Add utility functions for checking CSR and privkey

letsencrypt/client/crypto_util.py

@@ -198,3 +198,31 @@ def get_cert_info(filename):
         "pub_key": "RSA " + str(cert.get_pubkey().size() * 8),
     }
 
+def valid_csr(csr_filename):
+    """Check if csr_filename is a valid CSR.  (Currently, could raise
+    non-X.509-related errors such as IOError associated with problems
+    reading the file.)"""
+    try:
+        csr = M2Crypto.X509.load_request(csr_filename)
+        return bool(csr.verify(csr.get_pubkey()))
+    except M2Crypto.X509.X509Error:
+        return False
+
+def valid_privkey(privkey_filename):
+    """Check if privkey_filename is a valid RSA private key.  (Currently,
+    could raise non-RSA-related errors such as IOError associated with
+    problems reading the file.)"""
+    try:
+        privkey = M2Crypto.RSA.load_key(privkey_filename)
+        return bool(privkey.check_key())
+    except M2Crypto.RSA.RSAError:
+        return False
+
+def csr_matches_pubkey(csr_filename, privkey_filename):
+    """Check if the private key in the file corresponds to the subject
+    public key in the CSR."""
+    csr = M2Crypto.X509.load_request(csr_filename)
+    privkey = M2Crypto.RSA.load_key(privkey_filename)
+    csr_pub = csr.get_pubkey().get_rsa().pub()
+    privkey_pub = privkey.pub()
+    return csr_pub == privkey_pub