Add support to Transit, keysutil for XChaCha20-Poly1305 #36
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This adds support for XChaCha20-Poly1305, a variant of ChaCha20-Poly1305 with double the nonce size (12->24). Due to the construction of most AEAD cipher modes which lack a synthetic IV (mostly this and GCM), nonce reuse becomes problematic. A small default nonce size (96 bits) results in only 96/2 = 2^48 message encryptions before reuse becomes likely due to the birthday paradox. As a result, NIST has mandated 2^32 as the upper limit on AES-GCM encryption operations in FIPS to keep the threshold sufficiently small. This necessitates key rotation when the limit is reached. By using a larger nonce (24-bytes), key rotation can be avoided. Resolves: openbao#35 Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
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This adds support for XChaCha20-Poly1305, a variant of ChaCha20-Poly1305 with double the nonce size (12->24). Due to the construction of most AEAD cipher modes which lack a synthetic IV (mostly this and GCM), nonce reuse becomes problematic. A small default nonce size (96 bits) results in only 96/2 = 2^48 message encryptions before reuse becomes likely due to the birthday paradox. As a result, NIST has mandated 2^32 as the upper limit on AES-GCM encryption operations in FIPS to keep the threshold sufficiently small. This necessitates key rotation when the limit is reached.
By using a larger nonce (24-bytes), key rotation can be avoided.
Resolves: #35
cc: @DemiMarie
This can be tested by rebasing on top of my
prune-extra-pluginsbranch (to fix the build & most tests) and runninggo test github.com/openbao/openbao/builtin/logical/transitto avoid hitting issues discussed on matrix.