Objective-c – Creating SHA1 Hash from NSString


How can I create a SHA1 from a NSString.

Let's say the NSString is set up as:

NSString *message = @"Message";

I can use PHP to create a SHA1 hash with sha($message). But unfortunately it doesn't work like that within Objective-C.

Best Solution

I have this in a category on NSString (available at https://github.com/hypercrypt/NSString-Hashes):

#import <CommonCrypto/CommonDigest.h>


- (NSString *)sha1
    NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];

    CC_SHA1(data.bytes, (CC_LONG)data.length, digest);

    NSMutableString *output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];

    for (int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];

    return output;

Starting with Xcode 10.0, you should use import CommonCrypto instead since it is now natively available in Swift! If you have recently migrated to Xcode 10.0 and use the old approach, this can be your cue to make the change:

Command CompileSwift failed with a nonzero exit code