Skip to main content

SHA1Hash

Function SHA1Hash( const Input : String) : String

Example​

procedure ScriptEvent(var Value: Variant);
begin
  Value := SHA1Hash('fictional integration payload');
  // Non-empty input produces a 28-character padded Base64 value.
end;

Usage​

SHA1Hash returns a Base64-encoded SHA-1 digest of non-empty UTF-8 text.

Parameters

NameTypeDescription
InputString, constText to hash. Non-empty text is encoded as UTF-8 without Unicode normalisation.

Returns

For non-empty input, a 28-character standard Base64 representation of the 20-byte SHA-1 digest, including one = padding character. Empty input returns '' instead of the Base64 form of the standard empty-byte SHA-1 digest.

Behaviour

  • Identical Unicode code-point sequences produce identical output.
  • The result is deterministic, unsalted and unkeyed.
  • Output uses standard Base64 with +, /, padding and no line wrapping.
  • The encoded value represents raw digest bytes, not hexadecimal text.

Errors

Encoding, allocation or hashing failures propagate. The function has no separate error indicator.

Usage notes

Use only when an external protocol requires SHA-1 with this UTF-8/Base64 contract. Persist the algorithm and representation with stored values. For keyed authenticity, use an approved HMAC protocol with a strong secret and verification process.

Additional Technical Info​

SHA1Hash converts a string to UTF-8, calculates its 20-byte SHA-1 digest and returns the digest bytes as padded standard Base64. It is a legacy compatibility helper, not a current security primitive.

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

Implementation

The Velox wrapper initialises an empty result and exits when Input = ''. Otherwise it calls the installed Delphi 37.0 string overload System.Hash.THashSHA1.GetHashBytes. Delphi initialises a SHA-1 record, converts the string with TEncoding.UTF8.GetBytes, updates and finalises it, and returns 20 bytes. Velox formats those bytes through Base64EncodeBytes, using unwrapped standard Base64.

Edge cases and quirks

  • Empty input returns '' because Velox bypasses the Delphi terminal. That differs from normal SHA-1 of an empty byte sequence.
  • SHA-1 has practical collision attacks. Do not use it for signatures, certificates, password storage, tamper resistance or security-sensitive identity.
  • UTF-8 input differs from ANSI, UTF-16 and Free Pascal RawByteString byte contracts for non-ASCII text.
  • Unicode normalisation is not performed; visually identical strings can hash differently.
  • Base64 changes only the representation and does not repair SHA-1's security weaknesses.

Side effects

None beyond temporary managed memory.

Performance and concurrency

Work and temporary UTF-8 storage are linear in input size. Hash state and Base64 encoder instances are local to the call, so independent calls do not share mutable hash state.

Related entries

  • SHA1HashHex returns the same SHA-1 digest as lowercase hexadecimal.
  • MD5Hash is the analogous MD5/Base64 compatibility helper.
  • HashString returns a SHA-384 text fingerprint.
  • HMACSHA256 calculates a keyed SHA-256 MAC.

External references

Created 2026-07-15