> ## Documentation Index
> Fetch the complete documentation index at: https://pwapi.uuwallet.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Communication Encryption

> When requesting Powercard, add merchantid=**pre-registered merchantId** in http header, e.g. merchantid=uu

### 1. Generate RSA Key Pairs

> Powercard uses AES(AES/ECB/PKCS5Padding) + RSA(RSA/ECB/PKCS1Padding) for service communication encryption/decryption. Merchants must apply for merchantId and keys before integration.

1. Powercard generates RSA Key Pair A (PKCS8 format, 2048-bit). A-publicKey is provided to merchant, A-privateKey is kept by Powercard

```shell
# Example: Pre-registered A-publicKey from Powercard:
```

```shell
# Example: Powercard's A-privateKey:
```

2. Merchant generates RSA Key Pair B (PKCS8 format, 2048-bit). B-publicKey is provided to Powercard, B-privateKey is kept by merchant

```shell
# Example: Merchant generates Key Pair B, provides B-publicKey to Powercard:
```

```shell
# Example: Merchant keeps B-privateKey securely:
```

### 2. AES Encryption Process

> Merchant must AES-encrypt requestBody with 32-character random string for each API call

1. Generate random string as AES key (32 characters):

# Encrypt AES key with RSA public key

aesRandomKey = 38859e263747adad524566278efa64c6
2\. Encrypt requestBody with AES using the generated key:
data = AESEncrypt(requestBody, aesRandomKey)

```json
# RequestBody Example:
{
	"channel": "merchantCards",
	"merchantId": "uu",
	"merchantUserId": "testUser123",
	"powerCardId": "a9f4cb3bfa8649b88853eded3ad853dd"
}
```

### 3. RSA Encryption for AES Key

> After completing the first two steps, the merchant uses A's publicKey from the first step to RSA encrypt the AES Key from the second step, obtaining the final request key

```shell
# Encrypt AES key with RSA public key
aesRandomKey = 38859e263747adad524566278efa64c6
```

### 4. Construct Final Request

> After completing the first three steps, the merchant uses the data generated in the second step and the key generated in the third step to construct the final requestBody

```json
```

### 5. Response Decryption Process

> Powercard encrypts responses using same method. Merchant should decrypt with B-privateKey to get pw-aesRandomkey, then decrypt data with AES key

1. Decrypt response with merchant's B-privateKey to retrieve AES key:
   pw-aesRandomkey = RSADecrypt(response.key, B-privateKey)

```json
```

2. Decrypt response data with obtained AES key:
   responseBody = AESDecrypt(response.data, pw-aesRandomkey)

```json

"
```