checking in all the old panacean stuff

2016-07-25 15:42:39 -04:00
parent c996cdd81f
commit 8fd9e44ae5
1210 changed files with 220657 additions and 0 deletions
--- a/puttysrc/SSHRSAG.C
+++ b/puttysrc/SSHRSAG.C
@@ -0,0 +1,103 @@
+/*
+ * RSA key generation.
+ */
+
+#include "ssh.h"
+
+#define RSA_EXPONENT 37		       /* we like this prime */
+
+int rsa_generate(struct RSAKey *key, int bits, progfn_t pfn,
+		 void *pfnparam)
+{
+    Bignum pm1, qm1, phi_n;
+
+    /*
+     * 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.
+     */
+    key->exponent = bignum_from_long(RSA_EXPONENT);
+
+    /*
+     * Generate p and q: primes with combined length `bits', not
+     * congruent to 1 modulo e. (Strictly speaking, we wanted (p-1)
+     * and e to be coprime, and (q-1) and e to be coprime, but in
+     * general that's slightly more fiddly to arrange. By choosing
+     * a prime e, we can simplify the criterion.)
+     */
+    key->p = primegen(bits / 2, RSA_EXPONENT, 1, NULL,
+		      1, pfn, pfnparam);
+    key->q = primegen(bits - bits / 2, RSA_EXPONENT, 1, NULL,
+		      2, pfn, pfnparam);
+
+    /*
+     * Ensure p > q, by swapping them if not.
+     */
+    if (bignum_cmp(key->p, key->q) < 0) {
+	Bignum t = key->p;
+	key->p = key->q;
+	key->q = t;
+    }
+
+    /*
+     * Now we have p, q and e. All we need to do now is work out
+     * 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);
+    key->modulus = bigmul(key->p, key->q);
+    pfn(pfnparam, PROGFN_PROGRESS, 3, 2);
+    pm1 = copybn(key->p);
+    decbn(pm1);
+    qm1 = copybn(key->q);
+    decbn(qm1);
+    phi_n = bigmul(pm1, qm1);
+    pfn(pfnparam, PROGFN_PROGRESS, 3, 3);
+    freebn(pm1);
+    freebn(qm1);
+    key->private_exponent = modinv(key->exponent, phi_n);
+    pfn(pfnparam, PROGFN_PROGRESS, 3, 4);
+    key->iqmp = modinv(key->q, key->p);
+    pfn(pfnparam, PROGFN_PROGRESS, 3, 5);
+
+    /*
+     * Clean up temporary numbers.
+     */
+    freebn(phi_n);
+
+    return 1;
+}