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-rw-r--r--src/rng/hmac_rng/hmac_rng.cpp57
-rw-r--r--src/rng/hmac_rng/hmac_rng.h12
-rw-r--r--src/rng/randpool/randpool.cpp26
-rw-r--r--src/utils/entropy.cpp80
-rw-r--r--src/utils/entropy.h48
-rw-r--r--src/utils/info.txt2
-rw-r--r--src/utils/util.cpp32
-rw-r--r--src/utils/util.h1
8 files changed, 157 insertions, 101 deletions
diff --git a/src/rng/hmac_rng/hmac_rng.cpp b/src/rng/hmac_rng/hmac_rng.cpp
index 1a9fedb6c..769cdf4b2 100644
--- a/src/rng/hmac_rng/hmac_rng.cpp
+++ b/src/rng/hmac_rng/hmac_rng.cpp
@@ -4,6 +4,7 @@
*************************************************/
#include <botan/hmac_rng.h>
+#include <botan/entropy.h>
#include <botan/loadstor.h>
#include <botan/xor_buf.h>
#include <botan/util.h>
@@ -13,58 +14,6 @@
namespace Botan {
-namespace {
-
-class Entropy_Estimator
- {
- public:
- Entropy_Estimator()
- { last = last_delta = last_delta2 = 0; estimate = 0; }
-
- u32bit value() const { return estimate; }
-
- void set_upper_bound(u32bit upper_limit)
- { estimate = std::min(estimate, upper_limit); }
-
- void update(const byte buffer[], u32bit length, u32bit upper_limit = 0);
- private:
- u32bit estimate;
- byte last, last_delta, last_delta2;
- };
-
-void Entropy_Estimator::update(const byte buffer[], u32bit length,
- u32bit upper_limit)
- {
- u32bit this_buf_estimate = 0;
-
- for(u32bit j = 0; j != length; ++j)
- {
- byte delta = last ^ buffer[j];
- last = buffer[j];
-
- byte delta2 = delta ^ last_delta;
- last_delta = delta;
-
- byte delta3 = delta2 ^ last_delta2;
- last_delta2 = delta2;
-
- byte min_delta = delta;
- if(min_delta > delta2) min_delta = delta2;
- if(min_delta > delta3) min_delta = delta3;
-
- this_buf_estimate += hamming_weight(min_delta);
- }
-
- this_buf_estimate /= 2;
-
- if(upper_limit)
- estimate += std::min(upper_limit, this_buf_estimate);
- else
- estimate += this_buf_estimate;
- }
-
-}
-
/*************************************************
* Generate a buffer of random bytes *
*************************************************/
@@ -227,6 +176,10 @@ void HMAC_RNG::reseed_with_input(const byte input[], u32bit input_length)
SecureVector<byte> prk = extractor->final();
prf->set_key(prk, prk.size());
+ // Total gathered entropy is at most PRK bits (likely less, really,
+ // since PRF will probably hash it down further)
+ estimate.set_upper_bound(prk.size());
+
K.clear();
counter = 0;
diff --git a/src/rng/hmac_rng/hmac_rng.h b/src/rng/hmac_rng/hmac_rng.h
index dbadb2a04..e735a7899 100644
--- a/src/rng/hmac_rng/hmac_rng.h
+++ b/src/rng/hmac_rng/hmac_rng.h
@@ -13,12 +13,14 @@
namespace Botan {
/**
-HMAC_RNG - based on the design described in"On Extract-then-Expand Key
-Derivation Functions and an HMAC-based KDF" by Hugo Krawczyk
+HMAC_RNG - based on the design described in "On Extract-then-Expand
+Key Derivation Functions and an HMAC-based KDF" by Hugo Krawczyk
(henceforce, 'E-t-E')
However it actually can be parameterized with any two MAC functions,
-not restricted to HMAC (this is also described in Krawczyk's paper)
+not restricted to HMAC (this variation is also described in Krawczyk's
+paper), for instance one could use HMAC(SHA-512) as the extractor
+and CMAC(AES-256) as the PRF.
*/
class BOTAN_DLL HMAC_RNG : public RandomNumberGenerator
{
@@ -32,8 +34,8 @@ class BOTAN_DLL HMAC_RNG : public RandomNumberGenerator
void add_entropy_source(EntropySource* es);
void add_entropy(const byte[], u32bit);
- HMAC_RNG(MessageAuthenticationCode*,
- MessageAuthenticationCode*);
+ HMAC_RNG(MessageAuthenticationCode* extractor,
+ MessageAuthenticationCode* prf);
~HMAC_RNG();
private:
diff --git a/src/rng/randpool/randpool.cpp b/src/rng/randpool/randpool.cpp
index dd80a7f70..743123b9e 100644
--- a/src/rng/randpool/randpool.cpp
+++ b/src/rng/randpool/randpool.cpp
@@ -4,6 +4,7 @@
*************************************************/
#include <botan/randpool.h>
+#include <botan/entropy.h>
#include <botan/loadstor.h>
#include <botan/xor_buf.h>
#include <botan/util.h>
@@ -108,40 +109,41 @@ void Randpool::reseed()
{
SecureVector<byte> buffer(128);
- u32bit gathered_entropy = 0;
+ Entropy_Estimator estimate;
// First do a fast poll of all sources (no matter what)
for(u32bit j = 0; j != entropy_sources.size(); ++j)
{
u32bit got = entropy_sources[j]->fast_poll(buffer, buffer.size());
- u32bit entropy = std::min<u32bit>(96, entropy_estimate(buffer, got));
mac->update(buffer, got);
-
- gathered_entropy += entropy;
+ estimate.update(buffer, got, 96);
}
- // Limit assumed entropy from fast polls to 256 bits total
- gathered_entropy = std::min<u32bit>(256, gathered_entropy);
+ /* Limit assumed entropy from fast polls (to ensure we do at
+ least a few slow polls)
+ */
+ estimate.set_upper_bound(256);
// Then do a slow poll, until we think we have got enough entropy
for(u32bit j = 0; j != entropy_sources.size(); ++j)
{
u32bit got = entropy_sources[j]->slow_poll(buffer, buffer.size());
- u32bit entropy = std::min<u32bit>(256, entropy_estimate(buffer, got));
mac->update(buffer, got);
- gathered_entropy += entropy;
- if(gathered_entropy > 512)
+ estimate.update(buffer, got, 256);
+
+ if(estimate.value() > 384)
break;
}
SecureVector<byte> mac_val = mac->final();
+
xor_buf(pool, mac_val, mac_val.size());
mix_pool();
- entropy += gathered_entropy;
+ entropy += estimate.value();
}
/*************************************************
@@ -153,7 +155,9 @@ void Randpool::add_entropy(const byte input[], u32bit length)
xor_buf(pool, mac_val, mac_val.size());
mix_pool();
- entropy += entropy_estimate(input, length);
+ Entropy_Estimator estimate;
+ estimate.update(input, length);
+ entropy += estimate.value();
}
/*************************************************
diff --git a/src/utils/entropy.cpp b/src/utils/entropy.cpp
new file mode 100644
index 000000000..1562eb0d2
--- /dev/null
+++ b/src/utils/entropy.cpp
@@ -0,0 +1,80 @@
+/*************************************************
+* Entropy_Estimator Source File *
+* (C) 2008 Jack Lloyd *
+*************************************************/
+
+#include <botan/entropy.h>
+#include <botan/bit_ops.h>
+
+namespace Botan {
+
+/**
+Update the estimate
+*/
+void Entropy_Estimator::update(const byte buffer[], u32bit length,
+ u32bit upper_limit)
+ {
+ u32bit this_buf_estimate = 0;
+
+ /*
+ This is pretty naive
+ */
+ for(u32bit j = 0; j != length; ++j)
+ {
+ byte delta = last ^ buffer[j];
+ last = buffer[j];
+
+ byte delta2 = delta ^ last_delta;
+ last_delta = delta;
+
+ byte delta3 = delta2 ^ last_delta2;
+ last_delta2 = delta2;
+
+ byte min_delta = delta;
+ if(min_delta > delta2) min_delta = delta2;
+ if(min_delta > delta3) min_delta = delta3;
+
+ this_buf_estimate += hamming_weight(min_delta);
+ }
+
+ this_buf_estimate /= 2;
+
+ if(upper_limit)
+ estimate += std::min(upper_limit, this_buf_estimate);
+ else
+ estimate += this_buf_estimate;
+ }
+
+/*************************************************
+* Estimate the entropy of the buffer *
+*************************************************/
+u32bit entropy_estimate(const byte buffer[], u32bit length)
+ {
+ if(length <= 4)
+ return 0;
+
+ u32bit estimate = 0;
+ byte last = 0, last_delta = 0, last_delta2 = 0;
+
+ for(u32bit j = 0; j != length; ++j)
+ {
+ byte delta = last ^ buffer[j];
+ last = buffer[j];
+
+ byte delta2 = delta ^ last_delta;
+ last_delta = delta;
+
+ byte delta3 = delta2 ^ last_delta2;
+ last_delta2 = delta2;
+
+ byte min_delta = delta;
+ if(min_delta > delta2) min_delta = delta2;
+ if(min_delta > delta3) min_delta = delta3;
+
+ estimate += hamming_weight(min_delta);
+ }
+
+ return (estimate / 2);
+ }
+
+}
diff --git a/src/utils/entropy.h b/src/utils/entropy.h
new file mode 100644
index 000000000..24d2fbdbf
--- /dev/null
+++ b/src/utils/entropy.h
@@ -0,0 +1,48 @@
+/*************************************************
+* Entropy_Estimator Header File *
+* (C) 2008 Jack Lloyd *
+*************************************************/
+
+#ifndef BOTAN_ENTROPY_ESTIMATOR_H__
+#define BOTAN_ENTROPY_ESTIMATOR_H__
+
+#include <botan/types.h>
+#include <algorithm>
+
+namespace Botan {
+
+/**
+Naive Entropy Estimation using first, second, and third order deltas
+
+@todo It would be nice to extend this to test using zlib or bzip2 if
+those modules are compiled in to the library
+*/
+class BOTAN_DLL Entropy_Estimator
+ {
+ public:
+ Entropy_Estimator()
+ { last = last_delta = last_delta2 = 0; estimate = 0; }
+
+ /**
+ Return the current estimate
+ */
+ u32bit value() const { return estimate; }
+
+ /**
+ Set an upper bound on the estimate so far
+ */
+ void set_upper_bound(u32bit upper_limit)
+ { estimate = std::min(estimate, upper_limit); }
+
+ /**
+ Add more entropy data to the current estimation
+ */
+ void update(const byte buffer[], u32bit length, u32bit upper_limit = 0);
+ private:
+ u32bit estimate;
+ byte last, last_delta, last_delta2;
+ };
+
+}
+
+#endif
diff --git a/src/utils/info.txt b/src/utils/info.txt
index b20a16a56..0f0a18a35 100644
--- a/src/utils/info.txt
+++ b/src/utils/info.txt
@@ -19,6 +19,8 @@ charset.cpp
charset.h
datastor.cpp
datastor.h
+entropy.h
+entropy.cpp
loadstor.h
mem_ops.h
mlock.cpp
diff --git a/src/utils/util.cpp b/src/utils/util.cpp
index af1c62ebd..f8b98fcb8 100644
--- a/src/utils/util.cpp
+++ b/src/utils/util.cpp
@@ -64,36 +64,4 @@ u32bit dl_work_factor(u32bit bits)
#endif
}
-/*************************************************
-* Estimate the entropy of the buffer *
-*************************************************/
-u32bit entropy_estimate(const byte buffer[], u32bit length)
- {
- if(length <= 4)
- return 0;
-
- u32bit estimate = 0;
- byte last = 0, last_delta = 0, last_delta2 = 0;
-
- for(u32bit j = 0; j != length; ++j)
- {
- byte delta = last ^ buffer[j];
- last = buffer[j];
-
- byte delta2 = delta ^ last_delta;
- last_delta = delta;
-
- byte delta3 = delta2 ^ last_delta2;
- last_delta2 = delta2;
-
- byte min_delta = delta;
- if(min_delta > delta2) min_delta = delta2;
- if(min_delta > delta3) min_delta = delta3;
-
- estimate += hamming_weight(min_delta);
- }
-
- return (estimate / 2);
- }
-
}
diff --git a/src/utils/util.h b/src/utils/util.h
index 62ecb948d..d0e2e110a 100644
--- a/src/utils/util.h
+++ b/src/utils/util.h
@@ -30,7 +30,6 @@ BOTAN_DLL u32bit round_down(u32bit, u32bit);
/*************************************************
* Work Factor Estimates *
*************************************************/
-BOTAN_DLL u32bit entropy_estimate(const byte[], u32bit);
BOTAN_DLL u32bit dl_work_factor(u32bit);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 03:54:22 +0000