How to replicate hash_hmac('sha256', $key, $secret_key) function in Swift 4?
Swift 3/4:
HMAC with MD5, SHA1, SHA224, SHA256, SHA384, SHA512 (Swift 3)
These functions will hash either String or Data input with one of eight cryptographic hash algorithms.
The name parameter specifies the hash function name as a String
Supported functions are MD5, SHA1, SHA224, SHA256, SHA384 and SHA512
This example requires Common Crypto
It is necessary to have a bridging header to the project:#import <CommonCrypto/CommonCrypto.h>
Add the Security.framework to the project.
These functions takes a hash name, message to be hashed, a key and return a digest:
hashName: name of a hash function as String
message: message as Data
key: key as Data
returns: digest as Data
func hmac(hashName:String, message:Data, key:Data) -> Data? {
let algos = ["SHA1": (kCCHmacAlgSHA1, CC_SHA1_DIGEST_LENGTH),
"MD5": (kCCHmacAlgMD5, CC_MD5_DIGEST_LENGTH),
"SHA224": (kCCHmacAlgSHA224, CC_SHA224_DIGEST_LENGTH),
"SHA256": (kCCHmacAlgSHA256, CC_SHA256_DIGEST_LENGTH),
"SHA384": (kCCHmacAlgSHA384, CC_SHA384_DIGEST_LENGTH),
"SHA512": (kCCHmacAlgSHA512, CC_SHA512_DIGEST_LENGTH)]
guard let (hashAlgorithm, length) = algos[hashName] else { return nil }
var macData = Data(count: Int(length))
macData.withUnsafeMutableBytes {macBytes in
message.withUnsafeBytes {messageBytes in
key.withUnsafeBytes {keyBytes in
CCHmac(CCHmacAlgorithm(hashAlgorithm),
keyBytes, key.count,
messageBytes, message.count,
macBytes)
}
}
}
return macData
}
hashName: name of a hash function as String
message: message as String
key: key as String
returns: digest as Data
func hmac(hashName:String, message:String, key:String) -> Data? {
let messageData = message.data(using:.utf8)!
let keyData = key.data(using:.utf8)!
return hmac(hashName:hashName, message:messageData, key:keyData)
}
hashName: name of a hash function as String
message: message as String
key: key as Data
returns: digest as Data
func hmac(hashName:String, message:String, key:Data) -> Data? {
let messageData = message.data(using:.utf8)!
return hmac(hashName:hashName, message:messageData, key:key)
}
// Examples
let clearString = "clearData0123456"
let keyString = "keyData8901234562"
let clearData = clearString.data(using:.utf8)!
let keyData = keyString.data(using:.utf8)!
print("clearString: \(clearString)")
print("keyString: \(keyString)")
print("clearData: \(clearData as NSData)")
print("keyData: \(keyData as NSData)")
let hmacData1 = hmac(hashName:"SHA1", message:clearData, key:keyData)
print("hmacData1: \(hmacData1! as NSData)")
let hmacData2 = hmac(hashName:"SHA1", message:clearString, key:keyString)
print("hmacData2: \(hmacData2! as NSData)")
let hmacData3 = hmac(hashName:"SHA1", message:clearString, key:keyData)
print("hmacData3: \(hmacData3! as NSData)")
Output:
clearString: clearData0123456
keyString: keyData8901234562
clearData: <636c6561 72446174 61303132 33343536>
keyData: <6b657944 61746138 39303132 33343536 32>
hmacData1: <bb358f41 79b68c08 8e93191a da7dabbc 138f2ae6>
hmacData2: <bb358f41 79b68c08 8e93191a da7dabbc 138f2ae6>
hmacData3: <bb358f41 79b68c08 8e93191a da7dabbc 138f2ae6>
How to Hash sha256 in swift 4 with a secret key?
I admit that it can be confusing to get everything together but the final solution is quite simple:
extension String {
func hmac(key: String) -> String {
var digest = [UInt8](repeating: 0, count: Int(CC_SHA256_DIGEST_LENGTH))
CCHmac(CCHmacAlgorithm(kCCHmacAlgSHA256), key, key.count, self, self.count, &digest)
let data = Data(bytes: digest)
return data.map { String(format: "%02hhx", $0) }.joined()
}
}
Example:
let result = "test".hmac(key: "test")
Result:
88cd2108b5347d973cf39cdf9053d7dd42704876d8c9a9bd8e2d168259d3ddf7
HMAC SHA256 in Swift 4
I've been using this:
import Foundation
enum CryptoAlgorithm {
case MD5, SHA1, SHA224, SHA256, SHA384, SHA512
var HMACAlgorithm: CCHmacAlgorithm {
var result: Int = 0
switch self {
case .MD5: result = kCCHmacAlgMD5
case .SHA1: result = kCCHmacAlgSHA1
case .SHA224: result = kCCHmacAlgSHA224
case .SHA256: result = kCCHmacAlgSHA256
case .SHA384: result = kCCHmacAlgSHA384
case .SHA512: result = kCCHmacAlgSHA512
}
return CCHmacAlgorithm(result)
}
var digestLength: Int {
var result: Int32 = 0
switch self {
case .MD5: result = CC_MD5_DIGEST_LENGTH
case .SHA1: result = CC_SHA1_DIGEST_LENGTH
case .SHA224: result = CC_SHA224_DIGEST_LENGTH
case .SHA256: result = CC_SHA256_DIGEST_LENGTH
case .SHA384: result = CC_SHA384_DIGEST_LENGTH
case .SHA512: result = CC_SHA512_DIGEST_LENGTH
}
return Int(result)
}
}
extension String {
func hmac(algorithm: CryptoAlgorithm, key: String) -> String {
let str = self.cString(using: String.Encoding.utf8)
let strLen = Int(self.lengthOfBytes(using: String.Encoding.utf8))
let digestLen = algorithm.digestLength
let result = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: digestLen)
let keyStr = key.cString(using: String.Encoding.utf8)
let keyLen = Int(key.lengthOfBytes(using: String.Encoding.utf8))
CCHmac(algorithm.HMACAlgorithm, keyStr!, keyLen, str!, strLen, result)
let digest = stringFromResult(result: result, length: digestLen)
result.deallocate(capacity: digestLen)
return digest
}
private func stringFromResult(result: UnsafeMutablePointer<CUnsignedChar>, length: Int) -> String {
let hash = NSMutableString()
for i in 0..<length {
hash.appendFormat("%02x", result[i])
}
return String(hash).lowercased()
}
}
You'll need to add #import <CommonCrypto/CommonHMAC.h> to your Objective-C bridging header.
Source: @thevalyreangroup on this github thread
HMAC SHA256 in C# vs HMAC SHA256 in Swift don't match
The issue here seems to be a difference in the base64 strings between the given swift solution and then C# solution.
The output of the hash algorithm was the same at a byte level but it was being manipulated through various string conversions before being returned.
The function
private func stringFromResult(result: UnsafeMutablePointer<CUnsignedChar>, length: Int) -> String {
let hash = NSMutableString()
for i in 0..<length {
hash.appendFormat("%02x", result[i])
}
return String(hash).lowercased()
}
Which is part of the solution converts the raw hashed data to a string, which is then converted back to a data object in the calling class, which is then cast into a base64 string to be returned. As we are getting a base64 string of of the string that was returned and not the raw bytes, I think this is where the issue was.
By changing the hmac code from the solution to this, we can cast the raw output of the has to a base64 string and avoid the other steps. This matches the C# value.
func hmac(algorithm: CryptoAlgorithm, key: String) -> String {
let str = self.cString(using: String.Encoding.utf8)
let strLen = Int(self.lengthOfBytes(using: String.Encoding.utf8))
let digestLen = algorithm.digestLength
let result = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: digestLen)
let keyStr = key.cString(using: String.Encoding.utf8)
let keyLen = Int(key.lengthOfBytes(using: String.Encoding.utf8))
CCHmac(algorithm.HMACAlgorithm, keyStr!, keyLen, str!, strLen, result)
let a = UnsafeMutableBufferPointer(start: result, count: digestLen)
let b = Data(a)
result.deallocate()
let digest = b.base64EncodedString()
return digest
}
Implementing HMAC and SHA1 encryption in swift
Problem solved! First off i wasn't using the string function properly... I ended up with this:
let hmacResult:String = "myStringToHMAC".hmac(HMACAlgorithm.SHA1, key: "myKey")
Then I had forgotten I needed to base64 encode the hmac result. So i modified the string function linked in my question to...
enum HMACAlgorithm {
case MD5, SHA1, SHA224, SHA256, SHA384, SHA512
func toCCHmacAlgorithm() -> CCHmacAlgorithm {
var result: Int = 0
switch self {
case .MD5:
result = kCCHmacAlgMD5
case .SHA1:
result = kCCHmacAlgSHA1
case .SHA224:
result = kCCHmacAlgSHA224
case .SHA256:
result = kCCHmacAlgSHA256
case .SHA384:
result = kCCHmacAlgSHA384
case .SHA512:
result = kCCHmacAlgSHA512
}
return CCHmacAlgorithm(result)
}
func digestLength() -> Int {
var result: CInt = 0
switch self {
case .MD5:
result = CC_MD5_DIGEST_LENGTH
case .SHA1:
result = CC_SHA1_DIGEST_LENGTH
case .SHA224:
result = CC_SHA224_DIGEST_LENGTH
case .SHA256:
result = CC_SHA256_DIGEST_LENGTH
case .SHA384:
result = CC_SHA384_DIGEST_LENGTH
case .SHA512:
result = CC_SHA512_DIGEST_LENGTH
}
return Int(result)
}
}
extension String {
func hmac(algorithm: HMACAlgorithm, key: String) -> String {
let cKey = key.cStringUsingEncoding(NSUTF8StringEncoding)
let cData = self.cStringUsingEncoding(NSUTF8StringEncoding)
var result = [CUnsignedChar](count: Int(algorithm.digestLength()), repeatedValue: 0)
CCHmac(algorithm.toCCHmacAlgorithm(), cKey!, strlen(cKey!), cData!, strlen(cData!), &result)
var hmacData:NSData = NSData(bytes: result, length: (Int(algorithm.digestLength())))
var hmacBase64 = hmacData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding76CharacterLineLength)
return String(hmacBase64)
}
}
This is giving me the correct result of
lGCtbW+DNHFraNoxPGK3trgM/98=
SHA256 in swift
You have to convert explicitly between Int and CC_LONG, because Swift does not
do implicit conversions, as in (Objective-)C.
You also have to define hash as an array of the required size.
func sha256(data : NSData) -> NSData {
var hash = [UInt8](count: Int(CC_SHA256_DIGEST_LENGTH), repeatedValue: 0)
CC_SHA256(data.bytes, CC_LONG(data.length), &hash)
let res = NSData(bytes: hash, length: Int(CC_SHA256_DIGEST_LENGTH))
return res
}
Alternatively, you can use NSMutableData to allocate the needed buffer:
func sha256(data : NSData) -> NSData {
let res = NSMutableData(length: Int(CC_SHA256_DIGEST_LENGTH))
CC_SHA256(data.bytes, CC_LONG(data.length), UnsafeMutablePointer(res.mutableBytes))
return res
}
Update for Swift 3 and 4:
func sha256(data : Data) -> Data {
var hash = [UInt8](repeating: 0, count: Int(CC_SHA256_DIGEST_LENGTH))
data.withUnsafeBytes {
_ = CC_SHA256($0, CC_LONG(data.count), &hash)
}
return Data(bytes: hash)
}
Update for Swift 5:
func sha256(data : Data) -> Data {
var hash = [UInt8](repeating: 0, count: Int(CC_SHA256_DIGEST_LENGTH))
data.withUnsafeBytes {
_ = CC_SHA256($0.baseAddress, CC_LONG(data.count), &hash)
}
return Data(hash)
}
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How to Replicate Hash_Hmac('Sha256', $Key, $Secret_Key) Function in Swift 4