diff --git a/src/modules/data/HashFunction.cpp b/src/modules/data/HashFunction.cpp index 34d9e008d..79f4d25ef 100644 --- a/src/modules/data/HashFunction.cpp +++ b/src/modules/data/HashFunction.cpp @@ -50,6 +50,13 @@ inline uint64 rightrot(uint64 x, uint8 amount) return (x >> amount) | (x << (64 - amount)); } +// Extend the value of `a` to make it a multiple of `n`. +inline uint64 extend_multiple(uint64 a, uint64 n) +{ + uint64 r = a % n; + return r == 0 ? a : a + (n-r); +} + /** * The following implementation is based on the pseudocode provided by multiple * authors on wikipedia: https://en.wikipedia.org/wiki/MD5 @@ -79,25 +86,22 @@ public: uint32 c0 = 0x98badcfe; uint32 d0 = 0x10325476; - //Do the required padding (MD5, SHA1 and SHA2 use the same padding) - uint64 paddedLength = length + 1; //Consider the appended bit - if (paddedLength % 64 < 56) - paddedLength += 56 - paddedLength % 64; - if (paddedLength % 64 > 56) - paddedLength += 120 - paddedLength % 64; + // Compute final padded length, accounting for the appended bit (byte) and size + uint64 paddedLength = extend_multiple(length + 1 + 8, 64); - uint8 *padded = new uint8[paddedLength + 8]; + uint32 *padded = new uint32[paddedLength / 4]; memcpy(padded, input, length); - memset(padded + length, 0, paddedLength - length); - padded[length] = 0x80; + memset(((uint8*)padded) + length, 0, paddedLength - length); + *(((uint8*)padded) + length) = 0x80; // append bit - //Now we need the length in bits - *((uint64*) &padded[paddedLength]) = length * 8; - paddedLength += 8; + // Append length in bits + uint64 bit_length = length * 8; + memcpy(((uint8*)padded) + paddedLength - 8, &bit_length, 8); - for (uint64 i = 0; i < paddedLength; i += 64) + // Process chunks + for (uint64 i = 0; i < paddedLength/4; i += 16) { - uint32 *chunk = (uint32*) &padded[i]; + uint32 *chunk = &padded[i]; uint32 A = a0; uint32 B = b0;