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mirror of https://git.tartarus.org/simon/putty.git synced 2025-01-09 17:38:00 +00:00

Refactoring to prepare for extra public key types.

The OpenSSH key importer and exporter were structured in the
assumption that the strong commonality of format between OpenSSH RSA
and DSA keys would persist across all key types. Moved code around so
it's now clear that this is a peculiarity of those _particular_ two
key types which will not apply to others we add alongside them.

Also, a boolean 'is_dsa' in winpgen.c has been converted into a more
sensible key type enumeration, and the individually typed key pointers
have been piled on top of each other in a union.

This is a pure refactoring change which should have no functional
effect.
This commit is contained in:
Chris Staite 2014-11-01 09:14:19 +00:00 committed by Simon Tatham
parent a2b64dca47
commit df0ac30d46
2 changed files with 266 additions and 225 deletions

459
import.c
View File

@ -613,91 +613,96 @@ struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
else
num_integers = 0; /* placate compiler warnings */
/*
* Space to create key blob in.
*/
blobsize = 256+key->keyblob_len;
blob = snewn(blobsize, unsigned char);
PUT_32BIT(blob, 7);
if (key->type == OSSH_DSA)
memcpy(blob+4, "ssh-dss", 7);
else if (key->type == OSSH_RSA)
memcpy(blob+4, "ssh-rsa", 7);
blobptr = 4+7;
privptr = -1;
if (key->type == OSSH_RSA || key->type == OSSH_DSA) {
/*
* Space to create key blob in.
*/
blobsize = 256+key->keyblob_len;
blob = snewn(blobsize, unsigned char);
PUT_32BIT(blob, 7);
if (key->type == OSSH_DSA)
memcpy(blob+4, "ssh-dss", 7);
else if (key->type == OSSH_RSA)
memcpy(blob+4, "ssh-rsa", 7);
blobptr = 4+7;
privptr = -1;
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 ||
key->keyblob+key->keyblob_len-p < len) {
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 (len != 1 || p[0] != 0) {
errmsg = "version number mismatch";
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 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
} else if (key->type == OSSH_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. */
modptr = (char *)p;
modlen = len;
} else if (i != 6 && i != 7) {
if (i == 0) {
/*
* The first integer should be zero always (I think
* this is some sort of version indication).
*/
if (len != 1 || p[0] != 0) {
errmsg = "version number mismatch";
goto error;
}
} else if (key->type == OSSH_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. */
modptr = (char *)p;
modlen = len;
} else if (i != 6 && i != 7) {
PUT_32BIT(blob+blobptr, len);
memcpy(blob+blobptr+4, p, len);
blobptr += 4+len;
if (i == 2) {
PUT_32BIT(blob+blobptr, modlen);
memcpy(blob+blobptr+4, modptr, modlen);
blobptr += 4+modlen;
privptr = blobptr;
}
}
} else if (key->type == OSSH_DSA) {
/*
* Integers 1-4 go into the public blob; integer 5 goes
* into the private blob.
*/
PUT_32BIT(blob+blobptr, len);
memcpy(blob+blobptr+4, p, len);
blobptr += 4+len;
if (i == 2) {
PUT_32BIT(blob+blobptr, modlen);
memcpy(blob+blobptr+4, modptr, modlen);
blobptr += 4+modlen;
if (i == 4)
privptr = blobptr;
}
}
} else if (key->type == OSSH_DSA) {
/*
* Integers 1-4 go into the public blob; integer 5 goes
* into the private blob.
*/
PUT_32BIT(blob+blobptr, len);
memcpy(blob+blobptr+4, p, len);
blobptr += 4+len;
if (i == 4)
privptr = blobptr;
/* Skip past the number. */
p += len;
}
/* Skip past the number. */
p += 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(struct ssh2_userkey);
retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss);
retkey->data = retkey->alg->createkey(blob, privptr,
blob+privptr, blobptr-privptr);
if (!retkey->data) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
/*
* 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(struct ssh2_userkey);
retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss);
retkey->data = retkey->alg->createkey(blob, privptr,
blob+privptr, blobptr-privptr);
if (!retkey->data) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
} else {
assert(0 && "Bad key type from load_openssh_key");
}
retkey->comment = dupstr("imported-openssh-key");
@ -739,157 +744,142 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
privblob = key->alg->private_blob(key->data, &privlen);
spareblob = outblob = NULL;
outblob = NULL;
len = 0;
/*
* Find the sequence of integers to be encoded into the OpenSSH
* key blob, and also decide on the header line.
* Encode the OpenSSH key blob, and also decide on the header
* line.
*/
if (key->alg == &ssh_rsa) {
int pos;
struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
Bignum bd, bp, bq, bdmp1, bdmq1;
if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
/*
* The RSA and DSS 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 (key->alg == &ssh_rsa) {
int pos;
struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
Bignum bd, bp, bq, bdmp1, bdmq1;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
assert(e.start && iqmp.start); /* can't go wrong */
/* We also need d mod (p-1) and d mod (q-1). */
bd = bignum_from_bytes(d.start, d.bytes);
bp = bignum_from_bytes(p.start, p.bytes);
bq = bignum_from_bytes(q.start, q.bytes);
decbn(bp);
decbn(bq);
bdmp1 = bigmod(bd, bp);
bdmq1 = bigmod(bd, bq);
freebn(bd);
freebn(bp);
freebn(bq);
dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
sparelen = dmp1.bytes + dmq1.bytes;
spareblob = snewn(sparelen, unsigned char);
dmp1.start = spareblob;
dmq1.start = spareblob + dmp1.bytes;
for (i = 0; i < dmp1.bytes; i++)
spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
for (i = 0; i < dmq1.bytes; i++)
spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
freebn(bdmp1);
freebn(bdmq1);
numbers[0].start = zero; numbers[0].bytes = 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 */
int pos;
struct mpint_pos p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
assert(y.start && x.start); /* can't go wrong */
numbers[0].start = zero; numbers[0].bytes = 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";
}
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
* Now count up the total size of the ASN.1 encoded integers,
* so as to determine the length of the containing SEQUENCE.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
assert(e.start && iqmp.start); /* can't go wrong */
/* We also need d mod (p-1) and d mod (q-1). */
bd = bignum_from_bytes(d.start, d.bytes);
bp = bignum_from_bytes(p.start, p.bytes);
bq = bignum_from_bytes(q.start, q.bytes);
decbn(bp);
decbn(bq);
bdmp1 = bigmod(bd, bp);
bdmq1 = bigmod(bd, bq);
freebn(bd);
freebn(bp);
freebn(bq);
dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
sparelen = dmp1.bytes + dmq1.bytes;
spareblob = snewn(sparelen, unsigned char);
dmp1.start = spareblob;
dmq1.start = spareblob + dmp1.bytes;
for (i = 0; i < dmp1.bytes; i++)
spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
for (i = 0; i < dmq1.bytes; i++)
spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
freebn(bdmp1);
freebn(bdmq1);
numbers[0].start = zero; numbers[0].bytes = 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 if (key->alg == &ssh_dss) {
int pos;
struct mpint_pos p, q, g, y, x;
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);
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
* Now we know how big outblob needs to be. Allocate it.
*/
outblob = snewn(len, unsigned char);
/*
* And write the data into it.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
assert(y.start && x.start); /* can't go wrong */
numbers[0].start = zero; numbers[0].bytes = 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";
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;
}
} else {
assert(0); /* zoinks! */
exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
}
/*
* 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 = snewn(outlen, unsigned char);
/*
* 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;
}
/*
* 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.
*/
assert(pos == len);
while (pos < outlen) {
outblob[pos++] = outlen - len;
}
/*
* Encrypt the key.
*
@ -897,6 +887,44 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
* old-style 3DES.
*/
if (passphrase) {
struct MD5Context md5c;
unsigned char keybuf[32];
/*
* Round up to the cipher block size, ensuring we have at
* least one byte of padding (see below).
*/
outlen = (len+8) &~ 7;
{
unsigned char *tmp = snewn(outlen, unsigned char);
memcpy(tmp, outblob, len);
smemclr(outblob, len);
sfree(outblob);
outblob = tmp;
}
/*
* 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.
*/
assert(pos == len);
while (pos < outlen) {
outblob[pos++] = outlen - len;
}
/*
* Invent an iv. Then derive encryption key from passphrase
* and iv/salt:
@ -906,9 +934,6 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32];
for (i = 0; i < 8; i++) iv[i] = random_byte();
MD5Init(&md5c);
@ -929,6 +954,12 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
} else {
/*
* If no encryption, the blob has exactly its original
* cleartext size.
*/
outlen = len;
}
/*

View File

@ -315,6 +315,8 @@ static int CALLBACK AboutProc(HWND hwnd, UINT msg,
return 0;
}
typedef enum {RSA, DSA, ECDSA} keytype;
/*
* Thread to generate a key.
*/
@ -322,9 +324,11 @@ struct rsa_key_thread_params {
HWND progressbar; /* notify this with progress */
HWND dialog; /* notify this on completion */
int keysize; /* bits in key */
int is_dsa;
struct RSAKey *key;
struct dss_key *dsskey;
keytype keytype;
union {
struct RSAKey *key;
struct dss_key *dsskey;
};
};
static DWORD WINAPI generate_rsa_key_thread(void *param)
{
@ -335,7 +339,7 @@ static DWORD WINAPI generate_rsa_key_thread(void *param)
progress_update(&prog, PROGFN_INITIALISE, 0, 0);
if (params->is_dsa)
if (params->keytype == DSA)
dsa_generate(params->dsskey, params->keysize, progress_update, &prog);
else
rsa_generate(params->key, params->keysize, progress_update, &prog);
@ -352,12 +356,15 @@ struct MainDlgState {
int key_exists;
int entropy_got, entropy_required, entropy_size;
int keysize;
int ssh2, is_dsa;
int ssh2;
keytype keytype;
char **commentptr; /* points to key.comment or ssh2key.comment */
struct ssh2_userkey ssh2key;
unsigned *entropy;
struct RSAKey key;
struct dss_key dsskey;
union {
struct RSAKey key;
struct dss_key dsskey;
};
HMENU filemenu, keymenu, cvtmenu;
};
@ -990,7 +997,7 @@ static int CALLBACK MainDlgProc(HWND hwnd, UINT msg,
params->progressbar = GetDlgItem(hwnd, IDC_PROGRESS);
params->dialog = hwnd;
params->keysize = state->keysize;
params->is_dsa = state->is_dsa;
params->keytype = state->keytype;
params->key = &state->key;
params->dsskey = &state->dsskey;
@ -1070,7 +1077,10 @@ static int CALLBACK MainDlgProc(HWND hwnd, UINT msg,
state->keysize = DEFAULT_KEYSIZE;
/* If we ever introduce a new key type, check it here! */
state->ssh2 = !IsDlgButtonChecked(hwnd, IDC_KEYSSH1);
state->is_dsa = IsDlgButtonChecked(hwnd, IDC_KEYSSH2DSA);
state->keytype = RSA;
if (IsDlgButtonChecked(hwnd, IDC_KEYSSH2DSA)) {
state->keytype = DSA;
}
if (state->keysize < 256) {
int ret = MessageBox(hwnd,
"PuTTYgen will not generate a key"
@ -1276,7 +1286,7 @@ static int CALLBACK MainDlgProc(HWND hwnd, UINT msg,
MAKELPARAM(0, PROGRESSRANGE));
SendDlgItemMessage(hwnd, IDC_PROGRESS, PBM_SETPOS, PROGRESSRANGE, 0);
if (state->ssh2) {
if (state->is_dsa) {
if (state->keytype == DSA) {
state->ssh2key.data = &state->dsskey;
state->ssh2key.alg = &ssh_dss;
} else {
@ -1297,7 +1307,7 @@ static int CALLBACK MainDlgProc(HWND hwnd, UINT msg,
{
struct tm tm;
tm = ltime();
if (state->is_dsa)
if (state->keytype == DSA)
strftime(*state->commentptr, 30, "dsa-key-%Y%m%d", &tm);
else
strftime(*state->commentptr, 30, "rsa-key-%Y%m%d", &tm);