michael_mic.c 3.5 KB

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  1. /*
  2. * Cryptographic API
  3. *
  4. * Michael MIC (IEEE 802.11i/TKIP) keyed digest
  5. *
  6. * Copyright (c) 2004 Jouni Malinen <jkmaline@cc.hut.fi>
  7. *
  8. * This program is free software; you can redistribute it and/or modify
  9. * it under the terms of the GNU General Public License version 2 as
  10. * published by the Free Software Foundation.
  11. */
  12. #include <asm/byteorder.h>
  13. #include <linux/init.h>
  14. #include <linux/module.h>
  15. #include <linux/string.h>
  16. #include <linux/crypto.h>
  17. #include <linux/types.h>
  18. struct michael_mic_ctx {
  19. u8 pending[4];
  20. size_t pending_len;
  21. u32 l, r;
  22. };
  23. static inline u32 xswap(u32 val)
  24. {
  25. return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  26. }
  27. #define michael_block(l, r) \
  28. do { \
  29. r ^= rol32(l, 17); \
  30. l += r; \
  31. r ^= xswap(l); \
  32. l += r; \
  33. r ^= rol32(l, 3); \
  34. l += r; \
  35. r ^= ror32(l, 2); \
  36. l += r; \
  37. } while (0)
  38. static void michael_init(struct crypto_tfm *tfm)
  39. {
  40. struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  41. mctx->pending_len = 0;
  42. }
  43. static void michael_update(struct crypto_tfm *tfm, const u8 *data,
  44. unsigned int len)
  45. {
  46. struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  47. const __le32 *src;
  48. if (mctx->pending_len) {
  49. int flen = 4 - mctx->pending_len;
  50. if (flen > len)
  51. flen = len;
  52. memcpy(&mctx->pending[mctx->pending_len], data, flen);
  53. mctx->pending_len += flen;
  54. data += flen;
  55. len -= flen;
  56. if (mctx->pending_len < 4)
  57. return;
  58. src = (const __le32 *)mctx->pending;
  59. mctx->l ^= le32_to_cpup(src);
  60. michael_block(mctx->l, mctx->r);
  61. mctx->pending_len = 0;
  62. }
  63. src = (const __le32 *)data;
  64. while (len >= 4) {
  65. mctx->l ^= le32_to_cpup(src++);
  66. michael_block(mctx->l, mctx->r);
  67. len -= 4;
  68. }
  69. if (len > 0) {
  70. mctx->pending_len = len;
  71. memcpy(mctx->pending, src, len);
  72. }
  73. }
  74. static void michael_final(struct crypto_tfm *tfm, u8 *out)
  75. {
  76. struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  77. u8 *data = mctx->pending;
  78. __le32 *dst = (__le32 *)out;
  79. /* Last block and padding (0x5a, 4..7 x 0) */
  80. switch (mctx->pending_len) {
  81. case 0:
  82. mctx->l ^= 0x5a;
  83. break;
  84. case 1:
  85. mctx->l ^= data[0] | 0x5a00;
  86. break;
  87. case 2:
  88. mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
  89. break;
  90. case 3:
  91. mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
  92. 0x5a000000;
  93. break;
  94. }
  95. michael_block(mctx->l, mctx->r);
  96. /* l ^= 0; */
  97. michael_block(mctx->l, mctx->r);
  98. dst[0] = cpu_to_le32(mctx->l);
  99. dst[1] = cpu_to_le32(mctx->r);
  100. }
  101. static int michael_setkey(struct crypto_tfm *tfm, const u8 *key,
  102. unsigned int keylen)
  103. {
  104. struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  105. const __le32 *data = (const __le32 *)key;
  106. if (keylen != 8) {
  107. tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  108. return -EINVAL;
  109. }
  110. mctx->l = le32_to_cpu(data[0]);
  111. mctx->r = le32_to_cpu(data[1]);
  112. return 0;
  113. }
  114. static struct crypto_alg michael_mic_alg = {
  115. .cra_name = "michael_mic",
  116. .cra_flags = CRYPTO_ALG_TYPE_DIGEST,
  117. .cra_blocksize = 8,
  118. .cra_ctxsize = sizeof(struct michael_mic_ctx),
  119. .cra_module = THIS_MODULE,
  120. .cra_alignmask = 3,
  121. .cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list),
  122. .cra_u = { .digest = {
  123. .dia_digestsize = 8,
  124. .dia_init = michael_init,
  125. .dia_update = michael_update,
  126. .dia_final = michael_final,
  127. .dia_setkey = michael_setkey } }
  128. };
  129. static int __init michael_mic_init(void)
  130. {
  131. return crypto_register_alg(&michael_mic_alg);
  132. }
  133. static void __exit michael_mic_exit(void)
  134. {
  135. crypto_unregister_alg(&michael_mic_alg);
  136. }
  137. module_init(michael_mic_init);
  138. module_exit(michael_mic_exit);
  139. MODULE_LICENSE("GPL v2");
  140. MODULE_DESCRIPTION("Michael MIC");
  141. MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>");