From 6c4749a903744a16deb2fa6c426c4193afe76b4c Mon Sep 17 00:00:00 2001
From: rsiddharth <s@ricketyspace.net>
Date: Wed, 24 Feb 2021 19:58:23 -0500
Subject: lib: remove OracleAESRandomEncrypt

Move function into C11 where it is used.
---
 challenge/c11.go | 34 +++++++++++++++++++++++++++++++++-
 lib/oracle.go    | 32 --------------------------------
 lib/rand.go      |  2 +-
 3 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/challenge/c11.go b/challenge/c11.go
index 703b959..211d48c 100644
--- a/challenge/c11.go
+++ b/challenge/c11.go
@@ -10,11 +10,43 @@ import (
 )
 
 func C11() {
+	// Given an input `in`, this function AES encrypts `in` using a
+	// randomly generate 16-byte key using ECB or CBC mode and returns the
+	// cipher.
+	encrypt := func(in []byte) []byte {
+		// Generate random key.
+		key, err := lib.RandomBytes(16)
+		if err != nil {
+			panic(err)
+		}
+		// Generate random initialization vector; needed for AES CBC.
+		iv, err := lib.RandomBytes(16)
+		if err != nil {
+			panic(err)
+		}
+
+		// Add 5-10 bytes at the beginning and end of `in`
+		in = append(lib.RandomBytesWithLengthBetween(5, 10), in...)
+		in = append(in, lib.RandomBytesWithLengthBetween(5, 10)...)
+
+		// Randomly encrypt `in` with AES in ECB or CBC mode.
+		m := lib.RandomInt(0, 1)
+		var out []byte
+		if m == 0 {
+			// Encrypt with AES in ECB mode.
+			out = lib.AESEncryptECB(in, key)
+		} else {
+			// Encrypt with AES in CBC mode.
+			out = lib.AESEncryptCBC(in, key, iv)
+		}
+		return out
+	}
+
 	p := lib.StrToBytes("YellowSubmarine YellowSubmarine YellowSubmarine")
 	fmt.Printf("Input: %v (%d)\n", p, len(p))
 
 	for i := 0; i < 10; i++ {
-		o := lib.OracleAESRandomEncrypt(p)
+		o := encrypt(p)
 		if lib.CipherUsesECB(o) != nil {
 			fmt.Printf("%d -> Enciphered with ECB: %v (%d)\n", i, o, len(o))
 		} else {
diff --git a/lib/oracle.go b/lib/oracle.go
index 29338ff..8a449a1 100644
--- a/lib/oracle.go
+++ b/lib/oracle.go
@@ -25,38 +25,6 @@ func init() {
 	}
 }
 
-// Given an input `in`, this function AES encrypts `in` using a
-// randomly generate 16-byte key using ECB or CBC mode and returns the
-// cipher.
-func OracleAESRandomEncrypt(in []byte) []byte {
-	// Generate random key.
-	key, err := RandomBytes(16)
-	if err != nil {
-		panic(err)
-	}
-	// Generate random initialization vector; needed for AES CBC.
-	iv, err := RandomBytes(16)
-	if err != nil {
-		panic(err)
-	}
-
-	// Add 5-10 bytes at the beginning and end of `in`
-	in = append(randomBytesWithLengthBetween(5, 10), in...)
-	in = append(in, randomBytesWithLengthBetween(5, 10)...)
-
-	// Randomly encrypt `in` with AES in ECB or CBC mode.
-	m := RandomInt(0, 1)
-	var out []byte
-	if m == 0 {
-		// Encrypt with AES in ECB mode.
-		out = AESEncryptECB(in, key)
-	} else {
-		// Encrypt with AES in CBC mode.
-		out = AESEncryptCBC(in, key, iv)
-	}
-	return out
-}
-
 func OracleAESEncryptECB(in []byte) []byte {
 	return AESEncryptECB(append(in, Base64ToBytes(oracleUnknown)...), oracleKey)
 }
diff --git a/lib/rand.go b/lib/rand.go
index 1ba1679..be95366 100644
--- a/lib/rand.go
+++ b/lib/rand.go
@@ -37,7 +37,7 @@ func RandomBytes(size int) ([]byte, error) {
 }
 
 // Randomly generates `min` to `max` bytes.
-func randomBytesWithLengthBetween(min, max int64) []byte {
+func RandomBytesWithLengthBetween(min, max int64) []byte {
 	bs := make([]byte, RandomInt(min, max))
 	_, err := rand.Read(bs)
 	if err != nil {
-- 
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