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feat(pbkdf2): enforce iteration limit #50

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Merged
LimiNode merged 1 commit into from
Sep 5, 2025
Merged

feat(pbkdf2): enforce iteration limit #50

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6 changes: 6 additions & 0 deletions include/hmac_cpp/hmac_utils.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,14 @@
#include <string>
#include <vector>

#ifndef HMAC_CPP_MAX_PBKDF2_ITERATIONS
#define HMAC_CPP_MAX_PBKDF2_ITERATIONS 1000000u
#endif

namespace hmac_cpp {

static constexpr uint32_t MAX_PBKDF2_ITERATIONS = HMAC_CPP_MAX_PBKDF2_ITERATIONS;

/// \brief Compares two byte arrays in constant time
/// \param a Pointer to first array
/// \param a_len Length of the first array
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5 changes: 4 additions & 1 deletion src/hmac_utils.cpp
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Expand Up @@ -40,6 +40,8 @@ namespace hmac_cpp {
throw std::invalid_argument("Null pointer with non-zero length");
if (iterations < 1)
throw std::invalid_argument("PBKDF2: iterations must be >= 1");
if (iterations > MAX_PBKDF2_ITERATIONS)
throw std::invalid_argument("PBKDF2: iterations too large");
if (dk_len == 0)
throw std::invalid_argument("PBKDF2: dk_len must be positive");
if (salt_len < 16)
Expand Down Expand Up @@ -115,7 +117,8 @@ namespace hmac_cpp {
(salt_len > 0 && salt_ptr == nullptr) ||
out_ptr == nullptr)
return false;
if (iterations < 1 || dk_len == 0 || salt_len < 16)
if (iterations < 1 || dk_len == 0 || salt_len < 16 ||
iterations > MAX_PBKDF2_ITERATIONS)
return false;

const size_t hlen = hmac_hash::SHA256::DIGEST_SIZE;
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15 changes: 15 additions & 0 deletions test_all.cpp
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Expand Up @@ -237,6 +237,13 @@ TEST(PBKDF2Validation, TooLargeDkLenThrows) {
EXPECT_THROW(hmac::pbkdf2("password", salt, 1, too_large, hmac::Pbkdf2Hash::Sha1), std::invalid_argument);
}

TEST(PBKDF2Validation, IterationsLimit) {
std::string salt(16, 'a');
uint32_t limit = hmac::MAX_PBKDF2_ITERATIONS;
EXPECT_NO_THROW(hmac::pbkdf2("password", salt, limit - 1, 32, hmac::Pbkdf2Hash::Sha256));
EXPECT_THROW(hmac::pbkdf2("password", salt, limit + 1, 32, hmac::Pbkdf2Hash::Sha256), std::invalid_argument);
}

TEST(PBKDF2Test, SHA256WithValidSalt) {
auto salt = from_hex("000102030405060708090a0b0c0d0e0f");
std::string salt_str(salt.begin(), salt.end());
Expand All @@ -256,6 +263,14 @@ TEST(PBKDF2BufferApiTest, SHA256ArrayOutput) {
EXPECT_TRUE(std::equal(out.begin(), out.end(), ref.begin()));
}

TEST(PBKDF2BufferApiTest, IterationsLimit) {
std::string salt(16, 'a');
std::array<uint8_t,32> out{};
uint32_t limit = hmac::MAX_PBKDF2_ITERATIONS;
EXPECT_TRUE(hmac::pbkdf2_hmac_sha256(std::string("password"), salt, limit - 1, out));
EXPECT_FALSE(hmac::pbkdf2_hmac_sha256(std::string("password"), salt, limit + 1, out));
}

// SHA512 vector from BoringSSL pbkdf_test.cc
TEST(PBKDF2Test, BoringSSL_SHA512) {
auto dk = hmac::pbkdf2("passwordPASSWORDpassword",
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