1dfc9fa91SStephan Mueller /*
2dfc9fa91SStephan Mueller * Non-physical true random number generator based on timing jitter --
3dfc9fa91SStephan Mueller * Linux Kernel Crypto API specific code
4dfc9fa91SStephan Mueller *
5bb897c55SStephan Müller * Copyright Stephan Mueller <smueller@chronox.de>, 2015 - 2023
6dfc9fa91SStephan Mueller *
7dfc9fa91SStephan Mueller * Redistribution and use in source and binary forms, with or without
8dfc9fa91SStephan Mueller * modification, are permitted provided that the following conditions
9dfc9fa91SStephan Mueller * are met:
10dfc9fa91SStephan Mueller * 1. Redistributions of source code must retain the above copyright
11dfc9fa91SStephan Mueller * notice, and the entire permission notice in its entirety,
12dfc9fa91SStephan Mueller * including the disclaimer of warranties.
13dfc9fa91SStephan Mueller * 2. Redistributions in binary form must reproduce the above copyright
14dfc9fa91SStephan Mueller * notice, this list of conditions and the following disclaimer in the
15dfc9fa91SStephan Mueller * documentation and/or other materials provided with the distribution.
16dfc9fa91SStephan Mueller * 3. The name of the author may not be used to endorse or promote
17dfc9fa91SStephan Mueller * products derived from this software without specific prior
18dfc9fa91SStephan Mueller * written permission.
19dfc9fa91SStephan Mueller *
20dfc9fa91SStephan Mueller * ALTERNATIVELY, this product may be distributed under the terms of
21dfc9fa91SStephan Mueller * the GNU General Public License, in which case the provisions of the GPL2 are
22dfc9fa91SStephan Mueller * required INSTEAD OF the above restrictions. (This clause is
23dfc9fa91SStephan Mueller * necessary due to a potential bad interaction between the GPL and
24dfc9fa91SStephan Mueller * the restrictions contained in a BSD-style copyright.)
25dfc9fa91SStephan Mueller *
26dfc9fa91SStephan Mueller * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
27dfc9fa91SStephan Mueller * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28dfc9fa91SStephan Mueller * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
29dfc9fa91SStephan Mueller * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
30dfc9fa91SStephan Mueller * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31dfc9fa91SStephan Mueller * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
32dfc9fa91SStephan Mueller * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
33dfc9fa91SStephan Mueller * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34dfc9fa91SStephan Mueller * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35dfc9fa91SStephan Mueller * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
36dfc9fa91SStephan Mueller * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
37dfc9fa91SStephan Mueller * DAMAGE.
38dfc9fa91SStephan Mueller */
39dfc9fa91SStephan Mueller
40bb897c55SStephan Müller #include <crypto/hash.h>
41bb897c55SStephan Müller #include <crypto/sha3.h>
423fde2fe9SStephan Müller #include <linux/fips.h>
430c3dc787SHerbert Xu #include <linux/kernel.h>
44dfc9fa91SStephan Mueller #include <linux/module.h>
45dfc9fa91SStephan Mueller #include <linux/slab.h>
46dfc9fa91SStephan Mueller #include <linux/time.h>
47dfc9fa91SStephan Mueller #include <crypto/internal/rng.h>
48dfc9fa91SStephan Mueller
49965d7286SBen Dooks #include "jitterentropy.h"
50dfc9fa91SStephan Mueller
51bb897c55SStephan Müller #define JENT_CONDITIONING_HASH "sha3-256-generic"
52bb897c55SStephan Müller
53dfc9fa91SStephan Mueller /***************************************************************************
54dfc9fa91SStephan Mueller * Helper function
55dfc9fa91SStephan Mueller ***************************************************************************/
56dfc9fa91SStephan Mueller
jent_zalloc(unsigned int len)57dfc9fa91SStephan Mueller void *jent_zalloc(unsigned int len)
58dfc9fa91SStephan Mueller {
59dfc9fa91SStephan Mueller return kzalloc(len, GFP_KERNEL);
60dfc9fa91SStephan Mueller }
61dfc9fa91SStephan Mueller
jent_zfree(void * ptr)62dfc9fa91SStephan Mueller void jent_zfree(void *ptr)
63dfc9fa91SStephan Mueller {
64453431a5SWaiman Long kfree_sensitive(ptr);
65dfc9fa91SStephan Mueller }
66dfc9fa91SStephan Mueller
67b578456cSStephan Mueller /*
68b578456cSStephan Mueller * Obtain a high-resolution time stamp value. The time stamp is used to measure
69b578456cSStephan Mueller * the execution time of a given code path and its variations. Hence, the time
70b578456cSStephan Mueller * stamp must have a sufficiently high resolution.
71b578456cSStephan Mueller *
72b578456cSStephan Mueller * Note, if the function returns zero because a given architecture does not
73b578456cSStephan Mueller * implement a high-resolution time stamp, the RNG code's runtime test
74b578456cSStephan Mueller * will detect it and will not produce output.
75b578456cSStephan Mueller */
jent_get_nstime(__u64 * out)76dfc9fa91SStephan Mueller void jent_get_nstime(__u64 *out)
77dfc9fa91SStephan Mueller {
78dfc9fa91SStephan Mueller __u64 tmp = 0;
79dfc9fa91SStephan Mueller
80dfc9fa91SStephan Mueller tmp = random_get_entropy();
81dfc9fa91SStephan Mueller
82dfc9fa91SStephan Mueller /*
83b578456cSStephan Mueller * If random_get_entropy does not return a value, i.e. it is not
84b578456cSStephan Mueller * implemented for a given architecture, use a clock source.
85dfc9fa91SStephan Mueller * hoping that there are timers we can work with.
86dfc9fa91SStephan Mueller */
87b578456cSStephan Mueller if (tmp == 0)
88b578456cSStephan Mueller tmp = ktime_get_ns();
89dfc9fa91SStephan Mueller
90dfc9fa91SStephan Mueller *out = tmp;
91*69f1c387SStephan Müller jent_raw_hires_entropy_store(tmp);
92dfc9fa91SStephan Mueller }
93dfc9fa91SStephan Mueller
jent_hash_time(void * hash_state,__u64 time,u8 * addtl,unsigned int addtl_len,__u64 hash_loop_cnt,unsigned int stuck)94bb897c55SStephan Müller int jent_hash_time(void *hash_state, __u64 time, u8 *addtl,
95bb897c55SStephan Müller unsigned int addtl_len, __u64 hash_loop_cnt,
96bb897c55SStephan Müller unsigned int stuck)
97bb897c55SStephan Müller {
98bb897c55SStephan Müller struct shash_desc *hash_state_desc = (struct shash_desc *)hash_state;
99bb897c55SStephan Müller SHASH_DESC_ON_STACK(desc, hash_state_desc->tfm);
100bb897c55SStephan Müller u8 intermediary[SHA3_256_DIGEST_SIZE];
101bb897c55SStephan Müller __u64 j = 0;
102bb897c55SStephan Müller int ret;
103bb897c55SStephan Müller
104bb897c55SStephan Müller desc->tfm = hash_state_desc->tfm;
105bb897c55SStephan Müller
106bb897c55SStephan Müller if (sizeof(intermediary) != crypto_shash_digestsize(desc->tfm)) {
107bb897c55SStephan Müller pr_warn_ratelimited("Unexpected digest size\n");
108bb897c55SStephan Müller return -EINVAL;
109bb897c55SStephan Müller }
110bb897c55SStephan Müller
111bb897c55SStephan Müller /*
112bb897c55SStephan Müller * This loop fills a buffer which is injected into the entropy pool.
113bb897c55SStephan Müller * The main reason for this loop is to execute something over which we
114bb897c55SStephan Müller * can perform a timing measurement. The injection of the resulting
115bb897c55SStephan Müller * data into the pool is performed to ensure the result is used and
116bb897c55SStephan Müller * the compiler cannot optimize the loop away in case the result is not
117bb897c55SStephan Müller * used at all. Yet that data is considered "additional information"
118bb897c55SStephan Müller * considering the terminology from SP800-90A without any entropy.
119bb897c55SStephan Müller *
120bb897c55SStephan Müller * Note, it does not matter which or how much data you inject, we are
121bb897c55SStephan Müller * interested in one Keccack1600 compression operation performed with
122bb897c55SStephan Müller * the crypto_shash_final.
123bb897c55SStephan Müller */
124bb897c55SStephan Müller for (j = 0; j < hash_loop_cnt; j++) {
125bb897c55SStephan Müller ret = crypto_shash_init(desc) ?:
126bb897c55SStephan Müller crypto_shash_update(desc, intermediary,
127bb897c55SStephan Müller sizeof(intermediary)) ?:
128bb897c55SStephan Müller crypto_shash_finup(desc, addtl, addtl_len, intermediary);
129bb897c55SStephan Müller if (ret)
130bb897c55SStephan Müller goto err;
131bb897c55SStephan Müller }
132bb897c55SStephan Müller
133bb897c55SStephan Müller /*
134bb897c55SStephan Müller * Inject the data from the previous loop into the pool. This data is
135bb897c55SStephan Müller * not considered to contain any entropy, but it stirs the pool a bit.
136bb897c55SStephan Müller */
137bb897c55SStephan Müller ret = crypto_shash_update(desc, intermediary, sizeof(intermediary));
138bb897c55SStephan Müller if (ret)
139bb897c55SStephan Müller goto err;
140bb897c55SStephan Müller
141bb897c55SStephan Müller /*
142bb897c55SStephan Müller * Insert the time stamp into the hash context representing the pool.
143bb897c55SStephan Müller *
144bb897c55SStephan Müller * If the time stamp is stuck, do not finally insert the value into the
145bb897c55SStephan Müller * entropy pool. Although this operation should not do any harm even
146bb897c55SStephan Müller * when the time stamp has no entropy, SP800-90B requires that any
147bb897c55SStephan Müller * conditioning operation to have an identical amount of input data
148bb897c55SStephan Müller * according to section 3.1.5.
149bb897c55SStephan Müller */
150bb897c55SStephan Müller if (!stuck) {
151bb897c55SStephan Müller ret = crypto_shash_update(hash_state_desc, (u8 *)&time,
152bb897c55SStephan Müller sizeof(__u64));
153bb897c55SStephan Müller }
154bb897c55SStephan Müller
155bb897c55SStephan Müller err:
156bb897c55SStephan Müller shash_desc_zero(desc);
157bb897c55SStephan Müller memzero_explicit(intermediary, sizeof(intermediary));
158bb897c55SStephan Müller
159bb897c55SStephan Müller return ret;
160bb897c55SStephan Müller }
161bb897c55SStephan Müller
jent_read_random_block(void * hash_state,char * dst,unsigned int dst_len)162bb897c55SStephan Müller int jent_read_random_block(void *hash_state, char *dst, unsigned int dst_len)
163bb897c55SStephan Müller {
164bb897c55SStephan Müller struct shash_desc *hash_state_desc = (struct shash_desc *)hash_state;
165bb897c55SStephan Müller u8 jent_block[SHA3_256_DIGEST_SIZE];
166bb897c55SStephan Müller /* Obtain data from entropy pool and re-initialize it */
167bb897c55SStephan Müller int ret = crypto_shash_final(hash_state_desc, jent_block) ?:
168bb897c55SStephan Müller crypto_shash_init(hash_state_desc) ?:
169bb897c55SStephan Müller crypto_shash_update(hash_state_desc, jent_block,
170bb897c55SStephan Müller sizeof(jent_block));
171bb897c55SStephan Müller
172bb897c55SStephan Müller if (!ret && dst_len)
173bb897c55SStephan Müller memcpy(dst, jent_block, dst_len);
174bb897c55SStephan Müller
175bb897c55SStephan Müller memzero_explicit(jent_block, sizeof(jent_block));
176bb897c55SStephan Müller return ret;
177bb897c55SStephan Müller }
178bb897c55SStephan Müller
179dfc9fa91SStephan Mueller /***************************************************************************
180dfc9fa91SStephan Mueller * Kernel crypto API interface
181dfc9fa91SStephan Mueller ***************************************************************************/
182dfc9fa91SStephan Mueller
183dfc9fa91SStephan Mueller struct jitterentropy {
184dfc9fa91SStephan Mueller spinlock_t jent_lock;
185dfc9fa91SStephan Mueller struct rand_data *entropy_collector;
186bb897c55SStephan Müller struct crypto_shash *tfm;
187bb897c55SStephan Müller struct shash_desc *sdesc;
188dfc9fa91SStephan Mueller };
189dfc9fa91SStephan Mueller
jent_kcapi_cleanup(struct crypto_tfm * tfm)190dfc9fa91SStephan Mueller static void jent_kcapi_cleanup(struct crypto_tfm *tfm)
191dfc9fa91SStephan Mueller {
192dfc9fa91SStephan Mueller struct jitterentropy *rng = crypto_tfm_ctx(tfm);
193dfc9fa91SStephan Mueller
194dfc9fa91SStephan Mueller spin_lock(&rng->jent_lock);
195bb897c55SStephan Müller
196bb897c55SStephan Müller if (rng->sdesc) {
197bb897c55SStephan Müller shash_desc_zero(rng->sdesc);
198bb897c55SStephan Müller kfree(rng->sdesc);
199bb897c55SStephan Müller }
200bb897c55SStephan Müller rng->sdesc = NULL;
201bb897c55SStephan Müller
202bb897c55SStephan Müller if (rng->tfm)
203bb897c55SStephan Müller crypto_free_shash(rng->tfm);
204bb897c55SStephan Müller rng->tfm = NULL;
205bb897c55SStephan Müller
206dfc9fa91SStephan Mueller if (rng->entropy_collector)
207dfc9fa91SStephan Mueller jent_entropy_collector_free(rng->entropy_collector);
208dfc9fa91SStephan Mueller rng->entropy_collector = NULL;
209dfc9fa91SStephan Mueller spin_unlock(&rng->jent_lock);
210dfc9fa91SStephan Mueller }
211dfc9fa91SStephan Mueller
jent_kcapi_init(struct crypto_tfm * tfm)212bb897c55SStephan Müller static int jent_kcapi_init(struct crypto_tfm *tfm)
213bb897c55SStephan Müller {
214bb897c55SStephan Müller struct jitterentropy *rng = crypto_tfm_ctx(tfm);
215bb897c55SStephan Müller struct crypto_shash *hash;
216bb897c55SStephan Müller struct shash_desc *sdesc;
217bb897c55SStephan Müller int size, ret = 0;
218bb897c55SStephan Müller
219bb897c55SStephan Müller spin_lock_init(&rng->jent_lock);
220bb897c55SStephan Müller
221bb897c55SStephan Müller /*
222bb897c55SStephan Müller * Use SHA3-256 as conditioner. We allocate only the generic
223bb897c55SStephan Müller * implementation as we are not interested in high-performance. The
224bb897c55SStephan Müller * execution time of the SHA3 operation is measured and adds to the
225bb897c55SStephan Müller * Jitter RNG's unpredictable behavior. If we have a slower hash
226bb897c55SStephan Müller * implementation, the execution timing variations are larger. When
227bb897c55SStephan Müller * using a fast implementation, we would need to call it more often
228bb897c55SStephan Müller * as its variations are lower.
229bb897c55SStephan Müller */
230bb897c55SStephan Müller hash = crypto_alloc_shash(JENT_CONDITIONING_HASH, 0, 0);
231bb897c55SStephan Müller if (IS_ERR(hash)) {
232bb897c55SStephan Müller pr_err("Cannot allocate conditioning digest\n");
233bb897c55SStephan Müller return PTR_ERR(hash);
234bb897c55SStephan Müller }
235bb897c55SStephan Müller rng->tfm = hash;
236bb897c55SStephan Müller
237bb897c55SStephan Müller size = sizeof(struct shash_desc) + crypto_shash_descsize(hash);
238bb897c55SStephan Müller sdesc = kmalloc(size, GFP_KERNEL);
239bb897c55SStephan Müller if (!sdesc) {
240bb897c55SStephan Müller ret = -ENOMEM;
241bb897c55SStephan Müller goto err;
242bb897c55SStephan Müller }
243bb897c55SStephan Müller
244bb897c55SStephan Müller sdesc->tfm = hash;
245bb897c55SStephan Müller crypto_shash_init(sdesc);
246bb897c55SStephan Müller rng->sdesc = sdesc;
247bb897c55SStephan Müller
248bb897c55SStephan Müller rng->entropy_collector = jent_entropy_collector_alloc(1, 0, sdesc);
249bb897c55SStephan Müller if (!rng->entropy_collector) {
250bb897c55SStephan Müller ret = -ENOMEM;
251bb897c55SStephan Müller goto err;
252bb897c55SStephan Müller }
253bb897c55SStephan Müller
254bb897c55SStephan Müller spin_lock_init(&rng->jent_lock);
255bb897c55SStephan Müller return 0;
256bb897c55SStephan Müller
257bb897c55SStephan Müller err:
258bb897c55SStephan Müller jent_kcapi_cleanup(tfm);
259bb897c55SStephan Müller return ret;
260bb897c55SStephan Müller }
261bb897c55SStephan Müller
jent_kcapi_random(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * rdata,unsigned int dlen)262dfc9fa91SStephan Mueller static int jent_kcapi_random(struct crypto_rng *tfm,
263dfc9fa91SStephan Mueller const u8 *src, unsigned int slen,
264dfc9fa91SStephan Mueller u8 *rdata, unsigned int dlen)
265dfc9fa91SStephan Mueller {
266dfc9fa91SStephan Mueller struct jitterentropy *rng = crypto_rng_ctx(tfm);
267dfc9fa91SStephan Mueller int ret = 0;
268dfc9fa91SStephan Mueller
269dfc9fa91SStephan Mueller spin_lock(&rng->jent_lock);
270764428feSStephan Müller
271dfc9fa91SStephan Mueller ret = jent_read_entropy(rng->entropy_collector, rdata, dlen);
272764428feSStephan Müller
2733fde2fe9SStephan Müller if (ret == -3) {
2743fde2fe9SStephan Müller /* Handle permanent health test error */
2753fde2fe9SStephan Müller /*
2763fde2fe9SStephan Müller * If the kernel was booted with fips=1, it implies that
2773fde2fe9SStephan Müller * the entire kernel acts as a FIPS 140 module. In this case
2783fde2fe9SStephan Müller * an SP800-90B permanent health test error is treated as
2793fde2fe9SStephan Müller * a FIPS module error.
2803fde2fe9SStephan Müller */
2813fde2fe9SStephan Müller if (fips_enabled)
2823fde2fe9SStephan Müller panic("Jitter RNG permanent health test failure\n");
283764428feSStephan Müller
2843fde2fe9SStephan Müller pr_err("Jitter RNG permanent health test failure\n");
2853fde2fe9SStephan Müller ret = -EFAULT;
2863fde2fe9SStephan Müller } else if (ret == -2) {
2873fde2fe9SStephan Müller /* Handle intermittent health test error */
2883fde2fe9SStephan Müller pr_warn_ratelimited("Reset Jitter RNG due to intermittent health test failure\n");
289764428feSStephan Müller ret = -EAGAIN;
2903fde2fe9SStephan Müller } else if (ret == -1) {
2913fde2fe9SStephan Müller /* Handle other errors */
292764428feSStephan Müller ret = -EINVAL;
293764428feSStephan Müller }
294764428feSStephan Müller
295dfc9fa91SStephan Mueller spin_unlock(&rng->jent_lock);
296dfc9fa91SStephan Mueller
297dfc9fa91SStephan Mueller return ret;
298dfc9fa91SStephan Mueller }
299dfc9fa91SStephan Mueller
jent_kcapi_reset(struct crypto_rng * tfm,const u8 * seed,unsigned int slen)300dfc9fa91SStephan Mueller static int jent_kcapi_reset(struct crypto_rng *tfm,
301dfc9fa91SStephan Mueller const u8 *seed, unsigned int slen)
302dfc9fa91SStephan Mueller {
303dfc9fa91SStephan Mueller return 0;
304dfc9fa91SStephan Mueller }
305dfc9fa91SStephan Mueller
306dfc9fa91SStephan Mueller static struct rng_alg jent_alg = {
307dfc9fa91SStephan Mueller .generate = jent_kcapi_random,
308dfc9fa91SStephan Mueller .seed = jent_kcapi_reset,
309dfc9fa91SStephan Mueller .seedsize = 0,
310dfc9fa91SStephan Mueller .base = {
311dfc9fa91SStephan Mueller .cra_name = "jitterentropy_rng",
312dfc9fa91SStephan Mueller .cra_driver_name = "jitterentropy_rng",
313dfc9fa91SStephan Mueller .cra_priority = 100,
314dfc9fa91SStephan Mueller .cra_ctxsize = sizeof(struct jitterentropy),
315dfc9fa91SStephan Mueller .cra_module = THIS_MODULE,
316dfc9fa91SStephan Mueller .cra_init = jent_kcapi_init,
317dfc9fa91SStephan Mueller .cra_exit = jent_kcapi_cleanup,
318dfc9fa91SStephan Mueller }
319dfc9fa91SStephan Mueller };
320dfc9fa91SStephan Mueller
jent_mod_init(void)321dfc9fa91SStephan Mueller static int __init jent_mod_init(void)
322dfc9fa91SStephan Mueller {
323bb897c55SStephan Müller SHASH_DESC_ON_STACK(desc, tfm);
324bb897c55SStephan Müller struct crypto_shash *tfm;
325dfc9fa91SStephan Mueller int ret = 0;
326dfc9fa91SStephan Mueller
327*69f1c387SStephan Müller jent_testing_init();
328*69f1c387SStephan Müller
329bb897c55SStephan Müller tfm = crypto_alloc_shash(JENT_CONDITIONING_HASH, 0, 0);
330*69f1c387SStephan Müller if (IS_ERR(tfm)) {
331*69f1c387SStephan Müller jent_testing_exit();
332bb897c55SStephan Müller return PTR_ERR(tfm);
333*69f1c387SStephan Müller }
334bb897c55SStephan Müller
335bb897c55SStephan Müller desc->tfm = tfm;
336bb897c55SStephan Müller crypto_shash_init(desc);
337bb897c55SStephan Müller ret = jent_entropy_init(desc);
338bb897c55SStephan Müller shash_desc_zero(desc);
339bb897c55SStephan Müller crypto_free_shash(tfm);
340dfc9fa91SStephan Mueller if (ret) {
3413fde2fe9SStephan Müller /* Handle permanent health test error */
3423fde2fe9SStephan Müller if (fips_enabled)
3433fde2fe9SStephan Müller panic("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret);
3443fde2fe9SStephan Müller
345*69f1c387SStephan Müller jent_testing_exit();
346dfc9fa91SStephan Mueller pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret);
347dfc9fa91SStephan Mueller return -EFAULT;
348dfc9fa91SStephan Mueller }
349dfc9fa91SStephan Mueller return crypto_register_rng(&jent_alg);
350dfc9fa91SStephan Mueller }
351dfc9fa91SStephan Mueller
jent_mod_exit(void)352dfc9fa91SStephan Mueller static void __exit jent_mod_exit(void)
353dfc9fa91SStephan Mueller {
354*69f1c387SStephan Müller jent_testing_exit();
355dfc9fa91SStephan Mueller crypto_unregister_rng(&jent_alg);
356dfc9fa91SStephan Mueller }
357dfc9fa91SStephan Mueller
3589c5b34c2SEric Biggers module_init(jent_mod_init);
359dfc9fa91SStephan Mueller module_exit(jent_mod_exit);
360dfc9fa91SStephan Mueller
361dfc9fa91SStephan Mueller MODULE_LICENSE("Dual BSD/GPL");
362dfc9fa91SStephan Mueller MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
363dfc9fa91SStephan Mueller MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter");
364dfc9fa91SStephan Mueller MODULE_ALIAS_CRYPTO("jitterentropy_rng");
365