PKCS#11

New in version 1.11.31.


PKCS#11 is a platform-independent interface for accessing smart cards and hardware security modules (HSM). Vendors of PKCS#11 compatible devices usually provide a so called middleware or “PKCS#11 module” which implements the PKCS#11 standard. This middleware translates calls from the platform-independent PKCS#11 API to device specific calls. So application developers don’t have to write smart card or HSM specific code for each device they want to support.

Note

The Botan PKCS#11 interface is implemented against version v2.40 of the standard.

Botan wraps the C PKCS#11 API to provide a C++ PKCS#11 interface. This is done in two levels of abstraction: a low level API (see Low Level API) and a high level API (see High Level API). The low level API provides access to all functions that are specified by the standard. The high level API represents an object oriented approach to use PKCS#11 compatible devices but only provides a subset of the functions described in the standard.

To use the PKCS#11 implementation the pkcs11 module has to be enabled.

Note

Both PKCS#11 APIs live in the namespace Botan::PKCS11

Low Level API

The PKCS#11 standards committee provides header files (pkcs11.h, pkcs11f.h and pkcs11t.h) which define the PKCS#11 API in the C programming language. These header files could be used directly to access PKCS#11 compatible smart cards or HSMs. The external header files are shipped with Botan in version v2.4 of the standard. The PKCS#11 low level API wraps the original PKCS#11 API, but still allows to access all functions described in the standard and has the advantage that it is a C++ interface with features like RAII, exceptions and automatic memory management.

The low level API is implemented by the LowLevel class and can be accessed by including the header botan/p11.h.

Preface

All constants that belong together in the PKCS#11 standard are grouped into C++ enum classes. For example the different user types are grouped in the UserType enumeration:

enum class UserType : CK_USER_TYPE
enumerator UserType::SO = CKU_SO
enumerator UserType::User = CKU_USER
enumerator UserType::ContextSpecific = CKU_CONTEXT_SPECIFIC

Additionally, all types that are used by the low or high level API are mapped by type aliases to more C++ like names. For instance:

using FunctionListPtr = CK_FUNCTION_LIST_PTR

C-API Wrapping

There is at least one method in the LowLevel class that corresponds to a PKCS#11 function. For example the C_GetSlotList method in the LowLevel class is defined as follows:

class LowLevel
bool C_GetSlotList(Bbool token_present, SlotId *slot_list_ptr, Ulong *count_ptr, ReturnValue *return_value = ThrowException) const

The LowLevel class calls the PKCS#11 function from the function list of the PKCS#11 module:

CK_DEFINE_FUNCTION(CK_RV, C_GetSlotList)( CK_BBOOL tokenPresent, CK_SLOT_ID_PTR pSlotList,
                                          CK_ULONG_PTR pulCount )

Where it makes sense there is also an overload of the LowLevel method to make usage easier and safer:

bool C_GetSlotList(bool token_present, std::vector<SlotId> &slot_ids, ReturnValue *return_value = ThrowException) const

With this overload the user of this API just has to pass a vector of SlotId instead of pointers to preallocated memory for the slot list and the number of elements. Additionally, there is no need to call the method twice in order to determine the number of elements first.

Another example is the C_InitPIN overload:

template<typename Talloc>
bool C_InitPIN(SessionHandle session, const std::vector<uint8_t, TAlloc> &pin, ReturnValue *return_value = ThrowException) const

The templated pin parameter allows to pass the PIN as a std::vector<uint8_t> or a secure_vector<uint8_t>. If used with a secure_vector it is assured that the memory is securely erased when the pin object is no longer needed.

Error Handling

All possible PKCS#11 return values are represented by the enum class:

enum class ReturnValue : CK_RV

All methods of the LowLevel class have a default parameter ReturnValue* return_value = ThrowException. This parameter controls the error handling of all LowLevel methods. The default behaviour return_value = ThrowException is to throw an exception if the method does not complete successfully. If a non-NULL pointer is passed, return_value receives the return value of the PKCS#11 function and no exception is thrown. In case nullptr is passed as return_value, the exact return value is ignored and the method just returns true if the function succeeds and false otherwise.

Getting started

An object of this class can be instantiated by providing a FunctionListPtr to the LowLevel constructor:

explicit LowLevel(FunctionListPtr ptr)

The LowLevel class provides a static method to retrieve a FunctionListPtr from a PKCS#11 module file:

static bool C_GetFunctionList(Dynamically_Loaded_Library &pkcs11_module, FunctionListPtr *function_list_ptr_ptr, ReturnValue *return_value = ThrowException)

Code Example: Object Instantiation

Botan::Dynamically_Loaded_Library pkcs11_module( "C:\\pkcs11-middleware\\library.dll" );
Botan::PKCS11::FunctionListPtr func_list = nullptr;
Botan::PKCS11::LowLevel::C_GetFunctionList( pkcs11_module, &func_list );
Botan::PKCS11::LowLevel p11_low_level( func_list );

Code Example: PKCS#11 Module Initialization

Botan::PKCS11::LowLevel p11_low_level(func_list);

Botan::PKCS11::C_InitializeArgs init_args = { nullptr, nullptr, nullptr, nullptr,
        static_cast<CK_FLAGS>(Botan::PKCS11::Flag::OsLockingOk), nullptr };

p11_low_level.C_Initialize(&init_args);

// work with the token

p11_low_level.C_Finalize(nullptr);

More code examples can be found in the test suite in the test_pkcs11_low_level.cpp file.

High Level API

The high level API provides access to the most commonly used PKCS#11 functionality in an object oriented manner. Functionality of the high level API includes:

  • Loading/unloading of PKCS#11 modules
  • Initialization of tokens
  • Change of PIN/SO-PIN
  • Session management
  • Random number generation
  • Enumeration of objects on the token (certificates, public keys, private keys)
  • Import/export/deletion of certificates
  • Generation/import/export/deletion of RSA and EC public and private keys
  • Encryption/decryption using RSA with support for OAEP and PKCS1-v1_5 (and raw)
  • Signature generation/verification using RSA with support for PSS and PKCS1-v1_5 (and raw)
  • Signature generation/verification using ECDSA
  • Key derivation using ECDH

Module

The Module class represents a PKCS#11 shared library (module) and is defined in botan/p11_module.h.

It is constructed from a a file path to a PKCS#11 module and optional C_InitializeArgs:

class Module
Module(const std::string& file_path, C_InitializeArgs init_args =
   { nullptr, nullptr, nullptr, nullptr, static_cast<CK_FLAGS>(Flag::OsLockingOk), nullptr })

It loads the shared library and calls C_Initialize with the provided C_InitializeArgs. On destruction of the object C_Finalize is called.

There are two more methods in this class. One is for reloading the shared library and reinitializing the PKCS#11 module:

void reload(C_InitializeArgs init_args =
   { nullptr, nullptr, nullptr, nullptr, static_cast< CK_FLAGS >(Flag::OsLockingOk), nullptr });

The other one is for getting general information about the PKCS#11 module:

Info get_info() const

This function calls C_GetInfo internally.


Code example:

Botan::PKCS11::Module module( "C:\\pkcs11-middleware\\library.dll" );

// Sometimes useful if a newly connected token is not detected by the PKCS#11 module
module.reload();

Botan::PKCS11::Info info = module.get_info();

// print library version
std::cout << std::to_string( info.libraryVersion.major ) << "."
   << std::to_string( info.libraryVersion.minor ) << std::endl;

Slot

The Slot class represents a PKCS#11 slot and is defined in botan/p11_slot.h.

A PKCS#11 slot is usually a smart card reader that potentially contains a token.

class Slot
Slot(Module &module, SlotId slot_id)

To instantiate this class a reference to a Module object and a slot_id have to be passed to the constructor.

To retrieve available slot ids this class has the following static method:

static std::vector<SlotId> get_available_slots(Module &module, bool token_present)

The parameter token_present controls whether all slots or only slots with a token attached are returned by this method. This method calls C_GetSlotList.

Further methods:

SlotInfo get_slot_info() const

Returns information about the slot. Calls C_GetSlotInfo.

TokenInfo get_token_info() const

Obtains information about a particular token in the system. Calls C_GetTokenInfo.

std::vector<MechanismType> get_mechanism_list() const

Obtains a list of mechanism types supported by the slot. Calls C_GetMechanismList.

MechanismInfo get_mechanism_info(MechanismType mechanism_type) const

Obtains information about a particular mechanism possibly supported by a slot. Calls C_GetMechanismInfo.

void initialize(const std::string &label, const secure_string &so_pin) const

Calls C_InitToken to initialize the token. The label must not exceed 32 bytes. The current PIN of the security officer must be passed in so_pin if the token is reinitialized or if it’s a factory new token, the so_pin that is passed will initially be set.


Code example:

// only slots with connected token
std::vector<Botan::PKCS11::SlotId> slots = Botan::PKCS11::Slot::get_available_slots( module, true );

// use first slot
Botan::PKCS11::Slot slot( module, slots.at( 0 ) );

// print firmware version of the slot
Botan::PKCS11::SlotInfo slot_info = slot.get_slot_info();
std::cout << std::to_string( slot_info.firmwareVersion.major ) << "."
   << std::to_string( slot_info.firmwareVersion.minor ) << std::endl;

// print firmware version of the token
Botan::PKCS11::TokenInfo token_info = slot.get_token_info();
std::cout << std::to_string( token_info.firmwareVersion.major ) << "."
   << std::to_string( token_info.firmwareVersion.minor ) << std::endl;

// retrieve all mechanisms supported by the token
std::vector<Botan::PKCS11::MechanismType> mechanisms = slot.get_mechanism_list();

// retrieve information about a particular mechanism
Botan::PKCS11::MechanismInfo mech_info =
   slot.get_mechanism_info( Botan::PKCS11::MechanismType::RsaPkcsOaep );

// maximum RSA key length supported:
std::cout << mech_info.ulMaxKeySize << std::endl;

// initialize the token
Botan::PKCS11::secure_string so_pin( 8, '0' );
slot.initialize( "Botan PKCS11 documentation test label", so_pin );

Session

The Session class represents a PKCS#11 session and is defined in botan/p11_session.h.

A session is a logical connection between an application and a token.

class Session

There are two constructors to create a new session and one constructor to take ownership of an existing session.

Session(Slot &slot, bool read_only)

To initialize a session object a Slot has to be specified on which the session should operate. read_only specifies whether the session should be read only or read write. Calls C_OpenSession.

Session(Slot &slot, Flags flags, VoidPtr callback_data, Notify notify_callback)

Creates a new session by passing a Slot, session flags, callback_data and a notify_callback. Calls C_OpenSession.

Session(Slot &slot, SessionHandle handle)

Takes ownership of an existing session by passing Slot and a session handle.

The destructor calls C_Logout if a user is logged in to this session and always C_CloseSession.

SessionHandle release()

Returns the released SessionHandle

void login(UserType userType, const secure_string &pin)

Login to this session by passing UserType and pin. Calls C_Login.

void logoff()

Logout from this session. Not mandatory because on destruction of the Session object this is done automatically.

SessionInfo get_info() const

Returns information about this session. Calls C_GetSessionInfo.

void set_pin(const secure_string &old_pin, const secure_string &new_pin) const

Calls C_SetPIN to change the PIN of the logged in user using the old_pin.

void init_pin(const secure_string &new_pin)

Calls C_InitPIN to change or initialize the PIN using the SO_PIN (requires a logged in session).


Code example:

// open read only session
{
Botan::PKCS11::Session read_only_session( slot, true );
}

// open read write session
{
Botan::PKCS11::Session read_write_session( slot, false );
}

// open read write session by passing flags
{
Botan::PKCS11::Flags flags =
   Botan::PKCS11::flags( Botan::PKCS11::Flag::SerialSession | Botan::PKCS11::Flag::RwSession );

Botan::PKCS11::Session read_write_session( slot, flags, nullptr, nullptr );
}

// move ownership of a session
{
Botan::PKCS11::Session session( slot, false );
Botan::PKCS11::SessionHandle handle = session.release();

Botan::PKCS11::Session session2( slot, handle );
}

Botan::PKCS11::Session session( slot, false );

// get session info
Botan::PKCS11::SessionInfo info = session.get_info();
std::cout << info.slotID << std::endl;

// login
Botan::PKCS11::secure_string pin = { '1', '2', '3', '4', '5', '6' };
session.login( Botan::PKCS11::UserType::User, pin );

// set pin
Botan::PKCS11::secure_string new_pin = { '6', '5', '4', '3', '2', '1' };
session.set_pin( pin, new_pin );

// logoff
session.logoff();

// log in as security officer
Botan::PKCS11::secure_string so_pin = { '0', '0', '0', '0', '0', '0', '0', '0' };
session.login( Botan::PKCS11::UserType::SO, so_pin );

// change pin to old pin
session.init_pin( pin );

Objects

PKCS#11 objects consist of various attributes (CK_ATTRIBUTE). For example CKA_TOKEN describes if a PKCS#11 object is a session object or a token object. The helper class AttributeContainer helps with storing these attributes. The class is defined in botan/p11_object.h.

class AttributeContainer

Attributes can be set in an AttributeContainer by various add_ methods:

void add_class(ObjectClass object_class)

Add a class attribute (CKA_CLASS / AttributeType::Class)

void add_string(AttributeType attribute, const std::string &value)

Add a string attribute (e.g. CKA_LABEL / AttributeType::Label).

void AttributeContainer::add_binary(AttributeType attribute, const uint8_t *value, size_t length)

Add a binary attribute (e.g. CKA_ID / AttributeType::Id).

template<typename TAlloc>
void AttributeContainer::add_binary(AttributeType attribute, const std::vector<uint8_t, TAlloc> &binary)

Add a binary attribute by passing a vector/secure_vector (e.g. CKA_ID / AttributeType::Id).

void AttributeContainer::add_bool(AttributeType attribute, bool value)
Add a bool attribute (e.g. CKA_SENSITIVE / AttributeType::Sensitive).
template<typename T>
void AttributeContainer::add_numeric(AttributeType attribute, T value)

Add a numeric attribute (e.g. CKA_MODULUS_BITS / AttributeType::ModulusBits).

Object Properties

The PKCS#11 standard defines the mandatory and optional attributes for each object class. The mandatory and optional attribute requirements are mapped in so called property classes. Mandatory attributes are set in the constructor, optional attributes can be set via set_ methods.

In the top hierarchy is the ObjectProperties class which inherits from the AttributeContainer. This class represents the common attributes of all PKCS#11 objects.

class ObjectProperties : public AttributeContainer

The constructor is defined as follows:

ObjectProperties(ObjectClass object_class)

Every PKCS#11 object needs an object class attribute.

The next level defines the StorageObjectProperties class which inherits from ObjectProperties.

class StorageObjectProperties : public ObjectProperties

The only mandatory attribute is the object class, so the constructor is defined as follows:

StorageObjectProperties(ObjectClass object_class)

But in contrast to the ObjectProperties class there are various setter methods. For example to set the AttributeType::Label:

void set_label(const std::string &label)

Sets the label description of the object (RFC2279 string).

The remaining hierarchy is defined as follows:

PKCS#11 objects themself are represented by the Object class.

class Object

Following constructors are defined:

Object(Session &session, ObjectHandle handle)

Takes ownership over an existing object.

Object(Session &session, const ObjectProperties &obj_props)

Creates a new object with the ObjectProperties provided in obj_props.

The other methods are:

secure_vector<uint8_t> get_attribute_value(AttributeType attribute) const

Returns the value of the given attribute (using C_GetAttributeValue)

void set_attribute_value(AttributeType attribute, const secure_vector<uint8_t> &value) const

Sets the given value for the attribute (using C_SetAttributeValue)

void destroy() const

Destroys the object.

ObjectHandle copy(const AttributeContainer &modified_attributes) const

Allows to copy the object with modified attributes.

And static methods to search for objects:

template<typename T>
static std::vector<T> search(Session &session, const std::vector<Attribute> &search_template)

Searches for all objects of the given type that match search_template.

template<typename T>
static std::vector<T> search(Session &session, const std::string &label)

Searches for all objects of the given type using the label (CKA_LABEL).

template<typename T>
static std::vector<T> search(Session &session, const std::vector<uint8_t> &id)

Searches for all objects of the given type using the id (CKA_ID).

template<typename T>
static std::vector<T> search(Session &session, const std::string &label, const std::vector<uint8_t> &id)

Searches for all objects of the given type using the label (CKA_LABEL) and id (CKA_ID).

template<typename T>
static std::vector<T> search(Session &session)

Searches for all objects of the given type.

The ObjectFinder

Another way for searching objects is to use the ObjectFinder class. This class manages calls to the C_FindObjects* functions: C_FindObjectsInit, C_FindObjects and C_FindObjectsFinal.

class ObjectFinder

The constructor has the following signature:

ObjectFinder(Session &session, const std::vector<Attribute> &search_template)

A search can be prepared with an ObjectSearcher by passing a Session and a search_template.

The actual search operation is started by calling the find method:

std::vector<ObjectHandle> find(std::uint32_t max_count = 100) const

Starts or continues a search for token and session objects that match a template. max_count specifies the maximum number of search results (object handles) that are returned.

void finish()

Finishes the search operation manually to allow a new ObjectFinder to exist. Otherwise the search is finished by the destructor.


Code example:

// create an simple data object
Botan::secure_vector<uint8_t> value = { 0x00, 0x01 ,0x02, 0x03 };
std::size_t id = 1337;
std::string label = "test data object";

// set properties of the new object
Botan::PKCS11::DataObjectProperties data_obj_props;
data_obj_props.set_label( label );
data_obj_props.set_value( value );
data_obj_props.set_token( true );
data_obj_props.set_modifiable( true );
data_obj_props.set_object_id( Botan::DER_Encoder().encode( id ).get_contents_unlocked() );

// create the object
Botan::PKCS11::Object data_obj( session, data_obj_props );

// get label of this object
Botan::PKCS11::secure_string retrieved_label =
   data_obj.get_attribute_value( Botan::PKCS11::AttributeType::Label );

// set a new label
Botan::PKCS11::secure_string new_label = { 'B', 'o', 't', 'a', 'n' };
data_obj.set_attribute_value( Botan::PKCS11::AttributeType::Label, new_label );

// copy the object
Botan::PKCS11::AttributeContainer copy_attributes;
copy_attributes.add_string( Botan::PKCS11::AttributeType::Label, "copied object" );
Botan::PKCS11::ObjectHandle copied_obj_handle = data_obj.copy( copy_attributes );

// search for an object
Botan::PKCS11::AttributeContainer search_template;
search_template.add_string( Botan::PKCS11::AttributeType::Label, "Botan" );
auto found_objs =
   Botan::PKCS11::Object::search<Botan::PKCS11::Object>( session, search_template.attributes() );

// destroy the object
data_obj.destroy();

RSA

PKCS#11 RSA support is implemented in <botan/p11_rsa.h>.

RSA Public Keys

PKCS#11 RSA public keys are provided by the class PKCS11_RSA_PublicKey. This class inherits from RSA_PublicKey and Object. Furthermore there are two property classes defined to generate and import RSA public keys analogous to the other property classes described before: RSA_PublicKeyGenerationProperties and RSA_PublicKeyImportProperties.

class PKCS11_RSA_PublicKey : public RSA_PublicKey, public Object
PKCS11_RSA_PublicKey(Session &session, ObjectHandle handle)

Existing PKCS#11 RSA public keys can be used by providing an ObjectHandle to the constructor.

PKCS11_RSA_PublicKey(Session &session, const RSA_PublicKeyImportProperties &pubkey_props)

This constructor can be used to import an existing RSA public key with the RSA_PublicKeyImportProperties passed in pubkey_props to the token.

RSA Private Keys

The support for PKCS#11 RSA private keys is implemented in a similar way. There are two property classes: RSA_PrivateKeyGenerationProperties and RSA_PrivateKeyImportProperties. The PKCS11_RSA_PrivateKey class implements the actual support for PKCS#11 RSA private keys. This class inherits from Private_Key, RSA_PublicKey and Object. In contrast to the public key class there is a third constructor to generate private keys directly on the token or in the session and one method to export private keys.

class PKCS11_RSA_PrivateKey : public Private_Key, public RSA_PublicKey, public Object
PKCS11_RSA_PrivateKey(Session &session, ObjectHandle handle)

Existing PKCS#11 RSA private keys can be used by providing an ObjectHandle to the constructor.

PKCS11_RSA_PrivateKey(Session &session, const RSA_PrivateKeyImportProperties &priv_key_props)

This constructor can be used to import an existing RSA private key with the RSA_PrivateKeyImportProperties passed in priv_key_props to the token.

PKCS11_RSA_PrivateKey(Session &session, uint32_t bits, const RSA_PrivateKeyGenerationProperties &priv_key_props)

Generates a new PKCS#11 RSA private key with bit length provided in bits and the RSA_PrivateKeyGenerationProperties passed in priv_key_props.

RSA_PrivateKey export_key() const

Returns the exported RSA_PrivateKey.

PKCS#11 RSA key pairs can be generated with the following free function:

PKCS11_RSA_KeyPair PKCS11::generate_rsa_keypair(Session &session, const RSA_PublicKeyGenerationProperties &pub_props, const RSA_PrivateKeyGenerationProperties &priv_props)

Code example:

Botan::PKCS11::secure_string pin = { '1', '2', '3', '4', '5', '6' };
session.login( Botan::PKCS11::UserType::User, pin );

/************ import RSA private key *************/

// create private key in software
Botan::AutoSeeded_RNG rng;
Botan::RSA_PrivateKey priv_key_sw( rng, 2048 );

// set the private key import properties
Botan::PKCS11::RSA_PrivateKeyImportProperties
   priv_import_props( priv_key_sw.get_n(), priv_key_sw.get_d() );

priv_import_props.set_pub_exponent( priv_key_sw.get_e() );
priv_import_props.set_prime_1( priv_key_sw.get_p() );
priv_import_props.set_prime_2( priv_key_sw.get_q() );
priv_import_props.set_coefficient( priv_key_sw.get_c() );
priv_import_props.set_exponent_1( priv_key_sw.get_d1() );
priv_import_props.set_exponent_2( priv_key_sw.get_d2() );

priv_import_props.set_token( true );
priv_import_props.set_private( true );
priv_import_props.set_decrypt( true );
priv_import_props.set_sign( true );

// import
Botan::PKCS11::PKCS11_RSA_PrivateKey priv_key( session, priv_import_props );

/************ export PKCS#11 RSA private key *************/
Botan::RSA_PrivateKey exported = priv_key.export_key();

/************ import RSA public key *************/

// set the public key import properties
Botan::PKCS11::RSA_PublicKeyImportProperties pub_import_props( priv_key.get_n(), priv_key.get_e() );
pub_import_props.set_token( true );
pub_import_props.set_encrypt( true );
pub_import_props.set_private( false );

// import
Botan::PKCS11::PKCS11_RSA_PublicKey public_key( session, pub_import_props );

/************ generate RSA private key *************/

Botan::PKCS11::RSA_PrivateKeyGenerationProperties priv_generate_props;
priv_generate_props.set_token( true );
priv_generate_props.set_private( true );
priv_generate_props.set_sign( true );
priv_generate_props.set_decrypt( true );
priv_generate_props.set_label( "BOTAN_TEST_RSA_PRIV_KEY" );

Botan::PKCS11::PKCS11_RSA_PrivateKey private_key2( session, 2048, priv_generate_props );

/************ generate RSA key pair *************/

Botan::PKCS11::RSA_PublicKeyGenerationProperties pub_generate_props( 2048UL );
pub_generate_props.set_pub_exponent();
pub_generate_props.set_label( "BOTAN_TEST_RSA_PUB_KEY" );
pub_generate_props.set_token( true );
pub_generate_props.set_encrypt( true );
pub_generate_props.set_verify( true );
pub_generate_props.set_private( false );

Botan::PKCS11::PKCS11_RSA_KeyPair rsa_keypair =
   Botan::PKCS11::generate_rsa_keypair( session, pub_generate_props, priv_generate_props );

/************ RSA encrypt *************/

Botan::secure_vector<uint8_t> plaintext = { 0x00, 0x01, 0x02, 0x03 };
Botan::PK_Encryptor_EME encryptor( rsa_keypair.first, rng, "Raw" );
auto ciphertext = encryptor.encrypt( plaintext, rng );

/************ RSA decrypt *************/

Botan::PK_Decryptor_EME decryptor( rsa_keypair.second, rng, "Raw" );
plaintext = decryptor.decrypt( ciphertext );

/************ RSA sign *************/

Botan::PK_Signer signer( rsa_keypair.second, rng, "EMSA4(SHA-256)", Botan::IEEE_1363 );
auto signature = signer.sign_message( plaintext, rng );

/************ RSA verify *************/

Botan::PK_Verifier verifier( rsa_keypair.first, "EMSA4(SHA-256)", Botan::IEEE_1363 );
auto ok = verifier.verify_message( plaintext, signature );

ECDSA

PKCS#11 ECDSA support is implemented in <botan/p11_ecdsa.h>.

ECDSA Public Keys

PKCS#11 ECDSA public keys are provided by the class PKCS11_ECDSA_PublicKey. This class inherits from PKCS11_EC_PublicKey and ECDSA_PublicKey. The necessary property classes are defined in <botan/p11_ecc_key.h>. For public keys there are EC_PublicKeyGenerationProperties and EC_PublicKeyImportProperties.

class PKCS11_ECDSA_PublicKey : public PKCS11_EC_PublicKey, public virtual ECDSA_PublicKey
PKCS11_ECDSA_PublicKey(Session &session, ObjectHandle handle)

Existing PKCS#11 ECDSA private keys can be used by providing an ObjectHandle to the constructor.

PKCS11_ECDSA_PublicKey(Session &session, const EC_PublicKeyImportProperties &props)

This constructor can be used to import an existing ECDSA public key with the EC_PublicKeyImportProperties passed in props to the token.

ECDSA_PublicKey PKCS11_ECDSA_PublicKey::export_key() const

Returns the exported ECDSA_PublicKey.

ECDSA Private Keys

The class PKCS11_ECDSA_PrivateKey inherits from PKCS11_EC_PrivateKey and implements support for PKCS#11 ECDSA private keys. There are two property classes for key generation and import: EC_PrivateKeyGenerationProperties and EC_PrivateKeyImportProperties.

class PKCS11_ECDSA_PrivateKey : public PKCS11_EC_PrivateKey
PKCS11_ECDSA_PrivateKey(Session &session, ObjectHandle handle)

Existing PKCS#11 ECDSA private keys can be used by providing an ObjectHandle to the constructor.

PKCS11_ECDSA_PrivateKey(Session &session, const EC_PrivateKeyImportProperties &props)

This constructor can be used to import an existing ECDSA private key with the EC_PrivateKeyImportProperties passed in props to the token.

PKCS11_ECDSA_PrivateKey(Session &session, const std::vector<uint8_t> &ec_params, const EC_PrivateKeyGenerationProperties &props)

This constructor can be used to generate a new ECDSA private key with the EC_PrivateKeyGenerationProperties passed in props on the token. The ec_params parameter is the DER-encoding of an ANSI X9.62 Parameters value.

ECDSA_PrivateKey export_key() const

Returns the exported ECDSA_PrivateKey.

PKCS#11 ECDSA key pairs can be generated with the following free function:

PKCS11_ECDSA_KeyPair PKCS11::generate_ecdsa_keypair(Session &session, const EC_PublicKeyGenerationProperties &pub_props, const EC_PrivateKeyGenerationProperties &priv_props)

Code example:

Botan::PKCS11::secure_string pin = { '1', '2', '3', '4', '5', '6' };
session.login( Botan::PKCS11::UserType::User, pin );

/************ import ECDSA private key *************/

// create private key in software
Botan::AutoSeeded_RNG rng;

Botan::ECDSA_PrivateKey priv_key_sw( rng, Botan::EC_Group( "secp256r1" ) );
priv_key_sw.set_parameter_encoding( Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID );

// set the private key import properties
Botan::PKCS11::EC_PrivateKeyImportProperties priv_import_props(
   priv_key_sw.DER_domain(), priv_key_sw.private_value() );

priv_import_props.set_token( true );
priv_import_props.set_private( true );
priv_import_props.set_sign( true );
priv_import_props.set_extractable( true );

// label
std::string label = "test ECDSA key";
priv_import_props.set_label( label );

// import to card
Botan::PKCS11::PKCS11_ECDSA_PrivateKey priv_key( session, priv_import_props );

/************ export PKCS#11 ECDSA private key *************/
Botan::ECDSA_PrivateKey priv_exported = priv_key.export_key();

/************ import ECDSA public key *************/

// import to card
Botan::PKCS11::EC_PublicKeyImportProperties pub_import_props( priv_key_sw.DER_domain(),
   Botan::DER_Encoder().encode( EC2OSP( priv_key_sw.public_point(), Botan::PointGFp::UNCOMPRESSED ),
   Botan::OCTET_STRING ).get_contents_unlocked() );

pub_import_props.set_token( true );
pub_import_props.set_verify( true );
pub_import_props.set_private( false );

// label
label = "test ECDSA pub key";
pub_import_props.set_label( label );

Botan::PKCS11::PKCS11_ECDSA_PublicKey public_key( session, pub_import_props );

/************ export PKCS#11 ECDSA public key *************/
Botan::ECDSA_PublicKey pub_exported = public_key.export_key();

/************ generate PKCS#11 ECDSA private key *************/
Botan::PKCS11::EC_PrivateKeyGenerationProperties priv_generate_props;
priv_generate_props.set_token( true );
priv_generate_props.set_private( true );
priv_generate_props.set_sign( true );

Botan::PKCS11::PKCS11_ECDSA_PrivateKey pk( session,
   Botan::EC_Group( "secp256r1" ).DER_encode( Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID ),
   priv_generate_props );

/************ generate PKCS#11 ECDSA key pair *************/

Botan::PKCS11::EC_PublicKeyGenerationProperties pub_generate_props(
   Botan::EC_Group( "secp256r1" ).DER_encode(Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID ) );

pub_generate_props.set_label( "BOTAN_TEST_ECDSA_PUB_KEY" );
pub_generate_props.set_token( true );
pub_generate_props.set_verify( true );
pub_generate_props.set_private( false );
pub_generate_props.set_modifiable( true );

Botan::PKCS11::PKCS11_ECDSA_KeyPair key_pair = Botan::PKCS11::generate_ecdsa_keypair( session,
   pub_generate_props, priv_generate_props );

/************ PKCS#11 ECDSA sign and verify *************/

std::vector<uint8_t> plaintext( 20, 0x01 );

Botan::PK_Signer signer( key_pair.second, rng, "Raw", Botan::IEEE_1363, "pkcs11" );
auto signature = signer.sign_message( plaintext, rng );

Botan::PK_Verifier token_verifier( key_pair.first, "Raw", Botan::IEEE_1363, "pkcs11" );
bool ecdsa_ok = token_verifier.verify_message( plaintext, signature );

ECDH

PKCS#11 ECDH support is implemented in <botan/p11_ecdh.h>.

ECDH Public Keys

PKCS#11 ECDH public keys are provided by the class PKCS11_ECDH_PublicKey. This class inherits from PKCS11_EC_PublicKey. The necessary property classes are defined in <botan/p11_ecc_key.h>. For public keys there are EC_PublicKeyGenerationProperties and EC_PublicKeyImportProperties.

class PKCS11_ECDH_PublicKey : public PKCS11_EC_PublicKey
PKCS11_ECDH_PublicKey(Session &session, ObjectHandle handle)

Existing PKCS#11 ECDH private keys can be used by providing an ObjectHandle to the constructor.

PKCS11_ECDH_PublicKey(Session &session, const EC_PublicKeyImportProperties &props)

This constructor can be used to import an existing ECDH public key with the EC_PublicKeyImportProperties passed in props to the token.

ECDH_PublicKey export_key() const

Returns the exported ECDH_PublicKey.

ECDH Private Keys

The class PKCS11_ECDH_PrivateKey inherits from PKCS11_EC_PrivateKey and PK_Key_Agreement_Key and implements support for PKCS#11 ECDH private keys. There are two property classes. One for key generation and one for import: EC_PrivateKeyGenerationProperties and EC_PrivateKeyImportProperties.

class PKCS11_ECDH_PrivateKey : public virtual PKCS11_EC_PrivateKey, public virtual PK_Key_Agreement_Key
PKCS11_ECDH_PrivateKey(Session &session, ObjectHandle handle)

Existing PKCS#11 ECDH private keys can be used by providing an ObjectHandle to the constructor.

PKCS11_ECDH_PrivateKey(Session &session, const EC_PrivateKeyImportProperties &props)

This constructor can be used to import an existing ECDH private key with the EC_PrivateKeyImportProperties passed in props to the token.

PKCS11_ECDH_PrivateKey(Session &session, const std::vector<uint8_t> &ec_params, const EC_PrivateKeyGenerationProperties &props)

This constructor can be used to generate a new ECDH private key with the EC_PrivateKeyGenerationProperties passed in props on the token. The ec_params parameter is the DER-encoding of an ANSI X9.62 Parameters value.

ECDH_PrivateKey export_key() const

Returns the exported ECDH_PrivateKey.

PKCS#11 ECDH key pairs can be generated with the following free function:

PKCS11_ECDH_KeyPair PKCS11::generate_ecdh_keypair(Session &session, const EC_PublicKeyGenerationProperties &pub_props, const EC_PrivateKeyGenerationProperties &priv_props)

Code example:

Botan::PKCS11::secure_string pin = { '1', '2', '3', '4', '5', '6' };
session.login( Botan::PKCS11::UserType::User, pin );

/************ import ECDH private key *************/

Botan::AutoSeeded_RNG rng;

// create private key in software
Botan::ECDH_PrivateKey priv_key_sw( rng, Botan::EC_Group( "secp256r1" ) );
priv_key_sw.set_parameter_encoding( Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID );

// set import properties
Botan::PKCS11::EC_PrivateKeyImportProperties priv_import_props(
   priv_key_sw.DER_domain(), priv_key_sw.private_value() );

priv_import_props.set_token( true );
priv_import_props.set_private( true );
priv_import_props.set_derive( true );
priv_import_props.set_extractable( true );

// label
std::string label = "test ECDH key";
priv_import_props.set_label( label );

// import to card
Botan::PKCS11::PKCS11_ECDH_PrivateKey priv_key( session, priv_import_props );

/************ export ECDH private key *************/
Botan::ECDH_PrivateKey exported = priv_key.export_key();

/************ import ECDH public key *************/

// set import properties
Botan::PKCS11::EC_PublicKeyImportProperties pub_import_props( priv_key_sw.DER_domain(),
   Botan::DER_Encoder().encode( EC2OSP( priv_key_sw.public_point(), Botan::PointGFp::UNCOMPRESSED ),
   Botan::OCTET_STRING ).get_contents_unlocked() );

pub_import_props.set_token( true );
pub_import_props.set_private( false );
pub_import_props.set_derive( true );

// label
label = "test ECDH pub key";
pub_import_props.set_label( label );

// import
Botan::PKCS11::PKCS11_ECDH_PublicKey pub_key( session, pub_import_props );

/************ export ECDH private key *************/
Botan::ECDH_PublicKey exported_pub = pub_key.export_key();

/************ generate ECDH private key *************/

Botan::PKCS11::EC_PrivateKeyGenerationProperties priv_generate_props;
priv_generate_props.set_token( true );
priv_generate_props.set_private( true );
priv_generate_props.set_derive( true );

Botan::PKCS11::PKCS11_ECDH_PrivateKey priv_key2( session,
   Botan::EC_Group( "secp256r1" ).DER_encode( Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID ),
   priv_generate_props );

/************ generate ECDH key pair *************/

Botan::PKCS11::EC_PublicKeyGenerationProperties pub_generate_props(
   Botan::EC_Group( "secp256r1" ).DER_encode( Botan::EC_Group_Encoding::EC_DOMPAR_ENC_OID ) );

pub_generate_props.set_label( label + "_PUB_KEY" );
pub_generate_props.set_token( true );
pub_generate_props.set_derive( true );
pub_generate_props.set_private( false );
pub_generate_props.set_modifiable( true );

Botan::PKCS11::PKCS11_ECDH_KeyPair key_pair = Botan::PKCS11::generate_ecdh_keypair(
   session, pub_generate_props, priv_generate_props );

/************ ECDH derive *************/

Botan::PKCS11::PKCS11_ECDH_KeyPair key_pair_other = Botan::PKCS11::generate_ecdh_keypair(
   session, pub_generate_props, priv_generate_props );

Botan::PK_Key_Agreement ka( key_pair.second, rng, "Raw", "pkcs11" );
Botan::PK_Key_Agreement kb( key_pair_other.second, rng, "Raw", "pkcs11" );

Botan::SymmetricKey alice_key = ka.derive_key( 32,
   Botan::unlock( Botan::EC2OSP( key_pair_other.first.public_point(),
   Botan::PointGFp::UNCOMPRESSED ) ) );

Botan::SymmetricKey bob_key = kb.derive_key( 32,
   Botan::unlock( Botan::EC2OSP( key_pair.first.public_point(),
   Botan::PointGFp::UNCOMPRESSED ) ) );

bool eq = alice_key == bob_key;

RNG

The PKCS#11 RNG is defined in <botan/p11_randomgenerator.h>. The class PKCS11_RNG implements the Hardware_RNG interface.

class PKCS11_RNG : public Hardware_RNG
PKCS11_RNG(Session &session)

A PKCS#11 Session must be passed to instantiate a PKCS11_RNG.

void randomize(uint8_t output[], std::size_t length) override

Calls C_GenerateRandom to generate random data.

void add_entropy(const uint8_t in[], std::size_t length) override

Calls C_SeedRandom to add entropy to the random generation function of the token/middleware.


Code example:

Botan::PKCS11::PKCS11_RNG p11_rng( session );

/************ generate random data *************/
std::vector<uint8_t> random( 20 );
p11_rng.randomize( random.data(), random.size() );

/************ add entropy *************/
Botan::AutoSeeded_RNG auto_rng;
auto auto_rng_random = auto_rng.random_vec( 20 );
p11_rng.add_entropy( auto_rng_random.data(), auto_rng_random.size() );

/************ use PKCS#11 RNG to seed HMAC_DRBG *************/
Botan::HMAC_DRBG drbg( Botan::MessageAuthenticationCode::create( "HMAC(SHA-512)" ), p11_rng );
drbg.randomize( random.data(), random.size() );

Token Management Functions

The header file <botan/p11.h> also defines some free functions for token management:

void initialize_token(Slot &slot, const std::string &label, const secure_string &so_pin, const secure_string &pin)

Initializes a token by passing a Slot, a label and the so_pin of the security officer.

void change_pin(Slot &slot, const secure_string &old_pin, const secure_string &new_pin)

Change PIN with old_pin to new_pin.

void change_so_pin(Slot &slot, const secure_string &old_so_pin, const secure_string &new_so_pin)

Change SO_PIN with old_so_pin to new new_so_pin.

void set_pin(Slot &slot, const secure_string &so_pin, const secure_string &pin)

Sets user pin with so_pin.


Code example:

/************ set pin *************/

Botan::PKCS11::Module module( Middleware_path );

// only slots with connected token
std::vector<Botan::PKCS11::SlotId> slots = Botan::PKCS11::Slot::get_available_slots( module, true );

// use first slot
Botan::PKCS11::Slot slot( module, slots.at( 0 ) );

Botan::PKCS11::secure_string so_pin = { '1', '2', '3', '4', '5', '6', '7', '8' };
Botan::PKCS11::secure_string pin = { '1', '2', '3', '4', '5', '6' };
Botan::PKCS11::secure_string test_pin = { '6', '5', '4', '3', '2', '1' };

// set pin
Botan::PKCS11::set_pin( slot, so_pin, test_pin );

// change back
Botan::PKCS11::set_pin( slot, so_pin, pin );

/************ initialize *************/
Botan::PKCS11::initialize_token( slot, "Botan handbook example", so_pin, pin );

/************ change pin *************/
Botan::PKCS11::change_pin( slot, pin, test_pin );

// change back
Botan::PKCS11::change_pin( slot, test_pin, pin );

/************ change security officer pin *************/
Botan::PKCS11::change_so_pin( slot, so_pin, test_pin );

// change back
Botan::PKCS11::change_so_pin( slot, test_pin, so_pin );

X.509

The header file <botan/p11_x509.h> defines the property class X509_CertificateProperties and the class PKCS11_X509_Certificate.

class PKCS11_X509_Certificate : public Object, public X509_Certificate
PKCS11_X509_Certificate(Session &session, ObjectHandle handle)

Allows to use existing certificates on the token by passing a valid ObjectHandle.

PKCS11_X509_Certificate(Session &session, const X509_CertificateProperties &props)

Allows to import an existing X.509 certificate to the token with the X509_CertificateProperties passed in props.


Code example:

// load existing certificate
Botan::X509_Certificate root( "test.crt" );

// set props
Botan::PKCS11::X509_CertificateProperties props(
   Botan::DER_Encoder().encode( root.subject_dn() ).get_contents_unlocked(), root.BER_encode() );

props.set_label( "Botan PKCS#11 test certificate" );
props.set_private( false );
props.set_token( true );

// import
Botan::PKCS11::PKCS11_X509_Certificate pkcs11_cert( session, props );

// load by handle
Botan::PKCS11::PKCS11_X509_Certificate pkcs11_cert2( session, pkcs11_cert.handle() );

Tests

The PKCS#11 tests are not executed automatically because the depend on an external PKCS#11 module/middleware. The test tool has to be executed with --pkcs11-lib= followed with the path of the PKCS#11 module and a second argument which controls the PKCS#11 tests that are executed. Passing pkcs11 will execute all PKCS#11 tests but it’s also possible to execute only a subset with the following arguments:

  • pkcs11-ecdh
  • pkcs11-ecdsa
  • pkcs11-lowlevel
  • pkcs11-manage
  • pkcs11-module
  • pkcs11-object
  • pkcs11-rng
  • pkcs11-rsa
  • pkcs11-session
  • pkcs11-slot
  • pkcs11-x509