core.enc.sha1¶

SHA-1 message-digest hash.

Overview¶

core.enc.sha1 implements the SHA-1 hash algorithm (FIPS 180-4) for the kernel. It provides an incremental streaming interface (SHA1Init / SHA1Update / SHA1Final) for computing 160-bit digests over data arriving in multiple chunks. The implementation uses big-endian byte order for state words and digest output, as required by the SHA-1 specification.

Dependencies¶

core.util — memset
arch.x86.util — RolDWord, RorDWord (32-bit rotate operations)

Types¶

TSHA1Digest / PSHA1Digest¶

TSHA1Digest = array[0..19] of byte;

A 20-byte (160-bit) SHA-1 digest.

TSHA1Context / PSHA1Context¶

TSHA1Context = record
    State : array[0..4] of cardinal;
    Buffer: array[0..63] of uint8;
    BufCnt: uint32;
    Length: QWord;
end;

Incremental hashing context. State holds the five 32-bit SHA-1 state words initialised to the standard constants. Buffer is a 64-byte block accumulation buffer. BufCnt tracks the number of bytes currently in Buffer. Length accumulates the total number of complete 64-byte blocks processed (in bytes).

Functions and Procedures¶

SHA1Init¶

procedure SHA1Init(ctx : PSHA1Context);

Initialises the SHA-1 context to the standard initial state: - State[0] = $67452301 - State[1] = $EFCDAB89 - State[2] = $98BADCFE - State[3] = $10325476 - State[4] = $C3D2E1F0

Must be called before any SHA1Update calls.

SHA1Update¶

procedure SHA1Update(ctx : PSHA1Context; buffer : puint8; bufferLen : uint32);

Feeds bufferLen bytes from buffer into the hash context. Internally buffers partial blocks and calls SHA1Transform when a complete 64-byte block is assembled. May be called multiple times.

SHA1Final¶

procedure SHA1Final(ctx : PSHA1Context; digest : PSHA1Digest);

Finalises the hash by appending SHA-1 padding (0x80 followed by zeroes) and the 64-bit big-endian message bit-length. Writes the 20-byte digest into the caller-supplied digest buffer. Zeroes the context after extraction.

Unlike MD5Final, SHA1Final does not allocate a digest buffer; the caller must provide one.

Notes¶

SHA-1 is no longer considered cryptographically secure for collision resistance. It should not be used for new security-critical applications. It is included in Asuro for compatibility with existing protocols or formats that require it.

The internal SHA1Transform function processes data in big-endian format using the helper Invert to convert the 64-byte input buffer into 16 big-endian uint32 words before applying the four SHA-1 rounds (0–19, 20–39, 40–59, 60–79).

SHA1Final does not allocate memory; the caller is responsible for providing a TSHA1Digest-sized buffer.