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SHA1HashHex

Function SHA1HashHex( const Input : String) : String

Example​

procedure ScriptEvent(var Value: Variant);
begin
  Value := SHA1HashHex('fictional integration payload');
  // Non-empty input produces 40 lowercase hexadecimal characters.
end;

Usage​

SHA1HashHex returns a hexadecimal SHA-1 digest of non-empty UTF-8 text.

Parameters

NameTypeDescription
InputString, constText to hash. Non-empty input is converted to UTF-8 without trimming or Unicode normalisation.

Returns

For non-empty input, 40 lowercase hexadecimal characters using 0-9 and a-f. Empty input returns '', not the standard SHA-1 text for an empty byte sequence.

Behaviour

  • Output is deterministic, unkeyed and unsalted.
  • The helper hashes UTF-8 text, not arbitrary bytes or file content.
  • Alphabetic hexadecimal digits are lowercase and no prefix or separators are included.
  • Exact code-point sequences matter; whitespace and casing are not normalised.

Errors

UTF-8 conversion, allocation and hash failures propagate. There is no error flag or fallback value beyond the deliberate empty-input result.

Usage notes

When a stored or exchanged value must remain interoperable, specify SHA-1, UTF-8 and lowercase hexadecimal together. Do not infer authenticity merely because a supplied hash matches.

Additional Technical Info​

SHA1HashHex calculates SHA-1 over a string's UTF-8 bytes and returns the 20-byte digest as 40 lowercase hexadecimal characters. It is retained for interfaces that explicitly require the legacy SHA-1 representation.

The example is source-reviewed and was not executed by the documentation workflow.

Implementation

Velox exits with an empty result when Input = ''. Otherwise it calls the installed Delphi 37.0 string overload System.Hash.THashSHA1.GetHashString. Delphi initialises a SHA-1 state, passes it the result of TEncoding.UTF8.GetBytes(Input), finalises the 20-byte digest and converts each nibble through THash.DigestAsString using lowercase hexadecimal digits.

Edge cases and quirks

  • Empty input returns '' because of the Velox wrapper, although the Delphi terminal can calculate the standard empty-byte digest.
  • SHA-1 is collision-broken and unsuitable for adversarial integrity, signatures, password storage, authentication or new security protocols.
  • Free Pascal SHA1String accepts RawByteString; callers must not assume its byte encoding matches Velox UTF-8 for non-ASCII input.
  • Unicode normalisation is not applied, so visually identical text can have different hashes.
  • Ordinary string comparison is not documented as constant-time.

Side effects

None beyond temporary managed memory.

Performance and concurrency

Time and temporary UTF-8 storage are linear in input size. Each invocation owns its SHA-1 record, so independent calls do not share mutable hash state.

Related entries

  • SHA1Hash returns the same digest bytes as padded Base64.
  • MD5HashHex is the analogous legacy MD5 helper.
  • HashString returns an unkeyed SHA-384 fingerprint.
  • HMACSHA256Hex returns a keyed SHA-256 MAC as uppercase hexadecimal.

External references

Created 2026-07-15