Re: [openpgp] The combinatorial complexity of OpenPGPv4

I feel like perhaps this type of exhaustive testing is neither necessary
nor expected, and that a few end-to-end tests designed to exercise edge
cases could be combined with more exhaustive unit tests to achieve
reasonable results.  Protocol modularity is not evil.

--Falcon Darkstar Momot
--Shadytel

On 13/03/2015 17:04, David Leon Gil wrote:
> Suppose that I want to test whether an implementation
> handles all OpenPGPv4 signed-then-encrypted messages
> correctly. How many test cases do I need?
>
> Let's suppose, first, that I prove that handling of
> PTag formats is independent of the rest of the code.
>
> In that case, the packet composition is either:
>
>     PKESK
>     SEIPD
>       COMPRESSED
>       LITERAL
>       SIGNATURE
>     MDC
>
> Or:
>
>     PKESK
>     SE
>       COMPRESSED
>       LITERAL
>       SIGNATURE
>
> How many different ways can I compose this message?
>
> 15 * 24 * 4 * 3 * 35
> - 15: PKESK
>   - RSA-ES
>   - RSA-E
>   - ELG-E
>   - 12 ECDH combinations:
>     - 3 curves
>       - P-256
>       - P-384
>       - P-521
>     - 4 KDF hash algorithms
>       - SHA2-224
>       - SHA2-256
>       - SHA2-384
>       - SHA2-512
> - 24: SEIPD
>   - 2 choices of packet type
>     - SE
>     - SEIPD
>   - 12 encryption algorithms
>     - Plaintext (prohibited)
>     - IDEA
>     - TripleDES
>     - CAST5
>     - Blowfish
>     - AES128
>     - AES192
>     - AES256
>     - Twofish
>     - CAMELLIA128
>     - CAMELLIA192
>     - CAMELLIA256
> - 4: Compressed
>   - Uncompressed
>   - ZLIB
>   - DEFLATE
>   - BZIP2
> - 3: Literal
>   - UTF-8
>   - Binary
>   - Local
> - 35: Signature
>  - 5 asymmetric algorithms:
>    - RSA-ES
>    - RSA-S
>    - DSA
>    - ECDSA
>    - ED25519 (GnuPG)
>  - 7 hash algorithms:
>    - MD5
>    - SHA-1
>    - RIPEMD160
>    - SHA2-224
>    - SHA2-256
>    - SHA2-384
>    - SHA2-512
>
> Or: 151,200 test cases. For the simplest message anyone
> wants to send.
>
> Not including any of the details of signature subpackets,
> or unusual (but valid) variants of PKESKs etc. I previously
> calculated that number, but it is so absurdly huge I won't
> bother.
>
> - David
>
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