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/* rc6 (TM)
* Unoptimized sample implementation of Ron Rivest's submission to the
* AES bakeoff.
*
* Salvo Salasio, 19 June 1998
*
* Intellectual property notes: The name of the algorithm (RC6) is
* trademarked; any property rights to the algorithm or the trademark
* should be discussed with discussed with the authors of the defining
* paper "The RC6(TM) Block Cipher": Ronald L. Rivest (MIT),
* M.J.B. Robshaw (RSA Labs), R. Sidney (RSA Labs), and Y.L. Yin (RSA Labs),
* distributed 18 June 1998 and available from the lead author's web site.
*
* This sample implementation is placed in the public domain by the author,
* Salvo Salasio. The ROTL and ROTR definitions were cribbed from RSA Labs'
* RC5 reference implementation.
*/
#include <stdio.h>
/* RC6 is parameterized for w-bit words, b bytes of key, and
* r rounds. The AES version of RC6 specifies b=16, 24, or 32;
* w=32; and r=20.
*/
#define w 32 /* word size in bits */
#define r 20 /* based on security estimates */
#define P32 0xB7E15163 /* Magic constants for key setup */
#define Q32 0x9E3779B9
/* derived constants */
#define bytes (w / 8) /* bytes per word */
#define c ((b + bytes - 1) / bytes) /* key in words, rounded up */
#define R24 (2 * r + 4)
#define lgw 5 /* log2(w) -- wussed out */
/* Rotations */
#define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1)))))
#define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1)))))
unsigned int S[R24 - 1]; /* Key schedule */
void rc6_key_setup(unsigned char *K, int b)
{
int i, j, s, v;
unsigned int L[(32 + bytes - 1) / bytes]; /* Big enough for max b */
unsigned int A, B;
L[c - 1] = 0;
for (i = b - 1; i >= 0; i--)
L[i / bytes] = (L[i / bytes] << 8) + K[i];
S[0] = P32;
for (i = 1; i <= 2 * r + 3; i++)
S[i] = S[i - 1] + Q32;
A = B = i = j = 0;
v = R24;
if (c > v) v = c;
v *= 3;
for (s = 1; s <= v; s++)
{
A = S[i] = ROTL(S[i] + A + B, 3);
B = L[j] = ROTL(L[j] + A + B, A + B);
i = (i + 1) % R24;
j = (j + 1) % c;
}
}
void rc6_block_encrypt(unsigned int *pt, unsigned int *ct)
{
unsigned int A, B, C, D, t, u, x;
int i, j;
A = pt[0];
B = pt[1];
C = pt[2];
D = pt[3];
B += S[0];
D += S[1];
for (i = 2; i <= 2 * r; i += 2)
{
t = ROTL(B * (2 * B + 1), lgw);
u = ROTL(D * (2 * D + 1), lgw);
A = ROTL(A ^ t, u) + S[i];
C = ROTL(C ^ u, t) + S[i + 1];
x = A;
A = B;
B = C;
C = D;
D = x;
}
A += S[2 * r + 2];
C += S[2 * r + 3];
ct[0] = A;
ct[1] = B;
ct[2] = C;
ct[3] = D;
}
void rc6_block_decrypt(unsigned int *ct, unsigned int *pt)
{
unsigned int A, B, C, D, t, u, x;
int i, j;
A = ct[0];
B = ct[1];
C = ct[2];
D = ct[3];
C -= S[2 * r + 3];
A -= S[2 * r + 2];
for (i = 2 * r; i >= 2; i -= 2)
{
x = D;
D = C;
C = B;
B = A;
A = x;
u = ROTL(D * (2 * D + 1), lgw);
t = ROTL(B * (2 * B + 1), lgw);
C = ROTR(C - S[i + 1], t) ^ u;
A = ROTR(A - S[i], u) ^ t;
}
D -= S[1];
B -= S[0];
pt[0] = A;
pt[1] = B;
pt[2] = C;
pt[3] = D;
}
struct test_struct
{
int keylen;
unsigned char key[32];
unsigned int pt[4];
unsigned int ct[4];
} tests[] =
{
{ 16, {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
{0x00000000, 0x00000000, 0x00000000, 0x00000000},
{0x36a5c38f, 0x78f7b156, 0x4edf29c1, 0x1ea44898},
},
{ 16, {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78},
{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},
{0x2f194e52, 0x23c61547, 0x36f6511f, 0x183fa47e},
},
{ 24, {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
{0x00000000, 0x00000000, 0x00000000, 0x00000000},
{0xcb1bd66c, 0x38300b19, 0x163f8a4e, 0x82ae9086},
},
{ 24, {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0},
{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},
{0xd0298368, 0x0405e519, 0x2ae9521e, 0xd49152f9},
},
{ 32, {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
{0x00000000, 0x00000000, 0x00000000, 0x00000000},
{0x05bd5f8f, 0xa85fd110, 0xda3ffa93, 0xc27e856e},
},
{ 32, {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe},
{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},
{0x161824c8, 0x89e4d7f0, 0xa116ad20, 0x485d4e67},
},
{ 0,
}
};
int
main()
{
unsigned int ct[4], pt[4];
int i;
struct test_struct *p;
for (p = tests, i = 1; p->keylen; p++, i++)
{
rc6_key_setup(p->key, p->keylen);
rc6_block_encrypt(p->pt, ct);
printf("Test %d: %08x %08x %08x %08x\n",
i, ct[0], ct[1], ct[2], ct[3]);
printf("Should be: %08x %08x %08x %08x\n",
p->ct[0], p->ct[1], p->ct[2], p->ct[3]);
rc6_block_decrypt(ct, pt);
printf("Plain: %08x %08x %08x %08x\n",
pt[0], pt[1], pt[2], pt[3]);
printf("Should be: %08x %08x %08x %08x\n\n",
p->pt[0], p->pt[1], p->pt[2], p->pt[3]);
}
return 0;
}
Persönlich würde ich RC6 draußen lassen, nur sichere Algorithmen einbauen die man noch verwenden sollte und evt. an sonstigen Funktionen erweitern, z.B. Strom Chiffre Modi einbauen etc.The emphasis on the word "if" suggests that RSA Security Inc. may now require licensing and royalty payments for any products using the RC6 algorithm. RC6 is a patented encryption algorithm
Gerade dann sollte man sich meines Erachtens auf sehr wenige Algorithmen beschränken. Lieber weniger Algorithmen, dafür diese dann richtig, z.B. mit Optimierungen in Assembler o.ä.Original von csde_rats
Naja, ich schreibe die Lib eben nicht für die Krypto-Geeks, sondern eher für den Durchschnittsprogrammierer...
Naja wirklich viel Speicher braucht AES auch nicht, je nachdem auf was man es optimiert (Performance oder Speicherbedarf).Ich denke XTEA hat z.B. gegenüber RIJNDAEL den Vorteil, dass es relativ wenig Speicher braucht.
Wenn meine Library schon AES anbietet, wieso sollte ich dann RC4 wählen? Und wenn ich den Fehler begehe, was garaniert vor allem bei Anfänger geschieht, zwei mal den gleichen Key zu verwenden, dann ist RC4 auf einmal gar nicht mehr so sicher.Klar RC4 ist nicht so einfach zu nutzten, aber richtig benutzt ist er eben doch noch zu etwas zu gebrauchen. Und wenn man nur Daten gegen DAUs und nicht gegen "echte" Hacker schützen will, reicht RC4 alle male...