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| author | Sybren A. Stüvel <sybren@stuvel.eu> | 2020-11-15 15:48:27 +0100 |
|---|---|---|
| committer | Sybren A. Stüvel <sybren@stuvel.eu> | 2020-11-15 15:50:01 +0100 |
| commit | f878c374086e672e7806fdd18401ec6b71cfa960 (patch) | |
| tree | ccb4393399887e7e2ac338a735b1db90f1a65757 /rsa | |
| parent | dae8ce0d85478e16f2368b2341632775313d41ed (diff) | |
| download | rsa-git-f878c374086e672e7806fdd18401ec6b71cfa960.tar.gz | |
Fix #164: Add padding length check as described by PKCS#1 v1.5
According to PKCS#1 v1.5, the padding should be at least 8 bytes long.
See https://tools.ietf.org/html/rfc8017#section-7.2.2 step 3 for more info.
Diffstat (limited to 'rsa')
| -rw-r--r-- | rsa/pkcs1.py | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/rsa/pkcs1.py b/rsa/pkcs1.py index 19e24c7..8a85b1c 100644 --- a/rsa/pkcs1.py +++ b/rsa/pkcs1.py @@ -262,7 +262,12 @@ def decrypt(crypto: bytes, priv_key: key.PrivateKey) -> bytes: sep_idx = cleartext.index(b'\x00', 2) except ValueError: sep_idx = -1 - sep_idx_bad = sep_idx < 0 + # sep_idx indicates the position of the `\x00` separator that separates the + # padding from the actual message. The padding should be at least 8 bytes + # long (see https://tools.ietf.org/html/rfc8017#section-7.2.2 step 3), which + # means the separator should be at least at index 10 (because of the + # `\x00\x02` marker that preceeds it). + sep_idx_bad = sep_idx < 10 anything_bad = crypto_len_bad | cleartext_marker_bad | sep_idx_bad if anything_bad: |