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git.ipfire.org Git - thirdparty/openssl.git/blob - crypto/ffc/ffc_key_generate.c
2 * Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #include "internal/ffc.h"
13 * SP800-56Ar3 5.6.1.1.4 Key pair generation by testing candidates.
14 * Generates a private key in the interval [1, min(2 ^ N - 1, q - 1)].
16 * ctx must be set up with a libctx (for fips mode).
17 * params contains the FFC domain parameters p, q and g (for DH or DSA).
18 * N is the maximum bit length of the generated private key,
19 * s is the security strength.
20 * priv_key is the returned private key,
22 int ffc_generate_private_key(BN_CTX
*ctx
, const FFC_PARAMS
*params
,
23 int N
, int s
, BIGNUM
*priv
)
27 BIGNUM
*m
, *two_powN
= NULL
;
29 /* Step (2) : check range of N */
30 if (N
< 2 * s
|| N
> BN_num_bits(params
->q
))
35 if (two_powN
== NULL
|| !BN_lshift(two_powN
, BN_value_one(), N
))
38 /* Step (5) : M = min(2 ^ N, q) */
39 m
= (BN_cmp(two_powN
, params
->q
) > 0) ? params
->q
: two_powN
;
41 /* Steps (3, 4 & 7) : c + 1 = 1 + random[0..2^N - 1] */
42 if (!BN_priv_rand_range_ex(priv
, two_powN
, ctx
)
43 || !BN_add_word(priv
, 1))
45 /* Step (6) : loop if c > M - 2 (i.e. c + 1 >= M) */
46 if (BN_cmp(priv
, m
) < 0)
56 if (!BN_priv_rand_range_ex(priv
, params
->q
, ctx
))
58 } while (BN_is_zero(priv
) || BN_is_one(priv
));
60 #endif /* FIPS_MODE */