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/*
* XMSS WOTS Private Key
* (C) 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#ifndef BOTAN_XMSS_WOTS_PRIVATEKEY_H__
#define BOTAN_XMSS_WOTS_PRIVATEKEY_H__
#include <cstddef>
#include <memory>
#include <botan/alg_id.h>
#include <botan/assert.h>
#include <botan/exceptn.h>
#include <botan/pk_keys.h>
#include <botan/types.h>
#include <botan/xmss_wots_parameters.h>
#include <botan/xmss_address.h>
#include <botan/xmss_wots_publickey.h>
namespace Botan {
/** A Winternitz One Time Signature private key for use with Extended Hash-Based
* Signatures.
**/
class BOTAN_DLL XMSS_WOTS_PrivateKey : public virtual XMSS_WOTS_PublicKey,
public virtual Private_Key
{
public:
/**
* Creates a WOTS private key for the chosen XMSS WOTS signature method.
* Members need to be initialized manually.
*
* @param oid Identifier for the selected signature method.
**/
XMSS_WOTS_PrivateKey(XMSS_WOTS_Parameters::ots_algorithm_t oid)
: XMSS_WOTS_PublicKey(oid)
{}
/**
* Creates a WOTS private key for the chosen XMSS WOTS signature method.
*
* @param oid Identifier for the selected signature method.
* @param rng A random number generator to use for key generation.
**/
XMSS_WOTS_PrivateKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
RandomNumberGenerator& rng)
: XMSS_WOTS_PublicKey(oid, rng),
m_private_seed(rng.random_vec(m_wots_params.element_size()))
{
set_key_data(generate(m_private_seed));
}
/**
* Constructs a WOTS private key. Chains will be generated on demand
* applying a hash function to a unique value generated from a secret
* seed and a counter. The secret seed of length n, will be
* automatically generated using AutoSeeded_RNG(). "n" equals
* the element size of the chosen WOTS security parameter set.
*
* @param oid Identifier for the selected signature method.
* @param public_seed A public seed used for the pseudo random generation
* of public keys derived from this private key.
* @param rng A random number generator to use for key generation.
**/
XMSS_WOTS_PrivateKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
const secure_vector<uint8_t>& public_seed,
RandomNumberGenerator &rng)
: XMSS_WOTS_PublicKey(oid, public_seed),
m_private_seed(rng.random_vec(m_wots_params.element_size()))
{
set_key_data(generate(m_private_seed));
}
/**
* Constructs a WOTS private key. Chains will be generated on demand
* applying a hash function to a unique value generated from a secret
* seed and a counter. The secret seed of length n, will be
* automatically generated using AutoSeeded_RNG(). "n" equals
* the element size of the chosen WOTS security parameter set.
*
* @param oid Identifier for the selected signature method.
* @param public_seed A public seed used for the pseudo random generation
* of public keys derived from this private key.
**/
XMSS_WOTS_PrivateKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
const secure_vector<uint8_t>& public_seed)
: XMSS_WOTS_PublicKey(oid, public_seed)
{}
/**
* Constructs a WOTS private key. Chains will be generated on demand
* applying a hash function to a unique value generated from the
* secret seed and a counter.
*
* @param oid Identifier for the selected signature method.
* @param public_seed A public seed used for the pseudo random generation
* of public keys derived from this private key.
* @param private_seed A secret uniformly random n-byte value.
**/
XMSS_WOTS_PrivateKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
const secure_vector<uint8_t>& public_seed,
const secure_vector<uint8_t>& private_seed)
: XMSS_WOTS_PublicKey(oid, public_seed),
m_private_seed(private_seed)
{
set_key_data(generate(private_seed));
}
/**
* Retrieves the i-th WOTS private key using pseudo random key
* (re-)generation.
*
* @param i Index of the key to retrieve.
*
* @return WOTS secret key.
**/
wots_keysig_t operator[](size_t i)
{
secure_vector<uint8_t> idx_bytes;
XMSS_Tools::concat(idx_bytes, i, m_wots_params.element_size());
m_hash.h(idx_bytes, m_private_seed, idx_bytes);
return generate(idx_bytes);
}
/**
* Retrieves the i-th WOTS private key using pseudo random key
* (re-)generation.
*
* @param adrs The address of the key to retrieve.
*
* @return WOTS secret key.
**/
wots_keysig_t operator[](const XMSS_Address& adrs)
{
secure_vector<uint8_t> result;
m_hash.prf(result, m_private_seed, adrs.bytes());
return generate(result);
}
wots_keysig_t generate_private_key(const secure_vector<uint8_t>& priv_seed);
/**
* Algorithm 4: "WOTS_genPK"
* Generates a Winternitz One Time Signature+ (WOTS+) Public Key from a
* given private key.
*
* @param adrs Hash function address encoding the address of the WOTS+
* key pair within a greater structure.
*
* @return A XMSS_WOTS_PublicKey.
**/
XMSS_WOTS_PublicKey generate_public_key(XMSS_Address& adrs);
/**
* Algorithm 4: "WOTS_genPK"
* Initializes a Winternitz One Time Signature+ (WOTS+) Public Key's
* key_data() member, with data derived from in_key_data using the
* WOTS chaining function.
*
* @param[out] pub_key Public key to initialize key_data() member on.
* @param in_key_data Input key material from private key used for
* public key generation.
* @param adrs Hash function address encoding the address of
* the WOTS+ key pair within a greater structure.
**/
void generate_public_key(XMSS_WOTS_PublicKey& pub_key,
wots_keysig_t&& in_key_data,
XMSS_Address& adrs);
/**
* Algorithm 5: "WOTS_sign"
* Generates a signature from a private key and a message.
*
* @param msg A message to sign.
* @param adrs An OTS hash address identifying the WOTS+ key pair
* used for signing.
*
* @return signature for msg.
**/
wots_keysig_t sign(const secure_vector<uint8_t>& msg,
XMSS_Address& adrs);
/**
* Retrieves the secret seed used to generate WOTS+ chains. The seed
* should be a uniformly random n-byte value.
*
* @return secret seed.
**/
const secure_vector<uint8_t>& private_seed() const
{
return m_private_seed;
}
/**
* Sets the secret seed used to generate WOTS+ chains. The seed
* should be a uniformly random n-byte value.
*
* @param private_seed Uniformly random n-byte value.
**/
void set_private_seed(const secure_vector<uint8_t>& private_seed)
{
m_private_seed = private_seed;
}
/**
* Sets the secret seed used to generate WOTS+ chains. The seed
* should be a uniformly random n-byte value.
*
* @param private_seed Uniformly random n-byte value.
**/
void set_private_seed(secure_vector<uint8_t>&& private_seed)
{
m_private_seed = std::move(private_seed);
}
virtual AlgorithmIdentifier
pkcs8_algorithm_identifier() const override
{
throw Not_Implemented("No AlgorithmIdentifier available for XMSS-WOTS.");
}
virtual std::unique_ptr<PK_Ops::Signature>
create_signature_op(RandomNumberGenerator&,
const std::string&,
const std::string& provider) const override;
virtual secure_vector<uint8_t> private_key_bits() const override
{
throw Not_Implemented("No PKCS8 key format defined for XMSS-WOTS.");
}
private:
/**
* Algorithm 3: "Generating a WOTS+ Private Key".
* Generates a private key.
*
* @param private_seed Uniformly random n-byte value.
*
* @returns a vector of length key_size() of vectors of n bytes length
* containing uniformly random data.
**/
wots_keysig_t generate(const secure_vector<uint8_t>& private_seed);
secure_vector<uint8_t> m_private_seed;
};
}
#endif
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