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lib/sha1.c
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// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* SHA1 routine optimized to do word accesses rather than byte accesses, * and to avoid unnecessary copies into the context array. * * This was based on the git SHA1 implementation. |
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*/ #include <linux/kernel.h> |
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#include <linux/export.h> |
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#include <linux/bitops.h> |
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#include <linux/string.h> |
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#include <crypto/sha1.h> |
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#include <asm/unaligned.h> |
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/* * If you have 32 registers or more, the compiler can (and should) * try to change the array[] accesses into registers. However, on * machines with less than ~25 registers, that won't really work, * and at least gcc will make an unholy mess of it. * * So to avoid that mess which just slows things down, we force * the stores to memory to actually happen (we might be better off * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as * suggested by Artur Skawina - that will also make gcc unable to * try to do the silly "optimize away loads" part because it won't * see what the value will be). * * Ben Herrenschmidt reports that on PPC, the C version comes close * to the optimized asm with this (ie on PPC you don't want that * 'volatile', since there are lots of registers). * * On ARM we get the best code generation by forcing a full memory barrier * between each SHA_ROUND, otherwise gcc happily get wild with spilling and * the stack frame size simply explode and performance goes down the drain. */ |
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#ifdef CONFIG_X86 #define setW(x, val) (*(volatile __u32 *)&W(x) = (val)) #elif defined(CONFIG_ARM) #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0) #else #define setW(x, val) (W(x) = (val)) #endif |
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/* This "rolls" over the 512-bit array */ #define W(x) (array[(x)&15]) |
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/* * Where do we get the source from? The first 16 iterations get it from * the input data, the next mix it from the 512-bit array. */ #define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t) #define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1) #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \ __u32 TEMP = input(t); setW(t, TEMP); \ E += TEMP + rol32(A,5) + (fn) + (constant); \ |
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B = ror32(B, 2); \ TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0) |
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#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E ) #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E ) #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E ) |
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/** |
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* sha1_transform - single block SHA1 transform (deprecated) |
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* * @digest: 160 bit digest to update * @data: 512 bits of data to hash |
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* @array: 16 words of workspace (see note) |
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* |
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* This function executes SHA-1's internal compression function. It updates the * 160-bit internal state (@digest) with a single 512-bit data block (@data). * * Don't use this function. SHA-1 is no longer considered secure. And even if * you do have to use SHA-1, this isn't the correct way to hash something with * SHA-1 as this doesn't handle padding and finalization. |
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* * Note: If the hash is security sensitive, the caller should be sure * to clear the workspace. This is left to the caller to avoid * unnecessary clears between chained hashing operations. */ |
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void sha1_transform(__u32 *digest, const char *data, __u32 *array) |
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{ |
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__u32 A, B, C, D, E; |
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unsigned int i = 0; |
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A = digest[0]; B = digest[1]; C = digest[2]; D = digest[3]; E = digest[4]; /* Round 1 - iterations 0-16 take their input from 'data' */ |
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for (; i < 16; ++i) T_0_15(i, A, B, C, D, E); |
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/* Round 1 - tail. Input from 512-bit mixing array */ |
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for (; i < 20; ++i) T_16_19(i, A, B, C, D, E); |
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/* Round 2 */ |
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for (; i < 40; ++i) T_20_39(i, A, B, C, D, E); |
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/* Round 3 */ |
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for (; i < 60; ++i) T_40_59(i, A, B, C, D, E); |
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/* Round 4 */ |
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for (; i < 80; ++i) T_60_79(i, A, B, C, D, E); |
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digest[0] += A; digest[1] += B; digest[2] += C; digest[3] += D; digest[4] += E; |
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} |
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EXPORT_SYMBOL(sha1_transform); |
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/** |
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* sha1_init - initialize the vectors for a SHA1 digest |
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* @buf: vector to initialize */ |
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void sha1_init(__u32 *buf) |
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{ buf[0] = 0x67452301; buf[1] = 0xefcdab89; buf[2] = 0x98badcfe; buf[3] = 0x10325476; buf[4] = 0xc3d2e1f0; } |
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EXPORT_SYMBOL(sha1_init); |