validateCvvFromKey

validateCvvFromKey(
pan: string,
expiry: string,
derivedKey: Buffer,
cvv: string,
keyId: string,
): boolean

Validates a 4-digit CVV using a pre-derived HMAC key. Uses constant-time comparison (timingSafeEqual) to prevent timing attacks.

Parameters

pan (string) — 16-digit PAN string
expiry (string) — "MM/YY" formatted expiry string
derivedKey (Buffer) — 32-byte key from deriveHmacKey()
cvv (string) — The 4-digit CVV to validate
keyId (string) — Key identifier — must match the keyId used during issuance. Default: DEFAULT_KEY_ID ("default")

Returns