/*- * Copyright © 2011, 2014 * Thorsten Glaser * * Provided that these terms and disclaimer and all copyright notices * are retained or reproduced in an accompanying document, permission * is granted to deal in this work without restriction, including un‐ * limited rights to use, publicly perform, distribute, sell, modify, * merge, give away, or sublicence. * * This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to * the utmost extent permitted by applicable law, neither express nor * implied; without malicious intent or gross negligence. In no event * may a licensor, author or contributor be held liable for indirect, * direct, other damage, loss, or other issues arising in any way out * of dealing in the work, even if advised of the possibility of such * damage or existence of a defect, except proven that it results out * of said person’s immediate fault when using the work as intended. *- * This file provides BAFH (Better Avalanche for the Jenkins Hash) as * inline macro bodies that operate on “register uint32_t” variables, * with variants that use their local intermediate registers. * * Usage note for BAFH with entropy distribution: input up to 4 bytes * is best combined into a 32-bit unsigned integer, which is then run * through BAFHFinish_reg for mixing and then used as context instead * of 0. Longer input should be handled the same: take the first four * bytes as IV after mixing then add subsequent bytes the same way. * This needs counting input bytes and is endian-dependent, thus not, * for speed reasons, specified for the regular stable hash, but very * much recommended if the actual output value may differ across runs * (so is using a random value instead of 0 for the IV). */ #ifndef SYSKERN_MIRHASH_H #define SYSKERN_MIRHASH_H 1 #define SYSKERN_MIRHASH_BAFH #include __RCSID("$MirOS: src/bin/mksh/mirhash.h,v 1.2 2014/06/29 11:48:05 tg Exp $"); /*- * BAFH itself is defined by the following primitives: * * • BAFHInit(ctx) initialises the hash context, which consists of a * sole 32-bit unsigned integer (ideally in a register), to 0. * It is possible to use any initial value out of [0; 2³²[ – which * is, in fact, recommended if using BAFH for entropy distribution * – but for a regular stable hash, the IV 0 is needed. * * • BAFHUpdateOctet(ctx,val) compresses the unsigned 8-bit quantity * into the hash context. The algorithm used is Jenkins’ one-at-a- * time, except that an additional constant 1 is added so that, if * the context is (still) zero, adding a NUL byte is not ignored. * * • BAFHror(eax,cl) evaluates to the unsigned 32-bit integer “eax”, * rotated right by “cl” ∈ [0;31]; no casting, be careful! * * • BAFHFinish(ctx) avalanches the context around so every sub-byte * depends on all input octets; afterwards, the context variable’s * value is the hash output. BAFH does not use any padding, nor is * the input length added; this is due to the common use case (for * quick entropy distribution and use with a hashtable). * Warning: BAFHFinish uses the MixColumn algorithm of AES – which * is reversible (to avoid introducing funnels and reducing entro‐ * py), so blinding may need to be employed for some uses, e.g. in * mksh, after a fork. * * The BAFHUpdateOctet and BAFHFinish are available in two flavours: * suffixed with _reg (assumes the context is in a register) or _mem * (which doesn’t). * * The following high-level macros (with _reg and _mem variants) are * available: * * • BAFHUpdateMem(ctx,buf,len) adds a memory block to a context. * • BAFHUpdateStr(ctx,buf) is equivalent to using len=strlen(buf). * • BAFHHostMem(ctx,buf,len) calculates the hash of the memory buf‐ * fer using the first 4 octets (mixed) for IV, as outlined above; * the result is endian-dependent; “ctx” assumed to be a register. * • BAFHHostStr(ctx,buf) does the same for C strings. * * All macros may use ctx multiple times in their expansion, but all * other arguments are always evaluated at most once. * * To stay portable, never use the BAFHHost*() macros (these are for * host-local entropy shuffling), and encode numbers using ULEB128. */ #define BAFHInit(h) do { \ (h) = 0; \ } while (/* CONSTCOND */ 0) #define BAFHUpdateOctet_reg(h,b) do { \ (h) += (uint8_t)(b); \ ++(h); \ (h) += (h) << 10; \ (h) ^= (h) >> 6; \ } while (/* CONSTCOND */ 0) #define BAFHUpdateOctet_mem(m,b) do { \ register uint32_t BAFH_h = (m); \ \ BAFHUpdateOctet_reg(BAFH_h, (b)); \ (m) = BAFH_h; \ } while (/* CONSTCOND */ 0) #define BAFHror(eax,cl) (((eax) >> (cl)) | ((eax) << (32 - (cl)))) #define BAFHFinish_reg(h) do { \ register uint32_t BAFHFinish_v; \ \ BAFHFinish_v = ((h) >> 7) & 0x01010101U; \ BAFHFinish_v += BAFHFinish_v << 1; \ BAFHFinish_v += BAFHFinish_v << 3; \ BAFHFinish_v ^= ((h) << 1) & 0xFEFEFEFEU; \ \ BAFHFinish_v ^= BAFHror(BAFHFinish_v, 8); \ BAFHFinish_v ^= ((h) = BAFHror((h), 8)); \ BAFHFinish_v ^= ((h) = BAFHror((h), 8)); \ (h) = BAFHror((h), 8) ^ BAFHFinish_v; \ } while (/* CONSTCOND */ 0) #define BAFHFinish_mem(m) do { \ register uint32_t BAFHFinish_v, BAFH_h = (m); \ \ BAFHFinish_v = (BAFH_h >> 7) & 0x01010101U; \ BAFHFinish_v += BAFHFinish_v << 1; \ BAFHFinish_v += BAFHFinish_v << 3; \ BAFHFinish_v ^= (BAFH_h << 1) & 0xFEFEFEFEU; \ \ BAFHFinish_v ^= BAFHror(BAFHFinish_v, 8); \ BAFHFinish_v ^= (BAFH_h = BAFHror(BAFH_h, 8)); \ BAFHFinish_v ^= (BAFH_h = BAFHror(BAFH_h, 8)); \ (m) = BAFHror(BAFH_h, 8) ^ BAFHFinish_v; \ } while (/* CONSTCOND */ 0) #define BAFHUpdateMem_reg(h,p,z) do { \ register const uint8_t *BAFHUpdate_p; \ register size_t BAFHUpdate_z = (z); \ \ BAFHUpdate_p = (const void *)(p); \ while (BAFHUpdate_z--) \ BAFHUpdateOctet_reg((h), *BAFHUpdate_p++); \ } while (/* CONSTCOND */ 0) /* meh should have named them _r/m but that’s not valid C */ #define BAFHUpdateMem_mem(m,p,z) do { \ register uint32_t BAFH_h = (m); \ \ BAFHUpdateMem_reg(BAFH_h, (p), (z)); \ (m) = BAFH_h; \ } while (/* CONSTCOND */ 0) #define BAFHUpdateStr_reg(h,s) do { \ register const uint8_t *BAFHUpdate_s; \ register uint8_t BAFHUpdate_c; \ \ BAFHUpdate_s = (const void *)(s); \ while ((BAFHUpdate_c = *BAFHUpdate_s++) != 0) \ BAFHUpdateOctet_reg((h), BAFHUpdate_c); \ } while (/* CONSTCOND */ 0) #define BAFHUpdateStr_mem(m,s) do { \ register uint32_t BAFH_h = (m); \ \ BAFHUpdateStr_reg(BAFH_h, (s)); \ (m) = BAFH_h; \ } while (/* CONSTCOND */ 0) #define BAFHHostMem(h,p,z) do { \ register const uint8_t *BAFHUpdate_p; \ register size_t BAFHUpdate_z = (z); \ size_t BAFHHost_z; \ union { \ uint8_t as_u8[4]; \ uint32_t as_u32; \ } BAFHHost_v; \ \ BAFHUpdate_p = (const void *)(p); \ BAFHHost_v.as_u32 = 0; \ BAFHHost_z = BAFHUpdate_z < 4 ? BAFHUpdate_z : 4; \ memcpy(BAFHHost_v.as_u8, BAFHUpdate_p, BAFHHost_z); \ BAFHUpdate_p += BAFHHost_z; \ BAFHUpdate_z -= BAFHHost_z; \ (h) = BAFHHost_v.as_u32; \ BAFHFinish_reg(h); \ while (BAFHUpdate_z--) \ BAFHUpdateOctet_reg((h), *BAFHUpdate_p++); \ BAFHFinish_reg(h); \ } while (/* CONSTCOND */ 0) #define BAFHHostStr(h,s) do { \ register const uint8_t *BAFHUpdate_s; \ register uint8_t BAFHUpdate_c; \ union { \ uint8_t as_u8[4]; \ uint32_t as_u32; \ } BAFHHost_v; \ \ BAFHUpdate_s = (const void *)(s); \ if ((BAFHHost_v.as_u8[0] = *BAFHUpdate_s) != 0) \ ++BAFHUpdate_s; \ if ((BAFHHost_v.as_u8[1] = *BAFHUpdate_s) != 0) \ ++BAFHUpdate_s; \ if ((BAFHHost_v.as_u8[2] = *BAFHUpdate_s) != 0) \ ++BAFHUpdate_s; \ if ((BAFHHost_v.as_u8[3] = *BAFHUpdate_s) != 0) \ ++BAFHUpdate_s; \ (h) = BAFHHost_v.as_u32; \ BAFHFinish_reg(h); \ while ((BAFHUpdate_c = *BAFHUpdate_s++) != 0) \ BAFHUpdateOctet_reg((h), BAFHUpdate_c); \ BAFHFinish_reg(h); \ } while (/* CONSTCOND */ 0) #endif