# ConfidentialMPTConvertBack

[[Source]](https://github.com/XRPLF/rippled/blob/eeb0d15ea97ed506c65406635edf301eff62a6fd/src/libxrpl/tx/transactors/token/ConfidentialMPTConvertBack.cpp)

Convert your confidential MPT balance back to a public balance. This debits the confidential spending balance and credits the public balance with the plaintext amount. For the issuer's *second account*, this returns confidential supply to the issuer account reserve.

Note
Only the spending balance can be converted back. Amounts in the inbox must first be merged into the spending balance using [ConfidentialMPTMergeInbox][].

*(Requires the [ConfidentialTransfers amendment](https://xls.xrpl.org/xls/XLS-0096-confidential-mpt.html) )*

## Example  JSON


```json
{
  "TransactionType": "ConfidentialMPTConvertBack",
  "Account": "rUserAccount...",
  "MPTokenIssuanceID": "610F33...",
  "MPTAmount": "500",
  "HolderEncryptedAmount": "AD3F...",
  "IssuerEncryptedAmount": "BC2E...",
  "AuditorEncryptedAmount": "C1A9...",
  "BlindingFactor": "12AB...",
  "ZKProof": "ABCD...",
  "BalanceCommitment": "038A...",
  "Fee": "12",
  "Sequence": 2470665,
  "Flags": 2147483648
}
```

##  Fields

In addition to the [common fields](https://xrpl.org/docs/references/protocol/transactions/common-fields#transaction-common-fields),  transactions use the following fields:

| Field | JSON Type | [Internal Type](https://xrpl.org/docs/references/protocol/binary-format/) | Required? | Description |
|  --- | --- | --- | --- | --- |
| `MPTokenIssuanceID` | String | UInt192 | Yes | The unique identifier for the MPT issuance. |
| `MPTAmount` | String | UInt64 | Yes | The plaintext amount to credit to the public balance. |
| `HolderEncryptedAmount` | String | Blob | Yes | 66-byte Ciphertext to be subtracted from the holder's `sfConfidentialBalanceSpending`. |
| `IssuerEncryptedAmount` | String | Blob | Yes | 66-byte Ciphertext to be subtracted from the issuer's mirror balance. |
| `AuditorEncryptedAmount` | String | Blob | No | 66-byte Ciphertext for the auditor. Required if `sfAuditorEncryptionKey` is present on the issuance. |
| `BlindingFactor` | String | UInt256 | Yes | The 32-byte scalar value used to encrypt the amount. Used by validators to verify the ciphertexts match the plaintext `MPTAmount`. |
| `ZKProof` | String | Blob | Yes | A bundle containing the Pedersen Linkage Proof (linking the ElGamal balance to the commitment) and the Range Proof. |
| `BalanceCommitment` | String | Blob | Yes | A 33-byte cryptographic commitment to the user's confidential spending balance. |


## Error Cases

Besides errors that can occur for all transactions,  transactions can result in the following [transaction result codes](https://xrpl.org/docs/references/protocol/transactions/transaction-results):

| Error Code | Description |
|  --- | --- |
| `temDISABLED` | The ConfidentialTransfer is not enabled. |
| `temMALFORMED` | The account is the Issuer, or the `BlindingFactor` is not exactly 32 bytes. |
| `temBAD_CIPHERTEXT` | Ciphertext lengths or formats are invalid. |
| `temBAD_AMOUNT` | `MPTAmount` is zero or greater than the maximum allowable supply. |
| `tecOBJECT_NOT_FOUND` | The `MPToken` or `MPTokenIssuance` does not exist. |
| `tecNO_PERMISSION` | One of the following occurred:The issuance does not have the **Can Confidential Amount** flag.The user's `MPToken` is missing the `ConfidentialBalanceSpending` or `HolderEncryptionKey` fields.The issuance has `AuditorEncryptionKey` set but the transaction does not include `AuditorEncryptedAmount`. |
| `tecINSUFFICIENT_FUNDS` | The global `sfConfidentialOutstandingAmount` is less than the requested `MPTAmount`, or the user's confidential balance is insufficient. |
| `tecBAD_PROOF` | One of the following occurred:The `BlindingFactor` fails to verify the integrity of the ciphertexts.The `ZKProof` fails the Pedersen Linkage check (proving the commitment matches the on-ledger balance).The `ZKProof` fails the Range Proof (proving the remaining balance is non-negative). |
| `tecLOCKED` | The MPT asset is locked for the account, or the asset is globally locked. |