File: docs/Internals/Sapient.md

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File: docs/Internals/Sapient.md
Role: Auxiliary data
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Description: Auxiliary data
Class: sapient
Add a security layer to server to server requests
Author: By
Last change: Organize.
We are not getting into the game of encrypting headers. That's TLS's job.
Date: 3 years ago
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Sapient - Class Documentation

Canonical name: ParagonIE\Sapient\Sapient

Important

For encryption operations, only the body is encrypted. The HTTP headers are not.

For authentication operations, only the body is authenticated. The HTTP headers are not.

If this is unacceptable for your application, you may consider designing a custom encapsulation scheme that puts all of the sensitive metadata in the HTTP message body and, for encryption operations, sending a generic Content-Type header (if this is sensitive information).

HTTP Cryptography Methods

These methods generally have an API that looks like this:

function doSomethingWithARequest(
    RequestInterface $foo,
    CryptographyKey $bar
): RequestInferface;

function doSomethingWithAResponse(
    ResponseInterface $foo,
    CryptographyKey $bar
): ResponeInferface;

decryptRequestWithSharedKey() / decryptResponseWithSharedKey()

Function prototypes:

public function decryptRequestWithSharedKey(
    RequestInterface $request,
    SharedEncryptionKey $key
): RequestIterface;

public function decryptResponseWithSharedKey(
    ResponseInterface $respone,
    SharedEncryptionKey $key
): ResponeInterface;

These decrypt the body of the HTTP object with a shared key, which must be the same key that was used to encrypt the request. If anything fails, an InvalidMessageException will be thrown.

Algorithm: XChaCha20-Poly1305

encryptRequestWithSharedKey() / encryptResponseWithSharedKey()

Function prototypes:

public function encryptRequestWithSharedKey(
    RequestInterface $request,
    SharedEncryptionKey $key
): RequestIterface;

public function encryptResponseWithSharedKey(
    ResponseInterface $respone,
    SharedEncryptionKey $key
): ResponeInterface;

These encrypt the body of of the HTTP object with a shared key, which must be the same key that will be used to decrypt the request.

Algorithm: XChaCha20-Poly1305

sealRequest() / sealResponse()

Function prototypes:

function sealRequest(
    RequestInterface $request,
    SealingPublicKey $publicKey
): RequestInterface;

function sealResponse(
    ResponseInterface $response,
    SealingPublicKey $publicKey
): ResponseInterface;

These encrypt the body of an HTTP request or response with the recipient's public key, and can only be decrypted by the corresponding secret key.

Algorihm: X25519 + BLAKE2b + XChaCha20-Poly1305

unsealRequest() / unsealResponse()

Function prototypes:

function unsealRequest(
    RequestInterface $request,
    SealingSecretKey $secretKey
): RequestInterface;

function unsealResponse(
    ResponseInterface $response,
    SealingSecretKey $secretKey
): ResponseInterface;

These methods decrypt the body of an HTTP request or response, using your secret key, provided they were previously encrypted with your public key.

Algorihm: X25519 + BLAKE2b + XChaCha20-Poly1305

authenticateRequestWithSharedKey() / authenticateResponseWithSharedKey()

Function prototypes:

authenticateRequestWithSharedKey(
    RequestInterface $request,
    SharedAuthenticationKey $key
): RequestInterface;

function authenticateResponseWithSharedKey(
    ResponseInterface $response,
    SharedAuthenticationKey $key
): ResponseInterface;

These methods add an additional header (Body-HMAC-SHA512256) which contains the Base64url-encoded Message Authentication Code of the HTTP message body.

This authenticates an HTTP request or response body with shared-key authentication, which means any party capable of verifying the authentication header is also capable of issuing forged headers.

Algorithm: HMAC-SHA512 truncated to 256 bits.

verifySymmetricAuthenticatedRequest() / verifySymmetricAuthenticatedResponse()

Function prototypes:

function verifySymmetricAuthenticatedRequest(
    RequestInterface $request,
    SharedAuthenticationKey $key
): RequestInterface;

function verifySymmetricAuthenticatedResponse(
    ResponseInterface $response,
    SharedAuthenticationKey $key
): ResponseInterface;

These methods verify that the signature contained in the Body-HMAC-SHA512256 header is valid for the body of the HTTP request or response object, given the shared authentication key.

If there is no header present, a HeaderMissingException is thrown.

If the message authentication code is not valid, an InvalidMessageException is thrown.

Otherwise, it returns the object verbatim.

Algorithm: HMAC-SHA-512 truncated to 256 bits

signRequest() / signResponse()

Function prototypes:

function signRequest(
    RequestInterface $request,
    SigningSecretKey $secretKey
): RequestInterface;

function signResponse(
    ResponseInterface $response,
    SigningPublicKey $publicKey
): ResponseInterface;

These methods add an additional header (Body-Signature-Ed25519) which contains the Base64url-encoded Ed25519 signature of the HTTP request or response body.

As with all digital signatures: You sign them with your secret key, and they can be verified with your public key. Possessing the public key does not grant you the power to issue forgeries.

Algorithm: Ed25519

verifySignedRequest() / verifySignedResponse()

Function prototypes:

function verifySignedRequest(
    RequestInterface $request,
    SigningSecretKey $secretKey
): RequestInterface;

function verifySignedResponse(
    ResponseInterface $response,
    SigningPublicKey $publicKey
): ResponseInterface;

These methods verify that the signature contained in the Body-Signature-Ed25519 header is valid for the body of the HTTP request or response object, given the correct public key.

If there is no header present, a HeaderMissingException is thrown.

If the signature is not valid, an InvalidMessageException is thrown.

Otherwise, it returns the object verbatim.

Algorithm: Ed25519

JSON API Methods

See the JSON Sugar Trait for the JSON API helper methods.

Adapter Methods

If you're using an adapter that implements ConvenienceInterface, you can quickly create Request/Response objects specific to your framework and then use Sapient to secure them.

Not all adapters implement this interface.


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