Skip to content
  • Matt Caswell's avatar
    Add blinding to an ECDSA signature · a3e9d5aa
    Matt Caswell authored
    
    
    Keegan Ryan (NCC Group) has demonstrated a side channel attack on an
    ECDSA signature operation. During signing the signer calculates:
    
    s:= k^-1 * (m + r * priv_key) mod order
    
    The addition operation above provides a sufficient signal for a
    flush+reload attack to derive the private key given sufficient signature
    operations.
    
    As a mitigation (based on a suggestion from Keegan) we add blinding to
    the operation so that:
    
    s := k^-1 * blind^-1 (blind * m + blind * r * priv_key) mod order
    
    Since this attack is a localhost side channel only no CVE is assigned.
    
    Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
    a3e9d5aa
To find the state of this project's repository at the time of any of these versions, check out the tags.