JDK-8238448 : RSASSA-PSS signature verification fail when using certain odd key sizes
  • Type: Bug
  • Component: security-libs
  • Sub-Component: java.security
  • Affected Version: 8u251,openjdk8u252,11.0.1
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2020-02-04
  • Updated: 2020-11-30
  • Resolved: 2020-02-12
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JDK 11 JDK 15 JDK 8 Other
11.0.9Fixed 15 b10Fixed 8u270Fixed openjdk8u282Fixed
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Description
For certain odd key sizes (N = 8x+1, i.e. multiples of 8 plus 1), the encoded message for PSS processing is one-byte shorter than the key size. For example, per RFC 8017, PKCS#1 v2.2, if the key size is 1025 bits (rounded up to 129 bytes), the length of encoded message should be 128 byte. However, the current impl of SunRsaSign provider uses the key length which has been rounded up in bytes as the length of the encoded message instead of calculating from the key length in bits. This causes the signature verification to fail unexpectedly as the verification is being performed on wrong range of bytes.
Comments
Fix Request (8u) I would like to backport this patch to OpenJDK8u for parity with Oracle 8u270. The original patch does not apply cleanly, but conflicts are minor and has been reviewed by phh.
28-10-2020

8u code review: https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-October/012812.html
20-10-2020

Fix request (11u) -- will label after testing completed. I would like to downport this for parity with 11.0.9-oracle. Applies clean.
03-07-2020

URL: https://hg.openjdk.java.net/jdk/jdk/rev/0469ead7113c User: valeriep Date: 2020-02-12 02:45:50 +0000
12-02-2020

src/java.base/share/classes/sun/security/rsa/RSAPSSSignature.java, insides its decodeSignature() method: Instead of setting emLen to em.length, it should be calculated from the emBits value, i.e. (emBits + 7) >> 3;
04-02-2020

Note that the generated signature bytes are correct. Just the verification code needs to be fixed.
04-02-2020