Botan::DSA_PublicKey Class Reference

#include <dsa.h>

Inheritance diagram for Botan::DSA_PublicKey:

Public Member Functions
virtual Signature_Format	_default_x509_signature_format () const
std::optional< size_t >	_signature_element_size_for_DER_encoding () const override
std::string	algo_name () const override
AlgorithmIdentifier	algorithm_identifier () const override
bool	check_key (RandomNumberGenerator &rng, bool strong) const override
virtual std::unique_ptr< PK_Ops::Encryption >	create_encryption_op (RandomNumberGenerator &rng, std::string_view params, std::string_view provider) const
virtual std::unique_ptr< PK_Ops::KEM_Encryption >	create_kem_encryption_op (std::string_view params, std::string_view provider) const
std::unique_ptr< PK_Ops::Verification >	create_verification_op (std::string_view params, std::string_view provider) const override
std::unique_ptr< PK_Ops::Verification >	create_x509_verification_op (const AlgorithmIdentifier &signature_algorithm, std::string_view provider) const override
Signature_Format	default_x509_signature_format () const
	DSA_PublicKey (const AlgorithmIdentifier &alg_id, std::span< const uint8_t > key_bits)
	DSA_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	DSA_PrivateKey

Detailed Description

DSA Public Key

Definition at line 26 of file dsa.h.

Constructor & Destructor Documentation

DSA_PublicKey() [1/2]

Botan::DSA_PublicKey::DSA_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 59 of file dsa.cpp.

                                                                                               {
   m_public_key = std::make_shared<DL_PublicKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_57);
 
   BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");
}

References Botan::ANSI_X9_57, and BOTAN_ARG_CHECK.

Referenced by DSA_PrivateKey, and Botan::DSA_PrivateKey::public_key().

DSA_PublicKey() [2/2]

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

Load a public key from the integer value

Parameters

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

Definition at line 65 of file dsa.cpp.

                                                                   {
   m_public_key = std::make_shared<DL_PublicKey>(group, y);
 
   BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");
}

References BOTAN_ARG_CHECK.

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

Referenced by Botan::X509_Object::choose_sig_format(), Botan::Public_Key::default_x509_signature_format(), and Botan::PK_Verifier::PK_Verifier().

_signature_element_size_for_DER_encoding()

std::optional< size_t > Botan::DSA_PublicKey::_signature_element_size_for_DER_encoding ( ) const

overridevirtual

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 from Botan::Asymmetric_Key.

Definition at line 23 of file dsa.cpp.

                                                                                  {
   return m_public_key->group().q_bytes();
}

algo_name()

std::string Botan::DSA_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 44 of file dsa.h.

{ return "DSA"; }

Referenced by Botan::DSA_PrivateKey::create_signature_op(), create_verification_op(), create_x509_verification_op(), Botan::DSA_PrivateKey::get_int_field(), and get_int_field().

algorithm_identifier()

AlgorithmIdentifier Botan::DSA_PublicKey::algorithm_identifier ( ) const

overridevirtual

Returns

X.509 AlgorithmIdentifier for this key

Implements Botan::Public_Key.

Definition at line 39 of file dsa.cpp.

                                                              {
   return AlgorithmIdentifier(object_identifier(), m_public_key->group().DER_encode(DL_Group_Format::ANSI_X9_57));
}

References Botan::ANSI_X9_57, and Botan::Asymmetric_Key::object_identifier().

check_key()

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

overridevirtual

Implements Botan::Asymmetric_Key.

Definition at line 51 of file dsa.cpp.

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

create_encryption_op()

std::unique_ptr< PK_Ops::Encryption > Botan::Public_Key::create_encryption_op ( RandomNumberGenerator & rng, 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 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 in Botan::ElGamal_PublicKey, Botan::RSA_PublicKey, Botan::SM2_PublicKey, and Botan::TPM2::RSA_PublicKey.

Definition at line 98 of file pk_keys.cpp.

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

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

Referenced by Botan::PK_Encryptor_EME::PK_Encryptor_EME().

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::KEX_to_KEM_Adapter_PublicKey, Botan::Kyber_PublicKey, Botan::McEliece_PublicKey, Botan::RSA_PublicKey, and Botan::TLS::Hybrid_KEM_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::DSA_PublicKey::create_verification_op ( std::string_view params, std::string_view provider ) const

overridevirtual

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 from Botan::Public_Key.

Definition at line 254 of file dsa.cpp.

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

References algo_name().

create_x509_verification_op()

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

overridevirtual

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 from Botan::Public_Key.

Definition at line 262 of file dsa.cpp.

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

References algo_name().

default_x509_signature_format()

Signature_Format Botan::Public_Key::default_x509_signature_format ( ) const

inlineinherited

Definition at line 229 of file pk_keys.h.

                                                               {
         return _default_x509_signature_format();
      }

References Botan::Asymmetric_Key::_default_x509_signature_format(), and default_x509_signature_format().

Referenced by default_x509_signature_format().

estimated_strength()

size_t Botan::DSA_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 27 of file dsa.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 subject_public_key().

Referenced by public_key_bits().

generate_another()

std::unique_ptr< Private_Key > Botan::DSA_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 55 of file dsa.cpp.

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

get_int_field()

const BigInt & Botan::DSA_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 35 of file dsa.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 161 of file pk_keys.h.

{ return this->object_identifier(); }

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

Referenced by get_oid().

key_length()

size_t Botan::DSA_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 31 of file dsa.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 221 of file pk_keys.h.

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

References Botan::Asymmetric_Key::_signature_element_size_for_DER_encoding(), and message_part_size().

Referenced by message_part_size().

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 208 of file pk_keys.h.

                                                                                 {
         return _signature_element_size_for_DER_encoding() ? 2 : 1;
      }

References Botan::Asymmetric_Key::_signature_element_size_for_DER_encoding(), and message_parts().

Referenced by message_parts().

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

Referenced by Botan::DH_PublicKey::algorithm_identifier(), Botan::DSA_PublicKey::algorithm_identifier(), Botan::EC_PublicKey::algorithm_identifier(), Botan::Ed25519_PublicKey::algorithm_identifier(), Botan::Ed448_PublicKey::algorithm_identifier(), Botan::ElGamal_PublicKey::algorithm_identifier(), Botan::GOST_3410_PublicKey::algorithm_identifier(), Botan::McEliece_PublicKey::algorithm_identifier(), Botan::RSA_PublicKey::algorithm_identifier(), Botan::TPM_PrivateKey::algorithm_identifier(), Botan::X25519_PublicKey::algorithm_identifier(), Botan::X448_PublicKey::algorithm_identifier(), Botan::XMSS_PublicKey::algorithm_identifier(), estimated_strength(), and Botan::Public_Key::get_oid().

public_key_bits()

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

overridevirtual

Returns

BER encoded public key bits

Implements Botan::Public_Key.

Definition at line 47 of file dsa.cpp.

                                                        {
   return m_public_key->DER_encode();
}

raw_public_key_bits()

std::vector< uint8_t > Botan::DSA_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 43 of file dsa.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 algorithm_identifier(), Botan::BitString, Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), public_key_bits(), and Botan::DER_Encoder::start_sequence().

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

supports_operation()

bool Botan::DSA_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 28 of file dsa.h.

{ return (op == PublicKeyOperation::Signature); }

References Botan::Signature.

Friends And Related Symbol Documentation

DSA_PrivateKey

friend class DSA_PrivateKey

friend

Definition at line 69 of file dsa.h.

References DSA_PrivateKey, and DSA_PublicKey().

Referenced by DSA_PrivateKey.

---

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

• src/lib/pubkey/dsa/dsa.h
• src/lib/pubkey/dsa/dsa.cpp