SHA-1¶

Module: Std::Hash::Sha1

160-bit SHA-1 cryptographic hash.

Summary¶

struct Sha1

Sha1.Hash(message: char8[]) -> String

Constants¶

Constant	Value
`BlockSize`	64
`DigestSize`	20

Description¶

SHA-1 is a 160-bit hash function published by NIST in 1995 as a replacement to SHA-0. It uses a Merkle–Damgård construction processing 512-bit blocks through 80 rounds. The key difference from SHA-0 is a single left rotate added to the message expansion schedule, which fixed SHA-0's critical weakness.

The Hash method takes a char8[] and returns a hex-encoded digest string.

Example¶

import Std::Hash::Sha1;

func Main() {
    let digest = Sha1::Hash(c8"abc");
    PrintLine(digest);
    // a9993e364706816aba3e25717850c26c9cd0d89d
}

Test Vectors¶

Input	Expected Digest
`c8""`	`da39a3ee5e6b4b0d3255bfef95601890afd80709`
`c8"abc"`	`a9993e364706816aba3e25717850c26c9cd0d89d`
`c8"message digest"`	`c12252ceda8be8994d5fa0290a47231c1d16aae3`
`c8"Hello, World!"`	`0a0a9f2a6772942557ab5355d76af442f8f65e01`

Safety¶

SHA-1 is cryptographically broken. The SHAttered attack (2017) demonstrated a practical collision attack with a cost of approximately 110,000 GPU years. Since 2024, chosen-prefix collision attacks have become practical, and SHA-1 is no longer considered safe for any collision-resistant use case.

Do not use SHA-1 for: - Password hashing - Digital signatures - Certificate verification - Any security-critical integrity check

Use is acceptable for: - Legacy protocol compatibility (e.g., Git object hashes) - Non-cryptographic checksums - Hash table keys (where collisions are tolerable)