Re-adding transform_public_key() and updater_verify_file(); part of #196

.

Hydra/API/updates.m

@@ -1,11 +1,99 @@
 #import "helpers.h"
+#include <CommonCrypto/CommonDigest.h>
 
 /// updates
 ///
 /// Check for and install Hydra updates.
 
 
 
+// assumes pubkeypath is legit
+static SecKeyRef transform_public_key(NSString* pubkeypath) {
+    CFArrayRef items = NULL;
+    SecKeyRef security_key = NULL;
+
+    NSString* pubkey = [NSString stringWithContentsOfFile:pubkeypath encoding:NSUTF8StringEncoding error:NULL];
+    NSData* pubkeyData = [pubkey dataUsingEncoding:NSUTF8StringEncoding];
+    if ([pubkeyData length] == 0) goto cleanup;
+
+    SecExternalFormat format = kSecFormatOpenSSL;
+    SecExternalItemType itemType = kSecItemTypePublicKey;
+    SecItemImportExportKeyParameters parameters = {};
+
+    OSStatus status = SecItemImport((__bridge CFDataRef)pubkeyData, NULL, &format, &itemType, 0, &parameters, NULL, &items);
+
+    if (status != noErr) { printf("invalid status: %d\n", status); goto cleanup; }
+    if (items == NULL) { printf("items were unexpectedly null\n"); goto cleanup; }
+    if (format != kSecFormatOpenSSL) { printf("format isn't kSecFormatOpenSSL: %d\n", format); goto cleanup; }
+    if (itemType != kSecItemTypePublicKey) { printf("item type isn't kSecItemTypePublicKey: %d\n", itemType); goto cleanup; }
+    if (CFArrayGetCount(items) != 1) { printf("items count isn't 1, it's: %ld\n", CFArrayGetCount(items)); goto cleanup; }
+
+    security_key = (SecKeyRef)CFRetain(CFArrayGetValueAtIndex(items, 0));
+
+cleanup:
+    if (items) CFRelease(items);
+    return security_key;
+}
+
+static BOOL updater_verify_file(NSString* sig, NSString* pubkeypath, NSString* zipfilepath) {
+    BOOL verified = NO;
+
+    SecKeyRef security_key = NULL;
+
+    NSData *signature = nil;
+    NSInputStream *input_stream = nil;
+
+    SecGroupTransformRef group = SecTransformCreateGroupTransform();
+    SecTransformRef read_transform = NULL;
+    SecTransformRef digest_transform = NULL;
+    SecTransformRef verify_transform = NULL;
+    CFErrorRef error = NULL;
+    CFBooleanRef success = NULL;
+
+    security_key = transform_public_key(pubkeypath);
+    if (security_key == NULL) { printf("security key was null\n"); goto cleanup; }
+
+    signature = [[NSData alloc] initWithBase64EncodedString:[sig stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] options:NSDataBase64DecodingIgnoreUnknownCharacters];
+    if (signature == nil) { printf("signature was null\n"); goto cleanup; }
+
+    input_stream = [NSInputStream inputStreamWithFileAtPath:zipfilepath];
+    if (input_stream == nil) { printf("input stream was null\n"); goto cleanup; }
+
+    read_transform = SecTransformCreateReadTransformWithReadStream((__bridge CFReadStreamRef)input_stream);
+    if (read_transform == NULL) { printf("read transform was null\n"); goto cleanup; }
+
+    digest_transform = SecDigestTransformCreate(kSecDigestSHA1, CC_SHA1_DIGEST_LENGTH, NULL);
+    if (digest_transform == NULL) { printf("digest transform was null\n"); goto cleanup; }
+
+    verify_transform = SecVerifyTransformCreate(security_key, (__bridge CFDataRef)signature, NULL);
+    if (verify_transform == NULL) { printf("verify transform was null\n"); goto cleanup; }
+
+    SecTransformConnectTransforms(read_transform, kSecTransformOutputAttributeName, digest_transform, kSecTransformInputAttributeName, group, &error);
+    if (error) { printf("read transform failed to connect to digest transform:\n"); CFShow(error); goto cleanup; }
+
+    SecTransformConnectTransforms(digest_transform, kSecTransformOutputAttributeName, verify_transform, kSecTransformInputAttributeName, group, &error);
+    if (error) { printf("digest transform failed to connect to verify transform:\n"); CFShow(error); goto cleanup; }
+
+    success = SecTransformExecute(group, &error);
+    if (error) { printf("executing transform failed: %ld\n", CFErrorGetCode(error)); CFShow(error); goto cleanup; }
+
+    verified = CFBooleanGetValue(success);
+
+cleanup:
+
+    if (group) CFRelease(group);
+    if (security_key) CFRelease(security_key);
+    if (read_transform) CFRelease(read_transform);
+    if (digest_transform) CFRelease(digest_transform);
+    if (verify_transform) CFRelease(verify_transform);
+    if (success) CFRelease(success);
+    if (error) CFRelease(error);
+
+    return verified;
+}
+
+
+
 static NSString* updates_url = @"https://api.github.com/repos/sdegutis/hydra/releases";
 
 /// updates.getversions(fn(versions))