mike vorisis mike vorisis - 1 month ago 20
iOS Question

How can I calculate a digest

I want to create connections with banks and as I see in the documentation of cardlink they want to calculate digest.

The main idea of this calculation is this

Digest=base64( sha-1( utf8bytes(value1|value2|...|secret) ) )


.

MessageDigestmdigest = MessageDigest.getInstance("SHA-1");
byte[] digestResult =digest.digest(concatString.getBytes("UTF-8"));
String calculatedDigest = Base64.encode(digestResult);


This is the code they have for java.

I started for testing this manually but I stucked with the convertion of bytes.

this is the finall step for base64

this is for sha-1

So my main question is how can I do the conversion to bytes and if It would help a lot if someone knows a way to do it with swift (ios).

Thanks in advance

EDIT

This is the example string I got:

2.045020311114033331503343429780020454510MDAwMDAwMDAwMDAwMDA2ODkzOTI=https://myeshop.gr/orders/Payment_Okhttps://myeshop.gr/orders/Payment_FailEURO123


And this is the result I want:

wXRSbgCX2Kq6gSOVE6+c9VpvSRQ=

Answer

Is this what you need?

import UIKit

extension String {
    func sha1() -> String {
        let data = self.dataUsingEncoding(NSUTF8StringEncoding)!
        var digest = [UInt8](count:Int(CC_SHA1_DIGEST_LENGTH), repeatedValue: 0)
        CC_SHA1(data.bytes, CC_LONG(data.length), &digest)
        let hexBytes = digest.map { String(format: "%02hhx", $0) }
        return hexBytes.joinWithSeparator("")
    }

    func sha1Data() -> NSData {
        let data = self.dataUsingEncoding(NSUTF8StringEncoding)!
        var digest = [UInt8](count:Int(CC_SHA1_DIGEST_LENGTH), repeatedValue: 0)
        CC_SHA1(data.bytes, CC_LONG(data.length), &digest)
        let digestData = NSData(bytes: digest, length: digest.count)
        return digestData
    }
}


class TestSHA1Digest: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        if let b64 = calculateDigest("2.045020311114033331503343429780020454510MDAwMDAwMDAwMDAwMDA2ODkzOTI=https://myeshop.gr/orders/Payment_Okhttps://myeshop.gr/orders/Payment_FailEURO123") {
            print("SHA1: \(b64)")
        } else {
            print("Calcuate SHA1 failed")
        }
    }

    func calculateDigest(data: String) -> String? {
        let shaData = data.sha1Data()
        return shaData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions(rawValue: 0))
    }
}

[Output] SHA1: wXRSbgCX2Kq6gSOVE6+c9VpvSRQ=

PS. I am using swift 2 + Xcode 7.3.1. Please let me know if you are using swift 3.

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