openssl/openssl-rsakeygen-minimum-distance.patch

66 lines
2.5 KiB
Diff

Index: openssl-1.0.2g/crypto/rsa/rsa_gen.c
===================================================================
--- openssl-1.0.2g.orig/crypto/rsa/rsa_gen.c 2016-04-13 15:18:47.520016582 +0200
+++ openssl-1.0.2g/crypto/rsa/rsa_gen.c 2016-04-13 15:36:32.309233030 +0200
@@ -465,6 +465,19 @@ static int rsa_builtin_keygen(RSA *rsa,
bitsp = (bits + 1) / 2;
bitsq = bits - bitsp;
+ /* prepare a maximum for p and q */
+ /* 0xB504F334 is (sqrt(2)/2)*2^32 */
+ if (!BN_set_word(r0, 0xB504F334))
+ goto err;
+ if (!BN_lshift(r0, r0, bitsp - 32))
+ goto err;
+
+ /* prepare minimum p and q difference */
+ if (!BN_one(r3))
+ goto err;
+ if (!BN_lshift(r3, r3, bitsp - 100))
+ goto err;
+
/* We need the RSA components non-NULL */
if (!rsa->n && ((rsa->n = BN_new()) == NULL))
goto err;
@@ -489,6 +502,8 @@ static int rsa_builtin_keygen(RSA *rsa,
for (;;) {
if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
goto err;
+ if (BN_cmp(rsa->p, r0) < 0)
+ continue;
if (!BN_sub(r2, rsa->p, BN_value_one()))
goto err;
if (!BN_gcd(r1, r2, rsa->e, ctx))
@@ -501,21 +516,17 @@ static int rsa_builtin_keygen(RSA *rsa,
if (!BN_GENCB_call(cb, 3, 0))
goto err;
for (;;) {
- /*
- * When generating ridiculously small keys, we can get stuck
- * continually regenerating the same prime values. Check for this and
- * bail if it happens 3 times.
- */
- unsigned int degenerate = 0;
- do {
- if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
- goto err;
- } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
- if (degenerate == 3) {
- ok = 0; /* we set our own err */
- RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
+ /* This function will take care of setting the topmost bit via BN_rand(..,1,1), so
+ * the maximum distance between p and q is less than 2^bitsq */
+ if(!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
+ goto err;
+ if (BN_cmp(rsa->q, r0) < 0)
+ continue;
+ /* check for minimum distance between p and q, 2^(bitsp-100) */
+ if (!BN_sub(r2, rsa->q, rsa->p))
goto err;
- }
+ if (BN_ucmp(r2, r3) <= 0)
+ continue;
if (!BN_sub(r2, rsa->q, BN_value_one()))
goto err;
if (!BN_gcd(r1, r2, rsa->e, ctx))