From c78cf00bd8329dd339d2f73d1b43c366d0f46837 Mon Sep 17 00:00:00 2001 From: Giorgio Vazzana Date: Fri, 15 Jun 2012 17:21:36 +0200 Subject: [PATCH] md5: consistently use uint32_t instead of unsigned int Basically to make code clearer and adherent to the standard. RFC 1321, on page 2 states Let the symbol "+" denote addition of words (i.e., modulo-2^32 addition). Let X <<< s denote the 32-bit value obtained by circularly shifting (rotating) X left by s bit positions. on page 3, section 3.3 states: A four-word buffer (A,B,C,D) is used to compute the message digest. Here each of A, B, C, D is a 32-bit register. so the algorithm needs to work with integers that are exactly 32bits in length. And indeed in struct AVMD5 the MD buffer is declared as "uint32_t ABCD[4];", while in the function that performs the block transformation the state variables were "unsigned int"s. On architectures where sizeof(unsigned int) != sizeof(uint32_t) this could be a problem, although I can't name such an architecture from the top of my head. On a side note, both the reference implementation in RFC 1321 and the gnulib implementation (used by md5sum program on GNU systems) use uint32_t in the transform function. Signed-off-by: Michael Niedermayer --- libavutil/md5.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/libavutil/md5.c b/libavutil/md5.c index 471a510a73..00447f92f0 100644 --- a/libavutil/md5.c +++ b/libavutil/md5.c @@ -88,12 +88,12 @@ static const uint32_t T[64] = { // T[i]= fabs(sin(i+1)<<32) static void body(uint32_t ABCD[4], uint32_t X[16]) { - int t; int i av_unused; - unsigned int a = ABCD[3]; - unsigned int b = ABCD[2]; - unsigned int c = ABCD[1]; - unsigned int d = ABCD[0]; + uint32_t t; + uint32_t a = ABCD[3]; + uint32_t b = ABCD[2]; + uint32_t c = ABCD[1]; + uint32_t d = ABCD[0]; #if HAVE_BIGENDIAN for (i = 0; i < 16; i++)