Method GenerateKey

internal/js/modules/k6/webcrypto/hmac.go:87–161

GenerateKey generates a new HMAC key.

(
	extractable bool,
	keyUsages []CryptoKeyUsage,
)

// GenerateKey generates a new HMAC key.
func (hkgp *HMACKeyGenParams) GenerateKey(
	extractable bool,
	keyUsages []CryptoKeyUsage,
) (CryptoKeyGenerationResult, error) {
	// 1.
	for _, usage := range keyUsages {
		switch usage {
		case SignCryptoKeyUsage, VerifyCryptoKeyUsage:
			continue
		default:
			return nil, NewError(SyntaxError, "invalid key usage: "+usage)
		}
	}

	// 2.
	// We extract the length attribute from the algorithm object, as it's not
	// part of the normalized algorithm, and as accessing the runtime from the
	// callback below could lead to a race condition.
	if !hkgp.Length.Valid {
		var length bitLength
		switch hkgp.Hash.Name {
		case SHA1:
			length = byteLength(sha1.BlockSize).asBitLength()
		case SHA256:
			length = byteLength(sha256.BlockSize).asBitLength()
		case SHA384:
			length = byteLength(sha512.BlockSize).asBitLength()
		case SHA512:
			length = byteLength(sha512.BlockSize).asBitLength()
		default:
			// This case should never happen, as the normalization algorithm
			// should have thrown an error if the hash algorithm is invalid.
			return nil, NewError(ImplementationError, "invalid hash algorithm: "+hkgp.Hash.Name)
		}

		hkgp.Length = null.IntFrom(int64(length))
	}

	if hkgp.Length.Int64 == 0 {
		return nil, NewError(OperationError, "algorithm's length cannot be 0")
	}

	// 3.
	randomKey := make([]byte, bitLength(hkgp.Length.Int64).asByteLength())
	if _, err := rand.Read(randomKey); err != nil {
		// 4.
		return nil, NewError(OperationError, "failed to generate random key; reason:  "+err.Error())
	}

	// 5.
	key := &CryptoKey{Type: SecretCryptoKeyType, handle: randomKey}

	// 6.
	algorithm := &HMACKeyAlgorithm{}

	// 7.
	algorithm.Name = HMAC
	algorithm.Length = hkgp.Length.Int64