Revert "Switch to sslcrypto for cryptography tasks (#2338)"

This reverts commit fbc7b6fc4f.

src/util/Electrum.py

@@ -1,39 +0,0 @@
-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()