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basic: added cbc-mac with xxtea for messages with n*4 words

This commit is contained in:
schneider 2011-07-19 00:51:07 +02:00
parent 643e8365aa
commit 27412ef03d
2 changed files with 15 additions and 0 deletions
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14
firmware/basic/xxtea.c
View File

@ -37,6 +37,20 @@ void htonlp(uint32_t *v, uint8_t n)
}
}
void xxtea_cbcmac(uint32_t mac[4], uint32_t *data, uint32_t len, uint32_t key[4])
{
if( len & 0x03 )
return;
mac[0]=0;mac[1]=0;mac[2]=0;mac[3]=0;
for(int i=0; i<len;){
mac[0] ^= data[i++];
mac[1] ^= data[i++];
mac[2] ^= data[i++];
mac[3] ^= data[i++];
xxtea_encode_words(mac, 4, key);
}
}
#define DELTA 0x9e3779b9
#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (k[(p&3)^e] ^ z)))

1
firmware/basic/xxtea.h
View File

@ -1,6 +1,7 @@
#ifndef _XXTEA_H_
#define _XXTEA_H_
void xxtea_cbcmac(uint32_t mac[4], uint32_t *data, uint32_t len, uint32_t key[4]);
void xxtea_encode_words(uint32_t *v, int n, uint32_t const k[4]);
void xxtea_decode_words(uint32_t *v, int n, uint32_t const k[4]);