# AddressValidity

> Validates if a string is a legitimate external blockchain address.

> For the complete documentation index, see [llms.txt](/llms.txt). Markdown versions of documentation pages are available by appending `.md` to the page URL.

Source: https://dev.flare.network/fdc/attestation-types/address-validity

Assertion whether a given string represents a **valid address** on an external blockchain.

## Supported chains[​](#supported-chains "Direct link to Supported chains")

Network Type

Supported Chains

**Mainnet**

`BTC` (Bitcoin), `DOGE` (Dogecoin), `XRP` (XRP Ledger)

**Testnet**

`testBTC` (Bitcoin Testnet v3), `testDOGE`, `testXRP`

## Request[​](#request "Direct link to Request")

Field

Solidity Type

Description

`addressStr`

`string`

The address string to verify.

## Response[​](#response "Direct link to Response")

Field

Solidity Type

Description

`isValid`

`bool`

Indicates whether the provided address is valid.

`standardAddress`

`string`

The standardized form of the validated address if `isValid`; otherwise, an empty string.

`standardAddressHash`

`bytes32`

The `keccak256` hash of the `standardAddress` if `isValid`; otherwise, a zero `bytes32` string.

## Verification process[​](#verification-process "Direct link to Verification process")

The address is verified against the validity criteria specific to the chain identified by `sourceId`. If the address meets all criteria:

1.  `isValid` is set to `true`.
2.  The `standardAddress` and its `standardAddressHash` are computed.

If the address is invalid:

-   `isValid` is set to `false`.
-   The `standardAddress` is empty and `standardAddressHash` is zero value.

Lowest used timestamp

For the `lowestUsedTimestamp` parameter, the value `0xffffffffffffffff` (equivalent to 264−12^{64} - 1264−1) in hexadecimal) is used as the default.

## Address validity criteria[​](#address-validity-criteria "Direct link to Address validity criteria")

### Bitcoin[​](#bitcoin "Direct link to Bitcoin")

An address on Bitcoin is derived from the locking script (`pkscript`). Only standard locking scripts get assigned an address. There are two formats of the Bitcoin addresses, `Base58` and `Bech32(m)`. The format is determined based on the type of locking script.

#### `Base58`[​](#base58 "Direct link to base58")

Bitcoin's **Base58** format uses the following encoding dictionary:

```
123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz
```

##### Address Structure[​](#address-structure "Direct link to Address Structure")

Decoded addresses have the format:

```
<leadingByte><hash><checksum>
```

##### Components[​](#components "Direct link to Components")

-   **`leadingByte`**:
    -   On **mainnet**:
        -   `00` for Pay-to-PubKey (p2pk) and Pay-to-PubKey-Hash (p2pkh)
        -   `05` for Pay-to-Script-Hash (p2sh)
    -   On **testnet**:
        -   `6f` for p2pk and p2pkh
        -   `c4` for p2sh
-   **`hash`**: Represents either the public key, hash of the public key, or hash of a script.
-   **`checksum`**: The first four bytes of the double SHA-256 hash of `<leadingByte><hash>`.

##### Validation Criteria[​](#validation-criteria "Direct link to Validation Criteria")

1.  Address contains only characters from the Base58 dictionary.
2.  Decoded hexadecimal form is exactly **25 bytes** long (address length varies between **26 to 34 characters**).
3.  Starts with a valid `leadingByte`.
4.  The checksum is valid and matches the first four bytes of the double SHA-256 hash.

##### Resources[​](#resources "Direct link to Resources")

-   [Base58Check Encoding](https://en.bitcoin.it/wiki/Base58Check_encoding)
-   [BIP-0013](https://en.bitcoin.it/wiki/BIP_0013)
-   [BIP-0016](https://en.bitcoin.it/wiki/BIP_0016)

#### `Bech32(m)`[​](#bech32m "Direct link to bech32m")

Bech32 is a newer address format using the character set:

```
qpzry9x8gf2tvdw0s3jn54khce6mua7l
```

##### Address Structure[​](#address-structure-1 "Direct link to Address Structure")

A Bech32 address has the following components:

-   **Human-Readable Part (HRP)**:
    -   `bc` for **mainnet**
    -   `tb` for **testnet**
-   **Separator**: Always `1`
-   **Data Part**:
    -   The first character indicates the **witness version** (0-16).
    -   The last six characters form a **checksum**.

The checksum differs based on the witness version:

-   **Bech32** for witness version `0` ([BIP-0173](https://en.bitcoin.it/wiki/BIP_0173))
-   **Bech32m** for witness versions `1` to `16` ([BIP-0350](https://en.bitcoin.it/wiki/BIP_0350))

##### Validation Criteria[​](#validation-criteria-1 "Direct link to Validation Criteria")

1.  Address contains only characters from the Bech32 dictionary.
2.  All non-numeric characters must be either entirely uppercase or lowercase.
3.  Starts with a valid HRP followed by the separator (`1`).
4.  Length is between **14 to 74 characters**, with the length modulo 8 being **0, 3, or 5**.
    -   For witness version `0`, length must be **42 or 62 characters**.
5.  Checksum is validated based on the witness version.
6.  Addresses with witness versions `2` and above are unsupported and invalid.

##### Resources[​](#resources-1 "Direct link to Resources")

-   [Bech32](https://en.bitcoin.it/wiki/Bech32)
-   [SegWit](https://en.bitcoin.it/wiki/Segregated_Witness)
-   [BIP-0141](https://en.bitcoin.it/wiki/BIP_0141)
-   [BIP-0341](https://en.bitcoin.it/wiki/BIP_0341)
-   [BIP-0350](https://en.bitcoin.it/wiki/BIP_0350)

### Dogecoin (`Base58`)[​](#dogecoin-base58 "Direct link to dogecoin-base58")

Dogecoin uses a **Base58** dictionary, identical to Bitcoin's:

```
123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz
```

#### Address Structure[​](#address-structure-2 "Direct link to Address Structure")

Decoded addresses have the format:

```
<leadingByte><hash><checksum>
```

#### Components[​](#components-1 "Direct link to Components")

-   **`leadingByte`**:
    -   On **mainnet**:
        -   `1e` for p2pk and p2pkh
        -   `16` for p2sh
    -   On **testnet**:
        -   `6f` for p2pk and p2pkh
        -   `71` for p2sh
-   **`hash`**: Represents either the public key, hash of the public key, or script hash.
-   **`checksum`**: First four bytes of the double SHA-256 hash of `<leadingByte><hash>`.

#### Validation Criteria[​](#validation-criteria-2 "Direct link to Validation Criteria")

1.  Address contains only characters from the Base58 dictionary.
2.  Length is **26 to 34 characters**. Decoded hex form is **25 bytes**.
3.  Valid leading byte:
    -   **Mainnet**: Starts with `D`, `A`, or `9`.
    -   **Testnet**: Starts with `n`, `m`, or `2`.
4.  The checksum is validated.

### XRPL (`Base58`)[​](#xrpl-base58 "Direct link to xrpl-base58")

The XRP Ledger uses a custom **Base58** dictionary:

```
rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz
```

#### Address Structure[​](#address-structure-3 "Direct link to Address Structure")

Decoded to hexadecimal:

```
<leadingByte><publicKeyHash><checksum>
```

#### Components[​](#components-2 "Direct link to Components")

-   **`leadingByte`**:
    -   On **mainnet**: `00` (addresses start with `r`).
-   **`publicKeyHash`**: A **20-byte** hash of the public key.
-   **`checksum`**: The first four bytes of the double SHA-256 hash of `<leadingByte><publicKeyHash>`.

#### Validation Criteria[​](#validation-criteria-3 "Direct link to Validation Criteria")

1.  Address contains only characters from the XRPL Base58 dictionary.
2.  Length is **25 to 35 characters**. Decoded hex form is **25 bytes**.
3.  Address starts with `r`.
4.  The checksum is valid.

#### Resources[​](#resources-2 "Direct link to Resources")

-   [XRPL Base58 Encodings](https://xrpl.org/docs/references/protocol/data-types/base58-encodings)
-   [XRPL Addresses](https://xrpl.org/accounts.html#addresses)

## Contract Interface[​](#contract-interface "Direct link to Contract Interface")

For the complete interface definition, see [`IAddressValidity`](/fdc/reference/IAddressValidity).