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josephnoirjosephnoir
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Expose supported signature algorithms for private keys (#281)
### Motivation: When loading a private key from disk as a `Certificate.PrivateKey` there is no straight forward way to query the supported signature algorithms. For signature algorithm negotiation, the raw values defined in RFC are useful as well. ### Modifications: Add a new property to query the supported signature algorithms for a given key. Add a new property that translates a signature algorithm to the respective value defined in RFC 8446. ### Results: Working with certificate private keys and signature algorithms gets easier.
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‎Sources/X509/CertificatePrivateKey.swift‎

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@@ -378,3 +378,36 @@ extension Certificate.PrivateKey {
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}
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}
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}
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@available(macOS 10.15, iOS 13, watchOS 6, tvOS 13, macCatalyst 13, visionOS 1.0, *)
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extension Certificate.PrivateKey {
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/// Return a list of all supported signature types for this private key. The ordering is not a comment on the
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/// preference or security of the contained algorithms.
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@inlinable
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public var supportedSignatureAlgorithms: [Certificate.SignatureAlgorithm] {
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switch backing {
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case .p256, .p384, .p521:
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return [.ecdsaWithSHA512, .ecdsaWithSHA384, .ecdsaWithSHA256]
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case .rsa:
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return [
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.sha512WithRSAEncryption, .sha384WithRSAEncryption, .sha256WithRSAEncryption, .sha1WithRSAEncryption,
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]
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#if canImport(Darwin)
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case .secureEnclaveP256:
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return [.ecdsaWithSHA512, .ecdsaWithSHA384, .ecdsaWithSHA256]
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case .secKey(let key):
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switch key.type {
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case .RSA:
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return [
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.sha512WithRSAEncryption, .sha384WithRSAEncryption, .sha256WithRSAEncryption,
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.sha1WithRSAEncryption,
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]
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case .ECDSA:
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return [.ecdsaWithSHA512, .ecdsaWithSHA384, .ecdsaWithSHA256]
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}
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#endif
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case .ed25519:
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return [.ed25519]
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}
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}
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}

‎Sources/X509/SignatureAlgorithm.swift‎

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@@ -152,3 +152,64 @@ extension AlgorithmIdentifier {
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}
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}
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}
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@available(macOS 10.15, iOS 13, watchOS 6, tvOS 13, macCatalyst 13, visionOS 1.0, *)
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extension Certificate.SignatureAlgorithm {
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/// Map a signature algorithm to the signature scheme value defined in RFC 8446 for TLS 1.3.
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public var rfc8446SignatureSchemeValue: UInt16 {
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get throws {
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switch self {
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case .ecdsaWithSHA256:
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return 0x0403
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case .ecdsaWithSHA384:
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return 0x0503
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case .ecdsaWithSHA512:
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return 0x0603
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case .sha1WithRSAEncryption:
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return 0x0201
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case .sha256WithRSAEncryption:
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return 0x0401
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case .sha384WithRSAEncryption:
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return 0x0501
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case .sha512WithRSAEncryption:
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return 0x0601
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case .ed25519:
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return 0x0807
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default:
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throw CertificateError.unsupportedSignatureAlgorithm(
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reason: "SignatureAlgorithm(\(self)) has an unsupprted value"
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)
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}
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}
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}
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}
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@available(macOS 10.15, iOS 13, watchOS 6, tvOS 13, macCatalyst 13, visionOS 1.0, *)
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extension Certificate.SignatureAlgorithm {
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/// Initialize a signature algorithm from a raw value as defined in RFC8446.
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///
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/// Returns: The signature algorithm matching the value for the algorithms supported by Swift Certificates and
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/// nil otherwise.
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public init?(rfc8446SignatureSchemeValue value: UInt16) {
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switch value {
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case 0x0403:
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self = .ecdsaWithSHA256
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case 0x0503:
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self = .ecdsaWithSHA384
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case 0x0603:
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self = .ecdsaWithSHA512
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case 0x0201:
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self = .sha1WithRSAEncryption
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case 0x0401:
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self = .sha256WithRSAEncryption
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case 0x0501:
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self = .sha384WithRSAEncryption
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case 0x0601:
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self = .sha512WithRSAEncryption
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case 0x0807:
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self = .ed25519
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default:
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return nil
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}
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}
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}

‎Tests/X509Tests/SignatureTests.swift‎

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Original file line numberDiff line numberDiff line change
@@ -50,6 +50,68 @@ final class SignatureTests: XCTestCase {
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)
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#endif
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// RFC8446 defines the following values for signature schemes for TLS 1.3 (signature algorithms before).
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// Swift Certificates only supports a handful of them.
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//
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// enum {
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// /* RSASSA-PKCS1-v1_5 algorithms */
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// rsa_pkcs1_sha256(0x0401),
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// rsa_pkcs1_sha384(0x0501),
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// rsa_pkcs1_sha512(0x0601),
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//
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// /* ECDSA algorithms */
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// ecdsa_secp256r1_sha256(0x0403),
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// ecdsa_secp384r1_sha384(0x0503),
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// ecdsa_secp521r1_sha512(0x0603),
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//
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// /* RSASSA-PSS algorithms with public key OID rsaEncryption */
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// rsa_pss_rsae_sha256(0x0804),
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// rsa_pss_rsae_sha384(0x0805),
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// rsa_pss_rsae_sha512(0x0806),
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//
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// /* EdDSA algorithms */
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// ed25519(0x0807),
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// ed448(0x0808),
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//
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// /* RSASSA-PSS algorithms with public key OID RSASSA-PSS */
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// rsa_pss_pss_sha256(0x0809),
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// rsa_pss_pss_sha384(0x080a),
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// rsa_pss_pss_sha512(0x080b),
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//
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// /* Legacy algorithms */
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// rsa_pkcs1_sha1(0x0201),
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// ecdsa_sha1(0x0203),
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//
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// /* Reserved Code Points */
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// private_use(0xFE00..0xFFFF),
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// (0xFFFF)
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// } SignatureScheme;
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static let supportedRFC8446SignatureAlgorithms: [UInt16: Certificate.SignatureAlgorithm] = [
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// RSASSA-PKCS1-v1_5 algorithms
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0x0401: Certificate.SignatureAlgorithm.sha256WithRSAEncryption,
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0x0501: Certificate.SignatureAlgorithm.sha384WithRSAEncryption,
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0x0601: Certificate.SignatureAlgorithm.sha512WithRSAEncryption,
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// RSASSA-PSS algorithms with public key OID rsaEncryption
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// Currently not supported
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// ECDSA algorithms
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0x0403: Certificate.SignatureAlgorithm.ecdsaWithSHA256,
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0x0503: Certificate.SignatureAlgorithm.ecdsaWithSHA384,
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0x0603: Certificate.SignatureAlgorithm.ecdsaWithSHA512,
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// EdDSA algorithms
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0x0807: Certificate.SignatureAlgorithm.ed25519,
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// ed448 is currenlty not supported
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// RSASSA-PSS algorithms with public key OID RSASSA-PSS
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// Currently not supported
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// Legacy algorithms
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0x0201: Certificate.SignatureAlgorithm.sha1WithRSAEncryption,
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// ecdsa_sha1 is currenlty not supported
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]
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func testRSASignatureBytes() throws {
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let input = Array("Hello World".utf8)
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let privateKey = Certificate.PrivateKey(Self.rsaKey)
@@ -941,4 +1003,122 @@ final class SignatureTests: XCTestCase {
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0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
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])
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}
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func testSignatureAlgorithmTranslatesToCorrectRFC8446Value() throws {
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for (value, algorithm) in SignatureTests.supportedRFC8446SignatureAlgorithms {
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XCTAssertEqual(value, try! algorithm.rfc8446SignatureSchemeValue)
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}
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}
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func testSignatureAlgorithmInitializedWithRFC8446Value() {
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let supportedValues = Set(SignatureTests.supportedRFC8446SignatureAlgorithms.keys)
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for value in 0...UInt16.max {
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if supportedValues.contains(value) {
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let algo = Certificate.SignatureAlgorithm(rfc8446SignatureSchemeValue: value)
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XCTAssertNotNil(algo)
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XCTAssertEqual(algo, SignatureTests.supportedRFC8446SignatureAlgorithms[value])
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} else {
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XCTAssertNil(Certificate.SignatureAlgorithm(rfc8446SignatureSchemeValue: value))
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}
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}
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmRSA() throws {
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XCTAssertEqual(
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Set(Certificate.PrivateKey(Self.rsaKey).supportedSignatureAlgorithms),
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Set([.sha256WithRSAEncryption, .sha384WithRSAEncryption, .sha512WithRSAEncryption, .sha1WithRSAEncryption])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmECDSA() throws {
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XCTAssertEqual(
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Set(Certificate.PrivateKey(Self.p256Key).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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XCTAssertEqual(
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Set(Certificate.PrivateKey(Self.p384Key).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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XCTAssertEqual(
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Set(Certificate.PrivateKey(Self.p521Key).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmEdDSA() throws {
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XCTAssertEqual(Set(Certificate.PrivateKey(Self.ed25519Key).supportedSignatureAlgorithms), Set([.ed25519]))
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}
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#if canImport(Darwin)
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func testMapPrivateKeyToSupportedSignatureAlgorithmSecureEncalve() throws {
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guard let secureEnclaveP256 = Self.secureEnclaveP256 else {
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throw XCTSkip("No SEP")
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}
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XCTAssertEqual(
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Set(Certificate.PrivateKey(secureEnclaveP256).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmSecKeyRSA() async throws {
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guard let secKeyRSA = Self.secKeyRSA else {
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throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
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Set(try Certificate.PrivateKey(secKeyRSA).supportedSignatureAlgorithms),
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Set([.sha256WithRSAEncryption, .sha384WithRSAEncryption, .sha512WithRSAEncryption, .sha1WithRSAEncryption])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmSecKeyEC256() async throws {
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guard let secKeyEC256 = Self.secKeyEC256 else {
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throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
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Set(try Certificate.PrivateKey(secKeyEC256).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmSecKeyEC2384() async throws {
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guard let secKeyEC384 = Self.secKeyEC384 else {
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throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
1089+
Set(try Certificate.PrivateKey(secKeyEC384).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmSecKeyEC521() async throws {
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guard let secKeyEC521 = Self.secKeyEC521 else {
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throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
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Set(try Certificate.PrivateKey(secKeyEC521).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmsecKeyEnclaveEC256() async throws {
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guard let secKeyEnclaveEC256 = Self.secKeyEnclaveEC256 else {
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throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
1109+
Set(try Certificate.PrivateKey(secKeyEnclaveEC256).supportedSignatureAlgorithms),
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Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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func testMapPrivateKeyToSupportedSignatureAlgorithmsecKeyEnclaveEC384() async throws {
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guard let secKeyEnclaveEC384 = Self.secKeyEnclaveEC384 else {
1116+
throw XCTSkip("Key Error")
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}
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XCTAssertEqual(
1119+
Set(try Certificate.PrivateKey(secKeyEnclaveEC384).supportedSignatureAlgorithms),
1120+
Set([.ecdsaWithSHA256, .ecdsaWithSHA384, .ecdsaWithSHA512])
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)
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}
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#endif
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}

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