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import.c
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/*
* Code for PuTTY to import and export private key files in other
* SSH clients' formats.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <ctype.h>
#include "putty.h"
#include "ssh.h"
#include "mpint.h"
#include "misc.h"
static bool openssh_pem_encrypted(BinarySource *src);
static bool openssh_new_encrypted(BinarySource *src);
static ssh2_userkey *openssh_pem_read(
BinarySource *src, const char *passphrase, const char **errmsg_p);
static ssh2_userkey *openssh_new_read(
BinarySource *src, const char *passphrase, const char **errmsg_p);
static bool openssh_auto_write(
const Filename *file, ssh2_userkey *key, const char *passphrase);
static bool openssh_pem_write(
const Filename *file, ssh2_userkey *key, const char *passphrase);
static bool openssh_new_write(
const Filename *file, ssh2_userkey *key, const char *passphrase);
static bool sshcom_encrypted(BinarySource *src, char **comment);
static ssh2_userkey *sshcom_read(
BinarySource *src, const char *passphrase, const char **errmsg_p);
static bool sshcom_write(
const Filename *file, ssh2_userkey *key, const char *passphrase);
/*
* Given a key type, determine whether we know how to import it.
*/
bool import_possible(int type)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM)
return true;
if (type == SSH_KEYTYPE_OPENSSH_NEW)
return true;
if (type == SSH_KEYTYPE_SSHCOM)
return true;
return false;
}
/*
* Given a key type, determine what native key type
* (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
* we've imported it.
*/
int import_target_type(int type)
{
/*
* There are no known foreign SSH-1 key formats.
*/
return SSH_KEYTYPE_SSH2;
}
static inline char *bsgetline(BinarySource *src)
{
ptrlen line = get_chomped_line(src);
if (get_err(src))
return NULL;
return mkstr(line);
}
/*
* Determine whether a foreign key is encrypted.
*/
bool import_encrypted_s(const Filename *filename, BinarySource *src,
int type, char **comment)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM) {
/* OpenSSH PEM format doesn't contain a key comment at all */
*comment = dupstr(filename_to_str(filename));
return openssh_pem_encrypted(src);
} else if (type == SSH_KEYTYPE_OPENSSH_NEW) {
/* OpenSSH new format does, but it's inside the encrypted
* section for some reason */
*comment = dupstr(filename_to_str(filename));
return openssh_new_encrypted(src);
} else if (type == SSH_KEYTYPE_SSHCOM) {
return sshcom_encrypted(src, comment);
}
return false;
}
bool import_encrypted(const Filename *filename, int type, char **comment)
{
LoadedFile *lf = lf_load_keyfile(filename, NULL);
if (!lf)
return false; /* couldn't even open the file */
bool toret = import_encrypted_s(filename, BinarySource_UPCAST(lf),
type, comment);
lf_free(lf);
return toret;
}
/*
* Import an SSH-1 key.
*/
int import_ssh1_s(BinarySource *src, int type,
RSAKey *key, char *passphrase, const char **errmsg_p)
{
return 0;
}
int import_ssh1(const Filename *filename, int type,
RSAKey *key, char *passphrase, const char **errmsg_p)
{
LoadedFile *lf = lf_load_keyfile(filename, errmsg_p);
if (!lf)
return false;
int toret = import_ssh1_s(BinarySource_UPCAST(lf),
type, key, passphrase, errmsg_p);
lf_free(lf);
return toret;
}
/*
* Import an SSH-2 key.
*/
ssh2_userkey *import_ssh2_s(BinarySource *src, int type,
char *passphrase, const char **errmsg_p)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM)
return openssh_pem_read(src, passphrase, errmsg_p);
else if (type == SSH_KEYTYPE_OPENSSH_NEW)
return openssh_new_read(src, passphrase, errmsg_p);
if (type == SSH_KEYTYPE_SSHCOM)
return sshcom_read(src, passphrase, errmsg_p);
return NULL;
}
ssh2_userkey *import_ssh2(const Filename *filename, int type,
char *passphrase, const char **errmsg_p)
{
LoadedFile *lf = lf_load_keyfile(filename, errmsg_p);
if (!lf)
return false;
ssh2_userkey *toret = import_ssh2_s(BinarySource_UPCAST(lf),
type, passphrase, errmsg_p);
lf_free(lf);
return toret;
}
/*
* Export an SSH-1 key.
*/
bool export_ssh1(const Filename *filename, int type, RSAKey *key,
char *passphrase)
{
return false;
}
/*
* Export an SSH-2 key.
*/
bool export_ssh2(const Filename *filename, int type,
ssh2_userkey *key, char *passphrase)
{
if (type == SSH_KEYTYPE_OPENSSH_AUTO)
return openssh_auto_write(filename, key, passphrase);
if (type == SSH_KEYTYPE_OPENSSH_NEW)
return openssh_new_write(filename, key, passphrase);
if (type == SSH_KEYTYPE_SSHCOM)
return sshcom_write(filename, key, passphrase);
return false;
}
/*
* Strip trailing CRs and LFs at the end of a line of text.
*/
void strip_crlf(char *str)
{
char *p = str + strlen(str);
while (p > str && (p[-1] == '\r' || p[-1] == '\n'))
*--p = '\0';
}
/* ----------------------------------------------------------------------
* 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) == '=' \
)
/*
* 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)
/*
* 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.
*/
static void BinarySink_put_ber_id_len(BinarySink *bs,
int id, int length, int flags)
{
if (id <= 30) {
/*
* Identifier is one byte.
*/
put_byte(bs, 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.
*/
put_byte(bs, 0x1F | flags);
for (n = 1; (id >> (7*n)) > 0; n++)
continue; /* count the bytes */
while (n--)
put_byte(bs, (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F));
}
if (length < 128) {
/*
* Length is one byte.
*/
put_byte(bs, 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 */
put_byte(bs, 0x80 | n);
while (n--)
put_byte(bs, (length >> (8*n)) & 0xFF);
}
}
#define put_ber_id_len(bs, id, len, flags) \
BinarySink_put_ber_id_len(BinarySink_UPCAST(bs), id, len, flags)
typedef struct ber_item {
int id;
int flags;
ptrlen data;
} ber_item;
static ber_item BinarySource_get_ber(BinarySource *src)
{
ber_item toret;
unsigned char leadbyte, lenbyte;
size_t length;
leadbyte = get_byte(src);
toret.flags = (leadbyte & 0xE0);
if ((leadbyte & 0x1F) == 0x1F) {
unsigned char idbyte;
toret.id = 0;
do {
idbyte = get_byte(src);
toret.id = (toret.id << 7) | (idbyte & 0x7F);
} while (idbyte & 0x80);
} else {
toret.id = leadbyte & 0x1F;
}
lenbyte = get_byte(src);
if (lenbyte & 0x80) {
int nbytes = lenbyte & 0x7F;
length = 0;
while (nbytes-- > 0)
length = (length << 8) | get_byte(src);
} else {
length = lenbyte;
}
toret.data = get_data(src, length);
return toret;
}
#define get_ber(bs) BinarySource_get_ber(BinarySource_UPCAST(bs))
/* ----------------------------------------------------------------------
* Code to read and write OpenSSH private keys, in the old-style PEM
* format.
*/
typedef enum {
OP_DSA, OP_RSA, OP_ECDSA
} openssh_pem_keytype;
typedef enum {
OP_E_3DES, OP_E_AES
} openssh_pem_enc;
struct openssh_pem_key {
openssh_pem_keytype keytype;
bool encrypted;
openssh_pem_enc encryption;
char iv[32];
strbuf *keyblob;
};
void BinarySink_put_mp_ssh2_from_string(BinarySink *bs, ptrlen str)
{
const unsigned char *bytes = (const unsigned char *)str.ptr;
size_t nbytes = str.len;
while (nbytes > 0 && bytes[0] == 0) {
nbytes--;
bytes++;
}
if (nbytes > 0 && bytes[0] & 0x80) {
put_uint32(bs, nbytes + 1);
put_byte(bs, 0);
} else {
put_uint32(bs, nbytes);
}
put_data(bs, bytes, nbytes);
}
#define put_mp_ssh2_from_string(bs, str) \
BinarySink_put_mp_ssh2_from_string(BinarySink_UPCAST(bs), str)
static struct openssh_pem_key *load_openssh_pem_key(BinarySource *src,
const char **errmsg_p)
{
struct openssh_pem_key *ret;
char *line = NULL;
const char *errmsg;
char *p;
bool headers_done;
char base64_bit[4];
int base64_chars = 0;
ret = snew(struct openssh_pem_key);
ret->keyblob = strbuf_new_nm();
if (!(line = bsgetline(src))) {
errmsg = "unexpected end of file";
goto error;
}
if (!strstartswith(line, "-----BEGIN ") ||
!strendswith(line, "PRIVATE KEY-----")) {
errmsg = "file does not begin with OpenSSH key header";
goto error;
}
/*
* Parse the BEGIN line. For old-format keys, this tells us the
* type of the key; for new-format keys, all it tells us is the
* format, and we'll find out the key type once we parse the
* base64.
*/
if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) {
ret->keytype = OP_RSA;
} else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) {
ret->keytype = OP_DSA;
} else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----")) {
ret->keytype = OP_ECDSA;
} else if (!strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
errmsg = "this is a new-style OpenSSH key";
goto error;
} else {
errmsg = "unrecognised key type";
goto error;
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
ret->encrypted = false;
memset(ret->iv, 0, sizeof(ret->iv));
headers_done = false;
while (1) {
if (!(line = bsgetline(src))) {
errmsg = "unexpected end of file";
goto error;
}
if (strstartswith(line, "-----END ") &&
strendswith(line, "PRIVATE KEY-----")) {
sfree(line);
line = NULL;
break; /* done */
}
if ((p = strchr(line, ':')) != 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(line, "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"))
ret->encrypted = true;
} else if (!strcmp(line, "DEK-Info")) {
int i, ivlen;
if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
ret->encryption = OP_E_3DES;
ivlen = 8;
} else if (!strncmp(p, "AES-128-CBC,", 12)) {
ret->encryption = OP_E_AES;
ivlen = 16;
} else {
errmsg = "unsupported cipher";
goto error;
}
p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
for (i = 0; i < ivlen; i++) {
unsigned j;
if (1 != sscanf(p, "%2x", &j)) {
errmsg = "expected more iv data in DEK-Info";
goto error;
}
ret->iv[i] = j;
p += 2;
}
if (*p) {
errmsg = "more iv data than expected in DEK-Info";
goto error;
}
}
} else {
headers_done = true;
p = line;
while (isbase64(*p)) {
base64_bit[base64_chars++] = *p;
if (base64_chars == 4) {
unsigned char out[3];
int len;
base64_chars = 0;
len = base64_decode_atom(base64_bit, out);
if (len <= 0) {
errmsg = "invalid base64 encoding";
goto error;
}
put_data(ret->keyblob, out, len);
smemclr(out, sizeof(out));
}
p++;
}
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
if (!ret->keyblob || ret->keyblob->len == 0) {
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;
}
smemclr(base64_bit, sizeof(base64_bit));
if (errmsg_p) *errmsg_p = NULL;
return ret;
error:
if (line) {
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
smemclr(base64_bit, sizeof(base64_bit));
if (ret) {
if (ret->keyblob)
strbuf_free(ret->keyblob);
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
return NULL;
}
static bool openssh_pem_encrypted(BinarySource *src)
{
struct openssh_pem_key *key = load_openssh_pem_key(src, NULL);
bool ret;
if (!key)
return false;
ret = key->encrypted;
strbuf_free(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
return ret;
}
static void openssh_pem_derivekey(
ptrlen passphrase, const void *iv, uint8_t *keybuf)
{
/*
* Derive the encryption key for a PEM key file from the
* passphrase and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*
* (Note that only 8 bytes of the iv are used for key
* derivation, even when the key is encrypted with AES and
* hence there are 16 bytes available.)
*/
ssh_hash *h;
h = ssh_hash_new(&ssh_md5);
put_datapl(h, passphrase);
put_data(h, iv, 8);
ssh_hash_digest(h, keybuf);
ssh_hash_reset(h);
put_data(h, keybuf, 16);
put_datapl(h, passphrase);
put_data(h, iv, 8);
ssh_hash_final(h, keybuf + 16);
}
static ssh2_userkey *openssh_pem_read(
BinarySource *filesrc, const char *passphrase, const char **errmsg_p)
{
struct openssh_pem_key *key = load_openssh_pem_key(filesrc, errmsg_p);
ssh2_userkey *retkey;
const ssh_keyalg *alg;
BinarySource src[1];
int i, num_integers;
ssh2_userkey *retval = NULL;
const char *errmsg;
strbuf *blob = strbuf_new_nm();
int privptr = 0, publen;
if (!key) {
strbuf_free(blob);
return NULL;
}
if (key->encrypted) {
unsigned char keybuf[32];
openssh_pem_derivekey(ptrlen_from_asciz(passphrase), key->iv, keybuf);
/*
* Decrypt the key blob.
*/
if (key->encryption == OP_E_3DES)
des3_decrypt_pubkey_ossh(keybuf, key->iv,
key->keyblob->u, key->keyblob->len);
else {
ssh_cipher *cipher = ssh_cipher_new(&ssh_aes128_cbc);
ssh_cipher_setkey(cipher, keybuf);
ssh_cipher_setiv(cipher, key->iv);
ssh_cipher_decrypt(cipher, key->keyblob->u, key->keyblob->len);
ssh_cipher_free(cipher);
}
smemclr(keybuf, sizeof(keybuf));
}
/*
* 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.
*
* - In ECDSA the format is totally different: we see the
* SEQUENCE, but beneath is an INTEGER 1, OCTET STRING priv
* EXPLICIT [0] OID curve, EXPLICIT [1] BIT STRING pubPoint
*/
BinarySource_BARE_INIT(src, key->keyblob->u, key->keyblob->len);
{
/* Expect the SEQUENCE header. Take its absence as a failure to
* decrypt, if the key was encrypted. */
ber_item seq = get_ber(src);
if (get_err(src) || seq.id != 16) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
/* Reinitialise our BinarySource to parse just the inside of that
* SEQUENCE. */
BinarySource_BARE_INIT_PL(src, seq.data);
}
/* Expect a load of INTEGERs. */
if (key->keytype == OP_RSA)
num_integers = 9;
else if (key->keytype == OP_DSA)
num_integers = 6;
else
num_integers = 0; /* placate compiler warnings */
if (key->keytype == OP_ECDSA) {
/* And now for something completely different */
ber_item integer, privkey, sub0, sub1, oid, pubkey;
const ssh_keyalg *alg;
const struct ec_curve *curve;
/* Parse the outer layer of things inside the containing SEQUENCE */
integer = get_ber(src);
privkey = get_ber(src);
sub0 = get_ber(src);
sub1 = get_ber(src);
/* Now look inside sub0 for the curve OID */
BinarySource_BARE_INIT_PL(src, sub0.data);
oid = get_ber(src);
/* And inside sub1 for the public-key BIT STRING */
BinarySource_BARE_INIT_PL(src, sub1.data);
pubkey = get_ber(src);
if (get_err(src) ||
integer.id != 2 ||
integer.data.len != 1 ||
((const unsigned char *)integer.data.ptr)[0] != 1 ||
privkey.id != 4 ||
sub0.id != 0 ||
sub1.id != 1 ||
oid.id != 6 ||
pubkey.id != 3) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
alg = ec_alg_by_oid(oid.data.len, oid.data.ptr, &curve);
if (!alg) {
errmsg = "Unsupported ECDSA curve.";
retval = NULL;
goto error;
}
if (pubkey.data.len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
/* Skip 0x00 before point */
pubkey.data.ptr = (const char *)pubkey.data.ptr + 1;
pubkey.data.len -= 1;
/* Construct the key */
retkey = snew(ssh2_userkey);
put_stringz(blob, alg->ssh_id);
put_stringz(blob, curve->name);
put_stringpl(blob, pubkey.data);
publen = blob->len;
put_mp_ssh2_from_string(blob, privkey.data);
retkey->key = ssh_key_new_priv(
alg, make_ptrlen(blob->u, publen),
make_ptrlen(blob->u + publen, blob->len - publen));
if (!retkey->key) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
} else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
put_stringz(blob, key->keytype == OP_DSA ? "ssh-dss" : "ssh-rsa");
ptrlen rsa_modulus = PTRLEN_LITERAL("");
for (i = 0; i < num_integers; i++) {
ber_item integer = get_ber(src);
if (get_err(src) || integer.id != 2) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
if (i == 0) {
/*
* The first integer should be zero always (I think
* this is some sort of version indication).
*/
if (integer.data.len != 1 ||
((const unsigned char *)integer.data.ptr)[0] != 0) {
errmsg = "version number mismatch";
goto error;
}
} else if (key->keytype == OP_RSA) {
/*
* Integers 1 and 2 go into the public blob but in the
* opposite order; integers 3, 4, 5 and 8 go into the
* private blob. The other two (6 and 7) are ignored.
*/
if (i == 1) {
/* Save the details for after we deal with number 2. */
rsa_modulus = integer.data;
} else if (i != 6 && i != 7) {
put_mp_ssh2_from_string(blob, integer.data);
if (i == 2) {
put_mp_ssh2_from_string(blob, rsa_modulus);
privptr = blob->len;
}
}
} else if (key->keytype == OP_DSA) {
/*
* Integers 1-4 go into the public blob; integer 5 goes
* into the private blob.
*/
put_mp_ssh2_from_string(blob, integer.data);
if (i == 4)
privptr = blob->len;
}
}
/*
* 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.
*/
assert(privptr > 0); /* should have bombed by now if not */
retkey = snew(ssh2_userkey);
alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dsa);
retkey->key = ssh_key_new_priv(
alg, make_ptrlen(blob->u, privptr),
make_ptrlen(blob->u+privptr, blob->len-privptr));
if (!retkey->key) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
} else {
unreachable("Bad key type from load_openssh_pem_key");
errmsg = "Bad key type from load_openssh_pem_key";
goto error;
}
/*
* The old key format doesn't include a comment in the private
* key file.
*/
retkey->comment = dupstr("imported-openssh-key");
errmsg = NULL; /* no error */
retval = retkey;
error:
strbuf_free(blob);
strbuf_free(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return retval;
}
static bool openssh_pem_write(
const Filename *filename, ssh2_userkey *ukey, const char *passphrase)
{
strbuf *pubblob, *privblob, *outblob;
unsigned char *spareblob;
int sparelen = 0;
ptrlen numbers[9];
int nnumbers, i;
const char *header, *footer;
char zero[1];
unsigned char iv[8];
bool ret = false;
FILE *fp;
BinarySource src[1];
/* OpenSSH's private key files never contain a certificate, so
* revert to the underlying base key if necessary */
ssh_key *key = ssh_key_base_key(ukey->key);
/*
* Fetch the key blobs.
*/
pubblob = strbuf_new();
ssh_key_public_blob(key, BinarySink_UPCAST(pubblob));
privblob = strbuf_new_nm();
ssh_key_private_blob(key, BinarySink_UPCAST(privblob));
spareblob = NULL;
outblob = strbuf_new_nm();
/*
* Encode the OpenSSH key blob, and also decide on the header
* line.
*/
if (ssh_key_alg(key) == &ssh_rsa ||
ssh_key_alg(key) == &ssh_dsa) {
strbuf *seq;
/*
* The RSA and DSA handlers share some code because the two
* key types have very similar ASN.1 representations, as a
* plain SEQUENCE of big integers. So we set up a list of
* bignums per key type and then construct the actual blob in
* common code after that.
*/
if (ssh_key_alg(key) == &ssh_rsa) {
ptrlen n, e, d, p, q, iqmp, dmp1, dmq1;
mp_int *bd, *bp, *bq, *bdmp1, *bdmq1;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
BinarySource_BARE_INIT(src, pubblob->u, pubblob->len);
get_string(src); /* skip algorithm name */
e = get_string(src);
n = get_string(src);
BinarySource_BARE_INIT(src, privblob->u, privblob->len);
d = get_string(src);
p = get_string(src);
q = get_string(src);
iqmp = get_string(src);
assert(!get_err(src)); /* can't go wrong */
/* We also need d mod (p-1) and d mod (q-1). */
bd = mp_from_bytes_be(d);
bp = mp_from_bytes_be(p);
bq = mp_from_bytes_be(q);
mp_sub_integer_into(bp, bp, 1);
mp_sub_integer_into(bq, bq, 1);
bdmp1 = mp_mod(bd, bp);
bdmq1 = mp_mod(bd, bq);
mp_free(bd);
mp_free(bp);
mp_free(bq);
dmp1.len = (mp_get_nbits(bdmp1)+8)/8;
dmq1.len = (mp_get_nbits(bdmq1)+8)/8;
sparelen = dmp1.len + dmq1.len;
spareblob = snewn(sparelen, unsigned char);
dmp1.ptr = spareblob;
dmq1.ptr = spareblob + dmp1.len;
for (i = 0; i < dmp1.len; i++)
spareblob[i] = mp_get_byte(bdmp1, dmp1.len-1 - i);
for (i = 0; i < dmq1.len; i++)
spareblob[i+dmp1.len] = mp_get_byte(bdmq1, dmq1.len-1 - i);
mp_free(bdmp1);
mp_free(bdmq1);
numbers[0] = make_ptrlen(zero, 1); zero[0] = '\0';
numbers[1] = n;
numbers[2] = e;
numbers[3] = d;
numbers[4] = p;
numbers[5] = q;
numbers[6] = dmp1;
numbers[7] = dmq1;
numbers[8] = iqmp;
nnumbers = 9;
header = "-----BEGIN RSA PRIVATE KEY-----\n";
footer = "-----END RSA PRIVATE KEY-----\n";
} else { /* ssh-dss */
ptrlen p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
BinarySource_BARE_INIT(src, pubblob->u, pubblob->len);
get_string(src); /* skip algorithm name */
p = get_string(src);
q = get_string(src);
g = get_string(src);
y = get_string(src);
BinarySource_BARE_INIT(src, privblob->u, privblob->len);
x = get_string(src);
assert(!get_err(src)); /* can't go wrong */
numbers[0].ptr = zero; numbers[0].len = 1; zero[0] = '\0';
numbers[1] = p;
numbers[2] = q;
numbers[3] = g;
numbers[4] = y;
numbers[5] = x;
nnumbers = 6;
header = "-----BEGIN DSA PRIVATE KEY-----\n";
footer = "-----END DSA PRIVATE KEY-----\n";
}
seq = strbuf_new_nm();
for (i = 0; i < nnumbers; i++) {
put_ber_id_len(seq, 2, numbers[i].len, 0);
put_datapl(seq, numbers[i]);
}
put_ber_id_len(outblob, 16, seq->len, ASN1_CONSTRUCTED);
put_data(outblob, seq->s, seq->len);
strbuf_free(seq);
} else if (ssh_key_alg(key) == &ssh_ecdsa_nistp256 ||
ssh_key_alg(key) == &ssh_ecdsa_nistp384 ||
ssh_key_alg(key) == &ssh_ecdsa_nistp521) {
const unsigned char *oid;
struct ecdsa_key *ec = container_of(key, struct ecdsa_key, sshk);
int oidlen;
int pointlen;
strbuf *seq, *sub;
/*
* Structure of asn1:
* SEQUENCE
* INTEGER 1
* OCTET STRING (private key)
* [0]
* OID (curve)
* [1]
* BIT STRING (0x00 public key point)
*/
oid = ec_alg_oid(ssh_key_alg(key), &oidlen);
pointlen = (ec->curve->fieldBits + 7) / 8 * 2;
seq = strbuf_new_nm();
/* INTEGER 1 */
put_ber_id_len(seq, 2, 1, 0);
put_byte(seq, 1);
/* OCTET STRING private key */
put_ber_id_len(seq, 4, privblob->len - 4, 0);
put_data(seq, privblob->s + 4, privblob->len - 4);
/* Subsidiary OID */
sub = strbuf_new();
put_ber_id_len(sub, 6, oidlen, 0);
put_data(sub, oid, oidlen);
/* Append the OID to the sequence */
put_ber_id_len(seq, 0, sub->len,
ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
put_data(seq, sub->s, sub->len);
strbuf_free(sub);
/* Subsidiary BIT STRING */
sub = strbuf_new();
put_ber_id_len(sub, 3, 2 + pointlen, 0);
put_byte(sub, 0);