diff --git a/src/arguments.hpp b/src/arguments.hpp
index 547a55b6..83a961de 100644
--- a/src/arguments.hpp
+++ b/src/arguments.hpp
@@ -26,10 +26,11 @@ struct SeedingArguments {
             "results with non default values.", {'s'}}
         , bits{parser, "INT", "No. of top bits of hash to use as bucket indices (8-31)"
             "[determined from reference size]", {'b'}}
+        , digest{parser, "INT", "Number of bits to be selected from the second strobe hash [24]", {"digest"}}
     {
     }
     args::ArgumentParser& parser;
-    args::ValueFlag<int> r, m, k, l, u, c, s, bits;
+    args::ValueFlag<int> r, m, k, l, u, c, s, bits, digest;
 };
 
 #endif
diff --git a/src/cmdline.cpp b/src/cmdline.cpp
index c00c5479..d3917136 100644
--- a/src/cmdline.cpp
+++ b/src/cmdline.cpp
@@ -117,6 +117,7 @@ CommandLineOptions parse_command_line_arguments(int argc, char **argv) {
     if (seeding.s) { opt.s = args::get(seeding.s); opt.s_set = true; }
     if (seeding.c) { opt.c = args::get(seeding.c); opt.c_set = true; }
     if (seeding.bits) { opt.bits = args::get(seeding.bits); }
+    if (seeding.digest) { opt.digest = args::get(seeding.digest); }
 
     // Alignment
     // if (n) { n = args::get(n); }
diff --git a/src/cmdline.hpp b/src/cmdline.hpp
index 2ae3186e..1f3c80eb 100644
--- a/src/cmdline.hpp
+++ b/src/cmdline.hpp
@@ -45,6 +45,7 @@ struct CommandLineOptions {
     int u { 7 };
     int s { 16 };
     int c { 8 };
+    int digest {24};
 
     // Alignment
     int A { 2 };
diff --git a/src/dumpstrobes.cpp b/src/dumpstrobes.cpp
index 4a8a1d88..28da3cf9 100644
--- a/src/dumpstrobes.cpp
+++ b/src/dumpstrobes.cpp
@@ -101,7 +101,7 @@ int run_dumpstrobes(int argc, char **argv) {
     }
 
     // Seeding
-    int r{150}, k{20}, s{16}, c{8}, l{1}, u{7};
+    int r{150}, k{20}, s{16}, c{8}, l{1}, u{7}, digest{8};
     int max_seed_len{};
 
     bool k_set{false}, s_set{false}, c_set{false}, max_seed_len_set{false}, l_set{false}, u_set{false};
@@ -125,7 +125,8 @@ int run_dumpstrobes(int argc, char **argv) {
         l_set ? l : IndexParameters::DEFAULT,
         u_set ? u : IndexParameters::DEFAULT,
         c_set ? c : IndexParameters::DEFAULT,
-        max_seed_len_set ? max_seed_len : IndexParameters::DEFAULT
+        max_seed_len_set ? max_seed_len : IndexParameters::DEFAULT,
+        digest ? digest: IndexParameters::DEFAULT
     );
 
     logger.info() << index_parameters << '\n';
diff --git a/src/index.cpp b/src/index.cpp
index 7773e509..e2415a59 100644
--- a/src/index.cpp
+++ b/src/index.cpp
@@ -149,6 +149,8 @@ void StrobemerIndex::populate(float f, size_t n_threads) {
     }
     stats.tot_strobemer_count = total_randstrobes;
 
+    logger.info() << "Digest parameter is : " << parameters.randstrobe.digest;
+
     logger.debug() << "  Total number of randstrobes: " << total_randstrobes << '\n';
     uint64_t memory_bytes = references.total_length() + sizeof(RefRandstrobe) * total_randstrobes + sizeof(bucket_index_t) * (1u << bits);
     logger.debug() << "  Estimated total memory usage: " << memory_bytes / 1E9 << " GB\n";
diff --git a/src/index.hpp b/src/index.hpp
index 941db7de..3cf3273b 100644
--- a/src/index.hpp
+++ b/src/index.hpp
@@ -17,6 +17,7 @@
 #include "refs.hpp"
 #include "randstrobes.hpp"
 #include "indexparameters.hpp"
+#include "logger.hpp"
 
 
 struct IndexCreationStatistics {
@@ -38,6 +39,7 @@ struct StrobemerIndex {
     using bucket_index_t = uint64_t;
     StrobemerIndex(const References& references, const IndexParameters& parameters, int bits=-1)
         : filter_cutoff(0)
+        , partial_filter_cutoff(2000) //fixme initialize somewhere else
         , parameters(parameters)
         , references(references)
         , bits(bits == -1 ? pick_bits(references.total_length()) : bits)
@@ -47,6 +49,7 @@ struct StrobemerIndex {
         }
     }
     unsigned int filter_cutoff;
+    unsigned int partial_filter_cutoff;
     mutable IndexCreationStatistics stats;
 
     void write(const std::string& filename) const;
@@ -80,6 +83,37 @@ struct StrobemerIndex {
         return end();
     }
 
+    //Returns the first entry that matches the first strobe subhash (if using multi-context seeds)
+    size_t partial_find(randstrobe_hash_t key) const {
+        uint strobe2_digest = parameters.randstrobe.digest;
+        randstrobe_hash_t key_prefix = key >> strobe2_digest;
+
+        constexpr int MAX_LINEAR_SEARCH = 4;
+        const unsigned int top_N = key >> (64 - bits);
+        bucket_index_t position_start = randstrobe_start_indices[top_N];
+        bucket_index_t position_end = randstrobe_start_indices[top_N + 1];
+        if (position_start == position_end) {
+            return end();
+        }
+
+        if (position_end - position_start < MAX_LINEAR_SEARCH) {
+            for ( ; position_start < position_end; ++position_start) {
+                if (randstrobes[position_start].hash >> strobe2_digest == key_prefix) return position_start;
+                if (randstrobes[position_start].hash >> strobe2_digest > key_prefix) return end();
+            }
+            return end();
+        }
+        auto cmp = [&strobe2_digest](const RefRandstrobe lhs, const RefRandstrobe rhs) {
+            return (lhs.hash >> strobe2_digest) < (rhs.hash >> strobe2_digest); };
+
+        auto pos = std::lower_bound(randstrobes.begin() + position_start,
+                                    randstrobes.begin() + position_end,
+                                    RefRandstrobe{key, 0, 0},
+                                    cmp);
+        if (pos->hash == key) return pos - randstrobes.begin();
+        return end();
+    }
+
     randstrobe_hash_t get_hash(bucket_index_t position) const {
         if (position < randstrobes.size()) {
             return randstrobes[position].hash;
@@ -92,6 +126,11 @@ struct StrobemerIndex {
         return get_hash(position) == get_hash(position + filter_cutoff);
     }
 
+    bool is_partial_filtered(bucket_index_t position) const {
+        uint shift = parameters.randstrobe.digest;
+        return (get_hash(position) >> shift) == (get_hash(position + partial_filter_cutoff) >> shift);
+    }
+
     unsigned int get_strobe1_position(bucket_index_t position) const {
         return randstrobes[position].position;
     }
diff --git a/src/indexparameters.cpp b/src/indexparameters.cpp
index 2f634e9f..7235d4ce 100644
--- a/src/indexparameters.cpp
+++ b/src/indexparameters.cpp
@@ -18,7 +18,8 @@ bool RandstrobeParameters::operator==(const RandstrobeParameters& other) const {
         && this->q == other.q
         && this->max_dist == other.max_dist
         && this->w_min == other.w_min
-        && this->w_max == other.w_max;
+        && this->w_max == other.w_max
+        && this->digest == other.digest;
 }
 
 /* Pre-defined index parameters that work well for a certain
@@ -30,24 +31,25 @@ struct Profile {
     int s_offset;
     int l;
     int u;
+    int digest;
 };
 
 static auto max{std::numeric_limits<int>::max()};
 
 static std::vector<Profile> profiles = {
-        Profile{ 50,  90, 18, -4, -2,  1},
-        Profile{100, 110, 20, -4, -2,  2},
-        Profile{125, 135, 20, -4, -1,  4},
-        Profile{150, 175, 20, -4,  1,  7},
-        Profile{250, 375, 22, -4,  2, 12},
-        Profile{400, max, 23, -6,  2, 12},
+        Profile{ 50,  90, 18, -4, -2,  1, 24},
+        Profile{100, 110, 20, -4, -2,  2, 24},
+        Profile{125, 135, 20, -4, -1,  4, 24},
+        Profile{150, 175, 20, -4,  1,  7, 24},
+        Profile{250, 375, 22, -4,  2, 12, 24},
+        Profile{400, max, 23, -6,  2, 12, 24},
     };
 
 /* Create an IndexParameters instance based on a given read length.
  * k, s, l, u, c and max_seed_len can be used to override determined parameters
  * by setting them to a value other than IndexParameters::DEFAULT.
  */
-IndexParameters IndexParameters::from_read_length(int read_length, int k, int s, int l, int u, int c, int max_seed_len) {
+IndexParameters IndexParameters::from_read_length(int read_length, int k, int s, int l, int u, int c, int max_seed_len, int digest) {
     const int default_c = 8;
     size_t canonical_read_length = 50;
     for (const auto& p : profiles) {
@@ -64,6 +66,9 @@ IndexParameters IndexParameters::from_read_length(int read_length, int k, int s,
             if (u == DEFAULT) {
                 u = p.u;
             }
+            if (digest == DEFAULT) {
+                digest = p.digest;
+            }
             canonical_read_length = p.canonical_read_length;
             break;
         }
@@ -78,7 +83,7 @@ IndexParameters IndexParameters::from_read_length(int read_length, int k, int s,
     }
     int q = std::pow(2, c == DEFAULT ? default_c : c) - 1;
 
-    return IndexParameters(canonical_read_length, k, s, l, u, q, max_dist);
+    return IndexParameters(canonical_read_length, k, s, l, u, q, max_dist, digest);
 }
 
 void IndexParameters::write(std::ostream& os) const {
@@ -89,6 +94,7 @@ void IndexParameters::write(std::ostream& os) const {
     write_int_to_ostream(os, randstrobe.u);
     write_int_to_ostream(os, randstrobe.q);
     write_int_to_ostream(os, randstrobe.max_dist);
+    write_int_to_ostream(os, randstrobe.digest);
 }
 
 IndexParameters IndexParameters::read(std::istream& is) {
@@ -99,7 +105,8 @@ IndexParameters IndexParameters::read(std::istream& is) {
     int u = read_int_from_istream(is);
     int q = read_int_from_istream(is);
     int max_dist = read_int_from_istream(is);
-    return IndexParameters(canonical_read_length, k, s, l, u, q, max_dist);
+    int digest = read_int_from_istream(is);
+    return IndexParameters(canonical_read_length, k, s, l, u, q, max_dist, digest);
 }
 
 bool IndexParameters::operator==(const IndexParameters& other) const {
@@ -119,7 +126,7 @@ std::string IndexParameters::filename_extension() const {
         // nothing was overridden
         sstream << ".r" << canonical_read_length;
     }
-    sstream << ".sti";
+    sstream << ".stimc";
     return sstream.str();
 }
 
diff --git a/src/indexparameters.hpp b/src/indexparameters.hpp
index 75e6c258..db6de72c 100644
--- a/src/indexparameters.hpp
+++ b/src/indexparameters.hpp
@@ -43,14 +43,16 @@ struct RandstrobeParameters {
     const int max_dist;
     const unsigned w_min;
     const unsigned w_max;
+    const unsigned digest;
 
-    RandstrobeParameters(int l, int u, uint64_t q, int max_dist, unsigned w_min, unsigned w_max)
+    RandstrobeParameters(int l, int u, uint64_t q, int max_dist, unsigned w_min, unsigned w_max, unsigned digest)
         : l(l)
         , u(u)
         , q(q)
         , max_dist(max_dist)
         , w_min(w_min)
         , w_max(w_max)
+        , digest(digest)
     {
         verify();
     }
@@ -65,6 +67,9 @@ struct RandstrobeParameters {
         if (w_min > w_max) {
             throw BadParameter("w_min is greater than w_max (choose different -l/-u parameters)");
         }
+        if (digest > 63) {
+            throw BadParameter("digest size is larger than 63");
+        }
     }
 };
 
@@ -77,15 +82,15 @@ class IndexParameters {
 
     static const int DEFAULT = std::numeric_limits<int>::min();
 
-    IndexParameters(size_t canonical_read_length, int k, int s, int l, int u, int q, int max_dist)
+    IndexParameters(size_t canonical_read_length, int k, int s, int l, int u, int q, int max_dist, int digest)
         : canonical_read_length(canonical_read_length)
         , syncmer(k, s)
-        , randstrobe(l, u, q, max_dist, std::max(0, k / (k - s + 1) + l), k / (k - s + 1) + u)
+        , randstrobe(l, u, q, max_dist, std::max(0, k / (k - s + 1) + l), k / (k - s + 1) + u, digest)
     {
     }
 
     static IndexParameters from_read_length(
-        int read_length, int k = DEFAULT, int s = DEFAULT, int l = DEFAULT, int u = DEFAULT, int c = DEFAULT, int max_seed_len = DEFAULT
+        int read_length, int k = DEFAULT, int s = DEFAULT, int l = DEFAULT, int u = DEFAULT, int c = DEFAULT, int max_seed_len = DEFAULT, int digest = DEFAULT
     );
     static IndexParameters read(std::istream& os);
     std::string filename_extension() const;
diff --git a/src/main.cpp b/src/main.cpp
index dcc96774..6da5763e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -167,7 +167,8 @@ int run_strobealign(int argc, char **argv) {
         opt.l_set ? opt.l : IndexParameters::DEFAULT,
         opt.u_set ? opt.u : IndexParameters::DEFAULT,
         opt.c_set ? opt.c : IndexParameters::DEFAULT,
-        opt.max_seed_len_set ? opt.max_seed_len : IndexParameters::DEFAULT
+        opt.max_seed_len_set ? opt.max_seed_len : IndexParameters::DEFAULT,
+        opt.digest ? opt.digest : IndexParameters::DEFAULT
     );
     logger.debug() << index_parameters << '\n';
     AlignmentParameters aln_params;
diff --git a/src/nam.cpp b/src/nam.cpp
index 2dfbccdb..37e1cf76 100644
--- a/src/nam.cpp
+++ b/src/nam.cpp
@@ -1,4 +1,5 @@
 #include "nam.hpp"
+static Logger& logger = Logger::get();
 
 namespace {
 
@@ -14,12 +15,14 @@ inline void add_to_hits_per_ref(
     int query_start,
     int query_end,
     const StrobemerIndex& index,
-    size_t position
+    size_t position,
+    bool is_partial
 ) {
     int min_diff = std::numeric_limits<int>::max();
     for (const auto hash = index.get_hash(position); index.get_hash(position) == hash; ++position) {
         int ref_start = index.get_strobe1_position(position);
-        int ref_end = ref_start + index.strobe2_offset(position) + index.k();
+        uint strobe2_position = is_partial ? 0 : index.strobe2_offset(position);
+        int ref_end = ref_start + strobe2_position + index.k();
         int diff = std::abs((query_end - query_start) - (ref_end - ref_start));
         if (diff <= min_diff) {
             hits_per_ref[index.reference_index(position)].push_back(Hit{query_start, query_end, ref_start, ref_end});
@@ -171,7 +174,17 @@ std::pair<float, std::vector<Nam>> find_nams(
                 continue;
             }
             nr_good_hits++;
-            add_to_hits_per_ref(hits_per_ref[q.is_reverse], q.start, q.end, index, position);
+            add_to_hits_per_ref(hits_per_ref[q.is_reverse], q.start, q.end, index, position, false);
+        } else {
+            size_t partial_pos = index.partial_find(q.hash);
+            if (partial_pos != index.end()) {
+                total_hits++;
+                if (index.is_partial_filtered(position)) {
+                    continue;
+                }
+                nr_good_hits++;
+                add_to_hits_per_ref(hits_per_ref[q.is_reverse], q.start, q.end, index, partial_pos, true);
+            }
         }
     }
     float nonrepetitive_fraction = total_hits > 0 ? ((float) nr_good_hits) / ((float) total_hits) : 1.0;
@@ -231,12 +244,14 @@ std::vector<Nam> find_nams_rescue(
             if ((rh.count > rescue_cutoff && cnt >= 5) || rh.count > 1000) {
                 break;
             }
-            add_to_hits_per_ref(hits_per_ref[is_revcomp], rh.query_start, rh.query_end, index, rh.position);
+            add_to_hits_per_ref(hits_per_ref[is_revcomp], rh.query_start, rh.query_end, index, rh.position, false);
             cnt++;
         }
         is_revcomp++;
     }
 
+
+
     return merge_hits_into_nams_forward_and_reverse(hits_per_ref, index.k(), true);
 }
 
diff --git a/src/randstrobes.cpp b/src/randstrobes.cpp
index 3cfb5a0a..47f092d7 100644
--- a/src/randstrobes.cpp
+++ b/src/randstrobes.cpp
@@ -49,6 +49,12 @@ static inline randstrobe_hash_t randstrobe_hash(syncmer_hash_t hash1, syncmer_ha
     return hash1 + hash2;
 }
 
+static inline digest_hash_t digest_hash(syncmer_hash_t hash1, syncmer_hash_t hash2, size_t digest_size) {
+    syncmer_hash_t main_hash = std::min(hash1, hash2);
+    syncmer_hash_t aux_hash = std::max(hash1, hash2);
+    return ((main_hash >> digest_size) << digest_size) ^ (aux_hash >> (64 - digest_size));
+}
+
 std::ostream& operator<<(std::ostream& os, const Syncmer& syncmer) {
     os << "Syncmer(hash=" << syncmer.hash << ", position=" << syncmer.position << ")";
     return os;
@@ -167,7 +173,10 @@ Randstrobe RandstrobeIterator::get(unsigned int strobe1_index) const {
         }
     }
 
-    return Randstrobe{randstrobe_hash(strobe1.hash, strobe2.hash), static_cast<uint32_t>(strobe1.position), static_cast<uint32_t>(strobe2.position)};
+//    return Randstrobe{randstrobe_hash(strobe1.hash, strobe2.hash), static_cast<uint32_t>(strobe1.position), static_cast<uint32_t>(strobe2.position)};
+    return Randstrobe{digest_hash(strobe1.hash, strobe2.hash, digest),
+                      static_cast<uint32_t>(strobe1.position),
+                      static_cast<uint32_t>(strobe2.position)};
 }
 
 Randstrobe RandstrobeGenerator::next() {
@@ -198,7 +207,10 @@ Randstrobe RandstrobeGenerator::next() {
         }
     }
     syncmers.pop_front();
-    return Randstrobe{randstrobe_hash(strobe1.hash, strobe2.hash), static_cast<uint32_t>(strobe1.position), static_cast<uint32_t>(strobe2.position)};
+//    return Randstrobe{randstrobe_hash(strobe1.hash, strobe2.hash), static_cast<uint32_t>(strobe1.position), static_cast<uint32_t>(strobe2.position)};
+    return Randstrobe{digest_hash(strobe1.hash, strobe2.hash, digest),
+                      static_cast<uint32_t>(strobe1.position),
+                      static_cast<uint32_t>(strobe2.position)};
 }
 
 /*
diff --git a/src/randstrobes.hpp b/src/randstrobes.hpp
index 7a117b3c..9ff77dad 100644
--- a/src/randstrobes.hpp
+++ b/src/randstrobes.hpp
@@ -16,6 +16,7 @@
 
 using syncmer_hash_t = uint64_t;
 using randstrobe_hash_t = uint64_t;
+using digest_hash_t = uint64_t;
 
 struct RefRandstrobe {
     using packed_t = uint32_t;
@@ -97,6 +98,7 @@ class RandstrobeIterator {
       , w_max(parameters.w_max)
       , q(parameters.q)
       , max_dist(parameters.max_dist)
+      , digest(parameters.digest)
     {
         if (w_min > w_max) {
             throw std::invalid_argument("w_min is greater than w_max");
@@ -118,6 +120,7 @@ class RandstrobeIterator {
     const unsigned w_max;
     const uint64_t q;
     const unsigned int max_dist;
+    uint digest;
     unsigned int strobe1_index = 0;
 };
 
@@ -166,6 +169,7 @@ class RandstrobeGenerator {
       , w_max(randstrobe_parameters.w_max)
       , q(randstrobe_parameters.q)
       , max_dist(randstrobe_parameters.max_dist)
+      , digest(randstrobe_parameters.digest)
     { }
 
     Randstrobe next();
@@ -177,6 +181,7 @@ class RandstrobeGenerator {
     const unsigned w_max;
     const uint64_t q;
     const unsigned int max_dist;
+    uint digest;
     std::deque<Syncmer> syncmers;
 };