d22801101 Fix accientally removed variable for DSS
2022-11-10 16:52:42 +08:00

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/*
* Based on PuTTY's import.c for importing/exporting OpenSSH and SSH.com
* keyfiles.
*
* Modifications copyright 2003-2022 Matt Johnston
*
* PuTTY is copyright 1997-2003 Simon Tatham.
*
* Portions copyright Robert de Bath, Joris van Rantwijk, Delian
* Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
* Justin Bradford, and CORE SDI S.A.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE
* FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "keyimport.h"
#include "bignum.h"
#include "buffer.h"
#include "dbutil.h"
#include "ecc.h"
#include "ssh.h"
#include "rsa.h"
#include "dss.h"
#include "ed25519.h"
#include "ecdsa.h"
#include "signkey_ossh.h"
static const unsigned char OSSH_PKEY_BLOB[] =
"openssh-key-v1\0" /* AUTH_MAGIC */
"\0\0\0\4none" /* cipher name*/
"\0\0\0\4none" /* kdf name */
"\0\0\0\0" /* kdf */
"\0\0\0\1"; /* key num */
#define OSSH_PKEY_BLOBLEN (sizeof(OSSH_PKEY_BLOB) - 1)
#if DROPBEAR_ECDSA
static const unsigned char OID_SEC256R1_BLOB[] = {0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07};
static const unsigned char OID_SEC384R1_BLOB[] = {0x2b, 0x81, 0x04, 0x00, 0x22};
static const unsigned char OID_SEC521R1_BLOB[] = {0x2b, 0x81, 0x04, 0x00, 0x23};
#endif
#define PUT_32BIT(cp, value) do { \
(cp)[3] = (unsigned char)(value); \
(cp)[2] = (unsigned char)((value) >> 8); \
(cp)[1] = (unsigned char)((value) >> 16); \
(cp)[0] = (unsigned char)((value) >> 24); } while (0)
#define GET_32BIT(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
static int openssh_encrypted(const char *filename);
static sign_key *openssh_read(const char *filename, const char *passphrase);
static int openssh_write(const char *filename, sign_key *key,
const char *passphrase);
static int dropbear_write(const char*filename, sign_key * key);
static sign_key *dropbear_read(const char* filename);
static int toint(unsigned u);
#if 0
static int sshcom_encrypted(const char *filename, char **comment);
static struct ssh2_userkey *sshcom_read(const char *filename, char *passphrase);
static int sshcom_write(const char *filename, struct ssh2_userkey *key,
char *passphrase);
#endif
int import_encrypted(const char* filename, int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_encrypted(filename);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_encrypted(filename, NULL);
#endif
}
return 0;
}
sign_key *import_read(const char *filename, const char *passphrase, int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_read(filename, passphrase);
} else if (filetype == KEYFILE_DROPBEAR) {
return dropbear_read(filename);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_read(filename, passphrase);
#endif
}
return NULL;
}
int import_write(const char *filename, sign_key *key, const char *passphrase,
int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_write(filename, key, passphrase);
} else if (filetype == KEYFILE_DROPBEAR) {
return dropbear_write(filename, key);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_write(filename, key, passphrase);
#endif
}
return 0;
}
static sign_key *dropbear_read(const char* filename) {
buffer * buf = NULL;
sign_key *ret = NULL;
enum signkey_type type;
buf = buf_new(MAX_PRIVKEY_SIZE);
if (buf_readfile(buf, filename) == DROPBEAR_FAILURE) {
goto error;
}
buf_setpos(buf, 0);
ret = new_sign_key();
type = DROPBEAR_SIGNKEY_ANY;
if (buf_get_priv_key(buf, ret, &type) == DROPBEAR_FAILURE){
goto error;
}
buf_free(buf);
ret->type = type;
return ret;
error:
if (buf) {
buf_free(buf);
}
if (ret) {
sign_key_free(ret);
}
return NULL;
}
/* returns 0 on fail, 1 on success */
static int dropbear_write(const char*filename, sign_key * key) {
buffer * buf;
FILE*fp;
int len;
int ret;
buf = buf_new(MAX_PRIVKEY_SIZE);
buf_put_priv_key(buf, key, key->type);
fp = fopen(filename, "w");
if (!fp) {
ret = 0;
goto out;
}
buf_setpos(buf, 0);
do {
len = fwrite(buf_getptr(buf, buf->len - buf->pos),
1, buf->len - buf->pos, fp);
buf_incrpos(buf, len);
} while (len > 0 && buf->len != buf->pos);
fclose(fp);
if (buf->pos != buf->len) {
ret = 0;
} else {
ret = 1;
}
out:
buf_free(buf);
return ret;
}
/* ----------------------------------------------------------------------
* Helper routines. (The base64 ones are defined in sshpubk.c.)
*/
#define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
((c) >= 'a' && (c) <= 'z') || \
((c) >= '0' && (c) <= '9') || \
(c) == '+' || (c) == '/' || (c) == '=' \
)
/* cpl has to be less than 100 */
static void base64_encode_fp(FILE * fp, const unsigned char *data,
int datalen, int cpl)
{
unsigned char out[100];
int n;
unsigned long outlen;
int rawcpl;
rawcpl = cpl * 3 / 4;
dropbear_assert((unsigned int)cpl < sizeof(out));
while (datalen > 0) {
n = (datalen < rawcpl ? datalen : rawcpl);
outlen = sizeof(out);
base64_encode(data, n, out, &outlen);
data += n;
datalen -= n;
fwrite(out, 1, outlen, fp);
fputc('\n', fp);
}
}
/*
* Read an ASN.1/BER identifier and length pair.
*
* Flags are a combination of the #defines listed below.
*
* Returns -1 if unsuccessful; otherwise returns the number of
* bytes used out of the source data.
*/
/* ASN.1 tag classes. */
#define ASN1_CLASS_UNIVERSAL (0 << 6)
#define ASN1_CLASS_APPLICATION (1 << 6)
#define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
#define ASN1_CLASS_PRIVATE (3 << 6)
#define ASN1_CLASS_MASK (3 << 6)
/* Primitive versus constructed bit. */
#define ASN1_CONSTRUCTED (1 << 5)
static int ber_read_id_len(void *source, int sourcelen,
int *id, int *length, int *flags)
{
unsigned char *p = (unsigned char *) source;
if (sourcelen == 0)
return -1;
*flags = (*p & 0xE0);
if ((*p & 0x1F) == 0x1F) {
*id = 0;
while (*p & 0x80) {
p++, sourcelen--;
if (sourcelen == 0)
return -1;
*id = (*id << 7) | (*p & 0x7F);
}
p++, sourcelen--;
} else {
*id = *p & 0x1F;
p++, sourcelen--;
}
if (sourcelen == 0)
return -1;
if (*p & 0x80) {
unsigned len;
int n = *p & 0x7F;
p++, sourcelen--;
if (sourcelen < n)
return -1;
len = 0;
while (n--)
len = (len << 8) | (*p++);
sourcelen -= n;
*length = toint(len);
} else {
*length = *p;
p++, sourcelen--;
}
if (*length < 0) {
printf("Negative ASN.1 length\n");
return -1;
}
return p - (unsigned char *) source;
}
/*
* Write an ASN.1/BER identifier and length pair. Returns the
* number of bytes consumed. Assumes dest contains enough space.
* Will avoid writing anything if dest is NULL, but still return
* amount of space required.
*/
#if DROPBEAR_DSS
static int ber_write_id_len(void *dest, int id, int length, int flags)
{
unsigned char *d = (unsigned char *)dest;
int len = 0;
if (id <= 30) {
/*
* Identifier is one byte.
*/
len++;
if (d) *d++ = id | flags;
} else {
int n;
/*
* Identifier is multiple bytes: the first byte is 11111
* plus the flags, and subsequent bytes encode the value of
* the identifier, 7 bits at a time, with the top bit of
* each byte 1 except the last one which is 0.
*/
len++;
if (d) *d++ = 0x1F | flags;
for (n = 1; (id >> (7*n)) > 0; n++)
continue; /* count the bytes */
while (n--) {
len++;
if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
}
}
if (length < 128) {
/*
* Length is one byte.
*/
len++;
if (d) *d++ = length;
} else {
int n;
/*
* Length is multiple bytes. The first is 0x80 plus the
* number of subsequent bytes, and the subsequent bytes
* encode the actual length.
*/
for (n = 1; (length >> (8*n)) > 0; n++)
continue; /* count the bytes */
len++;
if (d) *d++ = 0x80 | n;
while (n--) {
len++;
if (d) *d++ = (length >> (8*n)) & 0xFF;
}
}
return len;
}
#endif /* DROPBEAR_DSS */
/* Simple structure to point to an mp-int within a blob. */
struct mpint_pos { void *start; int bytes; };
/* ----------------------------------------------------------------------
* Code to read and write OpenSSH private keys.
*/
enum { OSSH_DSA, OSSH_RSA, OSSH_EC, OSSH_PKEY };
struct openssh_key {
int type;
int encrypted;
char iv[32];
/* keyblob is publickey1 onwards (ref OpenSSH PROTOCOL.key) */
unsigned char *keyblob;
unsigned int keyblob_len, keyblob_size;
};
static struct openssh_key *load_openssh_key(const char *filename)
{
struct openssh_key *ret;
buffer *buf = NULL;
FILE *fp = NULL;
char buffer[256];
char *errmsg = NULL, *p = NULL;
int headers_done;
unsigned long len;
ret = (struct openssh_key*)m_malloc(sizeof(struct openssh_key));
ret->keyblob = NULL;
ret->keyblob_len = ret->keyblob_size = 0;
ret->encrypted = 0;
memset(ret->iv, 0, sizeof(ret->iv));
if (strlen(filename) == 1 && filename[0] == '-') {
fp = stdin;
} else {
fp = fopen(filename, "r");
}
if (!fp) {
errmsg = "Unable to open key file";
goto error;
}
if (!fgets(buffer, sizeof(buffer), fp) ||
0 != strncmp(buffer, "-----BEGIN ", 11) ||
0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) {
errmsg = "File does not begin with OpenSSH key header";
goto error;
}
if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n"))
ret->type = OSSH_RSA;
else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n"))
ret->type = OSSH_DSA;
else if (!strcmp(buffer, "-----BEGIN EC PRIVATE KEY-----\n"))
ret->type = OSSH_EC;
else if (!strcmp(buffer, "-----BEGIN OPENSSH PRIVATE KEY-----\n"))
ret->type = OSSH_PKEY;
else {
errmsg = "Unrecognised key type";
goto error;
}
headers_done = 0;
buf = buf_new(0);
while (1) {
if (!fgets(buffer, sizeof(buffer), fp)) {
errmsg = "Unexpected end of file";
goto error;
}
if (0 == strncmp(buffer, "-----END ", 9) &&
0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n"))
break; /* done */
if ((p = strchr(buffer, ':')) != NULL) {
if (headers_done) {
errmsg = "Header found in body of key data";
goto error;
}
*p++ = '\0';
while (*p && isspace((unsigned char)*p)) p++;
if (!strcmp(buffer, "Proc-Type")) {
if (p[0] != '4' || p[1] != ',') {
errmsg = "Proc-Type is not 4 (only 4 is supported)";
goto error;
}
p += 2;
if (!strcmp(p, "ENCRYPTED\n"))
ret->encrypted = 1;
} else if (!strcmp(buffer, "DEK-Info")) {
int i, j;
if (strncmp(p, "DES-EDE3-CBC,", 13)) {
errmsg = "Ciphers other than DES-EDE3-CBC not supported";
goto error;
}
p += 13;
for (i = 0; i < 8; i++) {
if (1 != sscanf(p, "%2x", &j))
break;
ret->iv[i] = j;
p += 2;
}
if (i < 8) {
errmsg = "Expected 16-digit iv in DEK-Info";
goto error;
}
}
} else {
headers_done = 1;
len = strlen(buffer);
buf = buf_resize(buf, buf->size + len);
buf_putbytes(buf, buffer, len);
}
}
if (buf && buf->len) {
ret->keyblob_size = ret->keyblob_len + buf->len*4/3 + 256;
ret->keyblob = (unsigned char*)m_realloc(ret->keyblob, ret->keyblob_size);
len = ret->keyblob_size;
if (base64_decode((const unsigned char *)buf->data, buf->len,
ret->keyblob, &len) != CRYPT_OK){
errmsg = "Error decoding base64";
goto error;
}
ret->keyblob_len = len;
}
if (ret->type == OSSH_PKEY) {
if (ret->keyblob_len < OSSH_PKEY_BLOBLEN ||
memcmp(ret->keyblob, OSSH_PKEY_BLOB, OSSH_PKEY_BLOBLEN)) {
errmsg = "Error decoding OpenSSH key";
goto error;
}
ret->keyblob_len -= OSSH_PKEY_BLOBLEN;
memmove(ret->keyblob, ret->keyblob + OSSH_PKEY_BLOBLEN, ret->keyblob_len);
}
if (ret->keyblob_len == 0 || !ret->keyblob) {
errmsg = "Key body not present";
goto error;
}
if (ret->encrypted && ret->keyblob_len % 8 != 0) {
errmsg = "Encrypted key blob is not a multiple of cipher block size";
goto error;
}
if (buf) {
buf_burn_free(buf);
}
m_burn(buffer, sizeof(buffer));
return ret;
error:
if (buf) {
buf_burn_free(buf);
}
m_burn(buffer, sizeof(buffer));
if (ret) {
if (ret->keyblob) {
m_burn(ret->keyblob, ret->keyblob_size);
m_free(ret->keyblob);
}
m_free(ret);
}
if (fp) {
fclose(fp);
}
if (errmsg) {
fprintf(stderr, "Error: %s\n", errmsg);
}
return NULL;
}
static int openssh_encrypted(const char *filename)
{
struct openssh_key *key = load_openssh_key(filename);
int ret;
if (!key)
return 0;
ret = key->encrypted;
m_burn(key->keyblob, key->keyblob_size);
m_free(key->keyblob);
m_free(key);
return ret;
}
static sign_key *openssh_read(const char *filename, const char * UNUSED(passphrase))
{
struct openssh_key *key;
unsigned char *p;
int ret, id, len, flags;
int i, num_integers = 0;
sign_key *retval = NULL;
char *errmsg;
unsigned char *modptr = NULL;
int modlen = -9999;
enum signkey_type type;
sign_key *retkey;
buffer * blobbuf = NULL;
retkey = new_sign_key();
key = load_openssh_key(filename);
if (!key)
return NULL;
if (key->encrypted) {
errmsg = "Encrypted keys are not supported. Please convert with ssh-keygen first";
goto error;
}
/*
* Now we have a decrypted key blob, which contains OpenSSH
* encoded private key. We must now untangle the OpenSSH format.
*/
if (key->type == OSSH_PKEY) {
blobbuf = buf_new(key->keyblob_len);
buf_putbytes(blobbuf, key->keyblob, key->keyblob_len);
buf_setpos(blobbuf, 0);
/* limit length of public key blob */
len = buf_getint(blobbuf);
type = DROPBEAR_SIGNKEY_ANY;
if (buf_get_pub_key(blobbuf, retkey, &type)
!= DROPBEAR_SUCCESS) {
errmsg = "Error parsing OpenSSH key";
goto ossh_error;
}
/* restore full length */
buf_setlen(blobbuf, key->keyblob_len);
/* length of private key part. we can discard it */
buf_getint(blobbuf);
/* discard checkkey1 */
buf_getint(blobbuf);
/* discard checkkey2 */
buf_getint(blobbuf);
errmsg = "Unsupported OpenSSH key type";
retkey->type = type;
ret = DROPBEAR_FAILURE;
/* Parse private key part */
#if DROPBEAR_RSA
if (type == DROPBEAR_SIGNKEY_RSA) {
errmsg = "Error parsing OpenSSH RSA key";
ret = buf_get_rsa_priv_ossh(blobbuf, retkey);
}
#endif
#if DROPBEAR_ED25519
if (type == DROPBEAR_SIGNKEY_ED25519) {
errmsg = "Error parsing OpenSSH ed25519 key";
ret = buf_get_ed25519_priv_ossh(blobbuf, retkey);
}
#endif
#if DROPBEAR_ECDSA
if (signkey_is_ecdsa(type)) {
errmsg = "Error parsing OpenSSH ecdsa key";
ret = buf_get_ecdsa_priv_ossh(blobbuf, retkey);
}
#endif
if (ret == DROPBEAR_SUCCESS) {
errmsg = NULL;
retval = retkey;
goto error;
}
ossh_error:
sign_key_free(retkey);
retkey = NULL;
goto error;
}
/*
* Now we have a decrypted key blob, which contains an ASN.1
* encoded private key. We must now untangle the ASN.1.
*
* We expect the whole key blob to be formatted as a SEQUENCE
* (0x30 followed by a length code indicating that the rest of
* the blob is part of the sequence). Within that SEQUENCE we
* expect to see a bunch of INTEGERs. What those integers mean
* depends on the key type:
*
* - For RSA, we expect the integers to be 0, n, e, d, p, q,
* dmp1, dmq1, iqmp in that order. (The last three are d mod
* (p-1), d mod (q-1), inverse of q mod p respectively.)
*
* - For DSA, we expect them to be 0, p, q, g, y, x in that
* order.
*/
p = key->keyblob;
/* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
p += ret;
if (ret < 0 || id != 16 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
/* Expect a load of INTEGERs. */
if (key->type == OSSH_RSA)
num_integers = 9;
else if (key->type == OSSH_DSA)
num_integers = 6;
else if (key->type == OSSH_EC)
num_integers = 1;
/*
* Space to create key blob in.
*/
blobbuf = buf_new(3000);
#if DROPBEAR_DSS
if (key->type == OSSH_DSA) {
buf_putstring(blobbuf, "ssh-dss", 7);
retkey->type = DROPBEAR_SIGNKEY_DSS;
}
#endif
#if DROPBEAR_RSA
if (key->type == OSSH_RSA) {
buf_putstring(blobbuf, "ssh-rsa", 7);
retkey->type = DROPBEAR_SIGNKEY_RSA;
}
#endif
for (i = 0; i < num_integers; i++) {
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 2 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
if (i == 0) {
/* First integer is a version indicator */
int expected = -1;
switch (key->type) {
case OSSH_RSA:
case OSSH_DSA:
expected = 0;
break;
case OSSH_EC:
expected = 1;
break;
}
if (len != 1 || p[0] != expected) {
errmsg = "Version number mismatch";
goto error;
}
} else if (key->type == OSSH_RSA) {
/*
* OpenSSH key order is n, e, d, p, q, dmp1, dmq1, iqmp
* but we want e, n, d, p, q
*/
if (i == 1) {
/* Save the details for after we deal with number 2. */
modptr = p;
modlen = len;
} else if (i >= 2 && i <= 5) {
buf_putstring(blobbuf, (const char*)p, len);
if (i == 2) {
buf_putstring(blobbuf, (const char*)modptr, modlen);
}
}
} else if (key->type == OSSH_DSA) {
/*
* OpenSSH key order is p, q, g, y, x,
* we want the same.
*/
buf_putstring(blobbuf, (const char*)p, len);
}
/* Skip past the number. */
p += len;
}
#if DROPBEAR_ECDSA
if (key->type == OSSH_EC) {
unsigned char* private_key_bytes = NULL;
int private_key_len = 0;
unsigned char* public_key_bytes = NULL;
int public_key_len = 0;
ecc_key *ecc = NULL;
const struct dropbear_ecc_curve *curve = NULL;
/* See SEC1 v2, Appendix C.4 */
/* OpenSSL (so OpenSSH) seems to include the optional parts. */
/* privateKey OCTET STRING, */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
/* id==4 for octet string */
if (ret < 0 || id != 4 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
private_key_bytes = p;
private_key_len = len;
p += len;
/* parameters [0] ECDomainParameters {{ SECGCurveNames }} OPTIONAL, */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
/* id==0 */
if (ret < 0 || id != 0 || len < 0) {
errmsg = "ASN.1 decoding failure";
goto error;
}
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
/* id==6 for object */
if (ret < 0 || id != 6 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
if (0) {}
#if DROPBEAR_ECC_256
else if (len == sizeof(OID_SEC256R1_BLOB)
&& memcmp(p, OID_SEC256R1_BLOB, len) == 0) {
retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP256;
curve = &ecc_curve_nistp256;
}
#endif
#if DROPBEAR_ECC_384
else if (len == sizeof(OID_SEC384R1_BLOB)
&& memcmp(p, OID_SEC384R1_BLOB, len) == 0) {
retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP384;
curve = &ecc_curve_nistp384;
}
#endif
#if DROPBEAR_ECC_521
else if (len == sizeof(OID_SEC521R1_BLOB)
&& memcmp(p, OID_SEC521R1_BLOB, len) == 0) {
retkey->type = DROPBEAR_SIGNKEY_ECDSA_NISTP521;
curve = &ecc_curve_nistp521;
}
#endif
else {
errmsg = "Unknown ECC key type";
goto error;
}
p += len;
/* publicKey [1] BIT STRING OPTIONAL */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
/* id==1 */
if (ret < 0 || id != 1 || len < 0) {
errmsg = "ASN.1 decoding failure";
goto error;
}
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
/* id==3 for bit string */
if (ret < 0 || id != 3 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
public_key_bytes = p+1;
public_key_len = len-1;
p += len;
buf_putbytes(blobbuf, public_key_bytes, public_key_len);
ecc = buf_get_ecc_raw_pubkey(blobbuf, curve);
if (!ecc) {
errmsg = "Error parsing ECC key";
goto error;
}
m_mp_alloc_init_multi((mp_int**)&ecc->k, NULL);
if (mp_from_ubin(ecc->k, private_key_bytes, private_key_len)
!= MP_OKAY) {
errmsg = "Error parsing ECC key";
goto error;
}
*signkey_key_ptr(retkey, retkey->type) = ecc;
}
#endif /* DROPBEAR_ECDSA */
/*
* Now put together the actual key. Simplest way to do this is
* to assemble our own key blobs and feed them to the createkey
* functions; this is a bit faffy but it does mean we get all
* the sanity checks for free.
*/
if (key->type == OSSH_RSA || key->type == OSSH_DSA) {
buf_setpos(blobbuf, 0);
type = DROPBEAR_SIGNKEY_ANY;
if (buf_get_priv_key(blobbuf, retkey, &type)
!= DROPBEAR_SUCCESS) {
errmsg = "unable to create key structure";
sign_key_free(retkey);
retkey = NULL;
goto error;
}
}
errmsg = NULL; /* no error */
retval = retkey;
error:
if (blobbuf) {
buf_burn_free(blobbuf);
}
m_burn(key->keyblob, key->keyblob_size);
m_free(key->keyblob);
m_burn(key, sizeof(*key));
m_free(key);
if (errmsg) {
fprintf(stderr, "Error: %s\n", errmsg);
}
return retval;
}
static int openssh_write(const char *filename, sign_key *key,
const char *passphrase)
{
buffer * keyblob = NULL;
buffer * extrablob = NULL; /* used for calculated values to write */
unsigned char *outblob = NULL;
int outlen = -9999;
int pos = 0, len = 0, i;
char *header = NULL, *footer = NULL;
int ret = 0;
FILE *fp;
#if DROPBEAR_DSS
if (key->type == DROPBEAR_SIGNKEY_DSS) {
char zero[1];
struct mpint_pos numbers[9];
int nnumbers = -1, seqlen;
/*
* Fetch the key blobs.
*/
keyblob = buf_new(3000);
buf_put_priv_key(keyblob, key, key->type);
buf_setpos(keyblob, 0);
/* skip the "ssh-rsa" or "ssh-dss" header */
buf_incrpos(keyblob, buf_getint(keyblob));
/*
* Find the sequence of integers to be encoded into the OpenSSH
* key blob, and also decide on the header line.
*/
numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
if (key->type == DROPBEAR_SIGNKEY_DSS) {
/* p */
numbers[1].bytes = buf_getint(keyblob);
numbers[1].start = buf_getptr(keyblob, numbers[1].bytes);
buf_incrpos(keyblob, numbers[1].bytes);
/* q */
numbers[2].bytes = buf_getint(keyblob);
numbers[2].start = buf_getptr(keyblob, numbers[2].bytes);
buf_incrpos(keyblob, numbers[2].bytes);
/* g */
numbers[3].bytes = buf_getint(keyblob);
numbers[3].start = buf_getptr(keyblob, numbers[3].bytes);
buf_incrpos(keyblob, numbers[3].bytes);
/* y */
numbers[4].bytes = buf_getint(keyblob);
numbers[4].start = buf_getptr(keyblob, numbers[4].bytes);
buf_incrpos(keyblob, numbers[4].bytes);
/* x */
numbers[5].bytes = buf_getint(keyblob);
numbers[5].start = buf_getptr(keyblob, numbers[5].bytes);
buf_incrpos(keyblob, numbers[5].bytes);
nnumbers = 6;
header = "-----BEGIN DSA PRIVATE KEY-----\n";
footer = "-----END DSA PRIVATE KEY-----\n";
}
/*
* Now count up the total size of the ASN.1 encoded integers,
* so as to determine the length of the containing SEQUENCE.
*/
len = 0;
for (i = 0; i < nnumbers; i++) {
len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
len += numbers[i].bytes;
}
seqlen = len;
/* Now add on the SEQUENCE header. */
len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
/* Round up to the cipher block size, ensuring we have at least one
* byte of padding (see below). */
outlen = len;
if (passphrase)
outlen = (outlen+8) &~ 7;
/*
* Now we know how big outblob needs to be. Allocate it.
*/
outblob = (unsigned char*)m_malloc(outlen);
/*
* And write the data into it.
*/
pos = 0;
pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
for (i = 0; i < nnumbers; i++) {
pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
pos += numbers[i].bytes;
}
} /* end DSS handling */
#endif /* DROPBEAR_DSS */
if (0
#if DROPBEAR_RSA
|| key->type == DROPBEAR_SIGNKEY_RSA
#endif
#if DROPBEAR_ED25519
|| key->type == DROPBEAR_SIGNKEY_ED25519
#endif
#if DROPBEAR_ECDSA
|| signkey_is_ecdsa(key->type)
#endif
) {
buffer *buf = buf_new(3200);
keyblob = buf_new(3000);
extrablob = buf_new(3100);
/* private key blob w/o header */
#if DROPBEAR_RSA
if (key->type == DROPBEAR_SIGNKEY_RSA) {
buf_put_rsa_priv_ossh(keyblob, key);
}
#endif
#if DROPBEAR_ED25519
if (key->type == DROPBEAR_SIGNKEY_ED25519) {
buf_put_ed25519_priv_ossh(keyblob, key);
}
#endif
#if DROPBEAR_ECDSA
if (signkey_is_ecdsa(key->type)) {
buf_put_ecdsa_priv_ossh(keyblob, key);
}
#endif
/* header */
buf_putbytes(buf, OSSH_PKEY_BLOB, OSSH_PKEY_BLOBLEN);
/* public key */
buf_put_pub_key(buf, key, key->type);
/* private key */
buf_putint(extrablob, 0); /* checkint 1 */
buf_putint(extrablob, 0); /* checkint 2 */
/* raw openssh private key */
buf_putbytes(extrablob, keyblob->data, keyblob->len);
/* comment */
buf_putstring(extrablob, "", 0);
/* padding to cipher block length */
len = (extrablob->len+8) & ~7;
for (i = 1; len - extrablob->len > 0; i++)
buf_putbyte(extrablob, i);
buf_setpos(extrablob, 0);
buf_putbytes(extrablob, "\0\0\0\0\0\0\0\0", 8);
buf_putbufstring(buf, extrablob);
outlen = len = pos = buf->len;
outblob = (unsigned char*)m_malloc(outlen);
memcpy(outblob, buf->data, buf->len);
buf_burn_free(buf);
buf = NULL;
header = "-----BEGIN OPENSSH PRIVATE KEY-----\n";
footer = "-----END OPENSSH PRIVATE KEY-----\n";
}
/*
* Padding on OpenSSH keys is deterministic. The number of
* padding bytes is always more than zero, and always at most
* the cipher block length. The value of each padding byte is
* equal to the number of padding bytes. So a plaintext that's
* an exact multiple of the block size will be padded with 08
* 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
* plaintext one byte less than a multiple of the block size
* will be padded with just 01.
*
* This enables the OpenSSL key decryption function to strip
* off the padding algorithmically and return the unpadded
* plaintext to the next layer: it looks at the final byte, and
* then expects to find that many bytes at the end of the data
* with the same value. Those are all removed and the rest is
* returned.
*/
dropbear_assert(pos == len);
while (pos < outlen) {
outblob[pos++] = outlen - len;
}
/*
* Encrypt the key.
*/
if (passphrase) {
fprintf(stderr, "Encrypted keys aren't supported currently\n");
goto error;
}
/*
* And save it. We'll use Unix line endings just in case it's
* subsequently transferred in binary mode.
*/
if (strlen(filename) == 1 && filename[0] == '-') {
fp = stdout;
} else {
fp = fopen(filename, "wb"); /* ensure Unix line endings */
}
if (!fp) {
fprintf(stderr, "Failed opening output file\n");
goto error;
}
fputs(header, fp);
base64_encode_fp(fp, outblob, outlen, 64);
fputs(footer, fp);
fclose(fp);
ret = 1;
error:
if (outblob) {
memset(outblob, 0, outlen);
m_free(outblob);
}
if (keyblob) {
buf_burn_free(keyblob);
}
if (extrablob) {
buf_burn_free(extrablob);
}
return ret;
}
/* From PuTTY misc.c */
static int toint(unsigned u)
{
/*
* Convert an unsigned to an int, without running into the
* undefined behaviour which happens by the strict C standard if
* the value overflows. You'd hope that sensible compilers would
* do the sensible thing in response to a cast, but actually I
* don't trust modern compilers not to do silly things like
* assuming that _obviously_ you wouldn't have caused an overflow
* and so they can elide an 'if (i < 0)' test immediately after
* the cast.
*
* Sensible compilers ought of course to optimise this entire
* function into 'just return the input value'!
*/
if (u <= (unsigned)INT_MAX)
return (int)u;
else if (u >= (unsigned)INT_MIN) /* wrap in cast _to_ unsigned is OK */
return INT_MIN + (int)(u - (unsigned)INT_MIN);
else
return INT_MIN; /* fallback; should never occur on binary machines */
}
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