constant-time= ( a b -- ? )
Cryptographic utilities

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constant-time-zero? ( seq -- ? )

Vocabulary
crypto.utils

Inputs

a	a sequence
b	a sequence

Outputs

?	t if equal, f otherwise

Word description
Compares two sequences for equality in constant time. Unlike = or sequence=, this function always examines all bytes of both sequences (when lengths match), preventing timing attacks that could reveal information about the contents.

Notes
If the sequences have different lengths, returns f immediately. This length check is not constant-time, but sequence lengths are typically not secret in cryptographic protocols.

Examples

USING: byte-arrays crypto.utils ; B{ 1 2 3 4 } B{ 1 2 3 4 } constant-time=
! => t

Definition

USING: kernel math sequences ;

IN: crypto.utils

:: constant-time= ( a b -- ? )
    a length b length =
    [ 0 a b [ bitxor bitor ] 2each 0 = ] [ f ] if ;