> For the complete documentation index, see [llms.txt](https://docs.arcan.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.arcan.finance/solidity/types.md).

# Encrypted types

Encrypted types are the confidential counterparts of Solidity values. A confidential token balance is an `euint64`. A hidden flag is an `ebool`. A hidden recipient can be an `eaddress`.

## In the contract

| Type                  | Meaning                                               |
| --------------------- | ----------------------------------------------------- |
| `ebool`               | Encrypted boolean                                     |
| `euint8` … `euint256` | Encrypted unsigned integers                           |
| `eaddress`            | Encrypted address                                     |
| `ebytes`              | Encrypted byte array, where the operation supports it |

## From the user

Inputs that were encrypted off-chain use the external form:

| Type                                  | Meaning                  |
| ------------------------------------- | ------------------------ |
| `externalEbool`                       | Encrypted boolean input  |
| `externalEuint8` … `externalEuint256` | Encrypted integer inputs |
| `externalEaddress`                    | Encrypted address input  |

An external value is not usable in `FHE.add` until `FHE.fromExternal` checks the input proof and returns the internal type.

## Lifting a public value

Sometimes a public number has to enter an encrypted expression. `FHE.asEuint64` and `FHE.asEbool` lift it. This is a trivial encryption. The original number is still visible, because it was public. Use it for constants and plaintext arguments, not for hiding a user amount.

```solidity
euint64 unit = FHE.asEuint64(1);
ebool yes = FHE.asEbool(true);
```

## Casting

`FHE.asEuint32` can widen or narrow another encrypted integer. Narrowing drops the high bits inside the ciphertext. Widening pads with encrypted zeros. The width change does not reveal the value.

## Initialization

`FHE.isInitialized` reports whether a handle has been set. An uninitialized integer behaves as an encryption of zero in arithmetic. Initialize balances explicitly before you depend on them.

## Token balances

Use `euint64` for confidential token amounts. That matches the ERC-7984 shape: the call looks like an ERC-20 call, and the amount is a 64-bit ciphertext handle.


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