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