Generate SHA1 hash from UTF8 encoding of a string

NSString+KJSHA1.m

- (NSData *)SHA1HashOfUTF8String {
    const char *UTF8 = [self UTF8String];
    size_t UTF8Length = strlen(UTF8);
    unsigned char hashedUTF8[CC_SHA1_DIGEST_LENGTH];
    CC_SHA1(UTF8, UTF8Length, hashedUTF8);
    return [NSData dataWithBytes:hashedUTF8 length:sizeof(hashedUTF8)];
}