1 files changed, 68 insertions, 0 deletions
diff --git a/recaptcha/client/mailhide.py b/recaptcha/client/mailhide.py
new file mode 100644
index 00000000..437b2c25
--- /dev/null
+++ b/recaptcha/client/mailhide.py
@@ -0,0 +1,68 @@
+import base64
+import cgi
+
+try:
+    from Crypto.Cipher import AES
+except:
+    raise Exception ("You need the pycrpyto library: http://cheeseshop.python.org/pypi/pycrypto/")
+
+MAIL_HIDE_BASE="http://www.google.com/recaptcha/mailhide"
+
+def asurl (email,
+                 public_key,
+                 private_key):
+    """Wraps an email address with reCAPTCHA mailhide and
+    returns the url. public_key is the public key from reCAPTCHA
+    (in the base 64 encoded format). Private key is the AES key, and should
+    be 32 hex chars."""
+    
+    cryptmail = _encrypt_string (email, base64.b16decode (private_key, casefold=True), '\0' * 16)
+    base64crypt = base64.urlsafe_b64encode (cryptmail)
+
+    return "%s/d?k=%s&c=%s" % (MAIL_HIDE_BASE, public_key, base64crypt)
+
+def ashtml (email,
+                  public_key,
+                  private_key):
+    """Wraps an email address with reCAPTCHA Mailhide and
+    returns html that displays the email"""
+
+    url = asurl (email, public_key, private_key)
+    (userpart, domainpart) = _doterizeemail (email)
+
+    return """%(user)s<a href='%(url)s' onclick="window.open('%(url)s', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;" title="Reveal this e-mail address">...</a>@%(domain)s""" % {
+        'user' : cgi.escape (userpart),
+        'domain' : cgi.escape (domainpart),
+        'url'  : cgi.escape (url),
+        }
+    
+
+def _pad_string (str, block_size):
+    numpad = block_size - (len (str) % block_size)
+    return str + numpad * chr (numpad)
+
+def _encrypt_string (str, aes_key, aes_iv):
+    if len (aes_key) != 16:
+        raise Exception ("expecting key of length 16")
+    if len (aes_iv) != 16:
+        raise Exception ("expecting iv of length 16")
+    return AES.new (aes_key, AES.MODE_CBC, aes_iv).encrypt (_pad_string (str, 16))
+
+def _doterizeemail (email):
+    """replaces part of the username with dots"""
+    
+    try:
+        [user, domain] = email.split ('@')
+    except:
+        # handle invalid emails... sorta
+        user = email
+        domain = ""
+
+    if len(user) <= 4:
+        user_prefix = user[:1]
+    elif len(user) <= 6:
+        user_prefix = user[:3]
+    else:
+        user_prefix = user[:4]
+
+    return (user_prefix, domain)