斯威夫特3:
基于密码的密钥派生既可以用于从密码文本派生加密密钥,也可以用于保存密码以进行身份验证。
有几种哈希算法可以使用,包括由该示例代码提供的SHA1、SHA256、SHA512。
rounds参数用于使计算变慢,以便攻击者每次尝试都要花费大量时间。典型的延迟值在100ms到500ms之间,如果性能不可接受,可以使用更短的值。
此示例需要Common Crypto
有必要为项目设置一个桥接头:
#import <CommonCrypto/CommonCrypto.h>
添加
Security.framework
项目。
参数:
password password String
salt salt Data
keyByteCount number of key bytes to generate
rounds Iteration rounds
returns Derived key
func pbkdf2SHA1(password: String, salt: Data, keyByteCount: Int, rounds: Int) -> Data? {
return pbkdf2(hash:CCPBKDFAlgorithm(kCCPRFHmacAlgSHA1), password:password, salt:salt, keyByteCount:keyByteCount, rounds:rounds)
}
func pbkdf2SHA256(password: String, salt: Data, keyByteCount: Int, rounds: Int) -> Data? {
return pbkdf2(hash:CCPBKDFAlgorithm(kCCPRFHmacAlgSHA256), password:password, salt:salt, keyByteCount:keyByteCount, rounds:rounds)
}
func pbkdf2SHA512(password: String, salt: Data, keyByteCount: Int, rounds: Int) -> Data? {
return pbkdf2(hash:CCPBKDFAlgorithm(kCCPRFHmacAlgSHA512), password:password, salt:salt, keyByteCount:keyByteCount, rounds:rounds)
}
func pbkdf2(hash :CCPBKDFAlgorithm, password: String, salt: Data, keyByteCount: Int, rounds: Int) -> Data? {
let passwordData = password.data(using:String.Encoding.utf8)!
var derivedKeyData = Data(repeating:0, count:keyByteCount)
let derivationStatus = derivedKeyData.withUnsafeMutableBytes {derivedKeyBytes in
salt.withUnsafeBytes { saltBytes in
CCKeyDerivationPBKDF(
CCPBKDFAlgorithm(kCCPBKDF2),
password, passwordData.count,
saltBytes, salt.count,
hash,
UInt32(rounds),
derivedKeyBytes, derivedKeyData.count)
}
}
if (derivationStatus != 0) {
print("Error: \(derivationStatus)")
return nil;
}
return derivedKeyData
}
示例用法:
let password = "password"
//let salt = "saltData".data(using: String.Encoding.utf8)!
let salt = Data(bytes: [0x73, 0x61, 0x6c, 0x74, 0x44, 0x61, 0x74, 0x61])
let keyByteCount = 16
let rounds = 100000
let derivedKey = pbkdf2SHA1(password:password, salt:salt, keyByteCount:keyByteCount, rounds:rounds)
print("derivedKey (SHA1): \(derivedKey! as NSData)")
示例输出:
derivedKey (SHA1): <6b9d4fa3 0385d128 f6d196ee 3f1d6dbf>
雨燕2.x:
参数类型和类到实例方法的细微更改用于测试。
func generateAesKeyForPassword(password: String, salt: NSData, roundCount: Int?, error: NSErrorPointer) -> (key: NSData, actualRoundCount: UInt32)?
{
let nsDerivedKey = NSMutableData(length: kCCKeySizeAES256)
var actualRoundCount: UInt32
// Create Swift intermediates for clarity in function calls
let algorithm: CCPBKDFAlgorithm = CCPBKDFAlgorithm(kCCPBKDF2)
let prf: CCPseudoRandomAlgorithm = CCPseudoRandomAlgorithm(kCCPRFHmacAlgSHA256)
let saltBytes = UnsafePointer<UInt8>(salt.bytes)
let saltLength = size_t(salt.length)
let nsPassword = password as NSString
let nsPasswordPointer = UnsafePointer<Int8>(nsPassword.cStringUsingEncoding(NSUTF8StringEncoding))
let nsPasswordLength = size_t(nsPassword.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
var nsDerivedKeyPointer = UnsafeMutablePointer<UInt8>(nsDerivedKey.mutableBytes)
let nsDerivedKeyLength = size_t(nsDerivedKey.length)
let msec: UInt32 = 300
if roundCount != nil {
actualRoundCount = UInt32(roundCount!)
}
else {
actualRoundCount = CCCalibratePBKDF(
algorithm,
nsPasswordLength,
saltLength,
prf,
nsDerivedKeyLength,
msec);
}
let result = CCKeyDerivationPBKDF(
algorithm,
nsPasswordPointer, nsPasswordLength,
saltBytes, saltLength,
prf, actualRoundCount,
nsDerivedKeyPointer, nsDerivedKeyLength)
if result != 0 {
let errorDescription = "CCKeyDerivationPBKDF failed with error: '\(result)'"
// error.memory = MyError(domain: ClientErrorType.errorDomain, code: Int(result), descriptionText: errorDescription)
return nil
}
return (nsDerivedKey, actualRoundCount)
}
//增加的奖金:
func salt(#length:UInt) -> NSData {
let salt = NSMutableData(length: Int(length))
var saltPointer = UnsafeMutablePointer<UInt8>(salt.mutableBytes)
SecRandomCopyBytes(kSecRandomDefault, length, saltPointer);
return salt
}
//测试呼叫:
let password = "test pass"
let salt = self.salt(length:32)
let roundCount = 300
var error: NSError?
let result = self.generateAesKeyForPassword(password, salt:salt, roundCount:roundCount, error:&error)
println("result: \(result)")
输出:
result: Optional((<d279ab8d 8ace67b7 abec844c b9979d20 f2bb0a7f 5af70502 085bf1e4 1016b20c>, 300))
