diff options
| author | Justus Winter <justus@sequoia-pgp.org> | 2020-12-14 16:37:33 +0100 |
|---|---|---|
| committer | Justus Winter <justus@sequoia-pgp.org> | 2020-12-14 16:37:33 +0100 |
| commit | 8c50ba96a5434aeefbf44e0d034072dfc6669521 (patch) | |
| tree | 7c6a5d31c22dac12fa97c4545de873a3605c7b2e /openpgp/src/cert/builder.rs | |
| parent | 7e57122f0bd6db27c6e2f0c7deac1333256e5146 (diff) | |
openpgp: Change general purpose keys to have a signing subkey.
- Certificates with a primary key that is not signing capable, and a
subkey that is, are strictly more secure than ones that combine
signing and certification capabilities in the primary key.
- If the owner of a certificate with a signing-capable primary key
can be tricked into creating a binary signature over carefully
chosen attacker-controlled data, this signature can be repurposed
to bind arbitrary attacker-controlled components to the
certificate using a chosen-prefix collision attack on the hash
function (see e.g. "SHA-1 is a Shambles" for a similar attack).
- Having a separate signing-subkey mitigates the attack, because
signatures by the signing subkey cannot bind components to the
certificate.
Diffstat (limited to 'openpgp/src/cert/builder.rs')
| -rw-r--r-- | openpgp/src/cert/builder.rs | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/openpgp/src/cert/builder.rs b/openpgp/src/cert/builder.rs index 15d0a350..627bd4f0 100644 --- a/openpgp/src/cert/builder.rs +++ b/openpgp/src/cert/builder.rs @@ -233,9 +233,10 @@ impl CertBuilder<'_> { /// Generates a general-purpose certificate. /// /// The returned builder is set to generate a certificate with a - /// certification- and signature-capable primary key, and an - /// encryption-capable subkey. The subkey is marked as being - /// appropriate for both data in transit and data at rest. + /// certification-capable primary key, a signing-capable subkye, + /// and an encryption-capable subkey. The encryption subkey is + /// marked as being appropriate for both data in transit and data + /// at rest. /// /// # Examples /// @@ -248,7 +249,7 @@ impl CertBuilder<'_> { /// CertBuilder::general_purpose(None, /// Some("Alice Lovelace <alice@example.org>")) /// .generate()?; - /// # assert_eq!(cert.keys().count(), 2); + /// # assert_eq!(cert.keys().count(), 3); /// # assert_eq!(cert.userids().count(), 1); /// # Ok(()) /// # } @@ -262,14 +263,19 @@ impl CertBuilder<'_> { ciphersuite: ciphersuite.into().unwrap_or(Default::default()), primary: KeyBlueprint { flags: KeyFlags::empty() - .set_certification() - .set_signing(), + .set_certification(), validity: Some(time::Duration::new(3 * 52 * 7 * 24 * 60 * 60, 0)), ciphersuite: None, }, subkeys: vec![ KeyBlueprint { flags: KeyFlags::empty() + .set_signing(), + validity: None, + ciphersuite: None, + }, + KeyBlueprint { + flags: KeyFlags::empty() .set_transport_encryption() .set_storage_encryption(), validity: None, |