Mutable data pack into json - swift

Question

How could I send hashed password with sha256 via post request ?
func sha256(string: String) -> Data? {
guard let messageData = string.data(using:String.Encoding.utf8) else { return nil; }
var digestData = Data(count: Int(CC_SHA256_DIGEST_LENGTH))
_ = digestData.withUnsafeMutableBytes {digestBytes in
messageData.withUnsafeBytes {messageBytes in
CC_SHA256(messageBytes, CC_LONG(messageData.count), digestBytes)
}
}
return digestData
}
This is how I am hasing a password.
Then whenever I try to pack it into an array as a [String: Any] it throws an exception in JSONSErialization 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (Foundation._SwiftNSData)'
guard let loginURL = URL(string: LOGIN_URL) else {
print("Error: cannot create URL")
return
}
var loginURLRequest = URLRequest(url: loginURL)
loginURLRequest.httpMethod = "POST"
let content: [String: Any] = ["username": username, "passwordHash": password]
let json: Data
do {
json = try JSONSerialization.data(withJSONObject: content, options: [])
loginURLRequest.httpBody = json
} catch {
print("Error: Can not create JSON")
return
}
Thanks in advance!

Answer 1

What you probably want to do is encode the hash as a hex string. Given your sha256 function defined above, The following will do that:
let password = sha256(string: "myPassword")
.map { return String(format: "%02x", $0) }
.joined()
let content = [
"username": username,
"passwordHash": password
]
Alternatively, you could change your sha256 function to return a string (and make it an extension of string):
func sha256() -> String? {
guard let messageData = data(using:String.Encoding.utf8) else {
return nil
}
var digestData = Data(count: Int(CC_SHA256_DIGEST_LENGTH))
_ = digestData.withUnsafeMutableBytes { digestBytes in
withUnsafeBytes { messageBytes in
CC_SHA256(messageBytes, CC_LONG(messageData.count), digestBytes)
}
}
return digestData.map { return String(format: "%02x", $0) }.joined()
}
Note: I'm winging this a little since CommonCrypto won't work in a playground and I'm too lazy to wrap a whole project around this, but the important parts are here.
Use data.map to iterate over each byte in the hash
convert it to a hex string with String(format: "%02x"...)
put it all back together with joined()