Add Account framework (#5657)

contracts/utils/cryptography/SignerRSA.sol

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+import {RSA} from "./RSA.sol";
+import {AbstractSigner} from "./AbstractSigner.sol";
+
+/**
+ * @dev Implementation of {AbstractSigner} using xref:api:utils#RSA[RSA] signatures.
+ *
+ * For {Account} usage, a {_setSigner} function is provided to set the {signer} public key.
+ * Doing so is easier for a factory, who is likely to use initializable clones of this contract.
+ *
+ * Example of usage:
+ *
+ * ```solidity
+ * contract MyAccountRSA is Account, SignerRSA, Initializable {
+ *     function initialize(bytes memory e, bytes memory n) public initializer {
+ *       _setSigner(e, n);
+ *     }
+ * }
+ * ```
+ *
+ * IMPORTANT: Failing to call {_setSigner} either during construction (if used standalone)
+ * or during initialization (if used as a clone) may leave the signer either front-runnable or unusable.
+ */
+abstract contract SignerRSA is AbstractSigner {
+    bytes private _e;
+    bytes private _n;
+
+    /**
+     * @dev Sets the signer with a RSA public key. This function should be called during construction
+     * or through an initializer.
+     */
+    function _setSigner(bytes memory e, bytes memory n) internal {
+        _e = e;
+        _n = n;
+    }
+
+    /// @dev Return the signer's RSA public key.
+    function signer() public view virtual returns (bytes memory e, bytes memory n) {
+        return (_e, _n);
+    }
+
+    /**
+     * @dev See {AbstractSigner-_rawSignatureValidation}. Verifies a PKCSv1.5 signature by calling
+     * xref:api:utils.adoc#RSA-pkcs1Sha256-bytes-bytes-bytes-bytes-[RSA.pkcs1Sha256].
+     *
+     * IMPORTANT: Following the RSASSA-PKCS1-V1_5-VERIFY procedure outlined in RFC8017 (section 8.2.2), the
+     * provided `hash` is used as the `M` (message) and rehashed using SHA256 according to EMSA-PKCS1-v1_5
+     * encoding as per section 9.2 (step 1) of the RFC.
+     */
+    function _rawSignatureValidation(
+        bytes32 hash,
+        bytes calldata signature
+    ) internal view virtual override returns (bool) {
+        (bytes memory e, bytes memory n) = signer();
+        return RSA.pkcs1Sha256(abi.encodePacked(hash), signature, e, n);
+    }
+}