Add a utility to compare multiple hash implementations

1 files changed, 80 insertions, 0 deletions

diff --git a/utils/fuzzy-hash-tester.py b/utils/fuzzy-hash-tester.py
new file mode 100755
index 0000000..2d0c426
--- /dev/null
+++ b/utils/fuzzy-hash-tester.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python
+# dumb utility to randomly test different hash implementations
+# for compliance
+
+import base64
+import functools
+import hashlib
+import random
+import subprocess
+import sys
+
+import pyblake2
+
+
+class ExternalToolHash(object):
+    def __init__(self, argv):
+        self.subp = subprocess.Popen(argv,
+                stdin=subprocess.PIPE,
+                stdout=subprocess.PIPE)
+
+    def update(self, data):
+        self.subp.stdin.write(data)
+
+    def hexdigest(self):
+        stdo, stde = self.subp.communicate()
+        return stdo.decode('ASCII').split()[0]
+
+
+ALGORITHMS = {
+    'md5': [hashlib.md5,
+            functools.partial(ExternalToolHash, 'md5sum')],
+    'sha1': [hashlib.sha1,
+             functools.partial(ExternalToolHash, 'sha1sum')],
+    'sha224': [hashlib.sha224,
+               functools.partial(ExternalToolHash, 'sha224sum')],
+    'sha256': [hashlib.sha256,
+               functools.partial(ExternalToolHash, 'sha256sum')],
+    'sha384': [hashlib.sha384,
+               functools.partial(ExternalToolHash, 'sha384sum')],
+    'sha512': [hashlib.sha512,
+               functools.partial(ExternalToolHash, 'sha512sum')],
+    'blake2b': [hashlib.blake2b, pyblake2.blake2b,
+                functools.partial(ExternalToolHash, 'b2sum')],
+}
+
+
+def main(algo_name, min_size, max_size=None):
+    impls = ALGORITHMS[algo_name]
+    if max_size is None:
+        max_size = min_size
+    min_size = int(min_size)
+    max_size = int(max_size)
+
+    with open('/dev/urandom', 'rb') as urandom:
+        i = 0
+        while True:
+            size = random.randint(min_size, max_size)
+            data = urandom.read(size)
+            digests = {}
+            for a in impls:
+                h = a()
+                h.update(data)
+                digests[a] = h.hexdigest()
+
+            if len(set(digests.values())) != 1:
+                print('Inconsistent hash values found!')
+                print('Hash values:')
+                for a, v in digests.items():
+                    print('  {}: {}'.format(a, v))
+                print('Data block as base64:')
+                print(base64.encodebytes(data).decode())
+                sys.exit(1)
+
+            i += 1
+            if i % 1000 == 0:
+                print('{} blocks tested.'.format(i))
+
+
+if __name__ == '__main__':
+    main(*sys.argv[1:])