1EVP_RAND-HMAC-DRBG(7ossl)           OpenSSL          EVP_RAND-HMAC-DRBG(7ossl)
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NAME

6       EVP_RAND-HMAC-DRBG - The HMAC DRBG EVP_RAND implementation
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DESCRIPTION

9       Support for the HMAC deterministic random bit generator through the
10       EVP_RAND API.
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12   Identity
13       "HMAC-DRBG" is the name for this implementation; it can be used with
14       the EVP_RAND_fetch() function.
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16   Supported parameters
17       The supported parameters are:
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19       "state" (OSSL_RAND_PARAM_STATE) <integer>
20       "strength" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>
21       "max_request" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>
22       "reseed_requests" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
23       "reseed_time_interval" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>
24       "min_entropylen" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>
25       "max_entropylen" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>
26       "min_noncelen" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>
27       "max_noncelen" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>
28       "max_perslen" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>
29       "max_adinlen" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>
30       "reseed_counter" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>
31       "properties" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>
32       "mac" (OSSL_DRBG_PARAM_MAC) <UTF8 string>
33       "digest" (OSSL_DRBG_PARAM_DIGEST) <UTF8 string>
34           These parameters work as described in "PARAMETERS" in EVP_RAND(3).
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NOTES

37       A context for HMAC DRBG can be obtained by calling:
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39        EVP_RAND *rand = EVP_RAND_fetch(NULL, "HMAC-DRBG", NULL);
40        EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);
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EXAMPLES

43        EVP_RAND *rand;
44        EVP_RAND_CTX *rctx;
45        unsigned char bytes[100];
46        OSSL_PARAM params[3], *p = params;
47        unsigned int strength = 128;
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49        rand = EVP_RAND_fetch(NULL, "HMAC-DRBG", NULL);
50        rctx = EVP_RAND_CTX_new(rand, NULL);
51        EVP_RAND_free(rand);
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53        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_MAC, SN_hmac, 0);
54        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_DIGEST, SN_sha256, 0);
55        *p = OSSL_PARAM_construct_end();
56        EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
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58        EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
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60        EVP_RAND_CTX_free(rctx);
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CONFORMING TO

63       NIST SP 800-90A and SP 800-90B
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SEE ALSO

66       EVP_RAND(3), "PARAMETERS" in EVP_RAND(3)
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69       Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
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71       Licensed under the Apache License 2.0 (the "License").  You may not use
72       this file except in compliance with the License.  You can obtain a copy
73       in the file LICENSE in the source distribution or at
74       <https://www.openssl.org/source/license.html>.
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783.0.5                             2022-11-01         EVP_RAND-HMAC-DRBG(7ossl)
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