Botan  2.7.0
Crypto and TLS for C++11
Public Member Functions | List of all members
Botan::ECIES_KA_Operation Class Reference

#include <ecies.h>

Public Member Functions

SymmetricKey derive_secret (const std::vector< uint8_t > &eph_public_key_bin, const PointGFp &other_public_key_point) const
 
 ECIES_KA_Operation (const PK_Key_Agreement_Key &private_key, const ECIES_KA_Params &ecies_params, bool for_encryption, RandomNumberGenerator &rng)
 

Detailed Description

ECIES secret derivation according to ISO 18033-2

Definition at line 185 of file ecies.h.

Constructor & Destructor Documentation

◆ ECIES_KA_Operation()

Botan::ECIES_KA_Operation::ECIES_KA_Operation ( const PK_Key_Agreement_Key private_key,
const ECIES_KA_Params ecies_params,
bool  for_encryption,
RandomNumberGenerator rng 
)
Parameters
private_keythe (ephemeral) private key which is used to derive the secret
ecies_paramssettings for ecies
for_encryptiondisable cofactor mode if the secret will be used for encryption (according to ISO 18033 cofactor mode is only used during decryption)
rngthe RNG to use

Definition at line 132 of file ecies.cpp.

135  :
136  m_ka(create_key_agreement(private_key, ecies_params, for_encryption, rng)),
137  m_params(ecies_params)
138  {
139  }

Member Function Documentation

◆ derive_secret()

SymmetricKey Botan::ECIES_KA_Operation::derive_secret ( const std::vector< uint8_t > &  eph_public_key_bin,
const PointGFp other_public_key_point 
) const

Performs a key agreement with the provided keys and derives the secret from the result

Parameters
eph_public_key_binthe encoded (ephemeral) public key which belongs to the used (ephemeral) private key
other_public_key_pointpublic key point of the other party

ECIES secret derivation according to ISO 18033-2

Definition at line 144 of file ecies.cpp.

References Botan::OctetString::begin(), Botan::BigInt::bytes(), Botan::ECIES_KA_Params::compression_type(), Botan::KDF::create_or_throw(), Botan::PK_Key_Agreement::derive_key(), Botan::ECIES_KA_Params::domain(), Botan::BigInt::encode(), Botan::OctetString::end(), Botan::EC_Group::get_cofactor(), Botan::EC_Group::get_order(), Botan::PointGFp::is_zero(), Botan::ECIES_KA_Params::kdf_spec(), Botan::ECIES_KA_Params::old_cofactor_mode(), Botan::ECIES_KA_Params::secret_length(), and Botan::ECIES_KA_Params::single_hash_mode().

146  {
147  if(other_public_key_point.is_zero())
148  {
149  throw Invalid_Argument("ECIES: other public key point is zero");
150  }
151 
152  std::unique_ptr<KDF> kdf = Botan::KDF::create_or_throw(m_params.kdf_spec());
153 
154  PointGFp other_point = other_public_key_point;
155 
156  // ISO 18033: step b
157  if(m_params.old_cofactor_mode())
158  {
159  other_point *= m_params.domain().get_cofactor();
160  }
161 
162  secure_vector<uint8_t> derivation_input;
163 
164  // ISO 18033: encryption step e / decryption step g
165  if(!m_params.single_hash_mode())
166  {
167  derivation_input += eph_public_key_bin;
168  }
169 
170  // ISO 18033: encryption step f / decryption step h
171  std::vector<uint8_t> other_public_key_bin = other_point.encode(m_params.compression_type());
172  // Note: the argument `m_params.secret_length()` passed for `key_len` will only be used by providers because
173  // "Raw" is passed to the `PK_Key_Agreement` if the implementation of botan is used.
174  const SymmetricKey peh = m_ka.derive_key(m_params.domain().get_order().bytes(), other_public_key_bin.data(), other_public_key_bin.size());
175  derivation_input.insert(derivation_input.end(), peh.begin(), peh.end());
176 
177  // ISO 18033: encryption step g / decryption step i
178  return kdf->derive_key(m_params.secret_length(), derivation_input);
179  }
const BigInt & get_order() const
Definition: ec_group.cpp:500
PointGFp::Compression_Type compression_type() const
Definition: ecies.h:105
const std::string & kdf_spec() const
Definition: ecies.h:110
bool single_hash_mode() const
Definition: ecies.h:85
const BigInt & get_cofactor() const
Definition: ec_group.cpp:515
SymmetricKey derive_key(size_t key_len, const uint8_t in[], size_t in_len, const uint8_t params[], size_t params_len) const
Definition: pubkey.cpp:203
OctetString SymmetricKey
Definition: symkey.h:136
size_t bytes() const
Definition: bigint.cpp:220
bool old_cofactor_mode() const
Definition: ecies.h:95
const EC_Group & domain() const
Definition: ecies.h:75
size_t secret_length() const
Definition: ecies.h:80
static std::vector< uint8_t > encode(const BigInt &n, Base base=Binary)
Definition: big_code.cpp:54
static std::unique_ptr< KDF > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: kdf.cpp:222

The documentation for this class was generated from the following files: