X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/4f743df55ac05e51bc69aaabd188132f2f94543b..b04a7659918367dcc8570e1c7b4246a97e88288d:/bbs-gen.c diff --git a/bbs-gen.c b/bbs-gen.c index 1855219..8780274 100644 --- a/bbs-gen.c +++ b/bbs-gen.c @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: bbs-gen.c,v 1.1 1999/12/10 23:14:59 mdw Exp $ + * $Id: bbs-gen.c,v 1.2 1999/12/22 15:52:28 mdw Exp $ * * Generate Blum integers * @@ -30,6 +30,9 @@ /*----- Revision history --------------------------------------------------* * * $Log: bbs-gen.c,v $ + * Revision 1.2 1999/12/22 15:52:28 mdw + * Reworking for new prime-search system. + * * Revision 1.1 1999/12/10 23:14:59 mdw * Blum-Blum-Shub generator, and Blum-Goldwasser encryption. * @@ -42,24 +45,71 @@ #include #include "bbs.h" -#include "fibrand.h" #include "mp.h" #include "mprand.h" #include "pgen.h" -#include "rabin.h" + +/*----- Data structures ---------------------------------------------------*/ + +typedef struct gcdctx { + mp *q; + mp *r; + pfilt p; +} gcdctx; + +/*----- Custom stepper ----------------------------------------------------*/ + +static int gcdstep(int rq, pgen_event *ev, void *p) +{ + gcdctx *g = p; + int rc = PGEN_ABORT; + mp *z = MP_NEW; + + switch (rq) { + case PGEN_BEGIN: { + mp *p = ev->m = mp_split(ev->m); + p->v[0] |= 3; + g->q = mp_lsr(MP_NEW, p, 1); + rc = pfilt_create(&g->p, p); + } break; + case PGEN_TRY: + g->q = mp_add(g->q, g->q, MP_FOUR); + rc = pfilt_step(&g->p, 4); + break; + case PGEN_DONE: + pfilt_destroy(&g->p); + mp_drop(g->q); + return (PGEN_DONE); + } + for (;;) { + if (rc != PGEN_FAIL) { + mp_gcd(&z, 0, 0, g->r, g->q); + if (MP_CMP(z, !=, MP_ONE)) + rc = PGEN_FAIL; + } + if (rc != PGEN_FAIL) + break; + g->q = mp_add(g->q, g->q, MP_FOUR); + rc = pfilt_step(&g->p, 4); + } + + mp_drop(z); + mp_drop(ev->m); + ev->m = MP_COPY(g->p.m); + return (rc); +} /*----- Main code ---------------------------------------------------------*/ /* --- @bbs_gen@ --- * * - * Arguments: @bbs_params *bp@ = pointer to parameter block + * Arguments: @bbs_param *bp@ = pointer to parameter block * @mp *p, *q@ = initial numbers to search from * @size_t n@ = number of attempts to make - * @void (*proc)(int ev, mp *m, void *p)@ = event handler - * @void *arg@ = argument for event handler + * @pgen_proc *event@ = event handler function + * @void *ectx@ = argument for event handler * - * Returns: Zero if all went well, otherwise an event code which explains - * the problem. + * Returns: If it worked OK, @PGEN_DONE@, otherwise @PGEN_ABORT@. * * Use: Finds two prime numbers %$p'$% and %$q'$% such that both are * congruent to %$3 \bmod 4$%, and $(p - 1)/2$% and @@ -68,181 +118,39 @@ * Shub pseudorandom bit generator. */ -int bbs_gen(bbs_params *bp, mp *p, mp *q, size_t n, - int (*proc)(int /*ev*/, mp */*m*/, void */*p*/), void *arg) +int bbs_gen(bbs_param *bp, mp *p, mp *q, size_t n, + pgen_proc *event, void *ectx) { - pgen px, py; - mp *pp; - mp *g = MP_NEW; - grand *gr = fibrand_create(0); - int rcx, rcy; - int fail = BBSEV_OK; - size_t sz; - - /* --- Initialize @p@ and @q@ --- * - * - * Divide both by two, and make the results odd. - */ - - p = mp_lsr(MP_NEW, p, 1); p->v[0] |= 1; - q = mp_lsr(MP_NEW, q, 1); q->v[0] |= 1; - - /* --- Set up the search for @p@ --- * - * - * I want a prime %$p$% such that %$(p - 1)/2$% has no small factors. - */ - - rcx = pgen_create(&px, p); mp_drop(p); - rcy = pgen_muladd(&py, &px, 2, 1); - - if (proc && (fail = proc(BBSEV_FINDP, 0, arg)) != 0) - goto fail_0; - - sz = mp_bits(py.m); - for (;;) { - if (rcx != PGEN_COMPOSITE && rcy != PGEN_COMPOSITE) { - if (rcy != PGEN_PRIME) { - rabin r; - int i; - - if (proc && (fail = proc(BBSEV_TRYP, py.m, arg)) != 0) - break; - rabin_create(&r, py.m); - for (i = 0; i < 5; i++) { - g = mprand(g, sz, gr, 1); - if ((rcy = rabin_test(&r, g)) == PGEN_COMPOSITE) - break; - if (proc && (fail = proc(BBSEV_PASSP, py.m, arg)) != 0) - break; - } - rabin_destroy(&r); - if (fail) - goto fail_0; - if (i < 5) { - if (proc && (fail = proc(BBSEV_FAILP, py.m, arg)) != 0) - goto fail_0; - if (n) { - n--; - if (!n) { - fail = BBSEV_FAILP; - goto fail_0; - } - } - } - } - - if (rcy != PGEN_COMPOSITE) - break; - } - rcx = pgen_step(&px, 2); - rcy = pgen_step(&py, 4); - } + rabin r; + pgen_safestepctx c; + gcdctx g; - if (proc && (fail = proc(BBSEV_GOODP, py.m, arg)) != 0) - goto fail_0; + /* --- Generate @p@ --- */ - /* --- I now have a @p@ (and a %$(p - 1)/2$%) --- */ + if ((bp->p = pgen("p", MP_NEW, p, event, ectx, n, pgen_safestep, &c, + rabin_iters(mp_bits(p)), pgen_test, &r)) == 0) + goto fail_p; - pp = MP_COPY(px.m); pgen_destroy(&px); - p = MP_COPY(py.m); pgen_destroy(&py); + /* --- Generate @q@ --- */ - /* --- Next trick is to generate @q@ --- * - * - * I don't care about small factors of %$(q - 1)/2$%, just that it's - * relatively prime to %$(p - 1)/2$%. - */ + g.r = mp_lsr(MP_NEW, bp->p, 1); + if ((bp->q = pgen("q", MP_NEW, q, event, ectx, n, gcdstep, &g, + rabin_iters(mp_bits(q)), pgen_test, &r)) == 0) + goto fail_q; - { - mp *m = mp_lsl(MP_NEW, q, 1); - m->v[0] |= 1; - rcx = pgen_create(&px, m); - mp_drop(m); - } + /* --- Compute @n@ --- */ - if (proc && (fail = proc(BBSEV_FINDQ, 0, arg)) != 0) - goto fail_1; + bp->n = mp_mul(MP_NEW, bp->p, bp->q); + mp_drop(g.r); + return (PGEN_DONE); - for (;;) { - if (rcx != PGEN_COMPOSITE) { - int ok; - - /* --- Ensure that %$(p - 1)/2$% and %$(q - 1)/2$% are coprime --- */ - - mp_gcd(&g, 0, 0, pp, q); - ok = MP_CMP(g, ==, MP_ONE); - - if (ok && rcx != PGEN_PRIME) { - rabin r; - int i; - - if (proc && (fail = proc(BBSEV_TRYQ, px.m, arg)) != 0) - break; - rabin_create(&r, px.m); - for (i = 0; i < 5; i++) { - g = mprand(g, sz, gr, 1); - if ((rcx = rabin_test(&r, g)) == PGEN_COMPOSITE) - break; - if (proc && (fail = proc(BBSEV_PASSQ, px.m, arg)) != 0) - break; - } - rabin_destroy(&r); - if (fail) - goto fail_1; - if (i < 5) { - if (proc && (fail = proc(BBSEV_FAILQ, px.m, arg)) != 0) - goto fail_1; - if (n) { - n--; - if (!n) { - fail = BBSEV_FAILQ; - goto fail_1; - } - } - } - } - - if (ok && rcx != PGEN_COMPOSITE) - break; - } - - q = mp_add(q, q, MP_TWO); - rcx = pgen_step(&px, 4); - } + /* --- Tidy up if things went wrong --- */ - if (proc && (fail = proc(BBSEV_GOODQ, px.m, arg)) != 0) - goto fail_1; - - /* --- Done --- */ - - mp_drop(g); - mp_drop(q); - mp_drop(pp); - q = MP_COPY(px.m); - bp->p = p; - bp->q = q; - pgen_destroy(&px); - bp->n = mp_mul(MP_NEW, p, q); - gr->ops->destroy(gr); - return (0); - - /* --- Failed --- */ - -fail_1: - pgen_destroy(&px); - mp_drop(p); - mp_drop(pp); - mp_drop(g); - gr->ops->destroy(gr); - return (fail); - -fail_0: - if (g) - mp_drop(g); - pgen_destroy(&px); - pgen_destroy(&py); - mp_drop(q); - gr->ops->destroy(gr); - return (fail); +fail_q: + mp_drop(g.r); + mp_drop(bp->p); +fail_p: + return (PGEN_ABORT); } /*----- That's all, folks -------------------------------------------------*/