Botan  2.4.0
Crypto and TLS for C++11
Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
Botan::ElGamal_PublicKey Class Reference

#include <elgamal.h>

Inheritance diagram for Botan::ElGamal_PublicKey:
Botan::DL_Scheme_PublicKey Botan::Public_Key Botan::ElGamal_PrivateKey

Public Member Functions

std::string algo_name () const override
 
AlgorithmIdentifier algorithm_identifier () const override
 
bool check_key (RandomNumberGenerator &rng, bool) const override
 
std::unique_ptr< PK_Ops::Encryptioncreate_encryption_op (RandomNumberGenerator &rng, const std::string &params, const std::string &provider) const override
 
virtual std::unique_ptr< PK_Ops::KEM_Encryptioncreate_kem_encryption_op (RandomNumberGenerator &rng, const std::string &params, const std::string &provider) const
 
virtual std::unique_ptr< PK_Ops::Verificationcreate_verification_op (const std::string &params, const std::string &provider) const
 
 ElGamal_PublicKey (const AlgorithmIdentifier &alg_id, const std::vector< uint8_t > &key_bits)
 
 ElGamal_PublicKey (const DL_Group &group, const BigInt &y)
 
size_t estimated_strength () const override
 
std::string fingerprint_public (const std::string &alg="SHA-256") const
 
const DL_Groupget_domain () const
 
virtual OID get_oid () const
 
const BigIntget_y () const
 
DL_Group::Format group_format () const override
 
const BigIntgroup_g () const
 
const BigIntgroup_p () const
 
const BigIntgroup_q () const
 
size_t key_length () const override
 
virtual size_t message_part_size () const
 
virtual size_t message_parts () const
 
std::vector< uint8_t > public_key_bits () const override
 
std::vector< uint8_t > subject_public_key () const
 

Protected Member Functions

 ElGamal_PublicKey ()=default
 

Protected Attributes

DL_Group m_group
 
BigInt m_y
 

Detailed Description

ElGamal Public Key

Definition at line 18 of file elgamal.h.

Constructor & Destructor Documentation

◆ ElGamal_PublicKey() [1/3]

Botan::ElGamal_PublicKey::ElGamal_PublicKey ( const AlgorithmIdentifier alg_id,
const std::vector< uint8_t > &  key_bits 
)
inline

Load a public key.

Parameters
alg_idthe X.509 algorithm identifier
key_bitsDER encoded public key bits

Definition at line 29 of file elgamal.h.

30  :
31  DL_Scheme_PublicKey(alg_id, key_bits, DL_Group::ANSI_X9_42)
32  {}

◆ ElGamal_PublicKey() [2/3]

Botan::ElGamal_PublicKey::ElGamal_PublicKey ( const DL_Group group,
const BigInt y 
)

Create a public key.

Parameters
groupthe underlying DL group
ythe public value y = g^x mod p

Definition at line 21 of file elgamal.cpp.

References Botan::DL_Scheme_PublicKey::m_group, and Botan::DL_Scheme_PublicKey::m_y.

22  {
23  m_group = grp;
24  m_y = y1;
25  }

◆ ElGamal_PublicKey() [3/3]

Botan::ElGamal_PublicKey::ElGamal_PublicKey ( )
protecteddefault

Member Function Documentation

◆ algo_name()

std::string Botan::ElGamal_PublicKey::algo_name ( ) const
inlineoverridevirtual

Get the name of the underlying public key scheme.

Returns
name of the public key scheme

Implements Botan::Public_Key.

Definition at line 21 of file elgamal.h.

Referenced by Botan::ElGamal_PrivateKey::create_decryption_op(), and create_encryption_op().

21 { return "ElGamal"; }

◆ algorithm_identifier()

AlgorithmIdentifier Botan::DL_Scheme_PublicKey::algorithm_identifier ( ) const
overridevirtualinherited
Returns
X.509 AlgorithmIdentifier for this key

Implements Botan::Public_Key.

Definition at line 26 of file dl_algo.cpp.

References Botan::DL_Group::DER_encode(), Botan::Public_Key::get_oid(), Botan::DL_Scheme_PublicKey::group_format(), and Botan::DL_Scheme_PublicKey::m_group.

27  {
28  return AlgorithmIdentifier(get_oid(),
30  }
virtual OID get_oid() const
Definition: pk_keys.cpp:51
std::vector< uint8_t > DER_encode(Format format) const
Definition: dl_group.cpp:223
virtual DL_Group::Format group_format() const =0

◆ check_key()

bool Botan::DL_Scheme_PublicKey::check_key ( RandomNumberGenerator rng,
bool  strong 
) const
overridevirtualinherited

Test the key values for consistency.

Parameters
rngrng to use
strongwhether to perform strong and lengthy version of the test
Returns
true if the test is passed

Implements Botan::Public_Key.

Reimplemented in Botan::DL_Scheme_PrivateKey, Botan::DSA_PrivateKey, and Botan::ElGamal_PrivateKey.

Definition at line 63 of file dl_algo.cpp.

References Botan::DL_Scheme_PublicKey::group_p(), Botan::DL_Scheme_PublicKey::group_q(), Botan::DL_Scheme_PublicKey::m_group, Botan::DL_Scheme_PublicKey::m_y, Botan::power_mod(), and Botan::DL_Group::verify_group().

65  {
66  const BigInt& p = group_p();
67 
68  if(m_y < 2 || m_y >= p)
69  return false;
70  if(!m_group.verify_group(rng, strong))
71  return false;
72 
73  try
74  {
75  const BigInt& q = group_q();
76  if(power_mod(m_y, q, p) != 1)
77  return false;
78  }
79  catch(const Invalid_State&)
80  {
81  return true;
82  }
83 
84  return true;
85  }
BigInt power_mod(const BigInt &base, const BigInt &exp, const BigInt &mod)
Definition: numthry.cpp:374
bool verify_group(RandomNumberGenerator &rng, bool strong) const
Definition: dl_group.cpp:159
const BigInt & group_p() const
Definition: dl_algo.h:43
const BigInt & group_q() const
Definition: dl_algo.h:49

◆ create_encryption_op()

std::unique_ptr< PK_Ops::Encryption > Botan::ElGamal_PublicKey::create_encryption_op ( RandomNumberGenerator rng,
const std::string &  params,
const std::string &  provider 
) const
overridevirtual

This is an internal library function exposed on key types. In almost all cases applications should use wrappers in pubkey.h

Return an encryption operation for this key/params or throw

Parameters
rnga random number generator. The PK_Op may maintain a reference to the RNG and use it many times. The rng must outlive any operations which reference it.
paramsadditional parameters
providerthe provider to use

Reimplemented from Botan::Public_Key.

Definition at line 179 of file elgamal.cpp.

References algo_name().

182  {
183  if(provider == "base" || provider.empty())
184  return std::unique_ptr<PK_Ops::Encryption>(new ElGamal_Encryption_Operation(*this, params));
185  throw Provider_Not_Found(algo_name(), provider);
186  }
std::string algo_name() const override
Definition: elgamal.h:21

◆ create_kem_encryption_op()

std::unique_ptr< PK_Ops::KEM_Encryption > Botan::Public_Key::create_kem_encryption_op ( RandomNumberGenerator rng,
const std::string &  params,
const std::string &  provider 
) const
virtualinherited

This is an internal library function exposed on key types. In almost all cases applications should use wrappers in pubkey.h

Return a KEM encryption operation for this key/params or throw

Parameters
rnga random number generator. The PK_Op may maintain a reference to the RNG and use it many times. The rng must outlive any operations which reference it.
paramsadditional parameters
providerthe provider to use

Reimplemented in Botan::RSA_PublicKey, and Botan::McEliece_PublicKey.

Definition at line 100 of file pk_keys.cpp.

References Botan::Public_Key::algo_name().

Referenced by Botan::PK_KEM_Encryptor::PK_KEM_Encryptor().

103  {
104  throw Lookup_Error(algo_name() + " does not support KEM encryption");
105  }
virtual std::string algo_name() const =0

◆ create_verification_op()

std::unique_ptr< PK_Ops::Verification > Botan::Public_Key::create_verification_op ( const std::string &  params,
const std::string &  provider 
) const
virtualinherited

This is an internal library function exposed on key types. In almost all cases applications should use wrappers in pubkey.h

Return a verification operation for this key/params or throw

Parameters
paramsadditional parameters
providerthe provider to use

Reimplemented in Botan::XMSS_PublicKey, Botan::RSA_PublicKey, Botan::XMSS_WOTS_Addressed_PublicKey, Botan::GOST_3410_PublicKey, Botan::Ed25519_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::SM2_Signature_PublicKey, and Botan::DSA_PublicKey.

Definition at line 108 of file pk_keys.cpp.

References Botan::Public_Key::algo_name().

Referenced by Botan::XMSS_WOTS_Addressed_PublicKey::create_verification_op(), and Botan::PK_Verifier::PK_Verifier().

110  {
111  throw Lookup_Error(algo_name() + " does not support verification");
112  }
virtual std::string algo_name() const =0

◆ estimated_strength()

size_t Botan::DL_Scheme_PublicKey::estimated_strength ( ) const
overridevirtualinherited

Return the estimated strength of the underlying key against the best currently known attack. Note that this ignores anything but pure attacks against the key itself and do not take into account padding schemes, usage mistakes, etc which might reduce the strength. However it does suffice to provide an upper bound.

Returns
estimated strength in bits

Implements Botan::Public_Key.

Definition at line 21 of file dl_algo.cpp.

References Botan::dl_work_factor(), and Botan::DL_Scheme_PublicKey::key_length().

22  {
23  return dl_work_factor(key_length());
24  }
size_t key_length() const override
Definition: dl_algo.cpp:16
size_t dl_work_factor(size_t bits)
Definition: workfactor.cpp:34

◆ fingerprint_public()

std::string Botan::Public_Key::fingerprint_public ( const std::string &  alg = "SHA-256") const
inherited
Returns
Hash of the subject public key

Definition at line 78 of file pk_keys.cpp.

References Botan::create_hex_fingerprint(), and Botan::Public_Key::subject_public_key().

79  {
81  }
AlgorithmIdentifier hash_algo
Definition: x509_obj.cpp:22
std::string create_hex_fingerprint(const uint8_t bits[], size_t bits_len, const std::string &hash_name)
Definition: pk_keys.cpp:17
std::vector< uint8_t > subject_public_key() const
Definition: pk_keys.cpp:38

◆ get_domain()

const DL_Group& Botan::DL_Scheme_PublicKey::get_domain ( ) const
inlineinherited

Get the DL domain parameters of this key.

Returns
DL domain parameters of this key

Definition at line 32 of file dl_algo.h.

32 { return m_group; }

◆ get_oid()

OID Botan::Public_Key::get_oid ( ) const
virtualinherited

◆ get_y()

const BigInt& Botan::DL_Scheme_PublicKey::get_y ( ) const
inlineinherited

Get the public value y with y = g^x mod p where x is the secret key.

Definition at line 37 of file dl_algo.h.

37 { return m_y; }

◆ group_format()

DL_Group::Format Botan::ElGamal_PublicKey::group_format ( ) const
inlineoverridevirtual

Get the underlying groups encoding format.

Returns
encoding format

Implements Botan::DL_Scheme_PublicKey.

Definition at line 22 of file elgamal.h.

References Botan::DL_Group::ANSI_X9_42.

◆ group_g()

const BigInt& Botan::DL_Scheme_PublicKey::group_g ( ) const
inlineinherited

Get the generator g of the underlying DL group.

Returns
generator g

Definition at line 55 of file dl_algo.h.

Referenced by Botan::DL_Scheme_PrivateKey::check_key(), Botan::DH_PrivateKey::DH_PrivateKey(), Botan::DSA_PrivateKey::DSA_PrivateKey(), and Botan::ElGamal_PrivateKey::ElGamal_PrivateKey().

55 { return m_group.get_g(); }
const BigInt & get_g() const
Definition: dl_group.cpp:203

◆ group_p()

const BigInt& Botan::DL_Scheme_PublicKey::group_p ( ) const
inlineinherited

◆ group_q()

const BigInt& Botan::DL_Scheme_PublicKey::group_q ( ) const
inlineinherited

Get the prime q of the underlying DL group.

Returns
prime q

Definition at line 49 of file dl_algo.h.

Referenced by Botan::DL_Scheme_PublicKey::check_key(), and Botan::DSA_PrivateKey::check_key().

49 { return m_group.get_q(); }
const BigInt & get_q() const
Definition: dl_group.cpp:212

◆ key_length()

size_t Botan::DL_Scheme_PublicKey::key_length ( ) const
overridevirtualinherited

Return an integer value best approximating the length of the primary security parameter. For example for RSA this will be the size of the modulus, for ECDSA the size of the ECC group, and for McEliece the size of the code will be returned.

Implements Botan::Public_Key.

Definition at line 16 of file dl_algo.cpp.

References Botan::BigInt::bits(), Botan::DL_Group::get_p(), and Botan::DL_Scheme_PublicKey::m_group.

Referenced by Botan::DL_Scheme_PublicKey::estimated_strength().

17  {
18  return m_group.get_p().bits();
19  }
size_t bits() const
Definition: bigint.cpp:183
const BigInt & get_p() const
Definition: dl_group.cpp:194

◆ message_part_size()

virtual size_t Botan::Public_Key::message_part_size ( ) const
inlinevirtualinherited

Returns how large each of the message parts refered to by message_parts() is

This function is public but applications should have few reasons to ever call this.

Returns
size of the message parts in bits

Reimplemented in Botan::GOST_3410_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::SM2_Signature_PublicKey, and Botan::DSA_PublicKey.

Definition at line 118 of file pk_keys.h.

Referenced by Botan::PK_Signer::PK_Signer(), and Botan::PK_Verifier::PK_Verifier().

118 { return 0; }

◆ message_parts()

virtual size_t Botan::Public_Key::message_parts ( ) const
inlinevirtualinherited

Returns more than 1 if the output of this algorithm (ciphertext, signature) should be treated as more than one value. This is used for algorithms like DSA and ECDSA, where the (r,s) output pair can be encoded as either a plain binary list or a TLV tagged DER encoding depending on the protocol.

This function is public but applications should have few reasons to ever call this.

Returns
number of message parts

Reimplemented in Botan::GOST_3410_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::SM2_Signature_PublicKey, and Botan::DSA_PublicKey.

Definition at line 107 of file pk_keys.h.

Referenced by Botan::choose_sig_format(), Botan::PK_Signer::PK_Signer(), Botan::PK_Verifier::PK_Verifier(), and Botan::X509_Object::verify_signature().

107 { return 1; }

◆ public_key_bits()

std::vector< uint8_t > Botan::DL_Scheme_PublicKey::public_key_bits ( ) const
overridevirtualinherited
Returns
BER encoded public key bits

Implements Botan::Public_Key.

Definition at line 32 of file dl_algo.cpp.

References Botan::DER_Encoder::encode(), Botan::DER_Encoder::get_contents_unlocked(), and Botan::DL_Scheme_PublicKey::m_y.

33  {
34  return DER_Encoder().encode(m_y).get_contents_unlocked();
35  }

◆ subject_public_key()

std::vector< uint8_t > Botan::Public_Key::subject_public_key ( ) const
inherited
Returns
X.509 subject key encoding for this key object

Definition at line 38 of file pk_keys.cpp.

References Botan::Public_Key::algorithm_identifier(), Botan::BIT_STRING, Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), Botan::DER_Encoder::get_contents_unlocked(), Botan::Public_Key::public_key_bits(), Botan::SEQUENCE, and Botan::DER_Encoder::start_cons().

Referenced by Botan::X509::BER_encode(), Botan::Public_Key::fingerprint_public(), and Botan::X509::PEM_encode().

39  {
40  return DER_Encoder()
41  .start_cons(SEQUENCE)
42  .encode(algorithm_identifier())
43  .encode(public_key_bits(), BIT_STRING)
44  .end_cons()
45  .get_contents_unlocked();
46  }
virtual std::vector< uint8_t > public_key_bits() const =0
virtual AlgorithmIdentifier algorithm_identifier() const =0

Member Data Documentation

◆ m_group

DL_Group Botan::DL_Scheme_PublicKey::m_group
protectedinherited

◆ m_y

BigInt Botan::DL_Scheme_PublicKey::m_y
protectedinherited

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