Botan::RSA_PublicKey Class Reference

#include <rsa.h>

Inheritance diagram for Botan::RSA_PublicKey:

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::Encryption >	create_encryption_op (RandomNumberGenerator &rng, std::string_view params, std::string_view provider) const override
std::unique_ptr< PK_Ops::KEM_Encryption >	create_kem_encryption_op (std::string_view params, std::string_view provider) const override
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 &alg_id, std::string_view provider) const override
virtual Signature_Format	default_x509_signature_format () const
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 override
const BigInt &	get_e () const
const BigInt &	get_int_field (std::string_view field) const override
const BigInt &	get_n () const
OID	get_oid () const
size_t	key_length () const override
virtual size_t	message_part_size () const
virtual size_t	message_parts () const
virtual OID	object_identifier () const
std::shared_ptr< const RSA_Public_Data >	public_data () const
std::vector< uint8_t >	public_key_bits () const override
std::vector< uint8_t >	raw_public_key_bits () const override
	RSA_PublicKey (const AlgorithmIdentifier &alg_id, std::span< const uint8_t > key_bits)
	RSA_PublicKey (const BigInt &n, const BigInt &e)
std::vector< uint8_t >	subject_public_key () const
bool	supports_operation (PublicKeyOperation op) const override

Protected Member Functions
void	init (BigInt &&n, BigInt &&e)
	RSA_PublicKey ()=default

Protected Attributes
std::shared_ptr< const RSA_Public_Data >	m_public

Detailed Description

RSA Public Key

Definition at line 25 of file rsa.h.

Constructor & Destructor Documentation

RSA_PublicKey() [1/3]

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

Load a public key.

Parameters

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

Definition at line 151 of file rsa.cpp.

                                                                                          {
   BigInt n, e;
   BER_Decoder(key_bits).start_sequence().decode(n).decode(e).end_cons();
 
   init(std::move(n), std::move(e));
}

References Botan::BER_Decoder::decode(), Botan::BER_Decoder::end_cons(), init, and Botan::BER_Decoder::start_sequence().

RSA_PublicKey() [2/3]

Botan::RSA_PublicKey::RSA_PublicKey	(	const BigInt &	n,
		const BigInt &	e )

Create a public key.

• n the modulus
• e the exponent

Definition at line 163 of file rsa.cpp.

                                                                          {
   BigInt n = modulus;
   BigInt e = exponent;
   init(std::move(n), std::move(e));
}

References init.

RSA_PublicKey() [3/3]

Botan::RSA_PublicKey::RSA_PublicKey ( )

protecteddefault

Member Function Documentation

algo_name()

std::string Botan::RSA_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 41 of file rsa.h.

{ return "RSA"; }

algorithm_identifier()

AlgorithmIdentifier Botan::RSA_PublicKey::algorithm_identifier ( ) const

overridevirtual

Returns

X.509 AlgorithmIdentifier for this key

Implements Botan::Public_Key.

Definition at line 177 of file rsa.cpp.

                                                              {
   return AlgorithmIdentifier(object_identifier(), AlgorithmIdentifier::USE_NULL_PARAM);
}

References Botan::Asymmetric_Key::object_identifier(), and Botan::AlgorithmIdentifier::USE_NULL_PARAM.

check_key()

bool Botan::RSA_PublicKey::check_key ( RandomNumberGenerator & rng, bool  ) const

overridevirtual

Implements Botan::Public_Key.

Definition at line 196 of file rsa.cpp.

                                                                    {
   if(get_n() < 35 || get_n().is_even() || get_e() < 3 || get_e().is_even()) {
      return false;
   }
   return true;
}

References get_e(), and get_n().

create_encryption_op()

std::unique_ptr< PK_Ops::Encryption > Botan::RSA_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.

Reimplemented in Botan::TPM2::RSA_PublicKey.

Definition at line 715 of file rsa.cpp.

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

create_kem_encryption_op()

std::unique_ptr< PK_Ops::KEM_Encryption > Botan::RSA_PublicKey::create_kem_encryption_op ( 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 a KEM encryption operation for this key/params or throw

Parameters

params	additional parameters
provider	the provider to use

Reimplemented from Botan::Public_Key.

Definition at line 724 of file rsa.cpp.

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

create_verification_op()

std::unique_ptr< PK_Ops::Verification > Botan::RSA_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.

Reimplemented in Botan::TPM2::RSA_PublicKey.

Definition at line 732 of file rsa.cpp.

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

create_x509_verification_op()

std::unique_ptr< PK_Ops::Verification > Botan::RSA_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 791 of file rsa.cpp.

                                                                                                                {
   if(provider == "base" || provider.empty()) {
      return std::make_unique<RSA_Verify_Operation>(*this, parse_rsa_signature_algorithm(alg_id));
   }
 
   throw Provider_Not_Found(algo_name(), provider);
}

default_x509_signature_format()

virtual Signature_Format Botan::Public_Key::default_x509_signature_format ( ) const

inlinevirtualinherited

Reimplemented in Botan::GOST_3410_PublicKey.

Definition at line 201 of file pk_keys.h.

                                                                     {
         return (this->message_parts() >= 2) ? Signature_Format::DerSequence : Signature_Format::Standard;
      }

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

estimated_strength()

size_t Botan::RSA_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 173 of file rsa.cpp.

                                               {
   return if_work_factor(key_length());
}

References Botan::if_work_factor(), and key_length().

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 79 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::RSA_PublicKey::generate_another ( RandomNumberGenerator & rng ) const

overridevirtual

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.

Reimplemented in Botan::TPM2::RSA_PublicKey.

Definition at line 132 of file rsa.cpp.

                                                                                           {
   return std::make_unique<RSA_PrivateKey>(rng, m_public->public_modulus_bits(), m_public->get_e().to_u32bit());
}

References m_public.

get_e()

const BigInt & Botan::RSA_PublicKey::get_e

(

)

const

Returns

public exponent

Definition at line 140 of file rsa.cpp.

                                         {
   return m_public->get_e();
}

References m_public.

Referenced by Botan::RSA_PrivateKey::check_key(), check_key(), Botan::RSA_PrivateKey::private_key_bits(), Botan::RSA_PrivateKey::public_key(), and public_key_bits().

get_int_field()

const BigInt & Botan::RSA_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.

Reimplemented from Botan::Asymmetric_Key.

Definition at line 122 of file rsa.cpp.

                                                                     {
   if(field == "n") {
      return m_public->get_n();
   } else if(field == "e") {
      return m_public->get_e();
   } else {
      return Public_Key::get_int_field(field);
   }
}

References Botan::Asymmetric_Key::get_int_field(), and m_public.

Referenced by Botan::RSA_PrivateKey::get_int_field().

get_n()

const BigInt & Botan::RSA_PublicKey::get_n

(

)

const

Returns

public modulus

Definition at line 136 of file rsa.cpp.

                                         {
   return m_public->get_n();
}

References m_public.

Referenced by Botan::RSA_PrivateKey::check_key(), check_key(), Botan::RSA_PrivateKey::private_key_bits(), Botan::RSA_PrivateKey::public_key(), and public_key_bits().

get_oid()

OID Botan::Public_Key::get_oid ( ) const

inlineinherited

Deprecated version of object_identifier

Definition at line 132 of file pk_keys.h.

{ return this->object_identifier(); }

init()

void Botan::RSA_PublicKey::init ( BigInt && n, BigInt && e )

protected

Definition at line 144 of file rsa.cpp.

                                               {
   if(n.is_negative() || n.is_even() || n.bits() < 5 /* n >= 3*5 */ || e.is_negative() || e.is_even()) {
      throw Decoding_Error("Invalid RSA public key parameters");
   }
   m_public = std::make_shared<RSA_Public_Data>(std::move(n), std::move(e));
}

References m_public.

Referenced by Botan::RSA_PrivateKey::RSA_PrivateKey(), Botan::RSA_PrivateKey::RSA_PrivateKey(), and Botan::RSA_PrivateKey::RSA_PrivateKey().

key_length()

size_t Botan::RSA_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 169 of file rsa.cpp.

                                       {
   return m_public->public_modulus_bits();
}

References m_public.

Referenced by estimated_strength().

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

Definition at line 199 of file pk_keys.h.

{ return 0; }

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

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

Definition at line 188 of file pk_keys.h.

{ return 1; }

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

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::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().

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(), algorithm_identifier(), Botan::TPM_PrivateKey::algorithm_identifier(), Botan::X25519_PublicKey::algorithm_identifier(), and Botan::X448_PublicKey::algorithm_identifier().

public_data()

std::shared_ptr< const RSA_Public_Data > Botan::RSA_PublicKey::public_data

(

)

const

Definition at line 118 of file rsa.cpp.

                                                                      {
   return m_public;
}

References m_public.

public_key_bits()

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

overridevirtual

Returns

BER encoded public key bits

Implements Botan::Public_Key.

Definition at line 185 of file rsa.cpp.

                                                        {
   std::vector<uint8_t> output;
   DER_Encoder der(output);
   der.start_sequence().encode(get_n()).encode(get_e()).end_cons();
 
   return output;
}

References Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), get_e(), get_n(), and Botan::DER_Encoder::start_sequence().

raw_public_key_bits()

std::vector< uint8_t > Botan::RSA_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.

Reimplemented in Botan::TPM2::RSA_PublicKey.

Definition at line 181 of file rsa.cpp.

                                                            {
   throw Not_Implemented("an RSA public key does not provide a raw binary representation.");
}

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 48 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::RSA_PublicKey::supports_operation ( PublicKeyOperation op ) const

overridevirtual

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

Implements Botan::Asymmetric_Key.

Reimplemented in Botan::TPM2::RSA_PublicKey.

Definition at line 158 of file rsa.cpp.

                                                                  {
   return op == PublicKeyOperation::Signature || op == PublicKeyOperation::Encryption ||
          op == PublicKeyOperation::KeyEncapsulation;
}

References Botan::Encryption, Botan::KeyEncapsulation, and Botan::Signature.

Member Data Documentation

m_public

std::shared_ptr<const RSA_Public_Data> Botan::RSA_PublicKey::m_public

protected

Definition at line 91 of file rsa.h.

Referenced by generate_another(), get_e(), get_int_field(), get_n(), init(), key_length(), and public_data().

---

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

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