core.enc.md5¶

MD5 message-digest checksum.

Overview¶

core.enc.md5 implements the MD5 hash algorithm (RFC 1321) for the kernel. It provides an incremental streaming interface (MD5Init / MD5Update / MD5Final) for computing digests over data that arrives in multiple chunks, as well as a single-call convenience function (MD5Buffer) for hashing a complete buffer at once. A utility function (MD5To32) folds a 128-bit digest to a 32-bit value for use as a compact key.

MD5 is used in Asuro for file integrity verification and as a legacy key-hash function (replaced by FNV-1a in the hash map but retained for compatibility).

Dependencies¶

core.util — memset, memcpy
arch.x86.util — roldword (32-bit left rotate)
memory.heap — kalloc, kfree
debug.tracer — call-stack tracing

Constants¶

MD5DefineBufferSize¶

Internal working buffer size: 1024. Not directly used by callers.

Types¶

TMD5Context / PMD5Context¶

TMD5Context = record
    Align       : uInt32;
    State       : array[0..3] of uInt32;
    BufferCount : uInt64;
    Buffer      : array[0..63] of uInt8;
    Length      : uInt64;
    Checksum    : array[0..15] of uInt8;
end;

Incremental hashing context. State holds the four 32-bit MD5 state words. Buffer is an internal 64-byte accumulation buffer. Length tracks the total number of bytes processed by MD5Transform. BufferCount tracks how many bytes are currently buffered. Align is set to 64 (the block size).

TMD5Digest / PMD5Digest¶

TMD5Digest = array[0..15] of uInt8;

A 16-byte MD5 digest. Returned as a heap-allocated pointer by MD5Final and MD5Buffer.

Functions and Procedures¶

MD5Init¶

procedure MD5Init(context : PMD5Context);

Initialises an MD5Context to the standard MD5 initial state. Must be called before any MD5Update calls.

MD5Update¶

procedure MD5Update(context : PMD5Context; buffer : PuInt8; bufferLen : uInt32);

Feeds bufferLen bytes from buffer into the hash context. May be called multiple times to hash data arriving in chunks.

MD5Final¶

function MD5Final(context : PMD5Context) : PMD5Digest;

Finalises the hash by appending MD5 padding and the message length, then extracts and returns a heap-allocated 16-byte digest. Zeroes the context after use. The caller must free the returned digest with kfree.

MD5Buffer¶

function MD5Buffer(buffer : PuInt8; bufferLen : uInt32) : PMD5Digest;

Convenience function: allocates a context, runs MD5Init + MD5Update + MD5Final, frees the context, and returns the digest. The caller must free the returned digest with kfree.

MD5To32¶

function MD5To32(Input : PuInt128) : uint32;

Folds a 128-bit MD5 digest to a 32-bit value by XOR-ing the four 32-bit words of the digest. Useful as a compact hash key derived from a full MD5 digest.

Notes¶

MD5 is not cryptographically secure and must not be used for security-critical purposes such as password hashing or digital signatures. It is retained in Asuro for non-security integrity checks and legacy compatibility.

MD5Transform operates on data in little-endian byte order, consistent with the MD5 specification. The internal Invert helper reorders bytes from a byte buffer into little-endian uint32 words.