How to compute shared secret using EC public key x and y values and private key d value #62
Description
Hi
How to compute shared secret using EC public key x and y values and private key d value using the below function and i am getting back nil. I tried to decode and i can see the privateD which i am passing returns back nil from importKey method where the value of status is -4302.
Can you please help what format Data should i be passing into the computeSharedSecret for it to work in this case ?
var publicX = "2_v-MuNZccqwM7PXlakW9oHLP5XyrjMG1UVS8OxYrgA" var publicY = "rm1ktLmFIsP2R0YyJGXtsCbaTUesUK31Xc04tHJRolc" let privateD = "iyn--IbkBeNoPu8cN245L6pOQWt2lTH8V0Ds92jQmWA" let binaryPrivateData = privateDData(base64String: privateD) let publicKeyData = dataFromPublicXandY(x: publicX, y: publicY) let shared = try? CC.EC.computeSharedSecret(binaryPrivateData, publicKey: publicKeyData) print(shared) // is nil func privateDData(base64String: String) -> Data { let base64Co = base64urlToBase64(base64url: base64String) //print(base64Q) // hJQWHABDBjoPHorYF5xghQ== let decodedDataCo = Data(base64Encoded: base64Co) return decodedDataCo! } func dataFromPublicXandY(x: String, y:String) -> Data { var xStr = x var yStr = y xStr = xStr.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/") if xStr.count % 4 == 2 { xStr.append("==") } if xStr.count % 4 == 3 { xStr.append("=") } yStr = yStr.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/") if yStr.count % 4 == 2 { yStr.append("==") } if yStr.count % 4 == 3 { yStr.append("=") } let xBytes = Data(base64Encoded: xStr) /*Same with y and d*/ let yBytes = Data(base64Encoded: yStr) //Now this bytes we have to append such that [0x04 , /* xBytes */, /* yBytes */, /* dBytes */] //Initial byte for uncompressed y as Key. let keyData = NSMutableData.init(bytes: [0x04], length: [0x04].count) keyData.append(xBytes!) keyData.append(yBytes!) return keyData as Data }