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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* Kernel cryptographic api.
0003  * cast6.c - Cast6 cipher algorithm [rfc2612].
0004  *
0005  * CAST-256 (*cast6*) is a DES like Substitution-Permutation Network (SPN)
0006  * cryptosystem built upon the CAST-128 (*cast5*) [rfc2144] encryption
0007  * algorithm.
0008  *
0009  * Copyright (C) 2003 Kartikey Mahendra Bhatt <kartik_me@hotmail.com>.
0010  */
0011 
0012 
0013 #include <asm/unaligned.h>
0014 #include <linux/init.h>
0015 #include <linux/crypto.h>
0016 #include <linux/module.h>
0017 #include <linux/errno.h>
0018 #include <linux/string.h>
0019 #include <linux/types.h>
0020 #include <crypto/cast6.h>
0021 
0022 #define s1 cast_s1
0023 #define s2 cast_s2
0024 #define s3 cast_s3
0025 #define s4 cast_s4
0026 
0027 #define F1(D, r, m)  ((I = ((m) + (D))), (I = rol32(I, (r))),   \
0028     (((s1[I >> 24] ^ s2[(I>>16)&0xff]) - s3[(I>>8)&0xff]) + s4[I&0xff]))
0029 #define F2(D, r, m)  ((I = ((m) ^ (D))), (I = rol32(I, (r))),   \
0030     (((s1[I >> 24] - s2[(I>>16)&0xff]) + s3[(I>>8)&0xff]) ^ s4[I&0xff]))
0031 #define F3(D, r, m)  ((I = ((m) - (D))), (I = rol32(I, (r))),   \
0032     (((s1[I >> 24] + s2[(I>>16)&0xff]) ^ s3[(I>>8)&0xff]) - s4[I&0xff]))
0033 
0034 static const u32 Tm[24][8] = {
0035     { 0x5a827999, 0xc95c653a, 0x383650db, 0xa7103c7c, 0x15ea281d,
0036         0x84c413be, 0xf39dff5f, 0x6277eb00 } ,
0037     { 0xd151d6a1, 0x402bc242, 0xaf05ade3, 0x1ddf9984, 0x8cb98525,
0038         0xfb9370c6, 0x6a6d5c67, 0xd9474808 } ,
0039     { 0x482133a9, 0xb6fb1f4a, 0x25d50aeb, 0x94aef68c, 0x0388e22d,
0040         0x7262cdce, 0xe13cb96f, 0x5016a510 } ,
0041     { 0xbef090b1, 0x2dca7c52, 0x9ca467f3, 0x0b7e5394, 0x7a583f35,
0042         0xe9322ad6, 0x580c1677, 0xc6e60218 } ,
0043     { 0x35bfedb9, 0xa499d95a, 0x1373c4fb, 0x824db09c, 0xf1279c3d,
0044         0x600187de, 0xcedb737f, 0x3db55f20 } ,
0045     { 0xac8f4ac1, 0x1b693662, 0x8a432203, 0xf91d0da4, 0x67f6f945,
0046         0xd6d0e4e6, 0x45aad087, 0xb484bc28 } ,
0047     { 0x235ea7c9, 0x9238936a, 0x01127f0b, 0x6fec6aac, 0xdec6564d,
0048         0x4da041ee, 0xbc7a2d8f, 0x2b541930 } ,
0049     { 0x9a2e04d1, 0x0907f072, 0x77e1dc13, 0xe6bbc7b4, 0x5595b355,
0050         0xc46f9ef6, 0x33498a97, 0xa2237638 } ,
0051     { 0x10fd61d9, 0x7fd74d7a, 0xeeb1391b, 0x5d8b24bc, 0xcc65105d,
0052         0x3b3efbfe, 0xaa18e79f, 0x18f2d340 } ,
0053     { 0x87ccbee1, 0xf6a6aa82, 0x65809623, 0xd45a81c4, 0x43346d65,
0054         0xb20e5906, 0x20e844a7, 0x8fc23048 } ,
0055     { 0xfe9c1be9, 0x6d76078a, 0xdc4ff32b, 0x4b29decc, 0xba03ca6d,
0056         0x28ddb60e, 0x97b7a1af, 0x06918d50 } ,
0057     { 0x756b78f1, 0xe4456492, 0x531f5033, 0xc1f93bd4, 0x30d32775,
0058         0x9fad1316, 0x0e86feb7, 0x7d60ea58 } ,
0059     { 0xec3ad5f9, 0x5b14c19a, 0xc9eead3b, 0x38c898dc, 0xa7a2847d,
0060         0x167c701e, 0x85565bbf, 0xf4304760 } ,
0061     { 0x630a3301, 0xd1e41ea2, 0x40be0a43, 0xaf97f5e4, 0x1e71e185,
0062         0x8d4bcd26, 0xfc25b8c7, 0x6affa468 } ,
0063     { 0xd9d99009, 0x48b37baa, 0xb78d674b, 0x266752ec, 0x95413e8d,
0064         0x041b2a2e, 0x72f515cf, 0xe1cf0170 } ,
0065     { 0x50a8ed11, 0xbf82d8b2, 0x2e5cc453, 0x9d36aff4, 0x0c109b95,
0066         0x7aea8736, 0xe9c472d7, 0x589e5e78 } ,
0067     { 0xc7784a19, 0x365235ba, 0xa52c215b, 0x14060cfc, 0x82dff89d,
0068         0xf1b9e43e, 0x6093cfdf, 0xcf6dbb80 } ,
0069     { 0x3e47a721, 0xad2192c2, 0x1bfb7e63, 0x8ad56a04, 0xf9af55a5,
0070         0x68894146, 0xd7632ce7, 0x463d1888 } ,
0071     { 0xb5170429, 0x23f0efca, 0x92cadb6b, 0x01a4c70c, 0x707eb2ad,
0072         0xdf589e4e, 0x4e3289ef, 0xbd0c7590 } ,
0073     { 0x2be66131, 0x9ac04cd2, 0x099a3873, 0x78742414, 0xe74e0fb5,
0074         0x5627fb56, 0xc501e6f7, 0x33dbd298 } ,
0075     { 0xa2b5be39, 0x118fa9da, 0x8069957b, 0xef43811c, 0x5e1d6cbd,
0076         0xccf7585e, 0x3bd143ff, 0xaaab2fa0 } ,
0077     { 0x19851b41, 0x885f06e2, 0xf738f283, 0x6612de24, 0xd4ecc9c5,
0078         0x43c6b566, 0xb2a0a107, 0x217a8ca8 } ,
0079     { 0x90547849, 0xff2e63ea, 0x6e084f8b, 0xdce23b2c, 0x4bbc26cd,
0080         0xba96126e, 0x296ffe0f, 0x9849e9b0 } ,
0081     { 0x0723d551, 0x75fdc0f2, 0xe4d7ac93, 0x53b19834, 0xc28b83d5,
0082         0x31656f76, 0xa03f5b17, 0x0f1946b8 }
0083 };
0084 
0085 static const u8 Tr[4][8] = {
0086     { 0x13, 0x04, 0x15, 0x06, 0x17, 0x08, 0x19, 0x0a } ,
0087     { 0x1b, 0x0c, 0x1d, 0x0e, 0x1f, 0x10, 0x01, 0x12 } ,
0088     { 0x03, 0x14, 0x05, 0x16, 0x07, 0x18, 0x09, 0x1a } ,
0089     { 0x0b, 0x1c, 0x0d, 0x1e, 0x0f, 0x00, 0x11, 0x02 }
0090 };
0091 
0092 /* forward octave */
0093 static inline void W(u32 *key, unsigned int i)
0094 {
0095     u32 I;
0096     key[6] ^= F1(key[7], Tr[i % 4][0], Tm[i][0]);
0097     key[5] ^= F2(key[6], Tr[i % 4][1], Tm[i][1]);
0098     key[4] ^= F3(key[5], Tr[i % 4][2], Tm[i][2]);
0099     key[3] ^= F1(key[4], Tr[i % 4][3], Tm[i][3]);
0100     key[2] ^= F2(key[3], Tr[i % 4][4], Tm[i][4]);
0101     key[1] ^= F3(key[2], Tr[i % 4][5], Tm[i][5]);
0102     key[0] ^= F1(key[1], Tr[i % 4][6], Tm[i][6]);
0103     key[7] ^= F2(key[0], Tr[i % 4][7], Tm[i][7]);
0104 }
0105 
0106 int __cast6_setkey(struct cast6_ctx *c, const u8 *in_key, unsigned int key_len)
0107 {
0108     int i;
0109     u32 key[8];
0110     __be32 p_key[8]; /* padded key */
0111 
0112     if (key_len % 4 != 0)
0113         return -EINVAL;
0114 
0115     memset(p_key, 0, 32);
0116     memcpy(p_key, in_key, key_len);
0117 
0118     key[0] = be32_to_cpu(p_key[0]);     /* A */
0119     key[1] = be32_to_cpu(p_key[1]);     /* B */
0120     key[2] = be32_to_cpu(p_key[2]);     /* C */
0121     key[3] = be32_to_cpu(p_key[3]);     /* D */
0122     key[4] = be32_to_cpu(p_key[4]);     /* E */
0123     key[5] = be32_to_cpu(p_key[5]);     /* F */
0124     key[6] = be32_to_cpu(p_key[6]);     /* G */
0125     key[7] = be32_to_cpu(p_key[7]);     /* H */
0126 
0127     for (i = 0; i < 12; i++) {
0128         W(key, 2 * i);
0129         W(key, 2 * i + 1);
0130 
0131         c->Kr[i][0] = key[0] & 0x1f;
0132         c->Kr[i][1] = key[2] & 0x1f;
0133         c->Kr[i][2] = key[4] & 0x1f;
0134         c->Kr[i][3] = key[6] & 0x1f;
0135 
0136         c->Km[i][0] = key[7];
0137         c->Km[i][1] = key[5];
0138         c->Km[i][2] = key[3];
0139         c->Km[i][3] = key[1];
0140     }
0141 
0142     return 0;
0143 }
0144 EXPORT_SYMBOL_GPL(__cast6_setkey);
0145 
0146 int cast6_setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
0147 {
0148     return __cast6_setkey(crypto_tfm_ctx(tfm), key, keylen);
0149 }
0150 EXPORT_SYMBOL_GPL(cast6_setkey);
0151 
0152 /*forward quad round*/
0153 static inline void Q(u32 *block, const u8 *Kr, const u32 *Km)
0154 {
0155     u32 I;
0156     block[2] ^= F1(block[3], Kr[0], Km[0]);
0157     block[1] ^= F2(block[2], Kr[1], Km[1]);
0158     block[0] ^= F3(block[1], Kr[2], Km[2]);
0159     block[3] ^= F1(block[0], Kr[3], Km[3]);
0160 }
0161 
0162 /*reverse quad round*/
0163 static inline void QBAR(u32 *block, const u8 *Kr, const u32 *Km)
0164 {
0165     u32 I;
0166     block[3] ^= F1(block[0], Kr[3], Km[3]);
0167     block[0] ^= F3(block[1], Kr[2], Km[2]);
0168     block[1] ^= F2(block[2], Kr[1], Km[1]);
0169     block[2] ^= F1(block[3], Kr[0], Km[0]);
0170 }
0171 
0172 void __cast6_encrypt(const void *ctx, u8 *outbuf, const u8 *inbuf)
0173 {
0174     const struct cast6_ctx *c = ctx;
0175     u32 block[4];
0176     const u32 *Km;
0177     const u8 *Kr;
0178 
0179     block[0] = get_unaligned_be32(inbuf);
0180     block[1] = get_unaligned_be32(inbuf + 4);
0181     block[2] = get_unaligned_be32(inbuf + 8);
0182     block[3] = get_unaligned_be32(inbuf + 12);
0183 
0184     Km = c->Km[0]; Kr = c->Kr[0]; Q(block, Kr, Km);
0185     Km = c->Km[1]; Kr = c->Kr[1]; Q(block, Kr, Km);
0186     Km = c->Km[2]; Kr = c->Kr[2]; Q(block, Kr, Km);
0187     Km = c->Km[3]; Kr = c->Kr[3]; Q(block, Kr, Km);
0188     Km = c->Km[4]; Kr = c->Kr[4]; Q(block, Kr, Km);
0189     Km = c->Km[5]; Kr = c->Kr[5]; Q(block, Kr, Km);
0190     Km = c->Km[6]; Kr = c->Kr[6]; QBAR(block, Kr, Km);
0191     Km = c->Km[7]; Kr = c->Kr[7]; QBAR(block, Kr, Km);
0192     Km = c->Km[8]; Kr = c->Kr[8]; QBAR(block, Kr, Km);
0193     Km = c->Km[9]; Kr = c->Kr[9]; QBAR(block, Kr, Km);
0194     Km = c->Km[10]; Kr = c->Kr[10]; QBAR(block, Kr, Km);
0195     Km = c->Km[11]; Kr = c->Kr[11]; QBAR(block, Kr, Km);
0196 
0197     put_unaligned_be32(block[0], outbuf);
0198     put_unaligned_be32(block[1], outbuf + 4);
0199     put_unaligned_be32(block[2], outbuf + 8);
0200     put_unaligned_be32(block[3], outbuf + 12);
0201 }
0202 EXPORT_SYMBOL_GPL(__cast6_encrypt);
0203 
0204 static void cast6_encrypt(struct crypto_tfm *tfm, u8 *outbuf, const u8 *inbuf)
0205 {
0206     __cast6_encrypt(crypto_tfm_ctx(tfm), outbuf, inbuf);
0207 }
0208 
0209 void __cast6_decrypt(const void *ctx, u8 *outbuf, const u8 *inbuf)
0210 {
0211     const struct cast6_ctx *c = ctx;
0212     u32 block[4];
0213     const u32 *Km;
0214     const u8 *Kr;
0215 
0216     block[0] = get_unaligned_be32(inbuf);
0217     block[1] = get_unaligned_be32(inbuf + 4);
0218     block[2] = get_unaligned_be32(inbuf + 8);
0219     block[3] = get_unaligned_be32(inbuf + 12);
0220 
0221     Km = c->Km[11]; Kr = c->Kr[11]; Q(block, Kr, Km);
0222     Km = c->Km[10]; Kr = c->Kr[10]; Q(block, Kr, Km);
0223     Km = c->Km[9]; Kr = c->Kr[9]; Q(block, Kr, Km);
0224     Km = c->Km[8]; Kr = c->Kr[8]; Q(block, Kr, Km);
0225     Km = c->Km[7]; Kr = c->Kr[7]; Q(block, Kr, Km);
0226     Km = c->Km[6]; Kr = c->Kr[6]; Q(block, Kr, Km);
0227     Km = c->Km[5]; Kr = c->Kr[5]; QBAR(block, Kr, Km);
0228     Km = c->Km[4]; Kr = c->Kr[4]; QBAR(block, Kr, Km);
0229     Km = c->Km[3]; Kr = c->Kr[3]; QBAR(block, Kr, Km);
0230     Km = c->Km[2]; Kr = c->Kr[2]; QBAR(block, Kr, Km);
0231     Km = c->Km[1]; Kr = c->Kr[1]; QBAR(block, Kr, Km);
0232     Km = c->Km[0]; Kr = c->Kr[0]; QBAR(block, Kr, Km);
0233 
0234     put_unaligned_be32(block[0], outbuf);
0235     put_unaligned_be32(block[1], outbuf + 4);
0236     put_unaligned_be32(block[2], outbuf + 8);
0237     put_unaligned_be32(block[3], outbuf + 12);
0238 }
0239 EXPORT_SYMBOL_GPL(__cast6_decrypt);
0240 
0241 static void cast6_decrypt(struct crypto_tfm *tfm, u8 *outbuf, const u8 *inbuf)
0242 {
0243     __cast6_decrypt(crypto_tfm_ctx(tfm), outbuf, inbuf);
0244 }
0245 
0246 static struct crypto_alg alg = {
0247     .cra_name = "cast6",
0248     .cra_driver_name = "cast6-generic",
0249     .cra_priority = 100,
0250     .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
0251     .cra_blocksize = CAST6_BLOCK_SIZE,
0252     .cra_ctxsize = sizeof(struct cast6_ctx),
0253     .cra_module = THIS_MODULE,
0254     .cra_u = {
0255           .cipher = {
0256                  .cia_min_keysize = CAST6_MIN_KEY_SIZE,
0257                  .cia_max_keysize = CAST6_MAX_KEY_SIZE,
0258                  .cia_setkey = cast6_setkey,
0259                  .cia_encrypt = cast6_encrypt,
0260                  .cia_decrypt = cast6_decrypt}
0261           }
0262 };
0263 
0264 static int __init cast6_mod_init(void)
0265 {
0266     return crypto_register_alg(&alg);
0267 }
0268 
0269 static void __exit cast6_mod_fini(void)
0270 {
0271     crypto_unregister_alg(&alg);
0272 }
0273 
0274 subsys_initcall(cast6_mod_init);
0275 module_exit(cast6_mod_fini);
0276 
0277 MODULE_LICENSE("GPL");
0278 MODULE_DESCRIPTION("Cast6 Cipher Algorithm");
0279 MODULE_ALIAS_CRYPTO("cast6");
0280 MODULE_ALIAS_CRYPTO("cast6-generic");
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