From 757c1483b44bb06b5e04a263f78c5f5317067eb0 Mon Sep 17 00:00:00 2001
From: derek mcquay <derekmcquay@gmail.com>
Date: Sat, 12 Mar 2016 23:06:24 -0800
Subject: [PATCH] got guess function to work for example from book

it calculates (hard coded) the example from the book.  Next step is
making it take any string, calculate the character frequency and then do
the same calculation and print out top answers
---
 main.go         | 17 +++++++++--
 psyfer/guess.go | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+), 2 deletions(-)
 create mode 100644 psyfer/guess.go

diff --git a/main.go b/main.go
index eeeb865..4a08bc9 100644
--- a/main.go
+++ b/main.go
@@ -106,7 +106,7 @@ func main() {
 	}
 
 	var vig = &cobra.Command{
-		Use:   "vig mode -c [cipher] -k [key] -i [input]",
+		Use:   "vig",
 		Short: "vignenere cipher",
 		Long:  `perform vigenere cipher`,
 		Run: func(cmd *cobra.Command, args []string) {
@@ -122,6 +122,19 @@ func main() {
 		},
 	}
 
+	var guess = &cobra.Command{
+		Use:   "guess",
+		Short: "guess cipher",
+		Long:  `will try to guess ceasar cipher`,
+		Run: func(cmd *cobra.Command, args []string) {
+			if len(args) < 1 {
+				fmt.Println("missing input, see -h (--help) for more info")
+				os.Exit(1)
+			}
+			psyfer.Guess()
+		},
+	}
+
 	var random = &cobra.Command{
 		Use:   "random",
 		Short: "randomly transpose",
@@ -236,7 +249,7 @@ func main() {
 	)
 
 	var rootCmd = &cobra.Command{Use: "app"}
-	rootCmd.AddCommand(sub, aes, trans, vig)
+	rootCmd.AddCommand(sub, aes, trans, vig, guess)
 	trans.AddCommand(random, railfence, split)
 	rootCmd.Execute()
 }
diff --git a/psyfer/guess.go b/psyfer/guess.go
new file mode 100644
index 0000000..2eb1738
--- /dev/null
+++ b/psyfer/guess.go
@@ -0,0 +1,79 @@
+package psyfer
+
+import (
+	"fmt"
+	"math"
+	"sort"
+)
+
+var charFreq = []float64{
+	0.080,
+	0.015,
+	0.030,
+	0.040,
+	0.130,
+	0.020,
+	0.015,
+	0.060,
+	0.065,
+	0.005,
+	0.005,
+	0.035,
+	0.030,
+	0.070,
+	0.080,
+	0.020,
+	0.002,
+	0.065,
+	0.060,
+	0.090,
+	0.030,
+	0.010,
+	0.015,
+	0.005,
+	0.020,
+	0.002,
+}
+
+func pc(position, i int) int {
+	if position-i < 0 {
+		return 26 - (int(math.Abs(float64((position - i) % 26))))
+	} else {
+		return int(math.Abs(float64((position - i) % 26)))
+	}
+}
+
+func (p phi) String() string {
+	return fmt.Sprintf("%d %f\n", p.position, p.value)
+}
+
+type phi struct {
+	position int
+	value    float64
+}
+
+type allPhi []phi
+
+func (p allPhi) Len() int           { return len(p) }
+func (p allPhi) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+func (p allPhi) Less(i, j int) bool { return p[i].value < p[j].value }
+
+func Guess() {
+	fmt.Println((6 - 7) % 26)
+	total := []phi{}
+	for i := 0; i < 26; i++ {
+		a := 0.0
+		a += 0.1 * charFreq[pc(6, i)]
+		a += 0.1 * charFreq[pc(7, i)]
+		a += 0.1 * charFreq[pc(10, i)]
+		a += 0.3 * charFreq[pc(14, i)]
+		a += 0.2 * charFreq[pc(17, i)]
+		a += 0.1 * charFreq[pc(20, i)]
+		a += 0.1 * charFreq[pc(25, i)]
+		p := phi{i, a}
+		total = append(total, p)
+	}
+	fmt.Println(total)
+	sort.Sort(allPhi(total))
+	fmt.Println(total)
+}