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36 * $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.6 2008/12/16 13:58:37 mav Exp $
39 #include <sys/kernel.h>
40 #include <sys/module.h>
41 #include <sys/types.h>
42 #include <crypto/rc4/rc4.h>
45 swap_bytes(u_char *a, u_char *b)
55 * Initialize an RC4 state buffer using the supplied key,
56 * which can have arbitrary length.
59 rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
64 /* Initialize state with identity permutation */
65 for (i = 0; i < 256; i++)
66 state->perm[i] = (u_char)i;
70 /* Randomize the permutation using key data */
71 for (j = i = k = 0; i < 256; i++) {
72 j += state->perm[i] + key[k];
73 swap_bytes(&state->perm[i], &state->perm[j]);
80 * Encrypt some data using the supplied RC4 state buffer.
81 * The input and output buffers may be the same buffer.
82 * Since RC4 is a stream cypher, this function is used
83 * for both encryption and decryption.
86 rc4_crypt(struct rc4_state *const state,
87 const u_char *inbuf, u_char *outbuf, int buflen)
92 for (i = 0; i < buflen; i++) {
94 /* Update modification indicies */
96 state->index2 += state->perm[state->index1];
98 /* Modify permutation */
99 swap_bytes(&state->perm[state->index1],
100 &state->perm[state->index2]);
102 /* Encrypt/decrypt next byte */
103 j = state->perm[state->index1] + state->perm[state->index2];
104 outbuf[i] = inbuf[i] ^ state->perm[j];
109 rc4_modevent(module_t mod, int type, void *unused)
120 static moduledata_t rc4_mod = {
125 DECLARE_MODULE(rc4, rc4_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
126 MODULE_VERSION(rc4, 1);