challenge/c12.go: refactor

Keep everything inside C12

1 files changed, 76 insertions, 81 deletions

diff --git a/challenge/c12.go b/challenge/c12.go
index a19777b..b76f28a 100644
--- a/challenge/c12.go
+++ b/challenge/c12.go
@@ -5,16 +5,89 @@ package challenge
 
 import (
 	"fmt"
+
 	"ricketyspace.net/cryptopals/lib"
 )
 
-var sheep byte = 65
-
 func C12() {
+	sheep := byte(65)
+	freshSheepBytes := func(n int) []byte {
+		in := make([]byte, n)
+		for i := 0; i < n; i++ {
+			in[i] = sheep
+		}
+		return in
+	}
+	findBlockSize := func() int {
+		in := make([]byte, 0)
+
+		in = append(in, sheep)
+		is := len(lib.OracleAESEncryptECB(in)) // initial size
+		bs := 0                                // block size
+		for {
+			in = append(in, sheep)
+			bs = len(lib.OracleAESEncryptECB(in))
+			if bs != is {
+				return (bs - is)
+			}
+		}
+	}
+	findUnknownStringCharacteristics := func(blocksize int) (int, int) {
+		in := make([]byte, 0)
+		c_sz := len(lib.OracleAESEncryptECB(in)) // Cipher size
+		nblocks := c_sz / blocksize              // number of blocks
+
+		// Figure out ize of unknown string.
+		for {
+			in = append(in, sheep)
+			bs := len(lib.OracleAESEncryptECB(in))
+			if bs != c_sz {
+				return nblocks, (c_sz - len(in))
+			}
+		}
+
+	}
+	isOracleUsingECB := func() bool {
+		in := lib.StrToBytes("OliverMkTukudzi OliverMkTukudzi OliverMkTukudzi")
+		oo := lib.OracleAESEncryptECB(in)
+		if lib.CipherUsesECB(oo) != nil {
+			return true
+		}
+		return false
+	}
+	// `blocksize` is the size of a block
+	// `block` is the nth block that is being deciphered
+	// `n` is the nth byte of the block `block` that is going to be deciphered.
+	// `in` (n-1)th block that is known
+	// `ds` deciphered unknown string
+	decipherUnknownStringIter := func(blocksize, block, n int, in, ds []byte) ([]byte, []byte) {
+		oo := lib.OracleAESEncryptECB(in[0:(blocksize - n)])
+
+		s := 16 * (block - 1)
+		e := s + 16
+		nbl := oo[s:e] // nth block of the cipher
+
+		// Shift `in` to the left by one place.
+		for i := 0; i < blocksize-1; i++ {
+			in[i] = in[i+1]
+		}
+
+		// Try all combinations.
+		for i := 0; i < 256; i++ {
+			in[15] = byte(i)
+			oo = lib.OracleAESEncryptECB(in)
+
+			if lib.BlocksEqual(nbl, oo[0:16]) {
+				ds = append(ds, in[15])
+				return in, ds
+			}
+		}
+		panic("not found!")
+	}
+
 	if !isOracleUsingECB() {
 		panic("oracle not using ecb mode")
 	}
-
 	blocksize := findBlockSize()
 	nbl, us_sz := findUnknownStringCharacteristics(blocksize)
 	in := freshSheepBytes(blocksize)
@@ -35,84 +108,6 @@ func C12() {
 	fmt.Printf("Unknown String:\n%v", lib.BytesToStr(ds))
 }
 
-func freshSheepBytes(n int) []byte {
-	in := make([]byte, n)
-	for i := 0; i < n; i++ {
-		in[i] = sheep
-	}
-	return in
-}
-
-func findBlockSize() int {
-	in := make([]byte, 0)
-
-	in = append(in, sheep)
-	is := len(lib.OracleAESEncryptECB(in)) // initial size
-	bs := 0                                // block size
-	for {
-		in = append(in, sheep)
-		bs = len(lib.OracleAESEncryptECB(in))
-		if bs != is {
-			return (bs - is)
-		}
-	}
-}
-
-func findUnknownStringCharacteristics(blocksize int) (int, int) {
-	in := make([]byte, 0)
-	c_sz := len(lib.OracleAESEncryptECB(in)) // Cipher size
-	nblocks := c_sz / blocksize              // number of blocks
-
-	// Figure out ize of unknown string.
-	for {
-		in = append(in, sheep)
-		bs := len(lib.OracleAESEncryptECB(in))
-		if bs != c_sz {
-			return nblocks, (c_sz - len(in))
-		}
-	}
-
-}
-
-func isOracleUsingECB() bool {
-	in := lib.StrToBytes("OliverMkTukudzi OliverMkTukudzi OliverMkTukudzi")
-	oo := lib.OracleAESEncryptECB(in)
-	if lib.CipherUsesECB(oo) != nil {
-		return true
-	}
-	return false
-}
-
-// `blocksize` is the size of a block
-// `block` is the nth block that is being deciphered
-// `n` is the nth byte of the block `block` that is going to be deciphered.
-// `in` (n-1)th block that is known
-// `ds` deciphered unknown string
-func decipherUnknownStringIter(blocksize, block, n int, in, ds []byte) ([]byte, []byte) {
-	oo := lib.OracleAESEncryptECB(in[0:(blocksize - n)])
-
-	s := 16 * (block - 1)
-	e := s + 16
-	nbl := oo[s:e] // nth block of the cipher
-
-	// Shift `in` to the left by one place.
-	for i := 0; i < blocksize-1; i++ {
-		in[i] = in[i+1]
-	}
-
-	// Try all combinations.
-	for i := 0; i < 256; i++ {
-		in[15] = byte(i)
-		oo = lib.OracleAESEncryptECB(in)
-
-		if lib.BlocksEqual(nbl, oo[0:16]) {
-			ds = append(ds, in[15])
-			return in, ds
-		}
-	}
-	panic("not found!")
-}
-
 // Output:
 // Unknown String:
 // Rollin' in my 5.0