Generalise ML-DSA with GYB (#355)

Generalises the definition of ML-DSA algorithms with GYB to allow the
addition of other parameter sets in the future

### Checklist
- [X] I've run tests to see all new and existing tests pass
- [X] I've followed the code style of the rest of the project
- [X] I've read the [Contribution Guidelines](CONTRIBUTING.md)
- [X] I've updated the documentation if necessary

#### If you've made changes to `gyb` files
- [X] I've run `.script/generate_boilerplate_files_with_gyb` and
included updated generated files in a commit of this pull request

### Motivation:

BoringSSL recently [made ML-DSA-87
public](https://boringssl.googlesource.com/boringssl/+/2a514a51baebd5a232fc64f7b082f7a8b28cd29d)
in its API, in addition to ML-DSA-65 which has already been [integrated
into Swift Crypto](#267).
By generating the code with GYB we will be able to add support for
ML-DSA-87 very easily in the future when the vendored version of
BoringSSL is updated.

### Modifications:

Generate the code for `MLDSA65` (and in future also for `MLDSA87`) with
GYB.

### Result:

Nothing changes in the public API, but adding `MLDSA87` in the future
will be instantaneous.

Author: fpseverino

Sources/_CryptoExtras/CMakeLists.txt

@@ -41,7 +41,7 @@ add_library(_CryptoExtras
   "Key Derivation/PBKDF2/PBKDF2.swift"
   "Key Derivation/Scrypt/BoringSSL/Scrypt_boring.swift"
   "Key Derivation/Scrypt/Scrypt.swift"
-  "MLDSA/MLDSA65_boring.swift"
+  "MLDSA/MLDSA_boring.swift"
   "MLKEM/MLKEM_boring.swift"
   "OPRFs/OPRF.swift"
   "OPRFs/OPRFClient.swift"

Sources/_CryptoExtras/MLDSA/MLDSA65_boring.swift renamed to Sources/_CryptoExtras/MLDSA/MLDSA_boring.swift

@@ -12,6 +12,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MARK: - Generated file, do NOT edit
+// any edits of this file WILL be overwritten and thus discarded
+// see section `gyb` in `README` for details.
+
 @_implementationOnly import CCryptoBoringSSL
 import Crypto
 import Foundation
@@ -86,7 +90,7 @@ extension MLDSA65 {
 
                 self.seed = try withUnsafeTemporaryAllocation(
                     of: UInt8.self,
-                    capacity: MLDSA65.seedByteCount
+                    capacity: MLDSA.seedByteCount
                 ) { seedPtr in
                     try withUnsafeTemporaryAllocation(
                         of: UInt8.self,
@@ -102,7 +106,7 @@ extension MLDSA65 {
                             throw CryptoKitError.internalBoringSSLError()
                         }
 
-                        return Data(bytes: seedPtr.baseAddress!, count: MLDSA65.seedByteCount)
+                        return Data(bytes: seedPtr.baseAddress!, count: MLDSA.seedByteCount)
                     }
                 }
             }
@@ -113,7 +117,7 @@ extension MLDSA65 {
             ///
             /// - Throws: `CryptoKitError.incorrectKeySize` if the seed is not 32 bytes long.
             init(seedRepresentation: some DataProtocol) throws {
-                guard seedRepresentation.count == MLDSA65.seedByteCount else {
+                guard seedRepresentation.count == MLDSA.seedByteCount else {
                     throw CryptoKitError.incorrectKeySize
                 }
 
@@ -125,7 +129,7 @@ extension MLDSA65 {
                         CCryptoBoringSSL_MLDSA65_private_key_from_seed(
                             &self.key,
                             seedPtr.baseAddress,
-                            MLDSA65.seedByteCount
+                            MLDSA.seedByteCount
                         )
                     }) == 1
                 else {
@@ -172,7 +176,7 @@ extension MLDSA65 {
             }
 
             /// The size of the private key in bytes.
-            static let byteCount = 4032
+            static let byteCount = Int(MLDSA65_PRIVATE_KEY_BYTES)
         }
     }
 }
@@ -311,16 +315,18 @@ extension MLDSA65 {
             }
 
             /// The size of the public key in bytes.
-            static let byteCount = 1952
+            static let byteCount = Int(MLDSA65_PUBLIC_KEY_BYTES)
         }
     }
 }
 
 @available(macOS 10.15, iOS 13, watchOS 6, tvOS 13, macCatalyst 13, visionOS 1.0, *)
 extension MLDSA65 {
-    /// The size of the seed in bytes.
-    private static let seedByteCount = 32
-
     /// The size of the signature in bytes.
-    private static let signatureByteCount = 3309
+    private static let signatureByteCount = Int(MLDSA65_SIGNATURE_BYTES)
+}
+
+private enum MLDSA {
+    /// The size of the seed in bytes.
+    fileprivate static let seedByteCount = 32
 }