/**
 * Checks that the provided method is supported for
 * signing and verifying signatures. Throws an error
 * in case the method isn't supported.
 *
 * @throws in case the method isn't supported
 * @param method defines signing algorithm
 */
export declare function assertSignatureMethod(method: string): void;
/**
 * Checks that the provided format is supported for
 * signers keypair. Throws an error
 * in case the format isn't supported.
 *
 * @throws in case the format isn't supported
 * @param format defines format of the key pair
 */
export declare function assertKeyFormat(format?: string): void;