Transform Secrets Engine | Vault

NOTE: Transform secrets engine requires Vault Enterprise Advanced Data Protection (ADP) license. To explore Vault Enterprise features, you can sign up for a free 30-day trial from here.

»Challenge

Vault's Transit secrets engine provides encryption service; however, the resulting ciphertext does not preserve the original data format or length.

Think of a scenario where an organization must cryptographically protect the personally identifiable information (PII) while preserving the data format and length. For example, the database schema expects a certain character length and/or only allows alphanumeric characters.

The preservation of the original data format or length may be driven by compliance with certain industry standards such as HIPAA or PCI.

»Solution

Vault Enterprise 1.4 with Advanced Data Protection module introduced the Transform secrets engine which handles secure data transformation and tokenization against the provided secrets. Transformation methods encompass NIST vetted cryptographic standards such as format-preserving encryption (FPE) via FF3-1 to encode your secrets while maintaining the data format and length. In addition, it can also perform pseudonymous transformations of the data through other means, such as masking.

This prevents the need for change in the existing database schema.

»Prerequisites

To perform the tasks described in this tutorial, you need to have Vault Enterprise v1.4 or later with Advanced Data Protection module.

NOTE: To explore Vault Enterprise features, you can sign up for a free 30-day trial.

»Policy requirements

NOTE: For the purpose of this tutorial, you can use root token to work with Vault. However, it is recommended that root tokens are only used for just enough initial setup or in emergencies. As a best practice, use tokens with appropriate set of policies based on your role in the organization.

To perform all tasks demonstrated in this tutorial, your policy must include the following permissions:

# Work with transform secrets engine
path "transform/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Enable secrets engine
path "sys/mounts/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# List enabled secrets engine
path "sys/mounts" {
  capabilities = [ "read", "list" ]
}

# Work with transform secrets engine
path "transform/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Enable secrets engine
path "sys/mounts/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# List enabled secrets engine
path "sys/mounts" {
  capabilities = [ "read", "list" ]
}

If you are not familiar with policies, complete the policies tutorial.

»Transform secrets engine workflow

Transform secrets engine configuration workflow:

Enable the transform secrets engine
Create a role containing the transformations that it can perform
Create an alphabet defining a set of characters to use for format-preserving encryption (FPE) if not using the built-in alphabets.
Create a template defining the rules for value matching if not using the built-in template
Create a transformation to specify the nature of the data manipulation

Alphabets define a set of valid input/output UTF-8 characters to be used when you perform FPE. In this step, you are going to leverage one of the built-in alphabets. Read the create custom alphabets section to learn how to define your own alphabets.

Data transformation templates are constructed of type (regex), pattern (regular expression) and allowed alphabet used in the input value. Currently, regex is the only supported type. The pattern defines the data format pattern. For example, the most credit card numbers would have a pattern that can be expressed as (\d{4})-(\d{4})-(\d{4})-(\d{4}) in regex.

In this step, the use of the builtin/creditcardnumber template is demonstrated. Read the create custom templates section to learn how to define your own templates.

Transformations define the transformation template, tweak source or the masking character to be used to transform the secrets.

»Tweak source types:

Source	Description
supplied (default)	User provide the tweak source which must be a base64-encoded 7-digit string
generated	Vault generates and returns the tweak source along with the encoded data. The user must securely store the tweak source which will be needed to decrypt the data
internal	Vault generates a tweak source for the transformation and the same tweak source will be used for every request

NOTE: Tweak source is only applicable to the FPE transformation.

»Create a new transformation

In this section, you are going to:

Enable the transform secrets engine
Create a payments role which includes card-number transformation
Create a card-number transformation which performs format preserving encryption

Execute the following command to enable the transform secrets engine at transform/.
```
$ vault secrets enable transform
```
```
$ vault secrets enable transform
```

Create a role named "payments" with "card-number" transformation attached which you will create next.

$ vault write transform/role/payments transformations=card-number

$ vault write transform/role/payments transformations=card-number

To list existing roles, execute the following command.

$ vault list transform/role
Keys
----
payments

$ vault list transform/role
Keys
----
payments

Create a transformation named "card-number" which will be used to transform credit card numbers. This uses the built-in template builtin/creditcardnumber to perform format-preserving encryption (FPE). The allowed role to use this transformation is payments, which you just created.
```
$ vault write transform/transformations/fpe/card-number \
    template="builtin/creditcardnumber" \
    tweak_source=internal \
    allowed_roles=payments
```
```
$ vault write transform/transformations/fpe/card-number \
    template="builtin/creditcardnumber" \
    tweak_source=internal \
    allowed_roles=payments
```
NOTE: The allowed_roles parameter can be set to a wildcard (*) instead of listing role names. Also, the role name can be expressed using globs at the end for pattern matching (e.g. pay*).
Output:
```
Success! Data written to: transform/transformations/fpe/card-number
```
```
Success! Data written to: transform/transformations/fpe/card-number
```
You will learn how to define your own template in the Create custom templates section.

To list the existing transformations, execute the following command.

$ vault list transform/transformations/fpe
Keys
----
card-number

$ vault list transform/transformations/fpe
Keys
----
card-number

To view the details of the newly created card-number transformation, execute the following command.

$ vault read transform/transformations/fpe/card-number
Key              Value
---              -----
allowed_roles    [payments]
templates        [builtin/creditcardnumber]
tweak_source     internal
type             fpe

$ vault read transform/transformations/fpe/card-number
Key              Value
---              -----
allowed_roles    [payments]
templates        [builtin/creditcardnumber]
tweak_source     internal
type             fpe

»Transform secrets

The Vault client applications must have the following in their policy to perform data encoding and decoding using the Transform secrets engine enabled at transform/.

# To request data encoding using any of the roles
# Specify the role name in the path to narrow down the scope
path "transform/encode/*" {
   capabilities = [ "update" ]
}

# To request data decoding using any of the roles
# Specify the role name in the path to narrow down the scope
path "transform/decode/*" {
   capabilities = [ "update" ]
}

# To request data encoding using any of the roles
# Specify the role name in the path to narrow down the scope
path "transform/encode/*" {
   capabilities = [ "update" ]
}

# To request data decoding using any of the roles
# Specify the role name in the path to narrow down the scope
path "transform/decode/*" {
   capabilities = [ "update" ]
}

Encode a value with the payments role.

$ vault write transform/encode/payments value=1111-2222-3333-4444

Key              Value
---              -----
encoded_value    8492-9808-1939-2623

$ vault write transform/encode/payments value=1111-2222-3333-4444

Key              Value
---              -----
encoded_value    8492-9808-1939-2623

Decode the value encoded with payments role where the value is set to the returned encoded_value.

$ vault write transform/decode/payments \
        value=8492-9808-1939-2623

$ vault write transform/decode/payments \
        value=8492-9808-1939-2623

Output:

Key              Value
---              -----
decoded_value    1111-2222-3333-4444

Key              Value
---              -----
decoded_value    1111-2222-3333-4444

»Create custom templates

Templates define the data format patterns that you wish to keep while transforming the secrets. In this section, you are going to create a transformation template which encodes British passport numbers.

The passport number on a British passport is a pattern consisting of a 9-digit numeric value which can be expressed using regular expression as (\d{9}). The parentheses tell Vault to encode all values grouped within; therefore, (\d{9}) will encode the entire passport number.

If you want to encode the last 7 digits leaving the first two numbers unchanged, the expression should be \d{2}(\d{7}).

Display all the exiting templates.

$ vault list transform/template

Keys
----
builtin/creditcardnumber
builtin/socialsecuritynumber

$ vault list transform/template

Keys
----
builtin/creditcardnumber
builtin/socialsecuritynumber

Create a template named uk-passport-tmpl.

$ vault write transform/template/uk-passport-tmpl \
    type=regex \
    pattern="(\d{9})" \
    alphabet=builtin/numeric

$ vault write transform/template/uk-passport-tmpl \
    type=regex \
    pattern="(\d{9})" \
    alphabet=builtin/numeric

This template uses the built-in alphabet, builtin/numeric.

Create a transformation named uk-passport with the uk-passport-tmpl template.

$ vault write transform/transformations/fpe/uk-passport \
    template=uk-passport-tmpl \
    tweak_source=internal \
    allowed_roles='*'

$ vault write transform/transformations/fpe/uk-passport \
    template=uk-passport-tmpl \
    tweak_source=internal \
    allowed_roles='*'

Update the payments role to include the uk-passport transformation.
```
$ vault write transform/role/payments transformations=card-number,uk-passport
```
```
$ vault write transform/role/payments transformations=card-number,uk-passport
```
The payments role has two transformations. Future requests to encode/decode require that the specific transformation is provided.

Encode a value with the payments role with the uk-passport.

$ vault write transform/encode/payments value="123456789" \
    transformation=uk-passport

$ vault write transform/encode/payments value="123456789" \
    transformation=uk-passport

Example output:

Key              Value
---              -----
encoded_value    128151714

Key              Value
---              -----
encoded_value    128151714

Remember that you must specify which transformation to use when you send an encode request since the payments role has two transformations associated with it.

»Advanced handling

This section walks you through the new template features introduced in Vault Enterprise v1.9:

Encoding customization
Decoding customization
Access control

»Encoding customization

In this section, you are going to create a transformation template which encodes Social Security numbers that may have an optional SSN: or ssn: prefix, and which are optionally separated by dashes or spaces.

A United States Social Security number is a 9-digit number, commonly written using a 3-2-4 digit pattern which can be expressed using the regular expression (\d{3})[- ]?(\d{2})[- ]?(\d{4}). The optional prefix can be expressed using the regular expression (?:SSN[: ]?|ssn[: ]?)?. The use of non-capturing groups tells Vault not to encode the prefix if it is present.

You will use the new encode_format field to specify what the encoded output should look like. In the value for encode_format, variables representing the capture groups of pattern are used to lay out the result. The variables are in the form of $1, $2, etc…, one for each of the capture groups in pattern; and in the form of ${name} or $name for the named capture groups. For more detailed information see the Go regexp.Expand documentation.

When a template has a value for encode_format, it will always be used. Make sure that the resulting encoded output can be matched by pattern, otherwise decoding will not be possible.

Create a template named us-ssn-tmpl.

$  vault write transform/template/us-ssn-tmpl \
     type=regex \
     pattern='(?:SSN[: ]?|ssn[: ]?)?(\d{3})[- ]?(\d{2})[- ]?(\d{4})' \
     encode_format='$1-$2-$3' \
     alphabet=builtin/numeric

$  vault write transform/template/us-ssn-tmpl \
     type=regex \
     pattern='(?:SSN[: ]?|ssn[: ]?)?(\d{3})[- ]?(\d{2})[- ]?(\d{4})' \
     encode_format='$1-$2-$3' \
     alphabet=builtin/numeric

Create a transformation named us-ssn with the us-ssn-tmpl template.

$ vault write transform/transformations/fpe/us-ssn \
    template=us-ssn-tmpl \
    tweak_source=internal \
    allowed_roles='*'

$ vault write transform/transformations/fpe/us-ssn \
    template=us-ssn-tmpl \
    tweak_source=internal \
    allowed_roles='*'

Update the payments role to include the us-ssn transformation.

$ vault write transform/role/payments transformations=card-number,uk-passport,us-ssn

$ vault write transform/role/payments transformations=card-number,uk-passport,us-ssn

»Validation

Encode values with the payments role with the us-ssn transformation.

$ vault write transform/encode/payments value="123-45-6789" \
    transformation=us-ssn

$ vault write transform/encode/payments value="123-45-6789" \
    transformation=us-ssn

Example output:

Key              Value
---              -----
encoded_value    766-52-7759

Key              Value
---              -----
encoded_value    766-52-7759

Try encoding value that starts with SSN.

$ vault write transform/encode/payments value="SSN:123 45 6789" \
    transformation=us-ssn

$ vault write transform/encode/payments value="SSN:123 45 6789" \
    transformation=us-ssn

Example output:

Key              Value
---              -----
encoded_value    766-52-7759

Key              Value
---              -----
encoded_value    766-52-7759

Try encoding value that starts with ssn.

$  vault write transform/encode/payments value="ssn:123456789" \
     transformation=us-ssn

$  vault write transform/encode/payments value="ssn:123456789" \
     transformation=us-ssn

Example output:

Key              Value
---              -----
encoded_value    766-52-7759

Key              Value
---              -----
encoded_value    766-52-7759

Decode the value encoded with the payments role with the us-ssn transformation where the value is set to the encoded_value.

$ vault write transform/decode/payments value="766-52-7759" \
    transformation=us-ssn

$ vault write transform/decode/payments value="766-52-7759" \
    transformation=us-ssn

Output:

Key              Value
---              -----
decoded_value    123-45-6789

Key              Value
---              -----
decoded_value    123-45-6789

»Decoding customization

When running Vault Enterprise v1.9 or later, you can specify one or more optional formats to use during decoding. In this section, you are going to modify the template us-ssn-tmpl, created in the previous section, to add two decoding formats: one to decode values separated by spaces, and the second to decode only the last four digits.

Like encode_format, decode_formats have variables representing the capture groups of pattern to lay out the decoded output. Specifying a decode format is optional, and it is specified as part of the path when performing the decode operation.

Create a template named us-ssn-tmpl.

$  vault write transform/template/us-ssn-tmpl \
     type=regex \
     pattern='(?:SSN[: ]?|ssn[: ]?)?(\d{3})[- ]?(\d{2})[- ]?(\d{4})' \
     encode_format='$1-$2-$3' \
     decode_formats=space-separated='$1 $2 $3' \
     decode_formats=last-four='*** ** $3' \
     alphabet=builtin/numeric

$  vault write transform/template/us-ssn-tmpl \
     type=regex \
     pattern='(?:SSN[: ]?|ssn[: ]?)?(\d{3})[- ]?(\d{2})[- ]?(\d{4})' \
     encode_format='$1-$2-$3' \
     decode_formats=space-separated='$1 $2 $3' \
     decode_formats=last-four='*** ** $3' \
     alphabet=builtin/numeric

Create a transformation named us-ssn with the us-ssn-tmpl template.

$ vault write transform/transformations/fpe/us-ssn \
    template=us-ssn-tmpl \
    tweak_source=internal \
    allowed_roles='*'

$ vault write transform/transformations/fpe/us-ssn \
    template=us-ssn-tmpl \
    tweak_source=internal \
    allowed_roles='*'

Update the payments role to include the us-ssn transformation.

$ vault write transform/role/payments transformations=card-number,uk-passport,us-ssn

$ vault write transform/role/payments transformations=card-number,uk-passport,us-ssn

Encode values with the payments role with the us-ssn transformation.

$ vault write transform/encode/payments value="123-45-6789" \
    transformation=us-ssn

$ vault write transform/encode/payments value="123-45-6789" \
    transformation=us-ssn

Example output:

Key              Value
---              -----
encoded_value    766-52-7759

Key              Value
---              -----
encoded_value    766-52-7759

Decode values with the payments role, the us-ssn transformation and the space-separated decoding format.

$ vault write transform/decode/payments/space-separated value="766-52-7759" \
     transformation=us-ssn

$ vault write transform/decode/payments/space-separated value="766-52-7759" \
     transformation=us-ssn

Output:

Key              Value
---              -----
decoded_value    123 45 6789

Key              Value
---              -----
decoded_value    123 45 6789

Decode values with the payments role, the us-ssn transformation and the last-four decoding format.

$ vault write transform/decode/payments/last-four value="766-52-7759" \
     transformation=us-ssn

$ vault write transform/decode/payments/last-four value="766-52-7759" \
     transformation=us-ssn

Output:

Key              Value
---              -----
decoded_value    *** ** 6789

Key              Value
---              -----
decoded_value    *** ** 6789

»Access control

As the decode format is part of the path of the write operation during decoding, Vault policies can be used to control access to them.

# Allow decoding using any of the decode formats
path "transform/decode/us-ssn/*"
{
    capabilities = ["update"]
}
# Allow decoding using only the last-four decode format
path "transform/decode/us-ssn/last-four"
{
    capabilities = ["update"]
}
# Allow decoding without specifying a decode format
path "transform/decode/us-ssn"
{
    capabilities = ["update"]
}

# Allow decoding using any of the decode formats
path "transform/decode/us-ssn/*"
{
    capabilities = ["update"]
}
# Allow decoding using only the last-four decode format
path "transform/decode/us-ssn/last-four"
{
    capabilities = ["update"]
}
# Allow decoding without specifying a decode format
path "transform/decode/us-ssn"
{
    capabilities = ["update"]
}

To demonstrate the functionality, create a token with a policy that will only permit decoding using the last-four decode format.

Define the policy in the file named last-four.hcl.

$ tee last-four.hcl <<EOF
# Allow decoding using only the last-four decode format
path "transform/decode/payments/last-four"
{
    capabilities = ["update"]
}
EOF

$ tee last-four.hcl <<EOF
# Allow decoding using only the last-four decode format
path "transform/decode/payments/last-four"
{
    capabilities = ["update"]
}
EOF

Create the last-four with the policy defined in last-four.hcl.

$ vault policy write last-four last-four.hcl
Success! Uploaded policy: us-ssn-last-four

$ vault policy write last-four last-four.hcl
Success! Uploaded policy: us-ssn-last-four

Create a token with the last-four policy attached and store the token in the variable $LAST_FOUR_TOKEN.

$ LAST_FOUR_TOKEN=$(vault token create -format=json -policy="last-four" | jq -r ".auth.client_token")

$ LAST_FOUR_TOKEN=$(vault token create -format=json -policy="last-four" | jq -r ".auth.client_token")

Using the token, decode values with the payments role, the us-ssn transformation and the last-four decoding format.

$ VAULT_TOKEN=$LAST_FOUR_TOKEN vault write transform/decode/payments/last-four \
     value="766-52-7759" \
     transformation=us-ssn

$ VAULT_TOKEN=$LAST_FOUR_TOKEN vault write transform/decode/payments/last-four \
     value="766-52-7759" \
     transformation=us-ssn

Output:

Key              Value
---              -----
decoded_value    *** ** 6789

Key              Value
---              -----
decoded_value    *** ** 6789

Trying to use the token to decode with the payments role with the us-ssn transformation with the space-separated decode format, or without specifying a decode format will fail.

$ VAULT_TOKEN=$LAST_FOUR_TOKEN vault write transform/decode/payments \
     value="766-52-7759" \
     transformation=us-ssn

$ VAULT_TOKEN=$LAST_FOUR_TOKEN vault write transform/decode/payments \
     value="766-52-7759" \
     transformation=us-ssn

Output:

Error writing data to transform/decode/payments: Error making API request.

URL: PUT http://localhost:8200/v1/transform/decode/payments
Code: 403. Errors:

* 1 error occurred:
    * permission denied

Error writing data to transform/decode/payments: Error making API request.

URL: PUT http://localhost:8200/v1/transform/decode/payments
Code: 403. Errors:

* 1 error occurred:
    * permission denied

»Create custom alphabets

Alphabet defines a set of characters (UTF-8) that is used for FPE to determine the validity of plaintext and ciphertext values.

These are a number of built-in alphabets available to use.

Alphabets	Description
builtin/numeric	Numbers
builtin/alphalower	Lower-case letters
builtin/alphaupper	Upper-case letters
builtin/alphanumericlower	Numbers and lower-case letters
builtin/alphanumericupper	Numbers and upper-case letters
builtin/alphanumeric	Numbers and letters

New alphabets can be created to satisfy the template requirements.

To learn the command, create a non-zero-numeric alphabet which contains non-zero numbers.

Display existing alphabets.

$ vault list transform/alphabet

Keys
----
builtin/alphalower
builtin/alphanumeric
builtin/alphanumericlower
builtin/alphanumericupper
builtin/alphaupper
builtin/numeric

$ vault list transform/alphabet

Keys
----
builtin/alphalower
builtin/alphanumeric
builtin/alphanumericlower
builtin/alphanumericupper
builtin/alphaupper
builtin/numeric

Create an alphabet named non-zero-numeric.

$ vault write transform/alphabet/non-zero-numeric alphabet="123456789"

$ vault write transform/alphabet/non-zero-numeric alphabet="123456789"

This new alphabet consists of only characters from the provided set 123456789.

»Data masking

Data masking is used to hide sensitive data from those who do not have a clearance to view them. For example, this allows a contractor to test the database environment without having access to the actual sensitive customer information. Data masking has become increasingly important with the enforcement of General Data Protection Regulation (GDPR) introduced in 2018.

The following steps demonstrate the use of masking to obscure your customer's phone number since it is personally identifiable information (PII).

NOTE: Masking is a unidirectional operation; therefore, encode is the only supported operation.

Now, create a phone-number-tmpl template which masks phone numbers with its country code visible.

Create a template named "phone-number-tmpl" with country code.

$ vault write transform/template/phone-number-tmpl type=regex \
    pattern="\+\d{1,2} (\d{3})-(\d{3})-(\d{4})" \
    alphabet=builtin/numeric

$ vault write transform/template/phone-number-tmpl type=regex \
    pattern="\+\d{1,2} (\d{3})-(\d{3})-(\d{4})" \
    alphabet=builtin/numeric

Create a transformation named "phone-number" with the phone-number-tmpl template and allow all roles to use it.

$ vault write transform/transformations/masking/phone-number \
    template=phone-number-tmpl \
    masking_character=# \
    allowed_roles='*'

$ vault write transform/transformations/masking/phone-number \
    template=phone-number-tmpl \
    masking_character=# \
    allowed_roles='*'

The type is set to masking and specifies the masking_character value instead of tweak_source. The default masking character is * if you don't specify one.

Next, you can test and verify the newly created phone-number mask transformation.

First, add the phone-number transformation to the payments role.

$ vault write transform/role/payments \
    transformations=card-number,uk-passport,phone-number

$ vault write transform/role/payments \
    transformations=card-number,uk-passport,phone-number

Finally, encode a value with the payments role with the phone-number transformation.

$ vault write transform/encode/payments value="+1 123-345-5678" \
    transformation=phone-number
Key              Value
---              -----
encoded_value    +1 ###-###-####

$ vault write transform/encode/payments value="+1 123-345-5678" \
    transformation=phone-number
Key              Value
---              -----
encoded_value    +1 ###-###-####

»Batch input processing

When you need to encode more than one secret value, you can send multiple secrets in a request payload as batch_input instead of invoking the API endpoint multiple times to encode secrets individually.

»Example Scenario 1:

You received a credit card number, British passport number and a phone number of a customer and wish to transform all these secrets using the payments role.

Create an API request payload with multiple values, each with the desired transformation.

$ tee input-multiple.json <<EOF
{
  "batch_input": [
    {
      "value": "1111-1111-1111-1111",
      "transformation": "card-number"
    },
    {
      "value": "123456789",
      "transformation": "uk-passport"
    },
    {
      "value": "+1 123-345-5678",
      "transformation": "phone-number"
    }
  ]
}
EOF

$ tee input-multiple.json <<EOF
{
  "batch_input": [
    {
      "value": "1111-1111-1111-1111",
      "transformation": "card-number"
    },
    {
      "value": "123456789",
      "transformation": "uk-passport"
    },
    {
      "value": "+1 123-345-5678",
      "transformation": "phone-number"
    }
  ]
}
EOF

Encode all the values with the payments role.

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
     --request POST \
     --data @input-multiple.json \
     $VAULT_ADDR/v1/transform/encode/payments | jq ".data"
{
  "batch_results": [
    {
      "encoded_value": "7998-7227-5261-3751"
    },
    {
      "encoded_value": "908547441"
    },
    {
      "encoded_value": "## ###-###-####"
    }
  ]
}

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
     --request POST \
     --data @input-multiple.json \
     $VAULT_ADDR/v1/transform/encode/payments | jq ".data"
{
  "batch_results": [
    {
      "encoded_value": "7998-7227-5261-3751"
    },
    {
      "encoded_value": "908547441"
    },
    {
      "encoded_value": "## ###-###-####"
    }
  ]
}

»Example Scenario 2:

An on-premise database stores corporate card numbers and your organization decided to migrate the data to another database. You wish to encode those card numbers before storing them in the new database.

Create a request payload with multiple card numbers.

$ tee payload-batch.json <<EOF
{
  "batch_input": [
    { "value": "1111-1111-1111-1111", "transformation": "card-number" },
    { "value": "2222-2222-2222-2222", "transformation": "card-number" },
    { "value": "3333-3333-3333-3333", "transformation": "card-number" },
    { "value": "4444-4444-4444-4444", "transformation": "card-number" }
  ]
}
EOF

$ tee payload-batch.json <<EOF
{
  "batch_input": [
    { "value": "1111-1111-1111-1111", "transformation": "card-number" },
    { "value": "2222-2222-2222-2222", "transformation": "card-number" },
    { "value": "3333-3333-3333-3333", "transformation": "card-number" },
    { "value": "4444-4444-4444-4444", "transformation": "card-number" }
  ]
}
EOF

Encode all the values with the payments role.

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
    --request POST \
    --data @payload-batch.json \
    $VAULT_ADDR/v1/transform/encode/payments | jq ".data"
{
  "batch_results": [
    {
      "encoded_value": "7998-7227-5261-3751"
    },
    {
      "encoded_value": "2026-7948-2166-0380"
    },
    {
      "encoded_value": "3979-1805-7116-8137"
    },
    {
      "encoded_value": "0196-8166-5765-0438"
    }
  ]
}

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
    --request POST \
    --data @payload-batch.json \
    $VAULT_ADDR/v1/transform/encode/payments | jq ".data"
{
  "batch_results": [
    {
      "encoded_value": "7998-7227-5261-3751"
    },
    {
      "encoded_value": "2026-7948-2166-0380"
    },
    {
      "encoded_value": "3979-1805-7116-8137"
    },
    {
      "encoded_value": "0196-8166-5765-0438"
    }
  ]
}

To decode these values.

First, create a request payload with the encoded card numbers.

$ tee payload-batch.json <<EOF
{
  "batch_input": [
    { "value": "7998-7227-5261-3751", "transformation": "card-number" },
    { "value": "2026-7948-2166-0380", "transformation": "card-number" },
    { "value": "3979-1805-7116-8137", "transformation": "card-number" },
    { "value": "0196-8166-5765-0438", "transformation": "card-number" }
  ]
}
EOF

$ tee payload-batch.json <<EOF
{
  "batch_input": [
    { "value": "7998-7227-5261-3751", "transformation": "card-number" },
    { "value": "2026-7948-2166-0380", "transformation": "card-number" },
    { "value": "3979-1805-7116-8137", "transformation": "card-number" },
    { "value": "0196-8166-5765-0438", "transformation": "card-number" }
  ]
}
EOF

Decode all the values with the payments role.

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
    --request POST \
    --data @payload-batch.json \
    $VAULT_ADDR/v1/transform/decode/payments | jq ".data"
{
  "batch_results": [
    {
      "decoded_value": "1111-1111-1111-1111"
    },
    {
      "decoded_value": "2222-2222-2222-2222"
    },
    {
      "decoded_value": "3333-3333-3333-3333"
    },
    {
      "decoded_value": "4444-4444-4444-4444"
    }
  ]
}

$ curl --header "X-Vault-Token: $VAULT_TOKEN" \
    --request POST \
    --data @payload-batch.json \
    $VAULT_ADDR/v1/transform/decode/payments | jq ".data"
{
  "batch_results": [
    {
      "decoded_value": "1111-1111-1111-1111"
    },
    {
      "decoded_value": "2222-2222-2222-2222"
    },
    {
      "decoded_value": "3333-3333-3333-3333"
    },
    {
      "decoded_value": "4444-4444-4444-4444"
    }
  ]
}

»Next steps

To actually integrate your application with Vault and leverage the transform secrets engine, there are a number of resources which must be configured.

Before the application can even request data transformation, it first needs to authenticate with Vault. Therefore, an auth method (e.g. AWS, Kubernetes, AppRole) must be enabled and configured for the application to use. In addition, an appropriate policy must be created and attached to the client token.

You can codify the Vault configuration using Terraform, and make the configuration repeatable. The Terraform Vault Provider supports the transform secrets engine. It can create policies, enable and configure auth methods and more.

Refer to the Codify Management of Vault Enterprise Using Terraform tutorial to learn how to leverage Terraform.

On the application side, you can run Vault Agent to authenticate with Vault and manage the lifecycle of the client token. Refer to the following tutorials to learn more about Vault Agent:

The Encrypting Data while Preserving Formatting with the Vault Enterprise Transform Secrets Engine blog post introduces some code examples to invoke the transform secrets engine using Vault API.

»Summary

The Transform secrets engine performs secure data transformation and tokenization against the input data. Transformation methods may encompass NIST vetted cryptographic standards such as format-preserving encryption (FPE) via FF3-1, but can also be pseudonymous transformations of the data through other means, such as masking. This tutorial walked through the use of the Transform secrets engine step-by-step.

»Limits:

The Transform secret engine obeys the FF3-1 minimum and maximum sizes on the length of an input, which are a function of the alphabet size.

»Help and reference

»Next steps

The Encrypting Data with Transform Secrets Engine tutorial introduces demo applications written in Go and Java to learn how to implement the Transform secrets engine API in your application.

If you are interested in data tokenization, refer to the Tokenize Data with Transform Secrets Engine tutorial.

Infrastructure

Security

Applications

Networking

cloud

»Challenge

»Solution

»Prerequisites

»Policy requirements

»Transform secrets engine workflow

»Tweak source types:

»Create a new transformation

»Transform secrets

»Create custom templates

»Advanced handling

»Encoding customization

»Validation

»Decoding customization

»Access control

»Create custom alphabets

»Data masking

»Batch input processing

»Example Scenario 1:

»Example Scenario 2:

»Next steps

»Summary

»Limits:

»Help and reference

»Next steps