Swift - 如何实现字符串的HMAC_SHA1加密

一、基本概念

1，HMAC（散列消息身份验证码：Hashed Message Authentication Code）

#import <CommonCrypto/CommonHMAC.h>

//HMAC.swift
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)
    }
}

let str = "welcome to hangge.com"
let key = "67FG"
let hmacStr = str.hmac(algorithm: .SHA1, key: key)

print("原始字符串：\(str)")
print("key：\(key)")
print("HMAC运算结果：\(hmacStr)")