---
name: "EVP_RAND-JITTER"
section: "7ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/EVP_RAND-JITTER"
---

# EVP\_RAND-JITTER(7ssl)

The randomness seed source EVP\_RAND implementation

## NAME

EVP\_RAND-JITTER - The randomness seed source EVP\_RAND implementation

## DESCRIPTION

Support for deterministic random number generator seeding through the **EVP\_RAND** API.

This software seed source produces randomness based on tiny CPU "jitter" fluctuations.

It is available when OpenSSL is compiled with **enable-jitter** option. When available it is listed in **openssl list** **-random-generators** and **openssl info -seeds**.

### Identity

"JITTER" is the name for this implementation; it can be used with the **EVP\_RAND\_fetch()** function.

### Supported parameters

The supported parameters are:

- "state" (**OSSL\_RAND\_PARAM\_STATE**) \<integer\>

  - "strength" (**OSSL\_RAND\_PARAM\_STRENGTH**) \<unsigned integer\>

  - "max\_request" (**OSSL\_RAND\_PARAM\_MAX\_REQUEST**) \<unsigned integer\>

  - "fips-indicator" (**OSSL\_RAND\_PARAM\_FIPS\_APPROVED\_INDICATOR**) \<integer\>

  This parameter is available in the FIPS provider and returns 1.

  These parameters work as described in "PARAMETERS" in **EVP\_RAND**(3).

## NOTES

A context for the seed source can be obtained by calling:

```
 EVP_RAND *rand = EVP_RAND_fetch(NULL, "JITTER", NULL);
 EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);
```

The **enable-jitter** option was added in OpenSSL 3.4.

By specifying the **enable-fips-jitter** configuration option, the FIPS provider will use an internal jitter source for its entropy.  Enabling this option will cause the FIPS provider to operate in a non-compliant mode unless an entropy assessment ESV \<https://csrc.nist.gov/Projects/cryptographic-module-validation-program/entropy-validations\> and validation through the CMVP \<https://csrc.nist.gov/projects/cryptographic-module-validation-program\> are additionally conducted.  This option was added in OpenSSL 3.5.

## EXAMPLES

```
 EVP_RAND *rand;
 EVP_RAND_CTX *seed, *rctx;
 unsigned char bytes[100];
 OSSL_PARAM params[2], *p = params;
 unsigned int strength = 128;
 /* Create and instantiate a seed source */
 rand = EVP_RAND_fetch(NULL, "JITTER", NULL);
 seed = EVP_RAND_CTX_new(rand, NULL);
 EVP_RAND_instantiate(seed, strength, 0, NULL, 0, NULL);
 EVP_RAND_free(rand);
 /* Feed this into a DRBG */
 rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
 rctx = EVP_RAND_CTX_new(rand, seed);
 EVP_RAND_free(rand);
 /* Configure the DRBG */
 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
                                         SN_aes_256_ctr, 0);
 *p = OSSL_PARAM_construct_end();
 EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
 EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
 EVP_RAND_CTX_free(rctx);
 EVP_RAND_CTX_free(seed);
```

## SEE ALSO

**EVP\_RAND**(3), "PARAMETERS" in **EVP\_RAND**(3)

## COPYRIGHT

Copyright 2024-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance with the License.  You can obtain a copy in the file LICENSE in the source distribution or at \<https://www.openssl.org/source/license.html\>.