new, derived from old avr/crypto + cast5

[avr-crypto-lib.git] / xtea.c

diff --git a/xtea.c b/xtea.c
new file mode 100644 (file)
index 0000000..c9fe103
--- /dev/null
+++ b/xtea.c
@@ -0,0 +1,32 @@
+/* 
+ * XTEA implemantation 
+ *  copy'n'pasted from http://en.wikipedia.org/wiki/XTEA
+ *   and slightly modified
+ * */
+ 
+#include <stdint.h> 
+ 
+
+void xtea_enc(uint32_t* dest, uint32_t* v, uint32_t* k) {
+    uint32_t v0=v[0], v1=v[1], i;
+    uint32_t sum=0, delta=0x9E3779B9;
+    for(i=0; i<32; i++) {
+        v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
+        sum += delta;
+        v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
+    }
+    dest[0]=v0; dest[1]=v1;
+}
+
+void xtea_dec(uint32_t* dest, uint32_t* v, uint32_t* k) {
+    uint32_t v0=v[0], v1=v[1], i;
+    uint32_t sum=0xC6EF3720, delta=0x9E3779B9;
+    for(i=0; i<32; i++) {
+        v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
+        sum -= delta;
+        v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
+    }
+    dest[0]=v0; dest[1]=v1;
+}
+
+