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#include "os.h"
#include <libsec.h>
/* rfc2104 */
DigestState*
hmac_x(uchar *p, ulong len, uchar *key, ulong klen, uchar *digest, DigestState *s,
DigestState*(*x)(uchar*, ulong, uchar*, DigestState*), int xlen)
{
int i;
uchar pad[Hmacblksz+1], innerdigest[256];
if(xlen > sizeof(innerdigest))
return nil;
if(klen > Hmacblksz){
if(xlen > Hmacblksz)
return nil;
(*x)(key, klen, innerdigest, nil);
key = innerdigest;
klen = xlen;
}
/* first time through */
if(s == nil || s->seeded == 0){
memset(pad, 0x36, Hmacblksz);
pad[Hmacblksz] = 0;
for(i = 0; i < klen; i++)
pad[i] ^= key[i];
s = (*x)(pad, Hmacblksz, nil, s);
if(s == nil)
return nil;
}
s = (*x)(p, len, nil, s);
if(digest == nil)
return s;
/* last time through */
memset(pad, 0x5c, Hmacblksz);
pad[Hmacblksz] = 0;
for(i = 0; i < klen; i++)
pad[i] ^= key[i];
(*x)(nil, 0, innerdigest, s);
s = (*x)(pad, Hmacblksz, nil, nil);
(*x)(innerdigest, xlen, digest, s);
return nil;
}
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