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/*
* XMSS WOTS Public Key
* (C) 2016,2017,2018 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#ifndef BOTAN_XMSS_WOTS_PUBLICKEY_H_
#define BOTAN_XMSS_WOTS_PUBLICKEY_H_
#include <cstddef>
#include <string>
#include <vector>
#include <botan/rng.h>
#include <botan/asn1_obj.h>
#include <botan/exceptn.h>
#include <botan/pk_keys.h>
#include <botan/xmss_wots_parameters.h>
#include <botan/xmss_hash.h>
namespace Botan {
class XMSS_Address;
typedef std::vector<secure_vector<uint8_t>> wots_keysig_t;
/**
* A Winternitz One Time Signature public key for use with Extended Hash-Based
* Signatures.
**/
class XMSS_WOTS_PublicKey : virtual public Public_Key
{
public:
class TreeSignature final
{
public:
TreeSignature() = default;
TreeSignature(const wots_keysig_t& ots_sig,
const wots_keysig_t& auth_path)
: m_ots_sig(ots_sig), m_auth_path(auth_path)
{}
TreeSignature(wots_keysig_t&& ots_sig,
wots_keysig_t&& auth_path)
: m_ots_sig(std::move(ots_sig)),
m_auth_path(std::move(auth_path))
{}
const wots_keysig_t& ots_signature() const
{
return m_ots_sig;
}
wots_keysig_t& ots_signature()
{
return m_ots_sig;
}
const wots_keysig_t& authentication_path() const
{
return m_auth_path;
}
wots_keysig_t& authentication_path()
{
return m_auth_path;
}
private:
wots_keysig_t m_ots_sig;
wots_keysig_t m_auth_path;
};
/**
* Creates a XMSS_WOTS_PublicKey for the signature method identified by
* oid. The public seed for this key will be initialized with a
* uniformly random n-byte value, where "n" is the element size of the
* selected signature method.
*
* @param oid Identifier for the selected signature method.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()) {}
/**
* Creates a XMSS_WOTS_PublicKey for the signature method identified by
* oid. The public seed for this key will be initialized with a
* uniformly random n-byte value, where "n" is the element size of the
* selected signature method.
*
* @param oid Identifier for the selected signature method.
* @param rng A random number generate used to generate the public seed.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
RandomNumberGenerator& rng)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()),
m_public_seed(rng.random_vec(m_wots_params.element_size())) {}
/**
* Creates a XMSS_WOTS_PrivateKey for the signature method identified by
* oid, with a precomputed public seed.
*
* @param oid Identifier for the selected signature method.
* @param public_seed A precomputed public seed of n-bytes length.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
secure_vector<uint8_t> public_seed)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()),
m_public_seed(public_seed) {}
/**
* Creates a XMSS_WOTS_PublicKey for the signature method identified by
* oid. The public seed will be initialized with a precomputed seed and
* and precomputed key data which should be derived from a
* XMSS_WOTS_PrivateKey.
*
* @param oid Ident:s/ifier for the selected signature methods.
* @param public_seed A precomputed public seed of n-bytes length.
* @param key Precomputed raw key data of the XMSS_WOTS_PublicKey.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
secure_vector<uint8_t>&& public_seed,
wots_keysig_t&& key)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()),
m_key(std::move(key)),
m_public_seed(std::move(public_seed))
{}
/**
* Creates a XMSS_WOTS_PublicKey for the signature method identified by
* oid. The public seed will be initialized with a precomputed seed and
* and precomputed key data which should be derived from a
* XMSS_WOTS_PrivateKey.
*
* @param oid Identifier for the selected signature methods.
* @param public_seed A precomputed public seed of n-bytes length.
* @param key Precomputed raw key data of the XMSS_WOTS_PublicKey.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
const secure_vector<uint8_t>& public_seed,
const wots_keysig_t& key)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()),
m_key(key),
m_public_seed(public_seed)
{}
/**
* Creates a XMSS_WOTS_PublicKey form a message and signature using
* Algorithm 6 WOTS_pkFromSig defined in the XMSS standard. This
* overload is used to verify a message using a public key.
*
* @param oid WOTSP algorithm identifier.
* @param msg A message.
* @param sig A WOTS signature for msg.
* @param adrs An XMSS_Address.
* @param public_seed The public public_seed.
**/
XMSS_WOTS_PublicKey(XMSS_WOTS_Parameters::ots_algorithm_t oid,
const secure_vector<uint8_t>& msg,
const wots_keysig_t& sig,
XMSS_Address& adrs,
const secure_vector<uint8_t>& public_seed)
: m_wots_params(oid),
m_hash(m_wots_params.hash_function_name()),
m_key(pub_key_from_signature(msg,
sig,
adrs,
public_seed)),
m_public_seed(public_seed)
{}
/**
* Retrieves the i-th element out of the length len chain of
* n-byte elements contained in the public key.
*
* @param i index of the element.
* @returns n-byte element addressed by i.
**/
const secure_vector<uint8_t>& operator[](size_t i) const { return m_key[i]; }
secure_vector<uint8_t>& operator[](size_t i) { return m_key[i]; }
/**
* Convert the key into the raw key data. The key becomes a length
* len vector of n-byte elements.
**/
operator const wots_keysig_t& () const { return m_key; }
/**
* Convert the key into the raw key data. The key becomes a length
* len vector of n-byte elements.
**/
operator wots_keysig_t& () { return m_key; }
const secure_vector<uint8_t>& public_seed() const { return m_public_seed; }
secure_vector<uint8_t>& public_seed() { return m_public_seed; }
void set_public_seed(const secure_vector<uint8_t>& public_seed)
{
m_public_seed = public_seed;
}
void set_public_seed(secure_vector<uint8_t>&& public_seed)
{
m_public_seed = std::move(public_seed);
}
const wots_keysig_t& key_data() const { return m_key; }
wots_keysig_t& key_data() { return m_key; }
void set_key_data(const wots_keysig_t& key_data)
{
m_key = key_data;
}
void set_key_data(wots_keysig_t&& key_data)
{
m_key = std::move(key_data);
}
const XMSS_WOTS_Parameters& wots_parameters() const
{
return m_wots_params;
}
std::string algo_name() const override
{
return m_wots_params.name();
}
AlgorithmIdentifier algorithm_identifier() const override
{
throw Not_Implemented("No AlgorithmIdentifier available for XMSS-WOTS.");
}
bool check_key(RandomNumberGenerator&, bool) const override
{
return true;
}
size_t estimated_strength() const override
{
return m_wots_params.estimated_strength();
}
size_t key_length() const override
{
return m_wots_params.estimated_strength();
}
std::vector<uint8_t> public_key_bits() const override
{
throw Not_Implemented("No key format defined for XMSS-WOTS");
}
bool operator==(const XMSS_WOTS_PublicKey& key)
{
return m_key == key.m_key;
}
bool operator!=(const XMSS_WOTS_PublicKey& key)
{
return !(*this == key);
}
protected:
/**
* Algorithm 2: Chaining Function.
*
* Takes an n-byte input string and transforms it into a the function
* result iterating the cryptographic hash function "F" steps times on
* the input x using the outputs of the PRNG "G".
*
* This overload is used in multithreaded scenarios, where it is
* required to provide seperate instances of XMSS_Hash to each
* thread.
*
* @param[out] x An n-byte input string, that will be transformed into
* the chaining function result.
* @param start_idx The start index.
* @param steps A number of steps.
* @param adrs An OTS Hash Address.
* @param public_seed A public seed.
* @param hash Instance of XMSS_Hash, that may only by the thead
* executing chain.
**/
void chain(secure_vector<uint8_t>& x,
size_t start_idx,
size_t steps,
XMSS_Address& adrs,
const secure_vector<uint8_t>& public_seed,
XMSS_Hash& hash);
/**
* Algorithm 2: Chaining Function.
*
* Takes an n-byte input string and transforms it into a the function
* result iterating the cryptographic hash function "F" steps times on
* the input x using the outputs of the PRNG "G".
*
* @param[out] x An n-byte input string, that will be transformed into
* the chaining function result.
* @param start_idx The start index.
* @param steps A number of steps.
* @param adrs An OTS Hash Address.
* @param public_seed A public seed.
**/
inline void chain(secure_vector<uint8_t>& x,
size_t start_idx,
size_t steps,
XMSS_Address& adrs,
const secure_vector<uint8_t>& public_seed)
{
chain(x, start_idx, steps, adrs, public_seed, m_hash);
}
XMSS_WOTS_Parameters m_wots_params;
XMSS_Hash m_hash;
wots_keysig_t m_key;
secure_vector<uint8_t> m_public_seed;
private:
/**
* Algorithm 6: "WOTS_pkFromSig"
* Computes a Winternitz One Time Signature+ public key from a message and
* its signature.
*
* @param msg A message.
* @param sig The signature for msg.
* @param adrs An address.
* @param public_seed A public_seed.
*
* @return Temporary WOTS+ public key.
**/
wots_keysig_t pub_key_from_signature(
const secure_vector<uint8_t>& msg,
const wots_keysig_t& sig,
XMSS_Address& adrs,
const secure_vector<uint8_t>& public_seed);
};
}
#endif
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