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2025-12-04T14:32:52Z

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[[Category:Lua]]
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'''function''' md5memory(''address'', ''size'') ''':''' string

Calculates and returns the MD5 checksum of a block of memory starting at the specified address. The result is returned as a lowercase hexadecimal string (32 hex characters). This is useful for integrity checks of memory regions, detecting runtime modifications, or comparing memory snapshots.

=== Function Parameters ===
{|width="85%" cellpadding="10%" cellpadding="5%" cellspacing="0" border="0"
!align="left"|Parameter
!align="left"|Type
!style="width: 70%;" align="left"|Description
|-
| address
| number|[[CEAddressString]] or Integer
| Start address of the memory block to hash.
|-
| size
| number
| Number of bytes to read from <code>address</code> and include in the hash.
|}

=== Returns ===
A string containing the MD5 hash of the memory block in lowercase hexadecimal (e.g. <code>9e107d9d372bb6826bd81d3542a419d6</code>).

=== Description ===
The function reads <code>size</code> raw bytes starting at <code>address</code>, computes the MD5 digest over those bytes, and returns the digest formatted as a 32-character lowercase hexadecimal string. If the memory region cannot be read (invalid address, insufficient permissions, or target process not available), the function may raise an error.

=== Usage Examples ===

<pre>
-- Simple usage with numeric address
local hash = md5memory(0x401000, 1024)
print("MD5: " .. hash) -- e.g. MD5: 9e107d9d372bb6826bd81d3542a419d6

-- Using a module+offset string
local hash2 = md5memory("kernel32.dll+0x1234", 256)
print("Region MD5: " .. hash2)

-- Output:
-- MD5: a754c02f5e872ca0008b37755928a914
-- Region MD5: 215a614d8b4156943fe865bb7d5e2c8c
</pre>

=== Notes ===

* The function hashes the raw bytes read from memory; CPU endianness or text encoding does not affect the MD5 result.
* Reading large regions can be slow and may consume significant memory depending on implementation; consider hashing in chunks if available.
* MD5 is not collision-resistant; do not rely on MD5 where collision resistance is required.
* When comparing MD5 strings, normalize case (lowercase) or use a case-insensitive comparison.
* Permission or process-targeting issues can prevent reading memory; ensure the correct process/context is selected before calling the function.

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