/* $OpenBSD: ip_cast.c,v 1.1 1997/11/04 09:11:05 provos Exp $ */ /* * CAST-128 in C * Written by Steve Reid * 100% Public Domain - no warranty * Released 1997.10.11 */ #include #include /* Macros to access 8-bit bytes out of a 32-bit word */ #define U8a(x) ( (u8) (x>>24) ) #define U8b(x) ( (u8) ((x>>16)&255) ) #define U8c(x) ( (u8) ((x>>8)&255) ) #define U8d(x) ( (u8) ((x)&255) ) /* Circular left shift */ #define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) ) /* CAST-128 uses three different round functions */ #define F1(l, r, i) \ t = ROL(key->xkey[i] + r, key->xkey[i+16]); \ l ^= ((cast_sbox1[U8a(t)] ^ cast_sbox2[U8b(t)]) - \ cast_sbox3[U8c(t)]) + cast_sbox4[U8d(t)]; #define F2(l, r, i) \ t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \ l ^= ((cast_sbox1[U8a(t)] - cast_sbox2[U8b(t)]) + \ cast_sbox3[U8c(t)]) ^ cast_sbox4[U8d(t)]; #define F3(l, r, i) \ t = ROL(key->xkey[i] - r, key->xkey[i+16]); \ l ^= ((cast_sbox1[U8a(t)] + cast_sbox2[U8b(t)]) ^ \ cast_sbox3[U8c(t)]) - cast_sbox4[U8d(t)]; /***** Encryption Function *****/ void cast_encrypt(cast_key* key, u8* inblock, u8* outblock) { u32 t, l, r; /* Get inblock into l,r */ l = ((u32)inblock[0] << 24) | ((u32)inblock[1] << 16) | ((u32)inblock[2] << 8) | (u32)inblock[3]; r = ((u32)inblock[4] << 24) | ((u32)inblock[5] << 16) | ((u32)inblock[6] << 8) | (u32)inblock[7]; /* Do the work */ F1(l, r, 0); F2(r, l, 1); F3(l, r, 2); F1(r, l, 3); F2(l, r, 4); F3(r, l, 5); F1(l, r, 6); F2(r, l, 7); F3(l, r, 8); F1(r, l, 9); F2(l, r, 10); F3(r, l, 11); /* Only do full 16 rounds if key length > 80 bits */ if (key->rounds > 12) { F1(l, r, 12); F2(r, l, 13); F3(l, r, 14); F1(r, l, 15); } /* Put l,r into outblock */ outblock[0] = U8a(r); outblock[1] = U8b(r); outblock[2] = U8c(r); outblock[3] = U8d(r); outblock[4] = U8a(l); outblock[5] = U8b(l); outblock[6] = U8c(l); outblock[7] = U8d(l); /* Wipe clean */ t = l = r = 0; } /***** Decryption Function *****/ void cast_decrypt(cast_key* key, u8* inblock, u8* outblock) { u32 t, l, r; /* Get inblock into l,r */ r = ((u32)inblock[0] << 24) | ((u32)inblock[1] << 16) | ((u32)inblock[2] << 8) | (u32)inblock[3]; l = ((u32)inblock[4] << 24) | ((u32)inblock[5] << 16) | ((u32)inblock[6] << 8) | (u32)inblock[7]; /* Do the work */ /* Only do full 16 rounds if key length > 80 bits */ if (key->rounds > 12) { F1(r, l, 15); F3(l, r, 14); F2(r, l, 13); F1(l, r, 12); } F3(r, l, 11); F2(l, r, 10); F1(r, l, 9); F3(l, r, 8); F2(r, l, 7); F1(l, r, 6); F3(r, l, 5); F2(l, r, 4); F1(r, l, 3); F3(l, r, 2); F2(r, l, 1); F1(l, r, 0); /* Put l,r into outblock */ outblock[0] = U8a(l); outblock[1] = U8b(l); outblock[2] = U8c(l); outblock[3] = U8d(l); outblock[4] = U8a(r); outblock[5] = U8b(r); outblock[6] = U8c(r); outblock[7] = U8d(r); /* Wipe clean */ t = l = r = 0; } /***** Key Schedual *****/ void cast_setkey(cast_key* key, u8* rawkey, int keybytes) { u32 t[4], z[4], x[4]; int i; /* Set number of rounds to 12 or 16, depending on key length */ key->rounds = (keybytes <= 10 ? 12 : 16); /* Copy key to workspace x */ for (i = 0; i < 4; i++) { x[i] = 0; if ((i*4+0) < keybytes) x[i] = (u32)rawkey[i*4+0] << 24; if ((i*4+1) < keybytes) x[i] |= (u32)rawkey[i*4+1] << 16; if ((i*4+2) < keybytes) x[i] |= (u32)rawkey[i*4+2] << 8; if ((i*4+3) < keybytes) x[i] |= (u32)rawkey[i*4+3]; } /* Generate 32 subkeys, four at a time */ for (i = 0; i < 32; i+=4) { switch (i & 4) { case 0: t[0] = z[0] = x[0] ^ cast_sbox5[U8b(x[3])] ^ cast_sbox6[U8d(x[3])] ^ cast_sbox7[U8a(x[3])] ^ cast_sbox8[U8c(x[3])] ^ cast_sbox7[U8a(x[2])]; t[1] = z[1] = x[2] ^ cast_sbox5[U8a(z[0])] ^ cast_sbox6[U8c(z[0])] ^ cast_sbox7[U8b(z[0])] ^ cast_sbox8[U8d(z[0])] ^ cast_sbox8[U8c(x[2])]; t[2] = z[2] = x[3] ^ cast_sbox5[U8d(z[1])] ^ cast_sbox6[U8c(z[1])] ^ cast_sbox7[U8b(z[1])] ^ cast_sbox8[U8a(z[1])] ^ cast_sbox5[U8b(x[2])]; t[3] = z[3] = x[1] ^ cast_sbox5[U8c(z[2])] ^ cast_sbox6[U8b(z[2])] ^ cast_sbox7[U8d(z[2])] ^ cast_sbox8[U8a(z[2])] ^ cast_sbox6[U8d(x[2])]; break; case 4: t[0] = x[0] = z[2] ^ cast_sbox5[U8b(z[1])] ^ cast_sbox6[U8d(z[1])] ^ cast_sbox7[U8a(z[1])] ^ cast_sbox8[U8c(z[1])] ^ cast_sbox7[U8a(z[0])]; t[1] = x[1] = z[0] ^ cast_sbox5[U8a(x[0])] ^ cast_sbox6[U8c(x[0])] ^ cast_sbox7[U8b(x[0])] ^ cast_sbox8[U8d(x[0])] ^ cast_sbox8[U8c(z[0])]; t[2] = x[2] = z[1] ^ cast_sbox5[U8d(x[1])] ^ cast_sbox6[U8c(x[1])] ^ cast_sbox7[U8b(x[1])] ^ cast_sbox8[U8a(x[1])] ^ cast_sbox5[U8b(z[0])]; t[3] = x[3] = z[3] ^ cast_sbox5[U8c(x[2])] ^ cast_sbox6[U8b(x[2])] ^ cast_sbox7[U8d(x[2])] ^ cast_sbox8[U8a(x[2])] ^ cast_sbox6[U8d(z[0])]; break; } switch (i & 12) { case 0: case 12: key->xkey[i+0] = cast_sbox5[U8a(t[2])] ^ cast_sbox6[U8b(t[2])] ^ cast_sbox7[U8d(t[1])] ^ cast_sbox8[U8c(t[1])]; key->xkey[i+1] = cast_sbox5[U8c(t[2])] ^ cast_sbox6[U8d(t[2])] ^ cast_sbox7[U8b(t[1])] ^ cast_sbox8[U8a(t[1])]; key->xkey[i+2] = cast_sbox5[U8a(t[3])] ^ cast_sbox6[U8b(t[3])] ^ cast_sbox7[U8d(t[0])] ^ cast_sbox8[U8c(t[0])]; key->xkey[i+3] = cast_sbox5[U8c(t[3])] ^ cast_sbox6[U8d(t[3])] ^ cast_sbox7[U8b(t[0])] ^ cast_sbox8[U8a(t[0])]; break; case 4: case 8: key->xkey[i+0] = cast_sbox5[U8d(t[0])] ^ cast_sbox6[U8c(t[0])] ^ cast_sbox7[U8a(t[3])] ^ cast_sbox8[U8b(t[3])]; key->xkey[i+1] = cast_sbox5[U8b(t[0])] ^ cast_sbox6[U8a(t[0])] ^ cast_sbox7[U8c(t[3])] ^ cast_sbox8[U8d(t[3])]; key->xkey[i+2] = cast_sbox5[U8d(t[1])] ^ cast_sbox6[U8c(t[1])] ^ cast_sbox7[U8a(t[2])] ^ cast_sbox8[U8b(t[2])]; key->xkey[i+3] = cast_sbox5[U8b(t[1])] ^ cast_sbox6[U8a(t[1])] ^ cast_sbox7[U8c(t[2])] ^ cast_sbox8[U8d(t[2])]; break; } switch (i & 12) { case 0: key->xkey[i+0] ^= cast_sbox5[U8c(z[0])]; key->xkey[i+1] ^= cast_sbox6[U8c(z[1])]; key->xkey[i+2] ^= cast_sbox7[U8b(z[2])]; key->xkey[i+3] ^= cast_sbox8[U8a(z[3])]; break; case 4: key->xkey[i+0] ^= cast_sbox5[U8a(x[2])]; key->xkey[i+1] ^= cast_sbox6[U8b(x[3])]; key->xkey[i+2] ^= cast_sbox7[U8d(x[0])]; key->xkey[i+3] ^= cast_sbox8[U8d(x[1])]; break; case 8: key->xkey[i+0] ^= cast_sbox5[U8b(z[2])]; key->xkey[i+1] ^= cast_sbox6[U8a(z[3])]; key->xkey[i+2] ^= cast_sbox7[U8c(z[0])]; key->xkey[i+3] ^= cast_sbox8[U8c(z[1])]; break; case 12: key->xkey[i+0] ^= cast_sbox5[U8d(x[0])]; key->xkey[i+1] ^= cast_sbox6[U8d(x[1])]; key->xkey[i+2] ^= cast_sbox7[U8a(x[2])]; key->xkey[i+3] ^= cast_sbox8[U8b(x[3])]; break; } if (i >= 16) { key->xkey[i+0] &= 31; key->xkey[i+1] &= 31; key->xkey[i+2] &= 31; key->xkey[i+3] &= 31; } } /* Wipe clean */ for (i = 0; i < 4; i++) { t[i] = x[i] = z[i] = 0; } } /* Made in Canada */