Fixed gmpy requirement

.travis.yml

@@ -4,12 +4,14 @@ env:
 language: python
 python:
   - "2.7"
+  - "3.4"
   - "3.5"
   - "3.6"
   - "3.7"
 install:
   - pip install pytest pycryptodome pytest-cov coveralls
   - pip install -r requirements.txt
+  - pip install -r requirements_extra.txt
   - pip install .
 script:
   - pytest --cov-config .coveragerc --cov=ctftools tests

ctftools/rsatools.py

@@ -26,11 +26,15 @@
 # low private exponent: wiener attack
 # low public exponent: coppersmith theorem, hastad's broadcast attack, related messages
 
-import gmpy2
+from pkgutil import iter_modules
 from six import iterbytes, binary_type, int2byte
 from .utils import egcd
 
 
+def module_exists(module_name):
+    return module_name in (name for loader, name, ispkg in iter_modules())
+
+
 def phi(p, q):
     return (p - 1) * (q - 1)
 
@@ -46,11 +50,14 @@ def modinv(a, m):
 
 def compute_root(n, r, precision=300):
     """Compute the r-th root of n"""
-    gmpy2.get_context().precision = precision
-    m = gmpy2.mpz(n)
-    root, exact = gmpy2.iroot(m, r)
+    if not module_exists('gmpy'):
+        raise ImportError("`compute_root` needs the gmpy module to work!")
+    import gmpy
+    gmpy.set_minprec(precision)
+    m = gmpy.mpz(n)
+    root, exact = gmpy.root(m, r)
     if not exact:
-        raise ValueError("The root is not exact, maybe try increasing the precision?")
+        raise ValueError("No exact root found, maybe try increasing the precision?")
     return int(root)
 
 

requirements.txt

@@ -1,2 +1 @@
 six
-gmpy2

requirements_extra.txt

@@ -0,0 +1 @@
+gmpy

setup.py

@@ -24,6 +24,7 @@
     package_data={"ctftools": ["data/english_words.txt"]},
     install_requires=requirements,
     extras_require={
+        "rsa": ["gmpy"],
         "tests": ["pytest", "pycryptodome"]
     },
     classifiers=[