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Category:   OS (UNIX)  >   OpenBSD Kernel Vendors:   OpenBSD
OpenBSD ECDSA Signature Calculation Timing Flaw Lets Local Users Obtain Private DSA Keys on the Target System
SecurityTracker Alert ID:  1041147
SecurityTracker URL:
CVE Reference:   CVE-2018-0495   (Links to External Site)
Date:  Jun 20 2018
Impact:   Disclosure of authentication information
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 6.2, 6.3
Description:   A vulnerability was reported in OpenBSD. A local user can obtain private keys in certain cases.

The code that performs modular addition in calculating ECDSA signatures does not run in constant time. A local user that can conduct memory-cache side-channel attacks against ECDSA signatures can recover the DSA private key.

This vulnerability is known as "The Return of the Hidden Number Problem" (ROHNP).

The original advisory is available at:

Keegan Ryan of NCC Group reported this vulnerability.

Impact:   A local user can obtain DSA private keys on the target system.
Solution:   The vendor has issued a source code fix, available at:

The vendor advisory is available at:

Vendor URL: (Links to External Site)
Cause:   State error

Message History:   None.

 Source Message Contents

[Original Message Not Available for Viewing]

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