My end goal is to use eciesEncryptionCofactorX963SHA256AESGCM with a key generated on the Secure Enclave using CryptoKit, that requires Biometric Authentication. CryptoKit does not implement the ECIES encryption algorithms, so my goal was to fall back to the Security framework. The public key can be easily converted to a SecKey because it implements x963Representation which can then be imported as follows: let enclaveSecKey: SecKey = SecKeyCreateWithData(enclaveKey.x963Representation as CFData, [ kSecAttrKeyType: kSecAttrKeyTypeECSECPrimeRandom, kSecAttrKeyClass: kSecAttrKeyClassPublic, kSecAttrKeySizeInBits: 256 ] as [String: Any] as CFDictionary, nil), I have everything working except the code to decrypt with the private key. Naturally, the Secure Enclave does not expose the private key - as is its design - rather some kind of token? I did read the Keychain documentation which notes that it is not possible to simply obtain an x963Representation of the private key (as it's a custom representation returned by the Secure Enclave). However, my ultimate question is this: can one convert the Secure Enclave representation into something that can be used as a SecKey for encryption/decryption (without necessarily being stored in the Keychain - i.e., 'correct') as it seems both CryptoKit and Security have a means of representing the private key token returned by the Secure Enclave? (Or is one's only recourse to use the Security framework for generating and storing the keys too?) I have also tried this code to create a SecKey representation, having retrieved the GenericPasswordConvertible out of the keychain (note the use of kSecAttrTokenID: kSecAttrTokenIDSecureEnclave) with the aforementioned goal of loading the Secure Enclave's private token as a SecKey: let enclaveSecKey: SecKey = SecKeyCreateWithData(enclaveKey.rawRepresentation as CFData, [ kSecAttrKeyType: kSecAttrKeyTypeECSECPrimeRandom, kSecAttrKeyClass: kSecAttrKeyClassPrivate, kSecAttrTokenID: kSecAttrTokenIDSecureEnclave, kSecAttrAccessible: kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly, kSecUseAuthenticationContext: try await createAuthContext( reason: "Decrypt data", fallbackTitle: "Enter your device password to decrypt data", mustEvaluate: true ), kSecAttrIsPermanent: true, kSecAttrIsExtractable: false, kSecAttrSynchronizable: false, kSecAttrKeySizeInBits: 256, kSecAttrAccessControl: SecAccessControlCreateWithFlags( nil, kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly, [.biometryAny, .privateKeyUsage], &cfSecKeyCreateError )! ] as [String: Any] as CFDictionary, nil) This works, in and of itself, (i.e., it loads without error and cfSecKeyCreateError is nil, however when I try SecSecKeyCopyPublicKey I get a different, incorrect public key and - naturally, I suppose - if I attempt to decrypt data with the private key that fails with: Optional(Swift.Unmanaged<__C.CFErrorRef>(_value: Error Domain=NSOSStatusErrorDomain Code=-50 "ECIES: Failed to aes-gcm decrypt data (err -69)" UserInfo={numberOfErrorsDeep=0, NSDescription=ECIES: Failed to aes-gcm decrypt data (err -69)}))

Hi, How do I generate the pem representation of a curve25519 public key? I can generate the key using :      let privateKey = Curve25519.KeyAgreement.PrivateKey() let publicKey = privateKey.publicKey print(publicKey.rawRepresentation.base64EncodedString()) This prints a string like this : GyQfzi3bLfpDpzi8e9j6lovX15EZY1t1fQQcnJlURxI= But the expected strings are more like : ----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEApxUNh3jHlNSAWE7fadipsh9AjXv6439VY3EWEC5kbgY=\n-----END PUBLIC KEY Even if I add the " -----BEGIN PUBLIC KEY-----" and "-----END PUBLIC KEY-----" tags, it still doesn't process the key. So what format is exactly the base64 encoded string of the raw format of curve25519 public key? And how do I generate the public key pem format? The requirement is for Swift iOS.

I am working on an application on IOS and I need to be able to decrypt an element that has been encrypted with a public key, but I only know the modulus and the private exponent of the private key. How can I obtain the private key from these elements in IOS? In java, with the following code I can get the private key from these elements and I can decrypt the element. final RSAPrivateKeySpec privateSpec = new RSAPrivateKeySpec(MODULUS, PRIVATE_EXPONENT); final KeyFactory factory = KeyFactory.getInstance("RSA"); final PrivateKey priv = factory.generatePrivate(privateSpec); On ios, I got the following code, but it doesn't return the private key:      let smodulus = "00c35d6ac32d287dab681c78272931b60ca442bd4505e1b306432af92ef6e07bc3e4e24c2bc2dac69c94753390c3793b80734ef906520a96cafb146ce587ab383e78efc58c5ccf56b5084f3f9bc719e646a0361155ab56b7d71b49f1f90673383ea0fdb4a67900c0973930aa3bc7071c479b4a5d229fcab7ce22b84c1637d7e70b"     let sPrivateExponent = "1f2535700832fc55e73322b49b8ca14942a6a125efda1b805414f5c4d6f6d2c45828fb9bbe64c2651405db42a8e71ae54f7cb7969a5db5cc865aab41ac6f4f77deccb51496fe588f9dcd724a1d49cab96712621afc9c656c56dea011f8ab8e12a321fd62430902b15586a36093a6679e31b67017397da83b0992f5f816017701"     let sPublicExponent = "010001"    public static func getPrivateKey(smodulus: String, sPrivateExponent: String) -> SecKey? {              let pubExponent: [UInt8] = [1, 0, 1]     let exponent: [UInt8] = sPrivateExponent.hexaBytes     var modulus: [UInt8] = smodulus.hexaBytes           //modulus.insert(0x00, at: 0)           var modulusEncoded: [UInt8] = []     modulusEncoded.append(0x02)     modulusEncoded.append(contentsOf: lengthField(of: modulus))     modulusEncoded.append(contentsOf: modulus)     var exponentEncoded: [UInt8] = []     exponentEncoded.append(0x02)     exponentEncoded.append(contentsOf: lengthField(of: exponent))     exponentEncoded.append(contentsOf: exponent)           var sequenceEncoded: [UInt8] = []     sequenceEncoded.append(0x30)     sequenceEncoded.append(contentsOf: lengthField(of: (modulusEncoded + exponentEncoded)))     sequenceEncoded.append(contentsOf: (modulusEncoded + exponentEncoded))           let keyData = Data(bytes: sequenceEncoded)           // RSA key size is the number of bits of the modulus.     let keySize = (modulus.count * 8)     let attributes: [String: Any] = [       kSecAttrKeyType as String: kSecAttrKeyTypeRSA,       kSecAttrKeyClass as String: kSecAttrKeyClassPrivate,       kSecAttrKeySizeInBits as String: keySize     ]                 let privateKey = SecKeyCreateWithData(keyData as CFData, attributes as CFDictionary, nil)                       return privateKey   }  private static func lengthField(of valueField: [UInt8]) -> [UInt8] {     var count = valueField.count     if count < 128 {       return [ UInt8(count) ]     }     // The number of bytes needed to encode count.     let lengthBytesCount = Int((log2(Double(count)) / 8) + 1)     // The first byte in the length field encoding the number of remaining bytes.     let firstLengthFieldByte = UInt8(128 + lengthBytesCount)     var lengthField: [UInt8] = []     for _ in 0..<lengthBytesCount {       // Take the last 8 bits of count.       let lengthByte = UInt8(count & 0xff)       // Add them to the length field.       lengthField.insert(lengthByte, at: 0)       // Delete the last 8 bits of count.       count = count >> 8     }     // Include the first byte.     lengthField.insert(firstLengthFieldByte, at: 0)     return lengthField   } extension StringProtocol {   var hexaData: Data { .init(hexa) }   var hexaBytes: [UInt8] { .init(hexa) }   private var hexa: UnfoldSequence<UInt8, Index> {     sequence(state: startIndex) { startIndex in       guard startIndex < self.endIndex else { return nil }       let endIndex = self.index(startIndex, offsetBy: 2, limitedBy: self.endIndex) ?? self.endIndex       defer { startIndex = endIndex }       return UInt8(self[startIndex..<endIndex], radix: 16)     }   } }

I have a continuous data stream encrypted by aesgcm, I did not find a way to decrypt it using CryptoKit unless I have the full data. My question is Can CryptoKit decrypt or encrypt a stream without a complete read? Like EVP_***_Update in OpenSSL. Thank you.