diff --git a/src/headers/tomcrypt_misc.h b/src/headers/tomcrypt_misc.h index ad23c39..c5e4ab3 100644 --- a/src/headers/tomcrypt_misc.h +++ b/src/headers/tomcrypt_misc.h @@ -39,6 +39,7 @@ int hkdf(int hash_idx, #endif /* LTC_HKDF */ /* ---- MEM routines ---- */ +int mem_neq(const void *a, const void *b, size_t len); void zeromem(volatile void *dst, size_t len); void burn_stack(unsigned long len); diff --git a/src/misc/mem_neq.c b/src/misc/mem_neq.c new file mode 100644 index 0000000..f28e36d --- /dev/null +++ b/src/misc/mem_neq.c @@ -0,0 +1,55 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtom.org + */ +#include "tomcrypt.h" + +/** + @file mem_neq.c + Compare two blocks of memory for inequality. + Steffen Jaeckel +*/ + +/** + Compare two blocks of memory for inequality. + + The usage is similar to that of standard memcmp(), but you can only test + if the memory is equal or not - you can not determine by how much the + first different byte differs. + + @param a The first memory region + @param b The second memory region + @param len The length of the area to compare (octets) + + @return 0 when a and b are equal for len bytes, else they are not equal. +*/ +int mem_neq(const void *a, const void *b, size_t len) +{ + unsigned char ret = 0; + const unsigned char* pa; + const unsigned char* pb; + + LTC_ARGCHK(a != NULL); + LTC_ARGCHK(b != NULL); + + pa = a; + pb = b; + + while (len-- > 0) { + ret |= *pa ^ *pb; + ++pa; + ++pb; + } + + return ret; +} + +/* $Source$ */ +/* $Revision$ */ +/* $Date$ */