diff --git a/zack/swh-dedup-blocks.py b/zack/swh-dedup-blocks.py
new file mode 100755
index 0000000..3428977
--- /dev/null
+++ b/zack/swh-dedup-blocks.py
@@ -0,0 +1,161 @@
+#!/usr/bin/python3
+
+"""compute Rabin fingerprints of Software Heritage content objects
+
+Read a list of Software Heritage content object IDs on standard input, fetch
+each of them from a (local) object storage and apply Rabin fingerprinting to
+its content. Store in a (sqlite) DB the mapping between content objects and
+(Rabin-delimited) chunks.
+
+"""
+
+import logging
+import os
+import rabin
+import sqlite3
+import sys
+
+from hashlib import sha1
+
+from swh.objstorage import PathSlicingObjStorage as ObjStorage
+from swh.objstorage.exc import ObjNotFoundError
+
+OBJS_ROOT = '/srv/softwareheritage/objects'
+OBJS_SLICING = '0:2/2:4'
+SQLITE_DB = 'swh-dedup.db'
+RABIN_PARAMS = {
+    # 'prime': 3,
+    # 'window_size': 48,  # bytes
+    # 'min_block_size':  2 * 1024,  # bytes
+    # 'avg_block_size':  8 * 1024,  # bytes
+    # 'max_block_size': 64 * 1024,  # bytes
+}
+
+
+def rabin_init(params):
+    if 'prime' in params:
+        rabin.set_prime(params['prime'])
+    if 'window_size' in params:
+        rabin.set_window_size(params['window_size'])
+    if 'min_block_size' in params:
+        rabin.set_min_block_size(params['min_block_size'])
+    if 'avg_block_size' in params:
+        rabin.set_avg_block_size(params['avg_block_size'])
+    if 'max_block_size' in params:
+        rabin.set_max_block_size(params['max_block_size'])
+
+
+def db_init(db):
+    with db:
+        db.execute('''CREATE TABLE content (
+id string PRIMARY KEY,  -- SHA1 checksum
+length integer
+)''')
+        db.execute('''CREATE TABLE chunk (
+id string PRIMARY KEY,  -- SHA1 checksum
+length integer
+)''')
+        db.execute('''CREATE TABLE chunked_content (
+content_id string REFERENCES content(sha1),
+chunk_id string REFERENCES chunk(sha1),
+offset integer
+)''')
+        db.execute('''CREATE INDEX idx_chunked_content_id
+ON chunked_content (content_id)
+''')
+
+
+def db_insert_chunk(db, content_id, chunk_id, offset, length):
+    with db:
+        c = db.cursor()
+
+        c.execute('SELECT 1 FROM chunk WHERE id = ?', [chunk_id])
+        if not c.fetchone():
+            c.execute('INSERT INTO chunk (id, length) VALUES (?, ?)',
+                      (chunk_id, length))
+
+        c.execute('''INSERT INTO chunked_content
+                      (content_id, chunk_id, offset) VALUES (?, ?, ?)''',
+                  (content_id, chunk_id, offset))
+
+
+def db_insert_content(db, content_id, length):
+    with db:
+        c = db.cursor()
+
+        c.execute('SELECT 1 FROM content WHERE id = ?', [content_id])
+        if not c.fetchone():
+            db.execute('INSERT INTO content (id, length) VALUES (?, ?)',
+                       (content_id, length))
+
+
+def print_summary(db):
+    with db:
+        c = db.cursor()
+
+        c.execute('SELECT count(*) FROM content')
+        print('contents:', c.fetchone()[0])
+        c.execute('SELECT count(*) FROM chunk')
+        print('chunks:', c.fetchone()[0])
+
+        c.execute('SELECT sum(length) FROM content')
+        content_size = int(c.fetchone()[0])
+        print('total content size:', content_size)
+
+        c.execute('SELECT sum(length) FROM chunk')
+        chunk_size = int(c.fetchone()[0])
+        print('total chunk size:', chunk_size)
+
+        print('compression gain: %.2f%%' %
+              (100 - float(chunk_size) / content_size * 100))
+
+
+def dedup(db, oid, content):
+    r = rabin.Rabin()
+    buf = bytearray()
+
+    for data in content:
+        buf.extend(data)  # TODO avoid loading the entire content in memory
+        r.update(data)
+
+    if buf:  # r.fingerprints() invoked on empty objects segfaults :-(
+        for (offset, length, _fpr) in r.fingerprints():
+            chunk = buf[offset:(offset+length)]
+            chunk_id = sha1(chunk).hexdigest()
+            db_insert_chunk(db, oid, chunk_id, offset, length)
+
+    r.clear()
+    return len(buf)
+
+
+def main():
+    rabin_init(RABIN_PARAMS)
+
+    objs = ObjStorage(OBJS_ROOT, OBJS_SLICING)
+
+    missing_db = not os.path.exists(SQLITE_DB)
+    db = sqlite3.connect('swh-dedup.db')
+    if missing_db:
+        db_init(db)
+
+    obj_count = 0
+    for line in sys.stdin:
+        oid = line.rstrip()
+        # print('object', oid)
+        try:
+            object_len = dedup(db, oid, objs.get_stream(oid))
+            db_insert_content(db, oid, object_len)
+        except ObjNotFoundError:
+            logging.warning('cannot find object "%s", skipping' % oid)
+
+        obj_count += 1
+        if obj_count % 1000 == 0:
+            logging.info('processed %d objects, currently at %s' %
+                         (obj_count, oid))
+
+    print_summary(db)
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+    main()