1 files changed, 19 insertions, 12 deletions
diff --git a/src/lib/pubkey/workfactor.cpp b/src/lib/pubkey/workfactor.cpp
index 8be64bef3..71604c06b 100644
--- a/src/lib/pubkey/workfactor.cpp
+++ b/src/lib/pubkey/workfactor.cpp
@@ -16,21 +16,32 @@ size_t ecp_work_factor(size_t bits)
    return bits / 2;
    }
 
-size_t if_work_factor(size_t bits)
-   {
-   // RFC 3766: k * e^((1.92 + o(1)) * cubrt(ln(n) * (ln(ln(n)))^2))
-   // It estimates k at .02 and o(1) to be effectively zero for sizes of interest
-   const double k = .02;
+namespace {
 
-   // approximates natural logarithm of p
+size_t nfs_workfactor(size_t bits, double k)
+   {
+   // approximates natural logarithm of integer of given bitsize
    const double log2_e = std::log2(std::exp(1));
    const double log_p = bits / log2_e;
 
-   const double est = 1.92 * std::pow(log_p * std::log(log_p) * std::log(log_p), 1.0/3.0);
+   const double log_log_p = std::log(log_p);
 
+   // RFC 3766: k * e^((1.92 + o(1)) * cubrt(ln(n) * (ln(ln(n)))^2))
+   const double est = 1.92 * std::pow(log_p * log_log_p * log_log_p, 1.0/3.0);
+
+   // return log2 of the workfactor
    return static_cast<size_t>(std::log2(k) + log2_e * est);
    }
 
+}
+
+size_t if_work_factor(size_t bits)
+   {
+   // RFC 3766 estimates k at .02 and o(1) to be effectively zero for sizes of interest
+
+   return nfs_workfactor(bits, .02);
+   }
+
 size_t dl_work_factor(size_t bits)
    {
    // Lacking better estimates...
@@ -46,12 +57,8 @@ size_t dl_exponent_size(size_t bits)
    (this only matters for very small primes).
    */
    const size_t MIN_WORKFACTOR = 64;
-   const double log2_e = std::log2(std::exp(1));
-   const double log_p = bits / log2_e;
-
-   const double strength = 1.92 * std::pow(log_p, 1.0/3.0) * std::pow(std::log(log_p), 2.0/3.0);
 
-   return 2 * std::max<size_t>(MIN_WORKFACTOR, static_cast<size_t>(log2_e * strength));
+   return 2 * std::max<size_t>(MIN_WORKFACTOR, nfs_workfactor(bits, 1));
    }
 
 }