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The XTEA implementation was incorrect due to a misinterpretation of operator precedence. Because of the wide-spread nature of this error, the erroneous implementation will be kept, albeit under the new name of XETA. Signed-off-by: Aaron Grothe <[email protected]> Signed-off-by: Herbert Xu <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -1,11 +1,15 @@ | ||
/* | ||
* Cryptographic API. | ||
* | ||
* TEA and Xtended TEA Algorithms | ||
* TEA, XTEA, and XETA crypto alogrithms | ||
* | ||
* The TEA and Xtended TEA algorithms were developed by David Wheeler | ||
* and Roger Needham at the Computer Laboratory of Cambridge University. | ||
* | ||
* Due to the order of evaluation in XTEA many people have incorrectly | ||
* implemented it. XETA (XTEA in the wrong order), exists for | ||
* compatibility with these implementations. | ||
* | ||
* Copyright (c) 2004 Aaron Grothe [email protected] | ||
* | ||
* This program is free software; you can redistribute it and/or modify | ||
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@@ -153,9 +157,9 @@ static void xtea_encrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
z = u32_in (src + 4); | ||
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while (sum != limit) { | ||
y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3]; | ||
y += ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum&3]); | ||
sum += XTEA_DELTA; | ||
z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3]; | ||
z += ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 &3]); | ||
} | ||
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u32_out (dst, y); | ||
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@@ -174,6 +178,51 @@ static void xtea_decrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
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sum = XTEA_DELTA * XTEA_ROUNDS; | ||
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while (sum) { | ||
z -= ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 & 3]); | ||
sum -= XTEA_DELTA; | ||
y -= ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum & 3]); | ||
} | ||
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u32_out (dst, y); | ||
u32_out (dst + 4, z); | ||
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} | ||
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static void xeta_encrypt(void *ctx_arg, u8 *dst, const u8 *src) | ||
{ | ||
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u32 y, z, sum = 0; | ||
u32 limit = XTEA_DELTA * XTEA_ROUNDS; | ||
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struct xtea_ctx *ctx = ctx_arg; | ||
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y = u32_in (src); | ||
z = u32_in (src + 4); | ||
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while (sum != limit) { | ||
y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3]; | ||
sum += XTEA_DELTA; | ||
z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3]; | ||
} | ||
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u32_out (dst, y); | ||
u32_out (dst + 4, z); | ||
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} | ||
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static void xeta_decrypt(void *ctx_arg, u8 *dst, const u8 *src) | ||
{ | ||
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u32 y, z, sum; | ||
struct tea_ctx *ctx = ctx_arg; | ||
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y = u32_in (src); | ||
z = u32_in (src + 4); | ||
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sum = XTEA_DELTA * XTEA_ROUNDS; | ||
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while (sum) { | ||
z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3]; | ||
sum -= XTEA_DELTA; | ||
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@@ -215,6 +264,21 @@ static struct crypto_alg xtea_alg = { | |
.cia_decrypt = xtea_decrypt } } | ||
}; | ||
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static struct crypto_alg xeta_alg = { | ||
.cra_name = "xeta", | ||
.cra_flags = CRYPTO_ALG_TYPE_CIPHER, | ||
.cra_blocksize = XTEA_BLOCK_SIZE, | ||
.cra_ctxsize = sizeof (struct xtea_ctx), | ||
.cra_module = THIS_MODULE, | ||
.cra_list = LIST_HEAD_INIT(xtea_alg.cra_list), | ||
.cra_u = { .cipher = { | ||
.cia_min_keysize = XTEA_KEY_SIZE, | ||
.cia_max_keysize = XTEA_KEY_SIZE, | ||
.cia_setkey = xtea_setkey, | ||
.cia_encrypt = xeta_encrypt, | ||
.cia_decrypt = xeta_decrypt } } | ||
}; | ||
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static int __init init(void) | ||
{ | ||
int ret = 0; | ||
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@@ -229,6 +293,13 @@ static int __init init(void) | |
goto out; | ||
} | ||
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ret = crypto_register_alg(&xeta_alg); | ||
if (ret < 0) { | ||
crypto_unregister_alg(&tea_alg); | ||
crypto_unregister_alg(&xtea_alg); | ||
goto out; | ||
} | ||
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out: | ||
return ret; | ||
} | ||
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@@ -237,12 +308,14 @@ static void __exit fini(void) | |
{ | ||
crypto_unregister_alg(&tea_alg); | ||
crypto_unregister_alg(&xtea_alg); | ||
crypto_unregister_alg(&xeta_alg); | ||
} | ||
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MODULE_ALIAS("xtea"); | ||
MODULE_ALIAS("xeta"); | ||
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module_init(init); | ||
module_exit(fini); | ||
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MODULE_LICENSE("GPL"); | ||
MODULE_DESCRIPTION("TEA & XTEA Cryptographic Algorithms"); | ||
MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms"); |