#include <elgamal.h>

Inheritance diagram for Botan::ElGamal_PublicKey:

Public Member Functions
virtual Signature_Format	_default_x509_signature_format () const

virtual std::optional< size_t >	_signature_element_size_for_DER_encoding () const

std::string	algo_name () const override

AlgorithmIdentifier	algorithm_identifier () const override

bool	check_key (RandomNumberGenerator &rng, bool strong) const override

std::unique_ptr< PK_Ops::Encryption >	create_encryption_op (RandomNumberGenerator &rng, std::string_view params, std::string_view provider) const override

virtual std::unique_ptr< PK_Ops::KEM_Encryption >	create_kem_encryption_op (std::string_view params, std::string_view provider) const

virtual std::unique_ptr< PK_Ops::Verification >	create_verification_op (std::string_view params, std::string_view provider) const

virtual std::unique_ptr< PK_Ops::Verification >	create_x509_verification_op (const AlgorithmIdentifier &signature_algorithm, std::string_view provider) const

Signature_Format	default_x509_signature_format () const

	ElGamal_PublicKey (const AlgorithmIdentifier &alg_id, std::span< const uint8_t > key_bits)

	ElGamal_PublicKey (const DL_Group &group, const BigInt &y)

size_t	estimated_strength () const override

std::string	fingerprint_public (std::string_view alg="SHA-256") const

std::unique_ptr< Private_Key >	generate_another (RandomNumberGenerator &rng) const final

const BigInt &	get_int_field (std::string_view field) const override

OID	get_oid () const

size_t	key_length () const override

size_t	message_part_size () const

size_t	message_parts () const

virtual OID	object_identifier () const

std::vector< uint8_t >	public_key_bits () const override

std::vector< uint8_t >	raw_public_key_bits () const override

std::vector< uint8_t >	subject_public_key () const

bool	supports_operation (PublicKeyOperation op) const override

Friends
class	ElGamal_PrivateKey

Detailed Description

ElGamal Public Key

Definition at line 24 of file elgamal.h.

Constructor & Destructor Documentation

◆ ElGamal_PublicKey() [1/2]

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

Load a public key from the ASN.1 encoding

Parameters

alg_id	the X.509 algorithm identifier
key_bits	DER encoded public key bits

Definition at line 22 of file elgamal.cpp.

                                                                                                       {
   m_public_key = std::make_shared<DL_PublicKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_42);
}

References Botan::ANSI_X9_42.

◆ ElGamal_PublicKey() [2/2]

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

Create a public key.

Parameters

group	the underlying DL group
y	the public value y = g^x mod p

Definition at line 18 of file elgamal.cpp.

                                                                           {
   m_public_key = std::make_shared<DL_PublicKey>(group, y);
}

Member Function Documentation

◆ _default_x509_signature_format()

Signature_Format Botan::Asymmetric_Key::_default_x509_signature_format ( ) const

virtualinherited

Reimplemented in Botan::GOST_3410_PublicKey.

Definition at line 30 of file pk_keys.cpp.

                                                                      {
   if(_signature_element_size_for_DER_encoding()) {
      return Signature_Format::DerSequence;
   } else {
      return Signature_Format::Standard;
   }
}

References Botan::Asymmetric_Key::_signature_element_size_for_DER_encoding(), Botan::DerSequence, and Botan::Standard.

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

◆ _signature_element_size_for_DER_encoding()

virtual std::optional< size_t > Botan::Asymmetric_Key::_signature_element_size_for_DER_encoding ( ) const

inlinevirtualinherited

Certain signatures schemes such as ECDSA have more than one element, and certain unfortunate protocols decided the thing to do was not concatenate them as normally done, but instead DER encode each of the elements as independent values.

If this returns a value x then the signature is checked to be exactly 2*x bytes and split in half for DER encoding.

Reimplemented in Botan::DSA_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::GOST_3410_PublicKey, and Botan::SM2_PublicKey.

Definition at line 136 of file pk_keys.h.

136{ return {}; }

Referenced by Botan::Asymmetric_Key::_default_x509_signature_format(), Botan::PK_Signer::PK_Signer(), Botan::PK_Verifier::PK_Verifier(), and Botan::PK_Verifier::PK_Verifier().

◆ 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::Asymmetric_Key.

Definition at line 51 of file elgamal.h.

51{ return "ElGamal"; }

Referenced by Botan::ElGamal_PrivateKey::get_int_field(), and get_int_field().

◆ algorithm_identifier()

AlgorithmIdentifier Botan::ElGamal_PublicKey::algorithm_identifier ( ) const

overridevirtual

Returns: X.509 AlgorithmIdentifier for this key

Implements Botan::Public_Key.

Definition at line 34 of file elgamal.cpp.

                                                                  {
   return AlgorithmIdentifier(object_identifier(), m_public_key->group().DER_encode(DL_Group_Format::ANSI_X9_42));
}

References Botan::ANSI_X9_42, and Botan::Asymmetric_Key::object_identifier().

◆ check_key()

bool Botan::ElGamal_PublicKey::check_key	(	RandomNumberGenerator &	rng,
		bool	strong ) const

overridevirtual

Implements Botan::Asymmetric_Key.

Definition at line 54 of file elgamal.cpp.

                                                                               {
   return m_public_key->check_key(rng, strong);
}

◆ create_encryption_op()

std::unique_ptr< PK_Ops::Encryption > Botan::ElGamal_PublicKey::create_encryption_op	(	RandomNumberGenerator &	rng,
		std::string_view	params,
		std::string_view	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

rng	a 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.
params	additional parameters
provider	the provider to use

Reimplemented from Botan::Public_Key.

Definition at line 206 of file elgamal.cpp.

                                                                                                           {
   if(provider == "base" || provider.empty()) {
      return std::make_unique<ElGamal_Encryption_Operation>(this->m_public_key, params);
   }
   throw Provider_Not_Found(algo_name(), provider);
}

◆ create_kem_encryption_op()

std::unique_ptr< PK_Ops::KEM_Encryption > Botan::Public_Key::create_kem_encryption_op	(	std::string_view	params,
		std::string_view	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

params	additional parameters
provider	the provider to use

Reimplemented in Botan::Classic_McEliece_PublicKey, Botan::FrodoKEM_PublicKey, Botan::Kyber_PublicKey, Botan::McEliece_PublicKey, Botan::RSA_PublicKey, Botan::TLS::Hybrid_KEM_PublicKey, and Botan::TLS::KEX_to_KEM_Adapter_PublicKey.

Definition at line 104 of file pk_keys.cpp.

                                                                                                     {
   throw Lookup_Error(fmt("{} does not support KEM encryption", algo_name()));
}

References Botan::Asymmetric_Key::algo_name(), and Botan::fmt().

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

◆ create_verification_op()

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

virtualinherited

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

Return a verification operation for this key/params or throw

Parameters

params	additional parameters
provider	the provider to use

Reimplemented in Botan::Dilithium_PublicKey, Botan::DSA_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::Ed25519_PublicKey, Botan::Ed448_PublicKey, Botan::GOST_3410_PublicKey, Botan::HSS_LMS_PublicKey, Botan::RSA_PublicKey, Botan::SM2_PublicKey, Botan::SphincsPlus_PublicKey, Botan::TPM2::EC_PublicKey, Botan::TPM2::RSA_PublicKey, and Botan::XMSS_PublicKey.

Definition at line 109 of file pk_keys.cpp.

                                                                                                 {
   throw Lookup_Error(fmt("{} does not support verification", algo_name()));
}

References Botan::Asymmetric_Key::algo_name(), and Botan::fmt().

Referenced by Botan::PK_Verifier::PK_Verifier().

◆ create_x509_verification_op()

std::unique_ptr< PK_Ops::Verification > Botan::Public_Key::create_x509_verification_op	(	const AlgorithmIdentifier &	signature_algorithm,
		std::string_view	provider ) const

virtualinherited

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

Return a verification operation for this combination of key and signature algorithm or throw.

Parameters

signature_algorithm	is the X.509 algorithm identifier encoding the padding scheme and hash hash function used in the signature if applicable.
provider	the provider to use

Reimplemented in Botan::Dilithium_PublicKey, Botan::DSA_PublicKey, Botan::ECDSA_PublicKey, Botan::ECGDSA_PublicKey, Botan::ECKCDSA_PublicKey, Botan::Ed25519_PublicKey, Botan::Ed448_PublicKey, Botan::GOST_3410_PublicKey, Botan::HSS_LMS_PublicKey, Botan::RSA_PublicKey, Botan::SphincsPlus_PublicKey, and Botan::XMSS_PublicKey.

Definition at line 114 of file pk_keys.cpp.

                                                                                                      {
   throw Lookup_Error(fmt("{} does not support X.509 verification", algo_name()));
}

References Botan::Asymmetric_Key::algo_name(), and Botan::fmt().

Referenced by Botan::PK_Verifier::PK_Verifier().

◆ default_x509_signature_format()

Signature_Format Botan::Public_Key::default_x509_signature_format ( ) const

inlineinherited

Definition at line 227 of file pk_keys.h.

                                                                                                           {
         return _default_x509_signature_format();
      }

◆ estimated_strength()

size_t Botan::ElGamal_PublicKey::estimated_strength ( ) const

overridevirtual

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::Asymmetric_Key.

Definition at line 26 of file elgamal.cpp.

                                                   {
   return m_public_key->estimated_strength();
}

◆ fingerprint_public()

std::string Botan::Public_Key::fingerprint_public ( std::string_view alg = "SHA-256" ) const

inherited

Returns: Hash of the subject public key

Definition at line 87 of file pk_keys.cpp.

                                                                       {
   return create_hex_fingerprint(subject_public_key(), hash_algo);
}

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

◆ generate_another()

std::unique_ptr< Private_Key > Botan::ElGamal_PublicKey::generate_another ( RandomNumberGenerator & rng ) const

finalvirtual

Generate another (cryptographically independent) key pair using the same algorithm parameters as this key. This is most useful for algorithms that support PublicKeyOperation::KeyAgreement to generate a fitting ephemeral key pair. For other key types it might throw Not_Implemented.

Implements Botan::Asymmetric_Key.

Definition at line 50 of file elgamal.cpp.

                                                                                               {
   return std::make_unique<ElGamal_PrivateKey>(rng, m_public_key->group());
}

◆ get_int_field()

const BigInt & Botan::ElGamal_PublicKey::get_int_field ( std::string_view field ) const

overridevirtual

Access an algorithm specific field

If the field is not known for this algorithm, an Invalid_Argument is thrown. The interpretation of the result requires knowledge of which algorithm is involved. For instance for RSA "p" represents one of the secret primes, while for DSA "p" is the public prime.

Some algorithms may not implement this method at all.

This is primarily used to implement the FFI botan_pubkey_get_field and botan_privkey_get_field functions.

TODO(Botan4) Change this to return by value

Reimplemented from Botan::Asymmetric_Key.

Definition at line 46 of file elgamal.cpp.

                                                                         {
   return m_public_key->get_int_field(algo_name(), field);
}

References algo_name().

◆ get_oid()

OID Botan::Public_Key::get_oid ( ) const

inlineinherited

Deprecated version of object_identifier

Definition at line 160 of file pk_keys.h.

160{ return this->object_identifier(); }

◆ key_length()

size_t Botan::ElGamal_PublicKey::key_length ( ) const

overridevirtual

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 30 of file elgamal.cpp.

                                           {
   return m_public_key->p_bits();
}

◆ message_part_size()

size_t Botan::Public_Key::message_part_size ( ) const

inlineinherited

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

Definition at line 220 of file pk_keys.h.

                                                                                     {
         return _signature_element_size_for_DER_encoding().value_or(0);
      }

◆ message_parts()

size_t Botan::Public_Key::message_parts ( ) const

inlineinherited

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

Definition at line 207 of file pk_keys.h.

                                                                                 {
         return _signature_element_size_for_DER_encoding() ? 2 : 1;
      }

◆ object_identifier()

OID Botan::Asymmetric_Key::object_identifier ( ) const

virtualinherited

Get the OID of the underlying public key scheme.

Returns: OID of the public key scheme

Reimplemented in Botan::Classic_McEliece_PublicKey, Botan::Dilithium_PublicKey, Botan::FrodoKEM_PublicKey, Botan::HSS_LMS_PublicKey, Botan::Kyber_PublicKey, and Botan::SphincsPlus_PublicKey.

Definition at line 22 of file pk_keys.cpp.

                                            {
   try {
      return OID::from_string(algo_name());
   } catch(Lookup_Error&) {
      throw Lookup_Error(fmt("Public key algorithm {} has no defined OIDs", algo_name()));
   }
}

References Botan::Asymmetric_Key::algo_name(), Botan::fmt(), and Botan::OID::from_string().

◆ public_key_bits()

std::vector< uint8_t > Botan::ElGamal_PublicKey::public_key_bits ( ) const

overridevirtual

Returns: BER encoded public key bits

Implements Botan::Public_Key.

Definition at line 42 of file elgamal.cpp.

                                                            {
   return m_public_key->DER_encode();
}

◆ raw_public_key_bits()

std::vector< uint8_t > Botan::ElGamal_PublicKey::raw_public_key_bits ( ) const

overridevirtual

Returns: binary public key bits, with no additional encoding

For key agreements this is an alias for PK_Key_Agreement_Key::public_value.

Note: some algorithms (for example RSA) do not have an obvious encoding for this value due to having many different values, and thus throw Not_Implemented when invoking this method.

Implements Botan::Public_Key.

Definition at line 38 of file elgamal.cpp.

                                                                {
   return m_public_key->public_key_as_bytes();
}

◆ 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 56 of file pk_keys.cpp.

                                                        {
   std::vector<uint8_t> output;
 
   DER_Encoder(output)
      .start_sequence()
      .encode(algorithm_identifier())
      .encode(public_key_bits(), ASN1_Type::BitString)
      .end_cons();
 
   return output;
}

References Botan::Public_Key::algorithm_identifier(), Botan::BitString, Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), Botan::Public_Key::public_key_bits(), and Botan::DER_Encoder::start_sequence().

Referenced by Botan::X509::BER_encode(), Botan::PKCS10_Request::create(), Botan::Public_Key::fingerprint_public(), and Botan::X509::PEM_encode().

◆ supports_operation()

bool Botan::ElGamal_PublicKey::supports_operation ( PublicKeyOperation op ) const

inlineoverridevirtual

Return true if this key could be used for the specified type of operation.

Implements Botan::Asymmetric_Key.

Definition at line 26 of file elgamal.h.

26{ return (op == PublicKeyOperation::Encryption); }

Botan::PublicKeyOperation::Encryption

@ Encryption

Friends And Related Symbol Documentation

◆ ElGamal_PrivateKey

friend class ElGamal_PrivateKey

friend

Definition at line 62 of file elgamal.h.

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

src/lib/pubkey/elgamal/elgamal.h
src/lib/pubkey/elgamal/elgamal.cpp

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ ElGamal_PublicKey() [1/2]

◆ ElGamal_PublicKey() [2/2]

Member Function Documentation

◆ _default_x509_signature_format()

◆ _signature_element_size_for_DER_encoding()

◆ algo_name()

◆ algorithm_identifier()

◆ check_key()

◆ create_encryption_op()

◆ create_kem_encryption_op()

◆ create_verification_op()

◆ create_x509_verification_op()

◆ default_x509_signature_format()

◆ estimated_strength()

◆ fingerprint_public()

◆ generate_another()

◆ get_int_field()

◆ get_oid()

◆ key_length()

◆ message_part_size()

◆ message_parts()

◆ object_identifier()

◆ public_key_bits()

◆ raw_public_key_bits()

◆ subject_public_key()

◆ supports_operation()

Friends And Related Symbol Documentation

◆ ElGamal_PrivateKey