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Diffstat (limited to 'src/rng/randpool/randpool.cpp')
| -rw-r--r-- | src/rng/randpool/randpool.cpp | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/src/rng/randpool/randpool.cpp b/src/rng/randpool/randpool.cpp new file mode 100644 index 000000000..69ef3b9e7 --- /dev/null +++ b/src/rng/randpool/randpool.cpp @@ -0,0 +1,223 @@ +/************************************************* +* Randpool Source File * +* (C) 1999-2008 Jack Lloyd * +*************************************************/ + +#include <botan/randpool.h> +#include <botan/lookup.h> +#include <botan/loadstor.h> +#include <botan/xor_buf.h> +#include <botan/util.h> +#include <botan/stl_util.h> +#include <algorithm> + +namespace Botan { + +namespace { + +/************************************************* +* PRF based on a MAC * +*************************************************/ +enum RANDPOOL_PRF_TAG { + CIPHER_KEY = 0, + MAC_KEY = 1, + GEN_OUTPUT = 2 +}; + +} + +/************************************************* +* Generate a buffer of random bytes * +*************************************************/ +void Randpool::randomize(byte out[], u32bit length) + { + if(!is_seeded()) + { + reseed(); + + if(!is_seeded()) + throw PRNG_Unseeded(name()); + } + + update_buffer(); + while(length) + { + const u32bit copied = std::min(length, buffer.size()); + copy_mem(out, buffer.begin(), copied); + out += copied; + length -= copied; + update_buffer(); + } + } + +/************************************************* +* Refill the output buffer * +*************************************************/ +void Randpool::update_buffer() + { + const u64bit timestamp = system_time(); + + for(u32bit j = 0; j != counter.size(); ++j) + if(++counter[j]) + break; + store_be(timestamp, counter + 4); + + mac->update(static_cast<byte>(GEN_OUTPUT)); + mac->update(counter, counter.size()); + SecureVector<byte> mac_val = mac->final(); + + for(u32bit j = 0; j != mac_val.size(); ++j) + buffer[j % buffer.size()] ^= mac_val[j]; + cipher->encrypt(buffer); + + if(counter[0] % ITERATIONS_BEFORE_RESEED == 0) + mix_pool(); + } + +/************************************************* +* Mix the entropy pool * +*************************************************/ +void Randpool::mix_pool() + { + const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE; + + mac->update(static_cast<byte>(MAC_KEY)); + mac->update(pool, pool.size()); + mac->set_key(mac->final()); + + mac->update(static_cast<byte>(CIPHER_KEY)); + mac->update(pool, pool.size()); + cipher->set_key(mac->final()); + + xor_buf(pool, buffer, BLOCK_SIZE); + cipher->encrypt(pool); + for(u32bit j = 1; j != POOL_BLOCKS; ++j) + { + const byte* previous_block = pool + BLOCK_SIZE*(j-1); + byte* this_block = pool + BLOCK_SIZE*j; + xor_buf(this_block, previous_block, BLOCK_SIZE); + cipher->encrypt(this_block); + } + + update_buffer(); + } + +/************************************************* +* Reseed the internal state * +*************************************************/ +void Randpool::reseed() + { + SecureVector<byte> buffer(1024); + u32bit gathered_entropy = 0; + + for(u32bit j = 0; j != entropy_sources.size(); ++j) + { + u32bit got = entropy_sources[j]->slow_poll(buffer, buffer.size()); + + mac->update(buffer, got); + + gathered_entropy += entropy_estimate(buffer, got); + if(gathered_entropy > 512) + break; + } + + SecureVector<byte> mac_val = mac->final(); + xor_buf(pool, mac_val, mac_val.size()); + mix_pool(); + + entropy += gathered_entropy; + } + +/************************************************* +* Add user-supplied entropy * +*************************************************/ +void Randpool::add_entropy(const byte input[], u32bit length) + { + SecureVector<byte> mac_val = mac->process(input, length); + xor_buf(pool, mac_val, mac_val.size()); + mix_pool(); + + entropy += entropy_estimate(input, length); + } + +/************************************************* +* Add another entropy source to the list * +*************************************************/ +void Randpool::add_entropy_source(EntropySource* src) + { + entropy_sources.push_back(src); + } + +/************************************************* +* Check if the the pool is seeded * +*************************************************/ +bool Randpool::is_seeded() const + { + return (entropy >= 384); + } + +/************************************************* +* Clear memory of sensitive data * +*************************************************/ +void Randpool::clear() throw() + { + cipher->clear(); + mac->clear(); + pool.clear(); + buffer.clear(); + counter.clear(); + entropy = 0; + } + +/************************************************* +* Return the name of this type * +*************************************************/ +std::string Randpool::name() const + { + return "Randpool(" + cipher->name() + "," + mac->name() + ")"; + } + +/************************************************* +* Randpool Constructor * +*************************************************/ +Randpool::Randpool(const std::string& cipher_name, + const std::string& mac_name) : + ITERATIONS_BEFORE_RESEED(128), POOL_BLOCKS(32) + { + cipher = get_block_cipher(cipher_name); + mac = get_mac(mac_name); + + const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE; + const u32bit OUTPUT_LENGTH = mac->OUTPUT_LENGTH; + + if(OUTPUT_LENGTH < BLOCK_SIZE || + !cipher->valid_keylength(OUTPUT_LENGTH) || + !mac->valid_keylength(OUTPUT_LENGTH)) + { + delete cipher; + delete mac; + throw Internal_Error("Randpool: Invalid algorithm combination " + + cipher_name + "/" + mac_name); + } + + buffer.create(BLOCK_SIZE); + pool.create(POOL_BLOCKS * BLOCK_SIZE); + counter.create(12); + entropy = 0; + } + +/************************************************* +* Randpool Destructor * +*************************************************/ +Randpool::~Randpool() + { + delete cipher; + delete mac; + + std::for_each(entropy_sources.begin(), entropy_sources.end(), + del_fun<EntropySource>()); + + entropy = 0; + } + +} |