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Diffstat (limited to 'libdes/quad_cksum.c')
| -rw-r--r-- | libdes/quad_cksum.c | 153 |
1 files changed, 0 insertions, 153 deletions
diff --git a/libdes/quad_cksum.c b/libdes/quad_cksum.c deleted file mode 100644 index 651e843..0000000 --- a/libdes/quad_cksum.c +++ /dev/null @@ -1,153 +0,0 @@ -/* - * $Source$ - * $Author$ - * - * Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute - * of Technology. - * - * For copying and distribution information, please see the file - * <mit-copyright.h>. - * - * Quadratic Congruential Manipulation Dectection Code - * - * ref: "Message Authentication" - * R.R. Jueneman, S. M. Matyas, C.H. Meyer - * IEEE Communications Magazine, - * Sept 1985 Vol 23 No 9 p 29-40 - * - * This routine, part of the Athena DES library built for the Kerberos - * authentication system, calculates a manipulation detection code for - * a message. It is a much faster alternative to the DES-checksum - * method. No guarantees are offered for its security. Refer to the - * paper noted above for more information - * - * Implementation for 4.2bsd - * by S.P. Miller Project Athena/MIT - */ - -/* - * Algorithm (per paper): - * define: - * message to be composed of n m-bit blocks X1,...,Xn - * optional secret seed S in block X1 - * MDC in block Xn+1 - * prime modulus N - * accumulator Z - * initial (secret) value of accumulator C - * N, C, and S are known at both ends - * C and , optionally, S, are hidden from the end users - * then - * (read array references as subscripts over time) - * Z[0] = c; - * for i = 1...n - * Z[i] = (Z[i+1] + X[i])**2 modulo N - * X[n+1] = Z[n] = MDC - * - * Then pick - * N = 2**31 -1 - * m = 16 - * iterate 4 times over plaintext, also use Zn - * from iteration j as seed for iteration j+1, - * total MDC is then a 128 bit array of the four - * Zn; - * - * return the last Zn and optionally, all - * four as output args. - * - * Modifications: - * To inhibit brute force searches of the seed space, this - * implementation is modified to have - * Z = 64 bit accumulator - * C = 64 bit C seed - * N = 2**63 - 1 - * S = S seed is not implemented here - * arithmetic is not quite real double integer precision, since we - * cant get at the carry or high order results from multiply, - * but nontheless is 64 bit arithmetic. - */ - -#ifndef lint -static char rcsid_quad_cksum_c[] = - "$Id$"; -#endif - -#include <stdio.h> -#include <sys/types.h> -#include <netinet/in.h> - -#include <mit-copyright.h> -#include "des.h" - -/* Externals */ -extern int des_debug; - -/*** Routines ***************************************************** */ - -unsigned long -des_quad_cksum(in,out,length,out_count,c_seed) - des_cblock c_seed; /* secret seed, 8 bytes */ - unsigned char *in; /* input block */ - u_int32 *out; /* optional longer output */ - int out_count; /* number of iterations */ - long length; /* original length in bytes */ -{ - - /* - * this routine both returns the low order of the final (last in - * time) 32bits of the checksum, and if "out" is not a null - * pointer, a longer version, up to entire 32 bytes of the - * checksum is written unto the address pointed to. - */ - - register u_int32 z; - register u_int32 z2; - register u_int32 x; - register u_int32 x2; - register unsigned char *p; - register long len; - register int i; - - /* use all 8 bytes of seed */ - - z = c_seed[0] + - ((u_int32)c_seed[1] << 8) + - ((u_int32)c_seed[2] << 16) + - ((u_int32)c_seed[3] << 24); - - z2 = c_seed[4] + - ((u_int32)c_seed[5] << 8) + - ((u_int32)c_seed[6] << 16) + - ((u_int32)c_seed[7] << 24); - - if (out == NULL) - out_count = 1; /* default */ - - /* This is repeated n times!! */ - for (i = 1; i <=4 && i<= out_count; i++) { - len = length; - p = in; - while (len) { - if (len > 1) { - x = (z + p[0] + (p[1]<<8)); - p += 2; - len -= 2; - } - else { - x = (z + *(unsigned char *)p++); - len = 0; - } - x2 = z2; - z = ((x * x) + (x2 * x2)) % 0x7fffffff; - z2 = (x * (x2+83653421)) % 0x7fffffff; /* modulo */ - if (des_debug & 8) - printf("%d %d\n",z,z2); - } - - if (out != NULL) { - *out++ = z; - *out++ = z2; - } - } - /* return final z value as 32 bit version of checksum */ - return z; -} |