From 9f009c6f0dff2f43818bf27d0aa50d494b89d82f Mon Sep 17 00:00:00 2001
From: Jan Wichelmann <code@jwichelmann.de>
Date: Mon, 29 Jul 2024 14:46:00 +0200
Subject: [PATCH] Add new cipher

---
 src/my_lib.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/my_lib.c b/src/my_lib.c
index 8764882..2da9908 100644
--- a/src/my_lib.c
+++ b/src/my_lib.c
@@ -5,6 +5,35 @@
 
 #define NOINLINE __attribute__((noinline))
 
+char caesarLookup[][26] = {
+    "abcdefghijklmnopqrstuvwxyz",
+    "bcdefghijklmnopqrstuvwxyza",
+    "cdefghijklmnopqrstuvwxyzab",
+    "defghijklmnopqrstuvwxyzabc",
+    "efghijklmnopqrstuvwxyzabcd",
+    "fghijklmnopqrstuvwxyzabcde",
+    "ghijklmnopqrstuvwxyzabcdef",
+    "hijklmnopqrstuvwxyzabcdefg",
+    "ijklmnopqrstuvwxyzabcdefgh",
+    "jklmnopqrstuvwxyzabcdefghi",
+    "klmnopqrstuvwxyzabcdefghij",
+    "lmnopqrstuvwxyzabcdefghijk",
+    "mnopqrstuvwxyzabcdefghijkl",
+    "nopqrstuvwxyzabcdefghijklm",
+    "opqrstuvwxyzabcdefghijklmn",
+    "pqrstuvwxyzabcdefghijklmno",
+    "qrstuvwxyzabcdefghijklmnop",
+    "rstuvwxyzabcdefghijklmnopq",
+    "stuvwxyzabcdefghijklmnopqr",
+    "tuvwxyzabcdefghijklmnopqrs",
+    "uvwxyzabcdefghijklmnopqrst",
+    "vwxyzabcdefghijklmnopqrstu",
+    "wxyzabcdefghijklmnopqrstuv",
+    "xyzabcdefghijklmnopqrstuvw",
+    "yzabcdefghijklmnopqrstuvwx",
+    "zabcdefghijklmnopqrstuvwxy"
+};
+
 uint8_t lookup[256];
 
 void init(void)
@@ -15,9 +44,29 @@ void init(void)
 		lookup[i] = (uint8_t)rand();
 }
 
+void caesarEncrypt(char input[], int length, char output[], int shift)
+{
+    for(int i = 0; i < length; ++i)
+    {
+		if(input[i] < 'a' || input[i] > 'z')
+		{
+			output[i] = input[i];
+			continue;
+		}
+        
+        output[i] = caesarLookup[shift][input[i] - 'a'];
+    }
+}
+
 void lookup_leakage(uint8_t *input, int inputLength, uint8_t *output)
 {
-	// Empty and constant time
+	// Convert input to alpha string
+	char *alpha = (char *)malloc(inputLength + 1);
+	for(int i = 0; i < inputLength; ++i)
+		alpha[i] = 'a' + (input[i] % 26);
+	alpha[inputLength] = '\0';
+
+	caesarEncrypt(alpha, inputLength, (char *)output, input[0] % 26);
 }
 
 int branch_leakage(uint8_t *input, int inputLength)