ory/kratos · error · ErrHashParametersOutOfBounds

scrypt N= not in [1, ]

Error message

scrypt N=%d not in [1, %d]

What it means

This error means a plain scrypt password hash declares an N (CPU/memory cost) parameter that is 0 or greater than 2^17 (131072). N=0 is invalid (no work); N above 2^17 would make each compare allocate up to 128*N*r bytes, risking memory exhaustion at login time. It wraps ErrHashParametersOutOfBounds from validateScryptParams during hash decode.

Solutions

1. Decode the hash parameters and confirm N is a power of two in [1, 131072]
2. Re-hash with an OWASP-recommended configuration (e.g. N=2^17, r=8, p=1)
3. If the hash came from file-encryption tooling, do not import it as a password hash — derive a password hash with this library instead

Example fix

// before (N=2^20, rejected)
$scrypt$N=1048576$r=8$p=1$...
// after (N=2^17, accepted)
$scrypt$N=131072$r=8$p=1$...

func scryptNOK(n uint32) bool { return n >= 1 && n <= 1<<17 }
// Or pre-validate the whole hash: hash.ValidateImportedHash(hashed)

if err := hash.ValidateImportedHash(raw); errors.Is(err, hash.ErrHashParametersOutOfBounds) {
    return fmt.Errorf("scrypt N out of range: %w", err)
}

When it happens

Trigger: decodeScryptHash encounters an scrypt hash string (e.g. sCrypt:/... or $scrypt$...) with N=0 or N>131072, via ValidateImportedHash or during password comparison.

Common situations: Importing scrypt hashes from file-encryption tooling (tarsnap, age) which use N far above 2^17; over-tuned security configs raising N beyond OWASP's 2^17 maximum; hand-edited hash parameters.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• firescrypt ln= exceeds max
• firescrypt r= not in [1, ]
• firescrypt p= not in [1, ]
• scrypt r= not in [1, ]
• scrypt p= not in [1, ]

AI-assisted analysis of ory/kratos@b86338da04 (2026-09-07). Data as JSON: /api/errors/063725aa0a7efa29. Report an issue: GitHub.

Appendix: source

Thrown at hash/hash_limits.go:94

	maxBcryptCost = 15
)

func validateFirebaseScryptParams(logN, r, p uint32) error {
	if logN > maxScryptLogN {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "firescrypt ln=%d exceeds max %d", logN, maxScryptLogN)
	}
	if r == 0 || r > maxScryptR {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "firescrypt r=%d not in [1, %d]", r, maxScryptR)
	}
	if p == 0 || p > maxScryptP {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "firescrypt p=%d not in [1, %d]", p, maxScryptP)
	}
	return nil
}

func validateScryptParams(n, r, p uint32) error {
	if n == 0 || n > maxScryptN {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "scrypt N=%d not in [1, %d]", n, maxScryptN)
	}
	if r == 0 || r > maxScryptR {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "scrypt r=%d not in [1, %d]", r, maxScryptR)
	}
	if p == 0 || p > maxScryptP {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "scrypt p=%d not in [1, %d]", p, maxScryptP)
	}
	return nil
}

func validateArgon2Params(memoryKiB uint64, iterations uint32, parallelism uint8) error {
	if memoryKiB == 0 || memoryKiB > uint64(maxArgon2MemoryKiB) {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "argon2 m=%d KiB not in [1, %d]", memoryKiB, maxArgon2MemoryKiB)
	}
	if iterations == 0 || iterations > maxArgon2Iterations {
		return errors.Wrapf(ErrHashParametersOutOfBounds, "argon2 t=%d not in [1, %d]", iterations, maxArgon2Iterations)
	}
	if parallelism == 0 || parallelism > maxArgon2Parallelism {

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