Commit 44d0c092 authored by Mark Haines's avatar Mark Haines
Browse files

initial commit: start implementing the crypto primitives

parents
#include <cstdint>
namespace axolotl {
struct Curve25519PublicKey {
static const int LENGTH = 32;
std::uint8_t public_key[32];
};
struct Curve25519KeyPair : public Curve25519PublicKey {
std::uint8_t private_key[32];
};
Curve25519KeyPair generate_key(
std::uint8_t const * random_32_bytes
);
const std::size_t CURVE25519_SHARED_SECRET_LENGTH = 16;
void curve25519_shared_secret(
Curve25519KeyPair const & our_key,
Curve25519PublicKey const & their_key,
std::uint8_t * output
);
struct Aes256Key {
static const int LENGTH = 32;
std::uint8_t key[32];
};
struct Aes256Iv {
static const int LENGTH = 16;
std::uint8_t iv[16];
};
std::size_t aes_pkcs_7_padded_length(
std::size_t input_length
);
void aes_pkcs_7_padding(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
void aes_encrypt_cbc(
Aes256Key const & key,
Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
void aes_decrypt_cbc(
Aes256Key const & key,
Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
const std::size_t HMAC_SHA256_OUTPUT_LENGTH = 32;
void hmac_sha256(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
void hkdf_sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t const * info, std::size_t info_length,
std::uint8_t const * salt, std::size_t salt_length,
std::uint8_t * output, std::size_t output_length
);
} // namespace axolotl
#include "axolotl/crypto.hh"
#include <cstring>
extern "C" {
int curve25519_donna(
uint8_t * output,
const uint8_t * secret,
const uint8_t * basepoint
);
#include "crypto-algorithms/aes.h"
#include "crypto-algorithms/sha256.h"
}
namespace {
static const std::uint8_t CURVE25519_BASEPOINT[32] = {9};
static const std::size_t AES_BLOCK_LENGTH = 16;
static const std::size_t SHA256_BLOCK_LENGTH = 32;
static const std::uint8_t HKDF_DEFAULT_SALT[32] = {};
template<std::size_t block_size>
inline static void xor_block(
std::uint8_t * block,
std::uint8_t const * input
) {
for (std::size_t i = 0; i < block_size; ++i) {
block[i] ^= input[i];
}
}
inline static void hmac_sha256_key(
std::uint8_t const * input_key, std::size_t input_key_length,
std::uint8_t * hmac_key
) {
if (input_key_length > SHA256_BLOCK_LENGTH) {
::SHA256_CTX context;
::sha256_init(&context);
::sha256_update(&context, input_key, input_key_length);
::sha256_final(&context, hmac_key);
} else {
std::memset(hmac_key, 0, SHA256_BLOCK_LENGTH);
std::memcpy(hmac_key, input_key, input_key_length);
}
}
inline void hmac_sha256_init(
::SHA256_CTX * context,
std::uint8_t const * hmac_key
) {
std::uint8_t i_pad[SHA256_BLOCK_LENGTH];
std::memcpy(i_pad, hmac_key, SHA256_BLOCK_LENGTH);
for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) {
i_pad[i] ^= 0x5C;
}
::sha256_init(context);
::sha256_update(context, i_pad, SHA256_BLOCK_LENGTH);
std::memset(i_pad, 0, sizeof(i_pad));
}
inline void hmac_sha256_final(
::SHA256_CTX * context,
std::uint8_t const * hmac_key,
std::uint8_t * output
) {
std::uint8_t o_pad[SHA256_BLOCK_LENGTH];
std::memcpy(o_pad, hmac_key, SHA256_BLOCK_LENGTH);
for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) {
o_pad[i] ^= 0x36;
}
::SHA256_CTX final_context;
::sha256_init(&final_context);
::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH);
::sha256_final(context, o_pad);
::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH);
::sha256_final(&final_context, output);
std::memset(o_pad, 0, sizeof(o_pad));
}
} // namespace
axolotl::Curve25519KeyPair axolotl::generate_key(
std::uint8_t const * random_32_bytes
) {
axolotl::Curve25519KeyPair key_pair;
std::memcpy(key_pair.private_key, random_32_bytes, 32);
::curve25519_donna(
key_pair.public_key, key_pair.private_key, CURVE25519_BASEPOINT
);
return key_pair;
}
void axolotl::curve25519_shared_secret(
axolotl::Curve25519KeyPair const & our_key,
axolotl::Curve25519PublicKey const & their_key,
std::uint8_t * output
) {
::curve25519_donna(output, our_key.private_key, their_key.public_key);
}
std::size_t axolotl::aes_pkcs_7_padded_length(
std::size_t input_length
) {
return input_length + AES_BLOCK_LENGTH - input_length % AES_BLOCK_LENGTH;
}
void axolotl::aes_pkcs_7_padding(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
std::memcpy(output, input, input_length);
std::size_t padded_length = axolotl::aes_pkcs_7_padded_length(input_length);
std::uint8_t padding = padded_length - input_length;
for (std::size_t i = input_length; i < padded_length; ++i) {
output[i] = padding;
}
}
void axolotl::aes_encrypt_cbc(
axolotl::Aes256Key const & key,
axolotl::Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
std::uint32_t key_schedule[60];
::aes_key_setup(key.key, key_schedule, 256);
std::uint8_t input_block[AES_BLOCK_LENGTH];
std::memcpy(input_block, iv.iv, AES_BLOCK_LENGTH);
for (std::size_t i = 0; i < input_length; i += AES_BLOCK_LENGTH) {
xor_block<AES_BLOCK_LENGTH>(input_block, &input[i]);
::aes_encrypt(input_block, &output[i], key_schedule, 256);
std::memcpy(input_block, &output[i], AES_BLOCK_LENGTH);
}
std::memset(key_schedule, 0, sizeof(key_schedule));
std::memset(input_block, 0, sizeof(AES_BLOCK_LENGTH));
}
void axolotl::aes_decrypt_cbc(
axolotl::Aes256Key const & key,
axolotl::Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
std::uint32_t key_schedule[60];
::aes_key_setup(key.key, key_schedule, 256);
for (std::size_t i = 0; i < input_length; i += AES_BLOCK_LENGTH) {
::aes_decrypt(&input[i], &output[i], key_schedule, 256);
if (i == 0) {
xor_block<AES_BLOCK_LENGTH>(&output[i], iv.iv);
} else {
xor_block<AES_BLOCK_LENGTH>(&output[i], &input[i - AES_BLOCK_LENGTH]);
}
}
std::memset(key_schedule, 0, sizeof(key_schedule));
}
void axolotl::hmac_sha256(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
std::uint8_t hmac_key[SHA256_BLOCK_LENGTH];
::SHA256_CTX context;
hmac_sha256_key(key, key_length, hmac_key);
hmac_sha256_init(&context, hmac_key);
::sha256_update(&context, input, input_length);
hmac_sha256_final(&context, hmac_key, output);
std::memset(hmac_key, 0, sizeof(hmac_key));
}
void axolotl::hkdf_sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t const * info, std::size_t info_length,
std::uint8_t const * salt, std::size_t salt_length,
std::uint8_t * output, std::size_t output_length
) {
::SHA256_CTX context;
std::uint8_t extract_key[SHA256_BLOCK_LENGTH];
std::uint8_t expand_key[SHA256_BLOCK_LENGTH];
std::uint8_t step_result[SHA256_BLOCK_LENGTH];
std::size_t bytes_remaining = output_length;
std::uint8_t iteration = 1;
if (!salt) {
salt = HKDF_DEFAULT_SALT;
salt_length = sizeof(HKDF_DEFAULT_SALT);
}
/* Expand */
hmac_sha256_key(salt, salt_length, extract_key);
hmac_sha256_init(&context, extract_key);
::sha256_update(&context, input, input_length);
hmac_sha256_final(&context, extract_key, expand_key);
/* Extract */
hmac_sha256_init(&context, expand_key);
::sha256_update(&context, info, info_length);
::sha256_update(&context, &iteration, 1);
hmac_sha256_final(&context, expand_key, step_result);
while (bytes_remaining > SHA256_BLOCK_LENGTH) {
std::memcpy(output, step_result, SHA256_BLOCK_LENGTH);
output += SHA256_BLOCK_LENGTH;
bytes_remaining -= SHA256_BLOCK_LENGTH;
iteration ++;
hmac_sha256_init(&context, expand_key);
::sha256_update(&context, step_result, SHA256_BLOCK_LENGTH);
::sha256_update(&context, info, info_length);
::sha256_update(&context, &iteration, 1);
hmac_sha256_final(&context, expand_key, step_result);
}
std::memcpy(output, step_result, bytes_remaining);
}
extern "C" {
#include "crypto-algorithms/sha256.c"
#include "crypto-algorithms/aes.c"
#include "curve25519-donna/curve25519-donna.c"
}
#include "axolotl/crypto.hh"
#include <cstring>
#include <iostream>
#include <iomanip>
#include <cstdlib>
std::ostream & print_hex(
std::ostream & os,
std::uint8_t const * data,
std::size_t length
) {
for (std::size_t i = 0; i < length; i++) {
std::cerr << std::setw(2) << std::setfill('0') << std::right
<< std::hex << (int) data[i];
}
return os;
}
char const * TEST_CASE;
void assert_equals(
std::uint8_t *expected,
std::uint8_t *actual,
std::size_t length
) {
if (std::memcmp(expected, actual, length)) {
std::cerr << "FAILED :" << TEST_CASE << std::endl;
print_hex(std::cerr << "Expected: ", expected, length) << std::endl;
print_hex(std::cerr << "Actual: ", actual, length) << std::endl;
std::exit(1);
}
}
int main() {
{ /* HDKF Test Case 1 */
TEST_CASE = "HDKF Test Case 1";
std::uint8_t input[22] = {
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b
};
std::uint8_t salt[13] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c
};
std::uint8_t info[10] = {
0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
0xf8, 0xf9
};
std::uint8_t hmac_expected_output[32] = {
0x07, 0x77, 0x09, 0x36, 0x2c, 0x2e, 0x32, 0xdf,
0x0d, 0xdc, 0x3f, 0x0d, 0xc4, 0x7b, 0xba, 0x63,
0x90, 0xb6, 0xc7, 0x3b, 0xb5, 0x0f, 0x9c, 0x31,
0x22, 0xec, 0x84, 0x4a, 0xd7, 0xc2, 0xb3, 0xe5,
};
std::uint8_t hmac_actual_output[32] = {};
axolotl::hmac_sha256(
salt, 0 * sizeof(salt),
input, 0 * sizeof(input),
hmac_actual_output
);
assert_equals(hmac_expected_output, hmac_actual_output, 32);
std::uint8_t hkdf_expected_output[42] {
0x3c, 0xb2, 0x5f, 0x25, 0xfa, 0xac, 0xd5, 0x7a,
0x90, 0x43, 0x4f, 0x64, 0xd0, 0x36, 0x2f, 0x2a,
0x2d, 0x2d, 0x0a, 0x90, 0xcf, 0x1a, 0x5a, 0x4c,
0x5d, 0xb0, 0x2d, 0x56, 0xec, 0xc4, 0xc5, 0xbf,
0x34, 0x00, 0x72, 0x08, 0xd5, 0xb8, 0x87, 0x18,
0x58, 0x65
};
std::uint8_t hkdf_actual_output[42] = {};
axolotl::hkdf_sha256(
input, sizeof(input),
salt, sizeof(salt),
info, sizeof(info),
hkdf_actual_output, sizeof(hkdf_actual_output)
);
assert_equals(hkdf_expected_output, hkdf_actual_output, 42);
} /* HDKF Test Case 1 */
}
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