Switch to sslcrypto for cryptography tasks (#2338)

* Use sslcrypto instead of pyelliptic and pybitcointools

* Fix CryptMessage

* Support Python 3.4

* Fix user creation

* Get rid of pyelliptic and pybitcointools

* Fix typo

* Delete test file

* Add sslcrypto to tree

* Update sslcrypto

* Add pyaes to src/lib

* Fix typo in tests

* Update sslcrypto version

* Use privatekey_bin instead of privatekey for bytes objects

* Fix sslcrypto

* Fix Benchmark plugin

* Don't calculate the same thing twice

* Only import sslcrypto once

* Handle fallback sslcrypto implementation during tests

* Fix sslcrypto fallback implementation selection

src/util/Electrum.py

@@ -0,0 +1,39 @@
+import hashlib
+import struct
+
+
+# Electrum, the heck?!
+
+def bchr(i):
+    return struct.pack("B", i)
+
+def encode(val, base, minlen=0):
+    base, minlen = int(base), int(minlen)
+    code_string = b"".join([bchr(x) for x in range(256)])
+    result = b""
+    while val > 0:
+        index = val % base
+        result = code_string[index:index + 1] + result
+        val //= base
+    return code_string[0:1] * max(minlen - len(result), 0) + result
+
+def insane_int(x):
+    x = int(x)
+    if x < 253:
+        return bchr(x)
+    elif x < 65536:
+        return bchr(253) + encode(x, 256, 2)[::-1]
+    elif x < 4294967296:
+        return bchr(254) + encode(x, 256, 4)[::-1]
+    else:
+        return bchr(255) + encode(x, 256, 8)[::-1]
+
+
+def magic(message):
+    return b"\x18Bitcoin Signed Message:\n" + insane_int(len(message)) + message
+
+def format(message):
+    return hashlib.sha256(magic(message)).digest()
+
+def dbl_format(message):
+    return hashlib.sha256(format(message)).digest()