nhyatt/putty-source
1
0
Fork 0
mirror of https://git.tartarus.org/simon/putty.git synced 2025-07-17 19:11:00 -05:00
Code Issues Projects Releases Wiki Activity

New vtable API for keygen progress reporting.

Browse Source 
The old API was one of those horrible things I used to do when I was
young and foolish, in which you have just one function, and indicate
which of lots of things it's doing by passing in flags. It was crying
out to be replaced with a vtable.

While I'm at it, I've reworked the code on the Windows side that
decides what to do with the progress bar, so that it's based on
actually justifiable estimates of probability rather than magic
integer constants.

Since computers are generally faster now than they were at the start
of this project, I've also decided there's no longer any point in
making the fixed final part of RSA key generation bother to report
progress at all. So the progress bars are now only for the variable
part, i.e. the actual prime generations.
This commit is contained in:
Simon Tatham
2020-02-23 15:29:40 +00:00
parent 63b8f537f2
commit a7bdefb394
13 changed files with 569 additions and 400 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
sshrsag.c
View File

@ -14,49 +14,12 @@
static void invent_firstbits(unsigned *one, unsigned *two,
unsigned min_separation);
int rsa_generate(RSAKey *key, int bits, progfn_t pfn,
void *pfnparam)
int rsa_generate(RSAKey *key, int bits, ProgressReceiver *prog)
{
unsigned pfirst, qfirst;
key->sshk.vt = &ssh_rsa;
/*
* Set up the phase limits for the progress report. We do this
* by passing minus the phase number.
*
* For prime generation: our initial filter finds things
* coprime to everything below 2^16. Computing the product of
* (p-1)/p for all prime p below 2^16 gives about 20.33; so
* among B-bit integers, one in every 20.33 will get through
* the initial filter to be a candidate prime.
*
* Meanwhile, we are searching for primes in the region of 2^B;
* since pi(x) ~ x/log(x), when x is in the region of 2^B, the
* prime density will be d/dx pi(x) ~ 1/log(B), i.e. about
* 1/0.6931B. So the chance of any given candidate being prime
* is 20.33/0.6931B, which is roughly 29.34 divided by B.
*
* So now we have this probability P, we're looking at an
* exponential distribution with parameter P: we will manage in
* one attempt with probability P, in two with probability
* P(1-P), in three with probability P(1-P)^2, etc. The
* probability that we have still not managed to find a prime
* after N attempts is (1-P)^N.
*
* We therefore inform the progress indicator of the number B
* (29.34/B), so that it knows how much to increment by each
* time. We do this in 16-bit fixed point, so 29.34 becomes
* 0x1D.57C4.
*/
pfn(pfnparam, PROGFN_PHASE_EXTENT, 1, 0x10000);
pfn(pfnparam, PROGFN_EXP_PHASE, 1, -0x1D57C4 / (bits / 2));
pfn(pfnparam, PROGFN_PHASE_EXTENT, 2, 0x10000);
pfn(pfnparam, PROGFN_EXP_PHASE, 2, -0x1D57C4 / (bits - bits / 2));
pfn(pfnparam, PROGFN_PHASE_EXTENT, 3, 0x4000);
pfn(pfnparam, PROGFN_LIN_PHASE, 3, 5);
pfn(pfnparam, PROGFN_READY, 0, 0);
/*
* We don't generate e; we just use a standard one always.
*/
@ -80,15 +43,23 @@ int rsa_generate(RSAKey *key, int bits, progfn_t pfn,
int pbits = bits - qbits;
assert(pbits >= qbits);
ProgressPhase phase_p = primegen_add_progress_phase(prog, pbits);
ProgressPhase phase_q = primegen_add_progress_phase(prog, qbits);
progress_ready(prog);
PrimeCandidateSource *pcs;
progress_start_phase(prog, phase_p);
pcs = pcs_new_with_firstbits(pbits, pfirst, NFIRSTBITS);
pcs_avoid_residue_small(pcs, RSA_EXPONENT, 1);
mp_int *p = primegen(pcs, 1, pfn, pfnparam);
mp_int *p = primegen(pcs, prog);
progress_report_phase_complete(prog);
progress_start_phase(prog, phase_q);
pcs = pcs_new_with_firstbits(qbits, qfirst, NFIRSTBITS);
pcs_avoid_residue_small(pcs, RSA_EXPONENT, 1);
mp_int *q = primegen(pcs, 2, pfn, pfnparam);
mp_int *q = primegen(pcs, prog);
progress_report_phase_complete(prog);
/*
* Ensure p > q, by swapping them if not.
@ -108,22 +79,17 @@ int rsa_generate(RSAKey *key, int bits, progfn_t pfn,
* the other helpful quantities: n=pq, d=e^-1 mod (p-1)(q-1),
* and (q^-1 mod p).
*/
pfn(pfnparam, PROGFN_PROGRESS, 3, 1);
mp_int *modulus = mp_mul(p, q);
pfn(pfnparam, PROGFN_PROGRESS, 3, 2);
mp_int *pm1 = mp_copy(p);
mp_sub_integer_into(pm1, pm1, 1);
mp_int *qm1 = mp_copy(q);
mp_sub_integer_into(qm1, qm1, 1);
mp_int *phi_n = mp_mul(pm1, qm1);
pfn(pfnparam, PROGFN_PROGRESS, 3, 3);
mp_free(pm1);
mp_free(qm1);
mp_int *private_exponent = mp_invert(exponent, phi_n);
pfn(pfnparam, PROGFN_PROGRESS, 3, 4);
mp_free(phi_n);
mp_int *iqmp = mp_invert(q, p);
pfn(pfnparam, PROGFN_PROGRESS, 3, 5);
/*
* Populate the returned structure.