SHA1FromFile

SHA1FromFile.m

#import <CommonCrypto/CommonDigest.h>

@implementation SHA1FromFile

+ (NSString *)sha1FromFileAtPath:(NSString *)path {

    CFReadStreamRef readStream = CFReadStreamCreateWithFile(kCFAllocatorDefault, CFURLCreateWithFileSystemPath(kCFAllocatorDefault, 
                                                                                                               (CFStringRef)path, 
                                                                                                               kCFURLPOSIXPathStyle, 
                                                                                                               (Boolean)false));
    
    CC_SHA1_CTX ctx;
    CC_SHA1_Init(&ctx);
    
    if (!CFReadStreamOpen(readStream)) {
        NSLog(@"ERROR!");
    }
    
    CFIndex numBytesRead;
    
    do {
        uint8_t buffer[1024];
        
        numBytesRead = CFReadStreamRead(readStream, (UInt8 *)buffer, (CFIndex)sizeof(buffer));
        
        if (numBytesRead == -1) {
            break;
        }
        if (numBytesRead == 0) {
            continue;
        }
        
        CC_SHA1_Update(&ctx, buffer, numBytesRead);
        
    } while (numBytesRead > 0);
    
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    CC_SHA1_Final(digest, &ctx);
    
    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;
}

@end