Merge pull request bitcoin#1245 from Mironenko/patch-1

Fix typo in BIP-32

Author: kallewoof

bip-0032.mediawiki

@@ -201,7 +201,7 @@ In addition to the expectations from the EC public-key cryptography itself:
 the intended security properties of this standard are:
 * Given a child extended private key (k<sub>i</sub>,c<sub>i</sub>) and the integer i, an attacker cannot find the parent private key k<sub>par</sub> more efficiently than a 2<sup>256</sup> brute force of HMAC-SHA512.
 * Given any number (2 ≤ N ≤ 2<sup>32</sup>-1) of (index, extended private key) tuples (i<sub>j</sub>,(k<sub>i<sub>j</sub></sub>,c<sub>i<sub>j</sub></sub>)), with distinct i<sub>j</sub>'s, determining whether they are derived from a common parent extended private key (i.e., whether there exists a (k<sub>par</sub>,c<sub>par</sub>) such that for each j in (0..N-1) CKDpriv((k<sub>par</sub>,c<sub>par</sub>),i<sub>j</sub>)=(k<sub>i<sub>j</sub></sub>,c<sub>i<sub>j</sub></sub>)), cannot be done more efficiently than a 2<sup>256</sup> brute force of HMAC-SHA512.
-Note however that the following properties does not exist:
+Note however that the following properties do not exist:
 * Given a parent extended public key (K<sub>par</sub>,c<sub>par</sub>) and a child public key (K<sub>i</sub>), it is hard to find i.
 * Given a parent extended public key (K<sub>par</sub>,c<sub>par</sub>) and a non-hardened child private key (k<sub>i</sub>), it is hard to find k<sub>par</sub>.