summaryrefslogtreecommitdiffstats
path: root/random/unix/apr_random.c
diff options
context:
space:
mode:
Diffstat (limited to 'random/unix/apr_random.c')
-rw-r--r--random/unix/apr_random.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/random/unix/apr_random.c b/random/unix/apr_random.c
new file mode 100644
index 0000000..9aee3e9
--- /dev/null
+++ b/random/unix/apr_random.c
@@ -0,0 +1,326 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * See the paper "On Randomness" by Ben Laurie for an explanation of this PRNG.
+ * http://www.apache-ssl.org/randomness.pdf
+ * XXX: Is there a formal proof of this PRNG? Couldn't we use the more popular
+ * Mersenne Twister PRNG (and BSD licensed)?
+ */
+
+#include "apr.h"
+#include "apr_pools.h"
+#include "apr_random.h"
+#include "apr_thread_proc.h"
+#include <assert.h>
+
+#ifdef min
+#undef min
+#endif
+#define min(a,b) ((a) < (b) ? (a) : (b))
+
+#define APR_RANDOM_DEFAULT_POOLS 32
+#define APR_RANDOM_DEFAULT_REHASH_SIZE 1024
+#define APR_RANDOM_DEFAULT_RESEED_SIZE 32
+#define APR_RANDOM_DEFAULT_HASH_SECRET_SIZE 32
+#define APR_RANDOM_DEFAULT_G_FOR_INSECURE 32
+#define APR_RANDOM_DEFAULT_G_FOR_SECURE 320
+
+typedef struct apr_random_pool_t {
+ unsigned char *pool;
+ unsigned int bytes;
+ unsigned int pool_size;
+} apr_random_pool_t;
+
+#define hash_init(h) (h)->init(h)
+#define hash_add(h,b,n) (h)->add(h,b,n)
+#define hash_finish(h,r) (h)->finish(h,r)
+
+#define hash(h,r,b,n) hash_init(h),hash_add(h,b,n),hash_finish(h,r)
+
+#define crypt_setkey(c,k) (c)->set_key((c)->data,k)
+#define crypt_crypt(c,out,in) (c)->crypt((c)->date,out,in)
+
+struct apr_random_t {
+ apr_pool_t *apr_pool;
+ apr_crypto_hash_t *pool_hash;
+ unsigned int npools;
+ apr_random_pool_t *pools;
+ unsigned int next_pool;
+ unsigned int generation;
+ apr_size_t rehash_size;
+ apr_size_t reseed_size;
+ apr_crypto_hash_t *key_hash;
+#define K_size(g) ((g)->key_hash->size)
+ apr_crypto_hash_t *prng_hash;
+#define B_size(g) ((g)->prng_hash->size)
+
+ unsigned char *H;
+ unsigned char *H_waiting;
+#define H_size(g) (B_size(g)+K_size(g))
+#define H_current(g) (((g)->insecure_started && !(g)->secure_started) \
+ ? (g)->H_waiting : (g)->H)
+
+ unsigned char *randomness;
+ apr_size_t random_bytes;
+ unsigned int g_for_insecure;
+ unsigned int g_for_secure;
+ unsigned int secure_base;
+ unsigned int insecure_started:1;
+ unsigned int secure_started:1;
+
+ apr_random_t *next;
+};
+
+static apr_random_t *all_random;
+
+static apr_status_t random_cleanup(void *data)
+{
+ apr_random_t *remove_this = data,
+ *cur = all_random,
+ **prev_ptr = &all_random;
+ while (cur) {
+ if (cur == remove_this) {
+ *prev_ptr = cur->next;
+ break;
+ }
+ prev_ptr = &cur->next;
+ cur = cur->next;
+ }
+ return APR_SUCCESS;
+}
+
+
+APR_DECLARE(void) apr_random_init(apr_random_t *g,apr_pool_t *p,
+ apr_crypto_hash_t *pool_hash,
+ apr_crypto_hash_t *key_hash,
+ apr_crypto_hash_t *prng_hash)
+{
+ unsigned int n;
+
+ g->apr_pool = p;
+
+ g->pool_hash = pool_hash;
+ g->key_hash = key_hash;
+ g->prng_hash = prng_hash;
+
+ g->npools = APR_RANDOM_DEFAULT_POOLS;
+ g->pools = apr_palloc(p,g->npools*sizeof *g->pools);
+ for (n = 0; n < g->npools; ++n) {
+ g->pools[n].bytes = g->pools[n].pool_size = 0;
+ g->pools[n].pool = NULL;
+ }
+ g->next_pool = 0;
+
+ g->generation = 0;
+
+ g->rehash_size = APR_RANDOM_DEFAULT_REHASH_SIZE;
+ /* Ensure that the rehash size is twice the size of the pool hasher */
+ g->rehash_size = ((g->rehash_size+2*g->pool_hash->size-1)/g->pool_hash->size
+ /2)*g->pool_hash->size*2;
+ g->reseed_size = APR_RANDOM_DEFAULT_RESEED_SIZE;
+
+ g->H = apr_pcalloc(p,H_size(g));
+ g->H_waiting = apr_pcalloc(p,H_size(g));
+
+ g->randomness = apr_palloc(p,B_size(g));
+ g->random_bytes = 0;
+
+ g->g_for_insecure = APR_RANDOM_DEFAULT_G_FOR_INSECURE;
+ g->secure_base = 0;
+ g->g_for_secure = APR_RANDOM_DEFAULT_G_FOR_SECURE;
+ g->secure_started = g->insecure_started = 0;
+
+ g->next = all_random;
+ all_random = g;
+ apr_pool_cleanup_register(p, g, random_cleanup, apr_pool_cleanup_null);
+}
+
+static void mix_pid(apr_random_t *g,unsigned char *H,pid_t pid)
+{
+ hash_init(g->key_hash);
+ hash_add(g->key_hash,H,H_size(g));
+ hash_add(g->key_hash,&pid,sizeof pid);
+ hash_finish(g->key_hash,H);
+}
+
+static void mixer(apr_random_t *g,pid_t pid)
+{
+ unsigned char *H = H_current(g);
+
+ /* mix the PID into the current H */
+ mix_pid(g,H,pid);
+ /* if we are in waiting, then also mix into main H */
+ if (H != g->H)
+ mix_pid(g,g->H,pid);
+ /* change order of pool mixing for good measure - note that going
+ backwards is much better than going forwards */
+ --g->generation;
+ /* blow away any lingering randomness */
+ g->random_bytes = 0;
+}
+
+APR_DECLARE(void) apr_random_after_fork(apr_proc_t *proc)
+{
+ apr_random_t *r;
+
+ for (r = all_random; r; r = r->next)
+ /*
+ * XXX Note: the pid does not provide sufficient entropy to
+ * actually call this secure. See Ben's paper referenced at
+ * the top of this file.
+ */
+ mixer(r,proc->pid);
+}
+
+APR_DECLARE(apr_random_t *) apr_random_standard_new(apr_pool_t *p)
+{
+ apr_random_t *r = apr_palloc(p,sizeof *r);
+
+ apr_random_init(r,p,apr_crypto_sha256_new(p),apr_crypto_sha256_new(p),
+ apr_crypto_sha256_new(p));
+ return r;
+}
+
+static void rekey(apr_random_t *g)
+{
+ unsigned int n;
+ unsigned char *H = H_current(g);
+
+ hash_init(g->key_hash);
+ hash_add(g->key_hash,H,H_size(g));
+ for (n = 0 ; n < g->npools && (n == 0 || g->generation&(1 << (n-1)))
+ ; ++n) {
+ hash_add(g->key_hash,g->pools[n].pool,g->pools[n].bytes);
+ g->pools[n].bytes = 0;
+ }
+ hash_finish(g->key_hash,H+B_size(g));
+
+ ++g->generation;
+ if (!g->insecure_started && g->generation > g->g_for_insecure) {
+ g->insecure_started = 1;
+ if (!g->secure_started) {
+ memcpy(g->H_waiting,g->H,H_size(g));
+ g->secure_base = g->generation;
+ }
+ }
+
+ if (!g->secure_started && g->generation > g->secure_base+g->g_for_secure) {
+ g->secure_started = 1;
+ memcpy(g->H,g->H_waiting,H_size(g));
+ }
+}
+
+APR_DECLARE(void) apr_random_add_entropy(apr_random_t *g,const void *entropy_,
+ apr_size_t bytes)
+{
+ unsigned int n;
+ const unsigned char *entropy = entropy_;
+
+ for (n = 0; n < bytes; ++n) {
+ apr_random_pool_t *p = &g->pools[g->next_pool];
+
+ if (++g->next_pool == g->npools)
+ g->next_pool = 0;
+
+ if (p->pool_size < p->bytes+1) {
+ unsigned char *np = apr_palloc(g->apr_pool,(p->bytes+1)*2);
+
+ if (p->pool) memcpy(np,p->pool,p->bytes);
+ p->pool = np;
+ p->pool_size = (p->bytes+1)*2;
+ }
+ p->pool[p->bytes++] = entropy[n];
+
+ if (p->bytes == g->rehash_size) {
+ apr_size_t r;
+
+ for (r = 0; r < p->bytes/2; r+=g->pool_hash->size)
+ hash(g->pool_hash,p->pool+r,p->pool+r*2,g->pool_hash->size*2);
+ p->bytes/=2;
+ }
+ assert(p->bytes < g->rehash_size);
+ }
+
+ if (g->pools[0].bytes >= g->reseed_size)
+ rekey(g);
+}
+
+/* This will give g->B_size bytes of randomness */
+static void apr_random_block(apr_random_t *g,unsigned char *random)
+{
+ /* FIXME: in principle, these are different hashes */
+ hash(g->prng_hash,g->H,g->H,H_size(g));
+ hash(g->prng_hash,random,g->H,B_size(g));
+}
+
+static void apr_random_bytes(apr_random_t *g,unsigned char *random,
+ apr_size_t bytes)
+{
+ apr_size_t n;
+
+ for (n = 0; n < bytes; ) {
+ apr_size_t l;
+
+ if (g->random_bytes == 0) {
+ apr_random_block(g,g->randomness);
+ g->random_bytes = B_size(g);
+ }
+ l = min(bytes-n,g->random_bytes);
+ memcpy(&random[n],g->randomness+B_size(g)-g->random_bytes,l);
+ g->random_bytes-=l;
+ n+=l;
+ }
+}
+
+APR_DECLARE(apr_status_t) apr_random_secure_bytes(apr_random_t *g,
+ void *random,
+ apr_size_t bytes)
+{
+ if (!g->secure_started)
+ return APR_ENOTENOUGHENTROPY;
+ apr_random_bytes(g,random,bytes);
+ return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_random_insecure_bytes(apr_random_t *g,
+ void *random,
+ apr_size_t bytes)
+{
+ if (!g->insecure_started)
+ return APR_ENOTENOUGHENTROPY;
+ apr_random_bytes(g,random,bytes);
+ return APR_SUCCESS;
+}
+
+APR_DECLARE(void) apr_random_barrier(apr_random_t *g)
+{
+ g->secure_started = 0;
+ g->secure_base = g->generation;
+}
+
+APR_DECLARE(apr_status_t) apr_random_secure_ready(apr_random_t *r)
+{
+ if (!r->secure_started)
+ return APR_ENOTENOUGHENTROPY;
+ return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_random_insecure_ready(apr_random_t *r)
+{
+ if (!r->insecure_started)
+ return APR_ENOTENOUGHENTROPY;
+ return APR_SUCCESS;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 00:16:37 +0000