Is using the SHA-1 algorithm insecure for hashing the ephemeral ECDH public key in the signed_params
structure?
There are some worrying articles about using SHA-1:
My server sends the following Server Key Exchange message for TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (0xc02b).
TLSv1.2 Record Layer: Handshake Protocol: Server Key Exchange
Content Type: Handshake (22)
Version: TLS 1.2 (0x0303)
Length: 148
Handshake Protocol: Server Key Exchange
Handshake Type: Server Key Exchange (12)
Length: 144
EC Diffie-Hellman Server Params
Curve Type: named_curve (0x03)
Named Curve: secp256r1 (0x0017)
Pubkey Length: 65
Pubkey: 0...
Signature Hash Algorithm: 0x0203
Signature Hash Algorithm Hash: SHA1 (2) <<<=============
Signature Hash Algorithm Signature: ECDSA (3)
Signature Length: 71
Signature: 3...
Should I change it to use SHA256 like server certificate? Or is it safe since it is used to sign the ephemeral key?