1 files changed, 52 insertions, 0 deletions
diff --git a/src/hmac_md5.c b/src/hmac_md5.c
new file mode 100644
index 0000000..310f0ef
--- /dev/null
+++ b/src/hmac_md5.c
@@ -0,0 +1,52 @@
+#include "global.h"
+#include "md5.h"
+#include "str.h"
+#include "byte.h"
+
+/**
+@file   hmac_md5
+@brief  caculates HMAC digest from challenge + password (DJB version)
+@param input:  unsigned char *text : pointer to challenge
+               int text_len        : length of challenge
+               unsigned char *key  : pointer to password
+               int key_len         : length of password
+      output: unsigned char *digest: pointer to calculated digest 
+*/
+
+void hmac_md5(unsigned char *text,int text_len,unsigned char * key,int key_len,unsigned char *digest)
+{
+   MD5_CTX context;
+   unsigned char k_ipad[65];    /* inner padding - key XORd with ipad */
+   unsigned char k_opad[65];    /* outer padding - key XORd with opad */
+   unsigned char tk[16];
+   int i;
+
+   if (key_len > 64) {
+     MD5_CTX tctx;
+     MD5Init(&tctx);
+     MD5Update(&tctx,key,key_len);
+     MD5Final(tk,&tctx);
+     key = tk;
+     key_len = 16;
+   }
+
+   byte_zero(k_ipad,sizeof(k_ipad));
+   byte_zero(k_opad,sizeof(k_opad));
+   byte_copy(k_ipad,key_len,key);
+   byte_copy(k_opad,key_len,key);
+
+   for (i = 0; i < 64; i++) {
+      k_ipad[i] ^= 0x36;
+      k_opad[i] ^= 0x5c;
+   }
+
+   MD5Init(&context);                   /* init context for 1st pass */
+   MD5Update(&context,k_ipad,64);       /* start with inner pad */
+   MD5Update(&context,text,text_len);   /* then text of datagram */
+   MD5Final(digest,&context);           /* finish up 1st pass */
+
+   MD5Init(&context);                   /* init context for 2nd pass */
+   MD5Update(&context,k_opad,64);       /* start with outer pad */
+   MD5Update(&context,digest,16);       /* then results of 1st hash */
+   MD5Final(digest,&context);           /* finish up 2nd pass */
+}