1 files changed, 82 insertions, 6 deletions
diff --git a/challenge/c13.go b/challenge/c13.go
index 4c9a6f7..130499d 100644
--- a/challenge/c13.go
+++ b/challenge/c13.go
@@ -10,18 +10,94 @@ import (
 )
 
 func C13() {
+	type Profile map[string]string
+
+	key, err := lib.RandomBytes(16)
+	if err != nil {
+		fmt.Printf("key generation error: %v\n", err)
+	}
+	counter := int64(10000)
+	profiles := make(map[string]Profile, 0)
+
+	genUid := func() int64 {
+		uid := counter
+		counter += 1
+
+		return uid
+	}
+	parse := func(encoded string) map[string]string {
+		m := make(map[string]string, 0)
+
+		kvs := lib.StrSplitAt('&', encoded)
+		for i := 0; i < len(kvs); i++ {
+			kv := lib.StrSplitAt('=', kvs[i])
+			m[lib.StripSpaceChars(kv[0])] = kv[1]
+		}
+		return m
+	}
+	encode := func(p Profile) string {
+		ep := "email=" + p["email"] // Encoded profile.
+		ep += "&uid=" + p["uid"]
+		ep += "&role=" + p["role"]
+		return ep
+	}
+	decode := func(encoded string) Profile {
+		return parse(encoded)
+	}
+	encrypt := func(encoded string) []byte {
+		return lib.AESEncryptECB(lib.StrToBytes(encoded), key)
+	}
+	decrypt := func(cipher []byte) string {
+		return lib.BytesToStr(lib.AESDecryptECB(cipher, key))
+	}
+	sanitize := func(email string) string {
+		if len(email) < 1 {
+			return ""
+		}
+		se := "" // sanitized email
+
+		// Strip meta characters
+		for i := 0; i < len(email); i++ {
+			if email[i] == '&' || email[i] == '=' {
+				continue
+			}
+			se += string(email[i])
+		}
+		return se
+	}
+	profileFor := func(email string) string {
+		e := sanitize(email)
+		if len(e) == 0 {
+			panic("email invalid")
+		}
+
+		if p, ok := profiles[e]; ok {
+			// Profile already exists.
+			return encode(p)
+		}
+
+		// Create profile.
+		p := make(Profile, 0)
+		p["email"] = e
+		p["uid"] = lib.NumToStr(genUid())
+		p["role"] = "user"
+		profiles[e] = p
+
+		return encode(p)
+	}
+
 	adminBlock := lib.BytesToStr(lib.Pkcs7Padding(lib.StrToBytes("admin"), 16))
-	ep := lib.WebProfileFor("foo@abacus" + adminBlock)
-	encryptedEP := lib.WebEncryptProfile(ep)
+	ep := profileFor("foo@abacus" + adminBlock)
+	encryptedEP := encrypt(ep)
 	adminBlockCipher := encryptedEP[16:32] // Second block in the cipher
 
-	ep = lib.WebProfileFor("foo@abacus")
-	encryptedEP = lib.WebEncryptProfile(ep)
+	ep = profileFor("foo@abacus")
+	encryptedEP = encrypt(ep)
 	for i := 0; i < 16; i++ { // Replace last block with the admin cipher block.
 		encryptedEP[32+i] = adminBlockCipher[i]
 	}
-	adminEP := lib.WebDecryptProfile(encryptedEP)
-	adminProfile := lib.WebDecodeProfile(adminEP)
+	adminEP := decrypt(encryptedEP)
+	adminProfile := decode(adminEP)
 	fmt.Printf("Admin Encoded Profile: %v\n", adminEP)
 	fmt.Printf("Admin Profile: %v\n", adminProfile)
 }