9 files changed, 78 insertions, 6 deletions
diff --git a/src/pubkey/dh/dh.cpp b/src/pubkey/dh/dh.cpp
index 0c9d02f0e..149bc5882 100644
--- a/src/pubkey/dh/dh.cpp
+++ b/src/pubkey/dh/dh.cpp
@@ -7,7 +7,7 @@
 
 #include <botan/dh.h>
 #include <botan/numthry.h>
-#include <botan/util.h>
+#include <botan/workfactor.h>
 
 namespace Botan {
 
diff --git a/src/pubkey/dl_group/dl_group.cpp b/src/pubkey/dl_group/dl_group.cpp
index 81c5d5e1d..13ea03016 100644
--- a/src/pubkey/dl_group/dl_group.cpp
+++ b/src/pubkey/dl_group/dl_group.cpp
@@ -12,7 +12,7 @@
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
 #include <botan/pipe.h>
-#include <botan/util.h>
+#include <botan/workfactor.h>
 #include <botan/pem.h>
 
 namespace Botan {
diff --git a/src/pubkey/ecc_key/ecc_key.cpp b/src/pubkey/ecc_key/ecc_key.cpp
index 615efecf1..677a5088e 100644
--- a/src/pubkey/ecc_key/ecc_key.cpp
+++ b/src/pubkey/ecc_key/ecc_key.cpp
@@ -10,7 +10,6 @@
 #include <botan/ecc_key.h>
 #include <botan/x509_key.h>
 #include <botan/numthry.h>
-#include <botan/util.h>
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
 #include <botan/secmem.h>
diff --git a/src/pubkey/ecdsa/ecdsa.cpp b/src/pubkey/ecdsa/ecdsa.cpp
index 9640c6397..ea2c35a19 100644
--- a/src/pubkey/ecdsa/ecdsa.cpp
+++ b/src/pubkey/ecdsa/ecdsa.cpp
@@ -9,7 +9,6 @@
 
 #include <botan/ecdsa.h>
 #include <botan/numthry.h>
-#include <botan/util.h>
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
 #include <botan/secmem.h>
diff --git a/src/pubkey/eckaeg/eckaeg.cpp b/src/pubkey/eckaeg/eckaeg.cpp
index b8ff75d89..dc6eb925b 100644
--- a/src/pubkey/eckaeg/eckaeg.cpp
+++ b/src/pubkey/eckaeg/eckaeg.cpp
@@ -9,7 +9,6 @@
 
 #include <botan/eckaeg.h>
 #include <botan/numthry.h>
-#include <botan/util.h>
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
 #include <botan/secmem.h>
diff --git a/src/pubkey/elgamal/elgamal.cpp b/src/pubkey/elgamal/elgamal.cpp
index 1f79df57a..8c07c5735 100644
--- a/src/pubkey/elgamal/elgamal.cpp
+++ b/src/pubkey/elgamal/elgamal.cpp
@@ -9,7 +9,7 @@
 #include <botan/numthry.h>
 #include <botan/keypair.h>
 #include <botan/look_pk.h>
-#include <botan/util.h>
+#include <botan/workfactor.h>
 
 namespace Botan {
 
diff --git a/src/pubkey/info.txt b/src/pubkey/info.txt
index ee8da5b9d..63af86c47 100644
--- a/src/pubkey/info.txt
+++ b/src/pubkey/info.txt
@@ -15,6 +15,8 @@ pubkey.cpp
 pubkey.h
 pubkey_enums.cpp
 pubkey_enums.h
+workfactor.cpp
+workfactor.h
 </add>
 
 <requires>
diff --git a/src/pubkey/workfactor.cpp b/src/pubkey/workfactor.cpp
new file mode 100644
index 000000000..e40b7919c
--- /dev/null
+++ b/src/pubkey/workfactor.cpp
@@ -0,0 +1,51 @@
+/*
+* Public Key Work Factor Functions
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/workfactor.h>
+#include <algorithm>
+#include <cmath>
+
+namespace Botan {
+
+/*
+* Choose the exponent size for a DL group
+*/
+u32bit dl_work_factor(u32bit bits)
+   {
+#if 0
+   /*
+   These values were taken from RFC 3526
+   */
+   if(bits <= 1536)
+      return 90;
+   else if(bits <= 2048)
+      return 110;
+   else if(bits <= 3072)
+      return 130;
+   else if(bits <= 4096)
+      return 150;
+   else if(bits <= 6144)
+      return 170;
+   else if(bits <= 8192)
+      return 190;
+   return 256;
+#else
+   const u32bit MIN_ESTIMATE = 64;
+
+   const double log_x = bits / 1.44;
+
+   const double strength =
+      2.76 * std::pow(log_x, 1.0/3.0) * std::pow(std::log(log_x), 2.0/3.0);
+
+   if(strength > MIN_ESTIMATE)
+      return static_cast<u32bit>(strength);
+   return MIN_ESTIMATE;
+#endif
+   }
+
+
+}
diff --git a/src/pubkey/workfactor.h b/src/pubkey/workfactor.h
new file mode 100644
index 000000000..653f697e3
--- /dev/null
+++ b/src/pubkey/workfactor.h
@@ -0,0 +1,22 @@
+/*
+* Public Key Work Factor Functions
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_WORKFACTOR_H__
+#define BOTAN_WORKFACTOR_H__
+
+#include <botan/types.h>
+
+namespace Botan {
+
+/*
+* Work Factor Estimates
+*/
+BOTAN_DLL u32bit dl_work_factor(u32bit prime_group_size);
+
+}
+
+#endif