nhyatt/putty-source
1
0
Fork 0
mirror of https://git.tartarus.org/simon/putty.git synced 2025-06-30 19:12:48 -05:00
Code Issues Projects Releases Wiki Activity

Following the recent advisory about attacks on PGP keys based on

Browse Source 
tampering with the unencrypted public part of the key but leaving
the private part intact ... we are now ultra-paranoid about RSA key
files, and we check that the public part matches the private part
_before_ we generate any signatures with them.

[originally from svn r1021]
This commit is contained in:
Simon Tatham
2001-03-22 21:48:33 +00:00
parent 3f63cf7d88
commit e3bcd35a37
2 changed files with 58 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
sshrsa.c
View File

@ -151,6 +151,37 @@ void rsa_fingerprint(char *str, int len, struct RSAKey *key) {
}
}
/*
* Verify that the public data in an RSA key matches the private
* data.
*/
int rsa_verify(struct RSAKey *key) {
Bignum n, ed, pm1, qm1, pm1qm1;
int cmp;
/* n must equal pq. */
n = bigmul(key->p, key->q);
cmp = bignum_cmp(n, key->modulus);
freebn(n);
if (cmp != 0)
return 0;
/* e * d must be congruent to 1, modulo (p-1)(q-1). */
pm1 = copybn(key->p);
decbn(pm1);
qm1 = copybn(key->q);
decbn(qm1);
pm1qm1 = bigmul(pm1, qm1);
freebn(pm1);
freebn(qm1);
ed = modmul(key->exponent, key->private_exponent, pm1qm1);
sfree(pm1qm1);
cmp = bignum_cmp(ed, One);
sfree(ed);
if (cmp != 0)
return 0;
}
void freersakey(struct RSAKey *key) {
if (key->modulus) freebn(key->modulus);
if (key->exponent) freebn(key->exponent);
@ -231,7 +262,7 @@ static char *rsa2_fmtkey(void *key) {
len = rsastr_len(rsa);
p = smalloc(len);
rsastr_fmt(p, rsa);
rsastr_fmt(p, rsa);
return p;
}
@ -304,6 +335,11 @@ static void *rsa2_createkey(unsigned char *pub_blob, int pub_len,
rsa->q = getmp(&pb, &priv_len);
rsa->iqmp = getmp(&pb, &priv_len);
if (!rsa_verify(rsa)) {
rsa2_freekey(rsa);
return NULL;
}
return rsa;
}