sergeych
d0d79d2f07
- New docs/LegacyDigest.md: full reference for lyng.legacy_digest, covering the sha1() API, input types (String / Buffer), FIPS compliance note, and explicit guidance on appropriate vs. inappropriate use. - docs/ai_stdlib_reference.md: entry in section 5 so AI agents know LegacyDigest.sha1() exists and is intentionally named as legacy-only. - docs/whats_new.md: release-note section alongside Complex, Decimal, and Matrix, with a minimal runnable example and cross-link. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
67 lines
2.0 KiB
Markdown
67 lines
2.0 KiB
Markdown
# Legacy Digest Functions (`lyng.legacy_digest`)
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> ⚠️ **Security warning:** The functions in this module use cryptographically broken
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> algorithms. Do **not** use them for passwords, digital signatures, integrity
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> verification against adversarial tampering, or any other security-sensitive
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> purpose. They exist solely for compatibility with legacy protocols and file
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> formats that require specific hash values.
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Import when you need to produce a SHA-1 digest for an existing protocol or format:
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```lyng
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import lyng.legacy_digest
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```
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## `LegacyDigest` Object
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### `sha1(data): String`
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Computes the SHA-1 digest of `data` and returns it as a 40-character lowercase
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hex string.
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`data` can be:
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| Type | Behaviour |
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|----------|----------------------------------------|
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| `String` | Encoded as UTF-8, then hashed |
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| `Buffer` | Raw bytes hashed directly |
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| anything | Falls back to `toString()` then UTF-8 |
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```lyng
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import lyng.legacy_digest
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// String input
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val h = LegacyDigest.sha1("abc")
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assertEquals("a9993e364706816aba3e25717850c26c9cd0d89d", h)
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// Empty string
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assertEquals("da39a3ee5e6b4b0d3255bfef95601890afd80709", LegacyDigest.sha1(""))
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```
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```lyng
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import lyng.legacy_digest
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import lyng.buffer
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// Buffer input (raw bytes)
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val buf = Buffer.decodeHex("616263") // 0x61 0x62 0x63 = "abc"
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assertEquals("a9993e364706816aba3e25717850c26c9cd0d89d", LegacyDigest.sha1(buf))
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```
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## Implementation Notes
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- Pure Kotlin/KMP — no native libraries or extra dependencies.
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- Follows FIPS 180-4.
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- The output is always lowercase hex, never uppercase or binary.
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## When to Use
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Use `lyng.legacy_digest` only when an external system you cannot change requires
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a SHA-1 value, for example:
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- old git-style content addresses
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- some OAuth 1.0 / HMAC-SHA1 signature schemes
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- legacy file checksums defined in published specs
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For any new design choose a current hash function (SHA-256 or better) once
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Lyng adds a `lyng.digest` module.
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