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Encrypted PIN Transfer

This guide describes how to implement secure PIN transfer for your end-users.

📘

Applicable only for the request that accepts the Signing-Method header.

Encrypted PIN Transfer

This feature allows you to transfer your end-users signing methods (PIN, Emergency Code, Biometrics) in a secure and encrypted way so that it is not visible on your system in any way. Your system won't be able to view or read the end-user signing method's value.

This feature also ensures that the original end-user request body is not tampered with and helps avoid duplicate transactions.

Flowchart

Encrypted PIN Transfer Flowchart

Encrypted PIN Transfer Flowchart

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View the TypeScript code example for Encrypted PIN Transfer.

1. Generate random AES 256-bit key

First, generate a random AES 256-bit key.

2. Generate a random iv vector (12 bytes)

Next, generate a random iv vector which should be 12 bytes.

3. Encrypt the AES 256-bit key

Next, encrypt the randomly generated AES 256-bit key with the AWS RSA-2048 public key that we expose in our publicly available endpoint:

Endpoint:

GET https://api-wallet.venly.io/api/security

Response Body:

{
    "success": true,
    "result": {
            "encryptionKeys": [
                {
                    "id": "837943da-82aa-49c5-bab7-503010985ae9",
                    "keyspec": "RSA_2048",
                    "publicKey": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnDcmfHx3yZxwgZW7r+iUlUdI4a6Ot5WP8P4gzc/emfafLgOGQCoZue6n99BD6iRynnwqHUKd3fS50UX5vmZmXOJGHXlXCRsv5Z1/P32s/q5bLnTGpmzZOQXeiaOMbXgcOWcS0XhVGfioB3VsfURFBOU7okmMY0iAPPA7cdBK5fLTb0CYulMdIKfgWzeBBbqT0J6mRdUfbvXqA2gOLmaZRXKerdJUBbnNc3oOxgsk2noMlyOUId6SZsJYxQZRyjErBSjM+qNitEYLKO8tlxiPtLFWOGAa782nSMNJaLcdGWdz5TeADyvlJbbsvItA1lDWTbnJQyeN0bMDzL5XYcPTkQIDAQAB",
                    "encryptionAlgorithm": "RSAES_OAEP_SHA_256",
                }
            ]
        
    }
}

4. Prepare the Request Body

Generate a SHA256 hash based on the request body.

Example Request Body:

{
  "transactionRequest": {
    "type" : "TRANSFER",
    "secretType" : "MATIC",
    "walletId": "56137f2d-b4e9-42de-943b-cee828eb222a",
    "to" : "0x8D6331D6C5ba3306961F0b4Ea13ff13aa43560b9",
    "value": 1
  }
}

Example SHA256 Hash:

9ad9900886a75c33c327168ed6b0f8892eeffab26369e74082bc120887653762

5. Encrypt Signing-Method body with the Raw AES key

Next, encrypt the Signing-Method body with your raw AES key. The structure of the Signing-Method body is as follows:

ParamDescriptionRequired?
idThe unique ID of the signing method.✅
valueThe value of the signing method.✅
physicalDeviceIdThe physicalDeviceId which is the unique ID of the user's device. (Applicable forBIOMETRIC only)❌
idempotencyKeyA unique UUID for every request.✅
signature.typeThis will be sha256✅
signature.valueSHA256 encoded hash of the JSON request body. - from Step#4✅
{
  id: string,
  value: string,
  idempotencyKey: string,
  signature: {
    type: 'sha256',
    value: string
  }
}

Example Signing-Method body with PIN:

{
   "id":"2bed9491-cdf2-454f-bdfa-716c94cbd922",
   "value":"123456",
   "idempotencyKey": "9ee45da6-193b-4b07-bdd5-92f5602bcf62",
   "signature":{
      "type":"sha256",
      "value":"9ad9900886a75c33c327168ed6b0f8892eeffab26369e74082bc120887653762"
   }
}

Example Signing-Method body with Emergency Code:

{
   "id":"a2ffea97-c199-4685-928d-b34b6f6b2133",
   "value":"UvHSS5SCYek3U2W9h4gEUa9VZ",
   "idempotencyKey": "d06e7754-4c27-4418-8f85-0eb4337a717b",
   "signature":{
      "type":"sha256",
      "value":"54f6e79117c0dc43e1bba7e57303c81da3588703e068f723bb1a7a410c6e0230"
   }
}

Example Signing-Method body with Biometric:

{
   "id":"64c10e41-114a-4ce7-9d02-7df48ba360e6",
   "value":"2f08ae38-b3b9-4857-b46e-3b20e1a936f8",
   "physicalDeviceId": "312b26a0-e6de-4d33-a011-c17cd5fb5e7f",
   "idempotencyKey": "659386e2-4c5a-4c1f-80c7-9e30ff65265e",
   "signature":{
      "type":"sha256",
      "value":"cd0d7f18ca78e1466dd593d88a21deabb80ee42069159e28ddfaa2ac0eb9de5c"
   }
}

6. Prepare Encrypted-Signing-Method Header

6.1 Preparing JSON Body for Encrypted-Signing-Method

Next, prepare the following JSON body.

ParamDescription
encryption.typeThis will be AES/GCM/NoPadding.
encryption.key.encryptedValueThe AES key that is encrypted with RSA-2048 public key (GET /api/security) - fromStep#3
encryption.key.encryptionKeyIdThe value corresponds to the result.encryptionKeys.id param in the response body of the GET /api/security endpoint - fromStep#3
encryption.ivYour randomly generated iv vector (12 bytes). - fromStep#2
valueThe body of the Signing-Method that is encrypted with the raw AES key. - fromStep#5
{
    "encryption":{
        "type":"AES/GCM/NoPadding",
        "key":{
           "encryptedValue": "base64string", 
           "encryptionKeyId": "<uuid>"
        	},
        "iv":"base64string" 
    },
    "value":"base64string"
}

6.2 BASE64 Encode the Body

Next, you have to base64 encode the JSON body which is to be passed in the Encrypted-Signing-Method header.

7. Send the correct header

There are two ways to supply the signing method in the header:

7.1 For Encrypted Transfer (Encrypted-Signing-Method)

You need to send the JSON base64 encoded body in the Encrypted-Signing-Method header from the previous step. The Encrypted-Signing-Method indicates that the signing method and the request body are encrypted.

7.2 For non-encrypted Transfer (Signing-Method)

The Signing-Method header can be passed as usual for non-encrypted transfers.

Parameter

Param Type

Value

Description

Example Value

Signing-Method

Header

id:value

id: This is the ID of the signing method
value: This is the value of the signing method

756ae7a7-3713-43ee-9936-0dff50306488:123456

Encrypted Request Example:

Executing a Transaction

Headers
Encrypted-Signing-Method: <<BASE64 ENCODED JSON BODY from Step#6>>

Body
{
  "transactionRequest": {
    "type" : "TRANSFER",
    "secretType" : "MATIC",
    "walletId": "56137f2d-b4e9-42de-943b-cee828eb222a",
    "to" : "0x8D6331D6C5ba3306961F0b4Ea13ff13aa43560b9",
    "value": 1
  }
}

Updating a PIN Signing Method

Headers
Encrypted-Signing-Method: <<BASE64 ENCODED JSON BODY from Step#6>>

Body
{
  "value": "987654"
}

Creating an additional Signing Method

Headers
Encrypted-Signing-Method: <<BASE64 ENCODED JSON BODY from Step#6>>

Body
{
    "type": "EMERGENCY_CODE",
    "value": "w2v7yertaad21lhudqghzwcg4"
}

Updated 16 days ago