usernames

var (
	// ErrMissingSeparator reports a username without a "." separator.
	ErrMissingSeparator = errors.New("username must contain a separator")
	// ErrNicknameCannotBeEmpty reports an empty username nickname.
	ErrNicknameCannotBeEmpty = errors.New("nickname cannot be empty")
	// ErrNicknameCannotStartWithDigit reports a nickname beginning with a digit.
	ErrNicknameCannotStartWithDigit = errors.New("nickname cannot start with digit")
	// ErrBadNicknameCharacter reports a nickname containing a disallowed character.
	ErrBadNicknameCharacter = errors.New("bad nickname character")
	// ErrNicknameTooShort reports a nickname below the configured soft minimum.
	ErrNicknameTooShort = errors.New("nickname too short")
	// ErrNicknameTooLong reports a nickname above the configured soft or hard maximum.
	ErrNicknameTooLong = errors.New("nickname too long")
	// ErrDiscriminatorCannotBeEmpty reports an empty discriminator.
	ErrDiscriminatorCannotBeEmpty = errors.New("discriminator cannot be empty")
	// ErrDiscriminatorCannotBeZero reports a zero discriminator.
	ErrDiscriminatorCannotBeZero = errors.New("discriminator cannot be zero")
	// ErrDiscriminatorCannotBeSingleDigit reports a single-digit discriminator.
	ErrDiscriminatorCannotBeSingleDigit = errors.New("discriminator cannot be a single digit")
	// ErrDiscriminatorCannotHaveLeadingZeros reports a multi-digit discriminator with leading zeros.
	ErrDiscriminatorCannotHaveLeadingZeros = errors.New("discriminator cannot have leading zeros")
	// ErrBadDiscriminatorCharacter reports a discriminator containing non-digits.
	ErrBadDiscriminatorCharacter = errors.New("bad discriminator character")
	// ErrDiscriminatorTooLarge reports a discriminator too large for uint64.
	ErrDiscriminatorTooLarge = errors.New("discriminator too large")

	// ErrInputDataTooLong reports username-link plaintext that exceeds Signal's four-block bound.
	ErrInputDataTooLong = errors.New("username link input data too long")
	// ErrInvalidEntropyDataLength reports entropy that is not LinkEntropySize bytes.
	ErrInvalidEntropyDataLength = errors.New("invalid username link entropy length")
	// ErrUsernameLinkDataTooShort reports encrypted username-link data missing IV/ciphertext/HMAC.
	ErrUsernameLinkDataTooShort = errors.New("username link data too short")
	// ErrHMACMismatch reports a username-link authentication failure.
	ErrHMACMismatch = errors.New("username link hmac mismatch")
	// ErrBadCiphertext reports username-link ciphertext that fails AES-CBC decryption.
	ErrBadCiphertext = errors.New("bad username link ciphertext")
	// ErrInvalidDecryptedDataStructure reports username-link plaintext that is not valid UsernameData.
	ErrInvalidDecryptedDataStructure = errors.New("invalid username link decrypted data")
)