2 * Copyright © 2011, 2014, 2015
3 * mirabilos <m@mirbsd.org>
5 * Provided that these terms and disclaimer and all copyright notices
6 * are retained or reproduced in an accompanying document, permission
7 * is granted to deal in this work without restriction, including un‐
8 * limited rights to use, publicly perform, distribute, sell, modify,
9 * merge, give away, or sublicence.
11 * This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
12 * the utmost extent permitted by applicable law, neither express nor
13 * implied; without malicious intent or gross negligence. In no event
14 * may a licensor, author or contributor be held liable for indirect,
15 * direct, other damage, loss, or other issues arising in any way out
16 * of dealing in the work, even if advised of the possibility of such
17 * damage or existence of a defect, except proven that it results out
18 * of said person’s immediate fault when using the work as intended.
20 * This file provides BAFH (Better Avalanche for the Jenkins Hash) as
21 * inline macro bodies that operate on “register uint32_t” variables,
22 * with variants that use their local intermediate registers.
24 * Usage note for BAFH with entropy distribution: input up to 4 bytes
25 * is best combined into a 32-bit unsigned integer, which is then run
26 * through BAFHFinish_reg for mixing and then used as context instead
27 * of 0. Longer input should be handled the same: take the first four
28 * bytes as IV after mixing then add subsequent bytes the same way.
29 * This needs counting input bytes and is endian-dependent, thus not,
30 * for speed reasons, specified for the regular stable hash, but very
31 * much recommended if the actual output value may differ across runs
32 * (so is using a random value instead of 0 for the IV).
35 * We are looking into it. Changing the core
36 * hash function in PHP isn't a trivial change
37 * and will take us some time.
41 #ifndef SYSKERN_MIRHASH_H
42 #define SYSKERN_MIRHASH_H 1
43 #define SYSKERN_MIRHASH_BAFH
45 #include <sys/types.h>
47 __RCSID("$MirOS: src/bin/mksh/mirhash.h,v 1.6 2015/11/29 17:05:02 tg Exp $");
50 * BAFH itself is defined by the following primitives:
52 * • BAFHInit(ctx) initialises the hash context, which consists of a
53 * sole 32-bit unsigned integer (ideally in a register), to 0.
54 * It is possible to use any initial value out of [0; 2³²[ – which
55 * is, in fact, recommended if using BAFH for entropy distribution
56 * – but for a regular stable hash, the IV 0 is needed.
58 * • BAFHUpdateOctet(ctx,val) compresses the unsigned 8-bit quantity
59 * into the hash context. The algorithm used is Jenkins’ one-at-a-
60 * time, except that an additional constant 1 is added so that, if
61 * the context is (still) zero, adding a NUL byte is not ignored.
63 * • BAFHror(eax,cl) evaluates to the unsigned 32-bit integer “eax”,
64 * rotated right by “cl” ∈ [0; 31] (no casting, be careful!) where
65 * “eax” must be uint32_t and “cl” an in-range integer.
67 * • BAFHFinish(ctx) avalanches the context around so every sub-byte
68 * depends on all input octets; afterwards, the context variable’s
69 * value is the hash output. BAFH does not use any padding, nor is
70 * the input length added; this is due to the common use case (for
71 * quick entropy distribution and use with a hashtable).
72 * Warning: BAFHFinish uses the MixColumn algorithm of AES – which
73 * is reversible (to avoid introducing funnels and reducing entro‐
74 * py), so blinding may need to be employed for some uses, e.g. in
77 * The BAFHUpdateOctet and BAFHFinish are available in two flavours:
78 * suffixed with _reg (assumes the context is in a register) or _mem
81 * The following high-level macros (with _reg and _mem variants) are
84 * • BAFHUpdateMem(ctx,buf,len) adds a memory block to a context.
85 * • BAFHUpdateStr(ctx,buf) is equivalent to using len=strlen(buf).
86 * • BAFHHostMem(ctx,buf,len) calculates the hash of the memory buf‐
87 * fer using the first 4 octets (mixed) for IV, as outlined above;
88 * the result is endian-dependent; “ctx” assumed to be a register.
89 * • BAFHHostStr(ctx,buf) does the same for C strings.
91 * All macros may use ctx multiple times in their expansion, but all
92 * other arguments are always evaluated at most once except BAFHror.
94 * To stay portable, never use the BAFHHost*() macros (these are for
95 * host-local entropy shuffling), and encode numbers using ULEB128.
98 #define BAFHInit(h) do { \
100 } while (/* CONSTCOND */ 0)
102 #define BAFHUpdateOctet_reg(h,b) do { \
103 (h) += (uint8_t)(b); \
107 } while (/* CONSTCOND */ 0)
109 #define BAFHUpdateOctet_mem(m,b) do { \
110 register uint32_t BAFH_h = (m); \
112 BAFHUpdateOctet_reg(BAFH_h, (b)); \
114 } while (/* CONSTCOND */ 0)
116 #define BAFHror(eax,cl) (((eax) >> (cl)) | ((eax) << (32 - (cl))))
118 #define BAFHFinish_reg(h) do { \
119 register uint32_t BAFHFinish_v; \
121 BAFHFinish_v = ((h) >> 7) & 0x01010101U; \
122 BAFHFinish_v += BAFHFinish_v << 1; \
123 BAFHFinish_v += BAFHFinish_v << 3; \
124 BAFHFinish_v ^= ((h) << 1) & 0xFEFEFEFEU; \
126 BAFHFinish_v ^= BAFHror(BAFHFinish_v, 8); \
127 BAFHFinish_v ^= ((h) = BAFHror((h), 8)); \
128 BAFHFinish_v ^= ((h) = BAFHror((h), 8)); \
129 (h) = BAFHror((h), 8) ^ BAFHFinish_v; \
130 } while (/* CONSTCOND */ 0)
132 #define BAFHFinish_mem(m) do { \
133 register uint32_t BAFHFinish_v, BAFH_h = (m); \
135 BAFHFinish_v = (BAFH_h >> 7) & 0x01010101U; \
136 BAFHFinish_v += BAFHFinish_v << 1; \
137 BAFHFinish_v += BAFHFinish_v << 3; \
138 BAFHFinish_v ^= (BAFH_h << 1) & 0xFEFEFEFEU; \
140 BAFHFinish_v ^= BAFHror(BAFHFinish_v, 8); \
141 BAFHFinish_v ^= (BAFH_h = BAFHror(BAFH_h, 8)); \
142 BAFHFinish_v ^= (BAFH_h = BAFHror(BAFH_h, 8)); \
143 (m) = BAFHror(BAFH_h, 8) ^ BAFHFinish_v; \
144 } while (/* CONSTCOND */ 0)
146 #define BAFHUpdateMem_reg(h,p,z) do { \
147 register const uint8_t *BAFHUpdate_p; \
148 register size_t BAFHUpdate_z = (z); \
150 BAFHUpdate_p = (const void *)(p); \
151 while (BAFHUpdate_z--) \
152 BAFHUpdateOctet_reg((h), *BAFHUpdate_p++); \
153 } while (/* CONSTCOND */ 0)
155 /* meh should have named them _r/m but that’s not valid C */
156 #define BAFHUpdateMem_mem(m,p,z) do { \
157 register uint32_t BAFH_h = (m); \
159 BAFHUpdateMem_reg(BAFH_h, (p), (z)); \
161 } while (/* CONSTCOND */ 0)
163 #define BAFHUpdateStr_reg(h,s) do { \
164 register const uint8_t *BAFHUpdate_s; \
165 register uint8_t BAFHUpdate_c; \
167 BAFHUpdate_s = (const void *)(s); \
168 while ((BAFHUpdate_c = *BAFHUpdate_s++) != 0) \
169 BAFHUpdateOctet_reg((h), BAFHUpdate_c); \
170 } while (/* CONSTCOND */ 0)
172 #define BAFHUpdateStr_mem(m,s) do { \
173 register uint32_t BAFH_h = (m); \
175 BAFHUpdateStr_reg(BAFH_h, (s)); \
177 } while (/* CONSTCOND */ 0)
179 #define BAFHHostMem(h,p,z) do { \
180 register const uint8_t *BAFHUpdate_p; \
181 register size_t BAFHUpdate_z = (z); \
188 BAFHUpdate_p = (const void *)(p); \
189 BAFHHost_v.as_u32 = 0; \
190 BAFHHost_z = BAFHUpdate_z < 4 ? BAFHUpdate_z : 4; \
191 memcpy(BAFHHost_v.as_u8, BAFHUpdate_p, BAFHHost_z); \
192 BAFHUpdate_p += BAFHHost_z; \
193 BAFHUpdate_z -= BAFHHost_z; \
194 (h) = BAFHHost_v.as_u32; \
196 while (BAFHUpdate_z--) \
197 BAFHUpdateOctet_reg((h), *BAFHUpdate_p++); \
199 } while (/* CONSTCOND */ 0)
201 #define BAFHHostStr(h,s) do { \
202 register const uint8_t *BAFHUpdate_s; \
203 register uint8_t BAFHUpdate_c; \
209 BAFHUpdate_s = (const void *)(s); \
210 BAFHHost_v.as_u32 = 0; \
211 if ((BAFHHost_v.as_u8[0] = *BAFHUpdate_s) != 0) \
213 if ((BAFHHost_v.as_u8[1] = *BAFHUpdate_s) != 0) \
215 if ((BAFHHost_v.as_u8[2] = *BAFHUpdate_s) != 0) \
217 if ((BAFHHost_v.as_u8[3] = *BAFHUpdate_s) != 0) \
219 (h) = BAFHHost_v.as_u32; \
221 while ((BAFHUpdate_c = *BAFHUpdate_s++) != 0) \
222 BAFHUpdateOctet_reg((h), BAFHUpdate_c); \
224 } while (/* CONSTCOND */ 0)