HTTP digest authentication no longer works in our app since iOS 10 due to wrong nonce-count in Authorization: Digest header generated by NSURLSession.
The same code works in iOS 9, but fail to auth in iOS 10
- Create a POST request with NSURLRequest
- Fire it with NSURLSession
- Handle NSURLAuthenticationMethodHTTPDigest in
urlSession(_:didReceive:completionHandler:)
delegate - The server responds with a 401 and qop="auth" string as expected
The app requests again with the Authorization: Digest header set.
According to RFC2617:
nonce-count
This MUST be specified if a qop directive is sent (see above), and MUST NOT be specified if the server did not send a qop directive in the WWW-Authenticate header field. The nc-value is the hexadecimal count of the number of requests (including the current request) that the client has sent with the nonce value in this request. For example, in the first request sent in response to a given nonce value, the client sends "nc=00000001". The purpose of this directive is to allow the server to detect request replays by maintaining its own copy of this count - if the same nc-value is seen twice, then the request is a replay. See the description below of the construction of the request-digest value.
However, the nonce-count start at "nc=00000002" even for the first request in iOS 10, which cause the server to reject it.
Expect server response 200 OK
iOS 9 & Before:
POST /Tunnel/Message.aspx HTTP/1.1
Host: 172.18.70.12:3454
Accept: */*
Content-Type: application/xml
User-Agent: iViewer/1 CFNetwork/758.5.3 Darwin/15.6.0
Connection: keep-alive
Cookie:
AuthType: digest
Accept-Language: zh-tw
Content-Length: 69
Accept-Encoding: gzip, deflate
Authorization: Digest username="admin", realm="ND8422P",
nonce="cc17a78cdd96d54e012eadefe7d13d82", uri="/Tunnel/Message.aspx",
response="51587db4bcf6eeece68c4ec21108f170",
cnonce="47b8df8a980f280038834b7817250e90", nc=00000001, qop="auth"
<?xml version="1.0" encoding="UTF-8"?><GetServerInfo></GetServerInfo>
HTTP/1.0 200 OK
Cache-Control: no-store, no-cache, must-revalidate
Cache-Control: post-check=0, pre-check=0
Pragma: no-cache
Content-Type: text/xml
Content-Length: 1127
iOS 10:
POST /Tunnel/Message.aspx HTTP/1.1
Host: 172.18.70.12:3454
Accept: */*
Content-Type: application/xml
User-Agent: iViewer/1 CFNetwork/808.0.2 Darwin/16.0.0
Connection: keep-alive
Cookie:
AuthType: digest
Accept-Language: en-us
Content-Length: 69
Accept-Encoding: gzip, deflate
Authorization: Digest username="admin", realm="ND8422P",
nonce="4b8bf8549da0c3010f031472e95f387d", uri="/Tunnel/Message.aspx",
response="91cf44bc0aadf2f743164d03b5c708c7",
cnonce="b5f9e6c69e19c1b396298d68f2aefe7e", nc=00000002, qop="auth"
<?xml version="1.0" encoding="UTF-8"?><GetServerInfo></GetServerInfo>
HTTP/1.0 401 Unauthorized
WWW-Authenticate: Digest qop="auth", realm="ND8422P", nonce="8e8b0538bb08876ac4d8203f1d14e9ac"
CSeq: 0
Is anyone facing the same issue?
The only related post I could find is: Apple Developer Forums : Problem of the digest authentication, but no further information.
How do you fix it or get workaround on client app side without asking server side to ignore the wrong nonce-count?
Thanks.