Botan 3.7.1
Crypto and TLS for C&
kdf1_iso18033.cpp
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1/*
2* KDF1 from ISO 18033-2
3* (C) 2016 Philipp Weber
4* (C) 2024 René Meusel, Rohde & Schwarz Cybersecurity
5*
6* Botan is released under the Simplified BSD License (see license.txt)
7*/
8
9#include <botan/internal/kdf1_iso18033.h>
10
11#include <botan/exceptn.h>
12#include <botan/internal/bit_ops.h>
13#include <botan/internal/fmt.h>
14#include <botan/internal/stl_util.h>
15
16namespace Botan {
17
18void KDF1_18033::perform_kdf(std::span<uint8_t> key,
19 std::span<const uint8_t> secret,
20 std::span<const uint8_t> salt,
21 std::span<const uint8_t> label) const {
22 if(key.empty()) {
23 return;
24 }
25
26 const auto hash_output_length = m_hash->output_length();
27 const auto blocks_required = ceil_division<uint64_t /* for 32bit systems */>(key.size(), hash_output_length);
28
29 // This KDF uses a 32-bit counter for the hash blocks, initialized at 0.
30 // It will wrap around after 2^32 iterations which limits the theoretically
31 // possible output to 2^32 blocks.
32 BOTAN_ARG_CHECK(blocks_required <= 0xFFFFFFFF, "KDF1-18033 maximum output length exceeeded");
33
34 BufferStuffer k(key);
35 for(uint32_t counter = 0; !k.full(); ++counter) {
36 m_hash->update(secret);
37 m_hash->update_be(counter);
38 m_hash->update(label);
39 m_hash->update(salt);
40
41 // Write straight into the output buffer, except if the hash output needs
42 // a truncation in the final iteration.
43 if(k.remaining_capacity() >= hash_output_length) {
44 m_hash->final(k.next(hash_output_length));
45 } else {
46 const auto h = m_hash->final();
47 k.append(std::span{h}.first(k.remaining_capacity()));
48 }
49 }
50}
51
52std::string KDF1_18033::name() const {
53 return fmt("KDF1-18033({})", m_hash->name());
54}
55
56std::unique_ptr<KDF> KDF1_18033::new_object() const {
57 return std::make_unique<KDF1_18033>(m_hash->new_object());
58}
59
60} // namespace Botan
#define BOTAN_ARG_CHECK(expr, msg)
Definition assert.h:29
std::unique_ptr< KDF > new_object() const override
std::string name() const override
std::string fmt(std::string_view format, const T &... args)
Definition fmt.h:53
constexpr T ceil_division(T a, T b)
Definition bit_ops.h:160