适用于iPhone的Objective-C中的Sha256

Question

当我使用此代码创建字符串的sha256时

unsigned char hashedChars[32];
NSString *inputString;
inputString = [NSString stringWithFormat:@"hello"];
NSData * inputData = [inputString dataUsingEncoding:NSUTF8StringEncoding];
CC_SHA256(inputData.bytes, inputData.length, hashedChars);

它正确地返回哈希，但是我需要插入一个类似于\ x00 \ x25 \ x53的字符串，在这种情况下，该函数返回一个空字符串的sha256，因为指定的编码不能用于转换接收器。

现在，我的问题是：如何插入此特殊字符以生成正确的哈希？谢谢

Answer 1

试试这个，它对我有用

1）获取纯文本输入的哈希值

-(NSString*)sha256HashFor:(NSString*)input
{   
    const char* str = [input UTF8String];
    unsigned char result[CC_SHA256_DIGEST_LENGTH];
    CC_SHA256(str, strlen(str), result);

    NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
    for(int i = 0; i<CC_SHA256_DIGEST_LENGTH; i++)
    {
        [ret appendFormat:@"%02x",result[i]];
    }
    return ret;
}

2）获取NSData的哈希作为输入

注意： - 我使用过NSData类别，所以代码如下

    - (NSString *)SHA256_HASH {
    //if (!self) return nil;

    unsigned char hash[CC_SHA256_DIGEST_LENGTH];
    if ( CC_SHA256([(NSData*)self bytes], [(NSData*)self length], hash) ) {
        NSData *sha2 = [NSData dataWithBytes:hash length:CC_SHA256_DIGEST_LENGTH]; 

        // description converts to hex but puts <> around it and spaces every 4 bytes
        NSString *hash = [sha2 description];
        hash = [hash stringByReplacingOccurrencesOfString:@" " withString:@""];
        hash = [hash stringByReplacingOccurrencesOfString:@"<" withString:@""];
        hash = [hash stringByReplacingOccurrencesOfString:@">" withString:@""];
        // hash is now a string with just the 40char hash value in it
        //NSLog(@"hash = %@",hash);

        // Format SHA256 fingerprint like
        // 00:00:00:00:00:00:00:00:00
        int keyLength=[hash length];
        NSString *formattedKey = @"";
        for (int i=0; i<keyLength; i+=2) {
            NSString *substr=[hash substringWithRange:NSMakeRange(i, 2)];
            if (i!=keyLength-2) 
                substr=[substr stringByAppendingString:@":"];
            formattedKey = [formattedKey stringByAppendingString:substr];
        }

        return formattedKey;
    }
    return nil;
}

Answer 2

知道您需要导入是很重要的：

#import <CommonCrypto/CommonDigest.h>

希望这有帮助！

Answer 3

你可能应该使用NSData而不是NSString。你从哪里得到那个字符串？

Answer 4

有人在Swift 3.0中寻找解决方案。这是

extension String {

// MARK: - SHA256
func get_sha256_String() -> String {
    guard let data = self.data(using: .utf8) else {
        print("Data not available")
        return ""
    }
    return getHexString(fromData: digest(input: data as NSData))
}

private func digest(input : NSData) -> NSData {
    let digestLength = Int(CC_SHA256_DIGEST_LENGTH)
    var hashValue = [UInt8](repeating: 0, count: digestLength)
    CC_SHA256(input.bytes, UInt32(input.length), &hashValue)
    return NSData(bytes: hashValue, length: digestLength)
}

private  func getHexString(fromData data: NSData) -> String {
    var bytes = [UInt8](repeating: 0, count: data.length)
    data.getBytes(&bytes, length: data.length)

    var hexString = ""
    for byte in bytes {
        hexString += String(format:"%02x", UInt8(byte))
    }
    return hexString
}}

如何使用它

let signatures = "yourStringToBeConverted".get_sha256_String()

也不要忘记在你的Bridging-Header.h中导入#import <CommonCrypto/CommonHMAC.h>