6 * Description: Implementation of the CAST6 (aka CAST-256) cipher algorithm as described in RFC 2612
12 #include <avr/pgmspace.h>
14 #include "cast6-sbox.h"
16 #define CHANGE_ENDIAN32(x) (((x)<<24 | (x)>>24 | ((x)&0xff00)<<8 | ((x)&0xff0000)>>8)&0xffffffff)
18 static uint8_t kr(uint8_t i, const cast6_ctx_t *ctx)
21 ret = ctx->krx[i / 2];
27 /* now get the high bit */
28 ret |= ((ctx->krx[24 + i / 8]) & (1 << (i % 8))) ? 0x10 : 0x00;
33 void set_kr(uint8_t value, uint8_t i, cast6_ctx_t *ctx)
37 (ctx->krx[i / 2]) &= 0xF0 >> ((i & 1) * 4); /* clear the location where v should go */
38 (ctx->krx[i / 2]) |= (value & 0x0f) << ((i & 1) * 4);
40 /* now set the high bit */
41 (ctx->krx[24 + i / 8]) &= ~(1 << (i % 8)); /* clear the location where v should go */
42 (ctx->krx[24 + i / 8]) |= (value >> 4) << (i % 8);
45 #define ROTL32(a,n) (((a)<<(n))|((a)>>(32-(n))))
46 #define ROTR32(a,n) (((a)>>(n))|((a)<<(32-(n))))
48 #define S1(a) (pgm_read_dword(&(s1[(a)])))
49 #define S2(a) (pgm_read_dword(&(s2[(a)])))
50 #define S3(a) (pgm_read_dword(&(s3[(a)])))
51 #define S4(a) (pgm_read_dword(&(s4[(a)])))
53 #define A ((uint8_t)(v>>(8*3)))
54 #define B ((uint8_t)(v>>(8*2)))
55 #define C ((uint8_t)(v>>(8*1)))
56 #define D ((uint8_t)(v>>(8*0)))
58 static uint32_t f1(uint32_t v, uint8_t kri, uint32_t kmi)
62 v = ROTL32(kmi + v, kri);
70 static uint32_t f2(uint32_t v, uint8_t kri, uint32_t kmi)
74 v = ROTL32(kmi ^ v, kri);
82 static uint32_t f3(uint32_t v, uint8_t kri, uint32_t kmi)
86 v = ROTL32(kmi - v, kri);
99 #define A (((uint32_t*)buffer)[0])
100 #define B (((uint32_t*)buffer)[1])
101 #define C (((uint32_t*)buffer)[2])
102 #define D (((uint32_t*)buffer)[3])
105 void q(void *buffer, uint8_t i, const cast6_ctx_t *ctx)
107 C ^= f1(D, kr(i * 4 + 0, ctx), ctx->km[i][0]);
108 B ^= f2(C, kr(i * 4 + 1, ctx), ctx->km[i][1]);
109 A ^= f3(B, kr(i * 4 + 2, ctx), ctx->km[i][2]);
110 D ^= f1(A, kr(i * 4 + 3, ctx), ctx->km[i][3]);
114 void qbar(void *buffer, uint8_t i, const cast6_ctx_t *ctx)
116 D ^= f1(A, kr(i * 4 + 3, ctx), ctx->km[i][3]);
117 A ^= f3(B, kr(i * 4 + 2, ctx), ctx->km[i][2]);
118 B ^= f2(C, kr(i * 4 + 1, ctx), ctx->km[i][1]);
119 C ^= f1(D, kr(i * 4 + 0, ctx), ctx->km[i][0]);
122 void cast6_enc(void *buffer, const cast6_ctx_t *ctx)
125 for (i = 0; i < 32 / 4; ++i) {
126 ((uint32_t*) buffer)[i] = CHANGE_ENDIAN32(((uint32_t* )buffer)[i]);
128 for (i = 0; i < 6; ++i) {
131 for (i = 6; i < 12; ++i) {
132 qbar(buffer, i, ctx);
134 for (i = 0; i < 32 / 4; ++i) {
135 ((uint32_t*) buffer)[i] = CHANGE_ENDIAN32(((uint32_t* )buffer)[i]);
139 void cast6_dec(void *buffer, const cast6_ctx_t *ctx)
142 for (i = 0; i < 32 / 4; ++i) {
143 ((uint32_t*) buffer)[i] = CHANGE_ENDIAN32(((uint32_t* )buffer)[i]);
145 for (i = 12; i > 6; --i) {
146 q(buffer, i - 1, ctx);
148 for (i = 6; i > 0; --i) {
149 qbar(buffer, i - 1, ctx);
151 for (i = 0; i < 32 / 4; ++i) {
152 ((uint32_t*) buffer)[i] = CHANGE_ENDIAN32(((uint32_t* )buffer)[i]);
161 #define A (((uint32_t*)buffer)[0])
162 #define B (((uint32_t*)buffer)[1])
163 #define C (((uint32_t*)buffer)[2])
164 #define D (((uint32_t*)buffer)[3])
165 #define E (((uint32_t*)buffer)[4])
166 #define F (((uint32_t*)buffer)[5])
167 #define G (((uint32_t*)buffer)[6])
168 #define H (((uint32_t*)buffer)[7])
171 * we might later make it optional to use this small thing
173 void w(void *buffer, uint8_t *tr, uint32_t *tm){
174 G ^= f1(H, (tr[0]&0x0f)+(tr[5]&0x01)?0x10:0x00, tm[0]);
175 F ^= f2(G, (tr[0]>>4) +(tr[5]&0x02)?0x10:0x00, tm[1]);
176 E ^= f3(F, (tr[1]&0x0f)+(tr[5]&0x04)?0x10:0x00, tm[2]);
177 D ^= f1(E, (tr[1]>>4) +(tr[5]&0x08)?0x10:0x00, tm[3]);
178 C ^= f2(D, (tr[2]&0x0f)+(tr[5]&0x10)?0x10:0x00, tm[4]);
179 B ^= f3(C, (tr[2]>>4) +(tr[5]&0x20)?0x10:0x00, tm[5]);
180 A ^= f1(B, (tr[3]&0x0f)+(tr[5]&0x40)?0x10:0x00, tm[6]);
181 H ^= f2(A, (tr[3]>>4) +(tr[5]&0x80)?0x10:0x00, tm[7]);
185 void w(void *buffer, uint8_t *tr, uint32_t *tm)
187 G ^= f1(H, tr[0], tm[0]);
188 F ^= f2(G, tr[1], tm[1]);
189 E ^= f3(F, tr[2], tm[2]);
190 D ^= f1(E, tr[3], tm[3]);
191 C ^= f2(D, tr[4], tm[4]);
192 B ^= f3(C, tr[5], tm[5]);
193 A ^= f1(B, tr[6], tm[6]);
194 H ^= f2(A, tr[7], tm[7]);
198 void dump_ctx(const cast6_ctx_t *ctx){
200 cli_putstr_P(PSTR("\r\n DBG:"));
202 cli_putstr_P(PSTR("\r\n DBG:"));
203 cli_putstr_P(PSTR(" rotk1="));
206 cli_putstr_P(PSTR(" rotk2="));
209 cli_putstr_P(PSTR(" rotk3="));
212 cli_putstr_P(PSTR(" rotk4="));
215 cli_putstr_P(PSTR("\r\n "));
216 cli_putstr_P(PSTR(" mask1="));
217 cli_hexdump(&(ctx->km[i][0]),4);
218 cli_putstr_P(PSTR(" mask2="));
219 cli_hexdump(&(ctx->km[i][1]),4);
220 cli_putstr_P(PSTR(" mask3="));
221 cli_hexdump(&(ctx->km[i][2]),4);
222 cli_putstr_P(PSTR(" mask4="));
223 cli_hexdump(&(ctx->km[i][3]),4);
224 cli_putstr_P(PSTR("\r\n;-----"));
230 #define CM 0x5A827999
232 #define MM 0x6ED9EBA1
234 void cast6_init(const void *key, uint16_t keysize_b, cast6_ctx_t *ctx)
237 uint8_t cr = CR, tr[8];
238 uint32_t cm = CM, tm[8];
241 memset(buffer, 0, 32);
242 memcpy(buffer, key, (keysize_b + 7) / 8);
243 for (i = 0; i < 32 / 4; ++i) {
244 ((uint32_t*) buffer)[i] = CHANGE_ENDIAN32(((uint32_t* )buffer)[i]);
247 for (i = 0; i < 24; ++i) {
248 for (j = 0; j < 8; ++j) {
262 set_kr(buffer[0 * 4], j * 4 + 0, ctx);
263 set_kr(buffer[2 * 4], j * 4 + 1, ctx);
264 set_kr(buffer[4 * 4], j * 4 + 2, ctx);
265 set_kr(buffer[6 * 4], j * 4 + 3, ctx);