From dc6cca42113ea7e9a292175e1704061d742014dd Mon Sep 17 00:00:00 2001
From: rsiddharth <s@ricketyspace.net>
Date: Tue, 8 Dec 2020 17:59:28 -0500
Subject: lib/blocks: move isECB from ch. 8 in here as BlockIsECB

---
 challenge/c08.go | 25 +------------------------
 lib/blocks.go    | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/challenge/c08.go b/challenge/c08.go
index 862c070..1f43b45 100644
--- a/challenge/c08.go
+++ b/challenge/c08.go
@@ -12,7 +12,7 @@ func C8() {
 	for i := 0; i < len(c08); i++ {
 		bs := lib.HexStrToBytes(c08[i])
 
-		block := isECB(bs)
+		block := lib.BlockIsECB(bs)
 		if block != nil {
 			fmt.Printf("Cipher at line %d (%s)", i+1, c08[i])
 			fmt.Printf(" might be AES encrypted in ECB mode.\n")
@@ -27,29 +27,6 @@ func C8() {
 // Cipher at line 133 (d880619740a8a19b7840a8a31c810a3d08649af70dc06f4fd5d2d69c744cd283e2dd052f6b641dbf9d11b0348542bb5708649af70dc06f4fd5d2d69c744cd2839475c9dfdbc1d46597949d9c7e82bf5a08649af70dc06f4fd5d2d69c744cd28397a93eab8d6aecd566489154789a6b0308649af70dc06f4fd5d2d69c744cd283d403180c98c8f6db1f2a3f9c4040deb0ab51b29933f2c123c58386b06fba186a) might be AES encrypted in ECB mode.
 // 16-byte block '08649af70dc06f4fd5d2d69c744cd283' occurs more than once in this cipher.
 
-func isECB(bs []byte) []byte {
-	blocks := lib.BreakIntoBlocks(bs, 16)
-
-	for i := 0; i < len(blocks); i++ {
-		if hasMatchingBlock(i, blocks) {
-			return blocks[i]
-		}
-	}
-	return nil
-}
-
-func hasMatchingBlock(id int, blocks [][]byte) bool {
-	for i := 0; i < len(blocks); i++ {
-		if i == id {
-			continue
-		}
-		if lib.BlocksEqual(blocks[i], blocks[id]) {
-			return true
-		}
-	}
-	return false
-}
-
 var c08 = []string{
 	"8a10247f90d0a05538888ad6205882196f5f6d05c21ec8dca0cb0be02c3f8b09e382963f443aa514daa501257b09a36bf8c4c392d8ca1bf4395f0d5f2542148c7e5ff22237969874bf66cb85357ef99956accf13ba1af36ca7a91a50533c4d89b7353f908c5a166774293b0bf6247391df69c87dacc4125a99ec417221b58170e633381e3847c6b1c28dda2913c011e13fc4406f8fe73bbf78e803e1d995ce4d",
 	"bd20aad820c9e387ea57408566e5844c1e470e9d6fbbdba3a6b4df1dd85bce2208f1944f1827d015df9c46c22803f41d1052acb721977f0ccc13db95c970252091ea5e36e423ee6a2f2d12ef909fcadd42529885d221af1225e32161b85e6dc03465cf398c937846b18bac05e88820a567caac113762753dffbe6ece09823bab5aee947a682bb3156f42df1d8dc320a897ee79981cf937390b4ae93eb8657f6c",
diff --git a/lib/blocks.go b/lib/blocks.go
index 1ba811f..452766b 100644
--- a/lib/blocks.go
+++ b/lib/blocks.go
@@ -61,6 +61,29 @@ func BlocksEqual(a, b []byte) bool {
 	return true
 }
 
+func BlockIsECB(bs []byte) []byte {
+	blocks := BreakIntoBlocks(bs, 16)
+
+	for i := 0; i < len(blocks); i++ {
+		if hasMatchingBlock(i, blocks) {
+			return blocks[i]
+		}
+	}
+	return nil
+}
+
+func hasMatchingBlock(id int, blocks [][]byte) bool {
+	for i := 0; i < len(blocks); i++ {
+		if i == id {
+			continue
+		}
+		if BlocksEqual(blocks[i], blocks[id]) {
+			return true
+		}
+	}
+	return false
+}
+
 // Performs PKCS#7 Padding on the input `in` and block size `k`.
 // Assumes 0 > `k` < 256
 // Reference: https://tools.ietf.org/html/rfc5652#section-6.3
-- 
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