WIP SPM

Sources/SecretKit/Common/OpenSSH/OpenSSHKeyWriter.swift

@@ -0,0 +1,59 @@
+import Foundation
+import CryptoKit
+
+// For the moment, only supports ecdsa-sha2-nistp256 and ecdsa-sha2-nistp386 keys
+public struct OpenSSHKeyWriter {
+
+    public init() {
+    }
+
+    public func data<SecretType: Secret>(secret: SecretType) -> Data {
+        lengthAndData(of: curveType(for: secret.algorithm, length: secret.keySize).data(using: .utf8)!) +
+            lengthAndData(of: curveIdentifier(for: secret.algorithm, length: secret.keySize).data(using: .utf8)!) +
+            lengthAndData(of: secret.publicKey)
+    }
+
+    public func openSSHString<SecretType: Secret>(secret: SecretType, comment: String? = nil) -> String {
+        [curveType(for: secret.algorithm, length: secret.keySize), data(secret: secret).base64EncodedString(), comment]
+            .compactMap { $0 }
+            .joined(separator: " ")
+    }
+
+    public func openSSHSHA256Fingerprint<SecretType: Secret>(secret: SecretType) -> String {
+        // OpenSSL format seems to strip the padding at the end.
+        let base64 = Data(SHA256.hash(data: data(secret: secret))).base64EncodedString()
+        let paddingRange = base64.index(base64.endIndex, offsetBy: -2)..<base64.endIndex
+        let cleaned = base64.replacingOccurrences(of: "=", with: "", range: paddingRange)
+        return "SHA256:\(cleaned)"
+    }
+
+    public func openSSHMD5Fingerprint<SecretType: Secret>(secret: SecretType) -> String {
+        Insecure.MD5.hash(data: data(secret: secret))
+            .compactMap { ("0" + String($0, radix: 16, uppercase: false)).suffix(2) }
+            .joined(separator: ":")
+    }
+
+}
+
+extension OpenSSHKeyWriter {
+
+    public func lengthAndData(of data: Data) -> Data {
+        let rawLength = UInt32(data.count)
+        var endian = rawLength.bigEndian
+        return Data(bytes: &endian, count: UInt32.bitWidth/8) + data
+    }
+
+    public func curveIdentifier(for algorithm: Algorithm, length: Int) -> String {
+        switch algorithm {
+        case .ellipticCurve:
+            return "nistp" + String(describing: length)
+        }
+    }
+
+    public func curveType(for algorithm: Algorithm, length: Int) -> String {
+        switch algorithm {
+        case .ellipticCurve:
+            return "ecdsa-sha2-nistp" + String(describing: length)
+        }
+    }
+}

Sources/SecretKit/Common/OpenSSH/OpenSSHReader.swift

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+import Foundation
+
+public class OpenSSHReader {
+
+    var remaining: Data
+
+    public init(data: Data) {
+        remaining = Data(data)
+    }
+
+    public func readNextChunk() -> Data {
+        let lengthRange = 0..<(UInt32.bitWidth/8)
+        let lengthChunk = remaining[lengthRange]
+        remaining.removeSubrange(lengthRange)
+        let littleEndianLength = lengthChunk.withUnsafeBytes { pointer in
+            return pointer.load(as: UInt32.self)
+        }
+        let length = Int(littleEndianLength.bigEndian)
+        let dataRange = 0..<length
+        let ret = Data(remaining[dataRange])
+        remaining.removeSubrange(dataRange)
+        return ret
+    }
+
+}