133 lines
3.3 KiB
Go
133 lines
3.3 KiB
Go
package transit
|
|
|
|
import (
|
|
"crypto/aes"
|
|
"crypto/cipher"
|
|
"encoding/base64"
|
|
"strings"
|
|
|
|
"github.com/hashicorp/vault/logical"
|
|
"github.com/hashicorp/vault/logical/framework"
|
|
)
|
|
|
|
func pathDecrypt() *framework.Path {
|
|
return &framework.Path{
|
|
Pattern: "decrypt/" + framework.GenericNameRegex("name"),
|
|
Fields: map[string]*framework.FieldSchema{
|
|
"name": &framework.FieldSchema{
|
|
Type: framework.TypeString,
|
|
Description: "Name of the policy",
|
|
},
|
|
|
|
"ciphertext": &framework.FieldSchema{
|
|
Type: framework.TypeString,
|
|
Description: "Ciphertext value to decrypt",
|
|
},
|
|
|
|
"context": &framework.FieldSchema{
|
|
Type: framework.TypeString,
|
|
Description: "Context for key derivation. Required for derived keys.",
|
|
},
|
|
},
|
|
|
|
Callbacks: map[logical.Operation]framework.OperationFunc{
|
|
logical.WriteOperation: pathDecryptWrite,
|
|
},
|
|
|
|
HelpSynopsis: pathDecryptHelpSyn,
|
|
HelpDescription: pathDecryptHelpDesc,
|
|
}
|
|
}
|
|
|
|
func pathDecryptWrite(
|
|
req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
|
|
name := d.Get("name").(string)
|
|
value := d.Get("ciphertext").(string)
|
|
if len(value) == 0 {
|
|
return logical.ErrorResponse("missing ciphertext to decrypt"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Decode the context if any
|
|
contextRaw := d.Get("context").(string)
|
|
var context []byte
|
|
if len(contextRaw) != 0 {
|
|
var err error
|
|
context, err = base64.StdEncoding.DecodeString(contextRaw)
|
|
if err != nil {
|
|
return logical.ErrorResponse("failed to decode context as base64"), logical.ErrInvalidRequest
|
|
}
|
|
}
|
|
|
|
// Get the policy
|
|
p, err := getPolicy(req, name)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Error if invalid policy
|
|
if p == nil {
|
|
return logical.ErrorResponse("policy not found"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Derive the key that should be used
|
|
key, err := p.DeriveKey(context)
|
|
if err != nil {
|
|
return logical.ErrorResponse(err.Error()), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Guard against a potentially invalid cipher-mode
|
|
switch p.CipherMode {
|
|
case "aes-gcm":
|
|
default:
|
|
return logical.ErrorResponse("unsupported cipher mode"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Verify the prefix
|
|
if !strings.HasPrefix(value, "vault:v0:") {
|
|
return logical.ErrorResponse("invalid ciphertext"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Decode the base64
|
|
decoded, err := base64.StdEncoding.DecodeString(strings.TrimPrefix(value, "vault:v0:"))
|
|
if err != nil {
|
|
return logical.ErrorResponse("invalid ciphertext"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Setup the cipher
|
|
aesCipher, err := aes.NewCipher(key)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Setup the GCM AEAD
|
|
gcm, err := cipher.NewGCM(aesCipher)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Extract the nonce and ciphertext
|
|
nonce := decoded[:gcm.NonceSize()]
|
|
ciphertext := decoded[gcm.NonceSize():]
|
|
|
|
// Verify and Decrypt
|
|
plain, err := gcm.Open(nil, nonce, ciphertext, nil)
|
|
if err != nil {
|
|
return logical.ErrorResponse("invalid ciphertext"), logical.ErrInvalidRequest
|
|
}
|
|
|
|
// Generate the response
|
|
resp := &logical.Response{
|
|
Data: map[string]interface{}{
|
|
"plaintext": base64.StdEncoding.EncodeToString(plain),
|
|
},
|
|
}
|
|
return resp, nil
|
|
}
|
|
|
|
const pathDecryptHelpSyn = `Decrypt a ciphertext value using a named key`
|
|
|
|
const pathDecryptHelpDesc = `
|
|
This path uses the named key from the request path to decrypt a user
|
|
provided ciphertext. The plaintext is returned base64 encoded.
|
|
`
|