Fix non-zero IV usages for AES-CFB#2012
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AES-CFB initialization vectors (IVs) were always set to be all zeros, even in cases where a random value was expected. This did not affect message body encryption or password-encrypted session keys (SKESK), where a zero IV is intentional per spec (see https://www.rfc-editor.org/rfc/rfc9580.html#section-5.13.1-4 and https://www.rfc-editor.org/rfc/rfc9580.html#section-5.3.1-5). It did affect password-encrypted keys, for which a random IV should be sampled. However, there was no security impact. This is because, while IV reuse is potentially problematic when paired with AES key reuse, that is not the case in this context (i.e. OpenPGP password-based encryption), since a reused password does not automatically produce the same AES input key, since non-legacy S2K ("string-to-key") modes also sample a random salt, meaning the derived key would change even on password reuse. (The random salt generation was performed properly.)
twiss
approved these changes
Jun 2, 2026
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(This issue was introduced in OpenPGP.js v6; previous versions are not impacted).
AES-CFB initialization vectors (IVs) were always set to be all zeros, even in cases where a random value was expected.
This did not affect message body encryption or password-encrypted session keys (SKESK), where a zero IV is intentional per spec
(see https://www.rfc-editor.org/rfc/rfc9580.html#section-5.13.1-4 and https://www.rfc-editor.org/rfc/rfc9580.html#section-5.3.1-5).
It did affect password-encrypted keys, for which a random IV should be sampled.
However, there was no security impact.
This is because, while IV reuse is potentially problematic when paired with AES key reuse, that is not the case in this context (i.e. OpenPGP password-based encryption), since a reused password does not automatically produce the same AES input key, since non-legacy S2K ("string-to-key") modes also sample a random salt, meaning the derived key would change even on password reuse. (The random salt generation was performed properly.)