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author | Richard van der Hoff <richard@matrix.org> | 2019-11-08 14:09:12 +0000 |
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committer | Richard van der Hoff <richard@matrix.org> | 2019-11-08 14:09:12 +0000 |
commit | 04690658558fd84cd635ee8dd34b163cccfcf420 (patch) | |
tree | 6a00e91781d2efe8dfb112fa6ac64ee12b424986 /docs/signing.md | |
parent | baaf00266314487f831726d7cb34ee2649f99e22 (diff) | |
parent | 5bcfeaffe3d465a16e472e98c99d6970e8dc80d8 (diff) |
Merge branch 'rav/fix_math' into 'master'
Fix some math blocks
See merge request matrix-org/olm!10
Diffstat (limited to 'docs/signing.md')
-rw-r--r-- | docs/signing.md | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/docs/signing.md b/docs/signing.md index fcc5342..58a2b5e 100644 --- a/docs/signing.md +++ b/docs/signing.md @@ -49,13 +49,14 @@ compromised keys, and sends a pre-key message using a shared secret $`S`$, where: ```math -S = ECDH\left(I_A,\,E_E\right)\;\parallel\;ECDH\left(E_A,\,I_B\right)\; - \parallel\;ECDH\left(E_A,\,E_E\right) +S = ECDH\left(I_A,E_E\right)\;\parallel\; + ECDH\left(E_A,I_B\right)\;\parallel\; + ECDH\left(E_A,E_E\right) ``` Eve cannot decrypt the message because she does not have the private parts of either $`E_A`$ nor $`I_B`$, so cannot calculate -$`ECDH\left(E_A,\,I_B\right)`$. However, suppose she later compromises +$`ECDH\left(E_A,I_B\right)`$. However, suppose she later compromises Bob's identity key $`I_B`$. This would give her the ability to decrypt any pre-key messages sent to Bob using the compromised one-time keys, and is thus a problematic loss of forward secrecy. If Bob signs his keys with his Ed25519 @@ -66,8 +67,9 @@ On the other hand, signing the one-time keys leads to a reduction in deniability. Recall that the shared secret is calculated as follows: ```math -S = ECDH\left(I_A,\,E_B\right)\;\parallel\;ECDH\left(E_A,\,I_B\right)\; - \parallel\;ECDH\left(E_A,\,E_B\right) +S = ECDH\left(I_A,E_B\right)\;\parallel\; + ECDH\left(E_A,I_B\right)\;\parallel\; + ECDH\left(E_A,E_B\right) ``` If keys are unsigned, a forger can make up values of $`E_A`$ and |