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/*
* OpenPGP PBKDF
* (C) 1999-2007,2017 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_OPENPGP_S2K_H__
#define BOTAN_OPENPGP_S2K_H__
#include <botan/pbkdf.h>
#include <botan/hash.h>
namespace Botan {
/**
* OpenPGP's S2K
*
* See RFC 4880 sections 3.7.1.1, 3.7.1.2, and 3.7.1.3
* If the salt is empty and iterations == 1, "simple" S2K is used
* If the salt is non-empty and iterations == 1, "salted" S2K is used
* If the salt is non-empty and iterations > 1, "iterated" S2K is used
*
* Due to complexities of the PGP S2K algorithm, time-based derivation
* is not supported. So if iterations == 0 and msec.count() > 0, an
* exception is thrown. In the future this may be supported, in which
* case "iterated" S2K will be used and the number of iterations
* performed is returned.
*
* Note that unlike PBKDF2, OpenPGP S2K's "iterations" are defined as
* the number of bytes hashed.
*/
class BOTAN_PUBLIC_API(2,2) OpenPGP_S2K final : public PBKDF
{
public:
/**
* @param hash the hash function to use
*/
explicit OpenPGP_S2K(HashFunction* hash) : m_hash(hash) {}
std::string name() const override
{
return "OpenPGP-S2K(" + m_hash->name() + ")";
}
PBKDF* clone() const override
{
return new OpenPGP_S2K(m_hash->clone());
}
size_t pbkdf(uint8_t output_buf[], size_t output_len,
const std::string& passphrase,
const uint8_t salt[], size_t salt_len,
size_t iterations,
std::chrono::milliseconds msec) const override;
/**
* RFC 4880 encodes the iteration count to a single-byte value
*/
static uint8_t encode_count(size_t iterations);
static size_t decode_count(uint8_t encoded_iter);
private:
std::unique_ptr<HashFunction> m_hash;
};
}
#endif
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