Styjun

I have a swift app that uses a RSA public key to send data to a python server, and have the server decrypt it with the server private key. However, swift returns a different cipher text each time. Is there any way to have it not salt it?

I've tried using SwiftyRSA, and SwiftUtils to implement the encryption, and while asking others for help, it seems swift automatically salts the message.

override func viewDidLoad() 
 ....
 do
 let data = "(message!)".data(using: String.Encoding.utf8)!
 // tag name to access the stored public key in keychain
 let TAG_PUBLIC_KEY = "com.example.keyPublic"
 let encryptStr = "encrypted_message="
 let encryptStrData = encryptStr.data(using: String.Encoding.utf8)!
 let keyString = getKeyStringFromPEMString(PEMString: """
-----BEGIN PUBLIC KEY-----
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
-----END PUBLIC KEY-----
""")
 let encryptedData = try RSAUtils.encryptWithRSAPublicKey(data: data, pubkeyBase64: keyString, tagName: TAG_PUBLIC_KEY)!
 let length = encryptStrData.count + encryptedData.count
 var array = [UInt8](repeating:0, count:length)
 encryptStrData.copyBytes(to: &array, count: encryptStrData.count)
 encryptedData.copyBytes(to: &array+encryptStrData.count, count: encryptedData.count)
 var st=""
 for byte in encryptedData
 st += String(format:"%02X", byte)
 
 print("ENCRYPTED MESSAGE")
 print(st)
 
 catch
 print(error)
 
 ...
 //Key function - remove header and footer
 func getKeyStringFromPEMString(PEMString: String) -> String 
 let keyArray = PEMString.split(separator: "n") //Remove new line characters
 var keyOutput : String = ""
 for item in keyArray 
 if !item.contains("-----") //Example: -----BEGIN PUBLIC KEY-----
 keyOutput += item //Join the text together as a single string
 
 
 return keyOutput
 
 ....

from Crypto.PublicKey import RSA
from Crypto import Random
from base64 import b64decode
def decText(encTest):
 random_generator = Random.new().read
 key = RSA.generate(2048, random_generator)
 with open('private.pem','r') as f:
 key=RSA.importKey(f.read())
 rawCipherData = b64decode(encTest)
 decrypted = key.decrypt(encTest)
 print(decrypted)
 return decrypted

Here's the plaintext.
33ba884d57161df955de45c50e3bba69c83233402bf460906b919bc0806b44356112b6e0b8dd8f2f5804d5b527e996ba91e91015915f03d0292d89b7ecfc3c44

And here's the ciphertext
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

Here's the hex of what python outputs with this cipher text:
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

I see difference in encoding and decoding

in the Swift encryption code the encryption seems to output:

hex_encode( "encrypted_message=" + encrypt( data ) )

while the python is doing

base64_decode( ciphertext )

If there's something else, you will need to provide working and verifiable code sample, inputs you use and exception you get