Made changes to ch04.asciidoc

ch04.asciidoc

@@ -97,12 +97,12 @@ The public key is calculated from the private key using elliptic curve multiplic
 [[elliptic_curve]]
 ==== Elliptic Curve Cryptography Explained
 ((("elliptic curve cryptography", "ECC")))
-Elliptic Curve Cryptography is a type of asymmetric or public-key cryptography based on the discrete logarithm problem as expressed by addition and multiplication on the points of an elliptic curve. 
+Elliptic curve cryptography is a type of asymmetric or public-key cryptography based on the discrete logarithm problem as expressed by addition and multiplication on the points of an elliptic curve. 
 
-Below we see an example of an elliptic curve, similar to that used by bitcoin:
+<<ecc-curve>> shows we see an example of an elliptic curve, similar to that used by bitcoin.
 
 [[ecc-curve]]
-.An Elliptic Curve
+.An elliptic curve
 image::images/msbt_0402.png["ecc-curve"]
 
 Bitcoin uses a specific elliptic curve and set of mathematical constants, as defined in a standard called +secp256k1+, established by the National Institute of Standards and Technology (NIST). The +secp256k1+ curve is defined by the following function, which produces an elliptic curve:
@@ -123,7 +123,7 @@ or
 \end{equation}
 ++++
 
-The +mod p+ (modulo prime number p) indicates that this curve is over a finite field of prime order +p+, also written as latexmath:[\(\mathbb{F}_p\)], where p = 2^256^ - 2^32^ - 2^9^ - 2^8^ - 2^7^ - 2^6^ - 2^4^ - 1, a very large prime number. 
+The _mod p_ (modulo prime number p) indicates that this curve is over a finite field of prime order _p_, also written as latexmath:[\(\mathbb{F}_p\)], where p = 2^256^ – 2^32^ – 2^9^ – 2^8^ – 2^7^ – 2^6^ – 2^4^ – 1, a very large prime number. 
 
 Because this curve is defined over a finite field of prime order instead of over the real numbers it looks like a pattern of dots scattered in two dimensions, which makes it difficult to visualize. However, the math is identical as that of an elliptic curve over the real numbers shown above. As an example, below is the same elliptic curve over a much smaller finite field of prime order 17, showing a pattern of dots on a grid. The +secp256k1+ bitcoin elliptic curve can be thought of as a much more complex pattern of dots on a unfathomably large grid.