I was testing PKCS#1 v1.5 signature verification as implemented in cryptonite and noticed it rejects valid signature whose encoded message uses an implicit NULL parameter for hash algorithm (where digestAlgorithm ANS.1 der encoded does not have NULL parameter TLV; that is, 0x0500 is absent).
According to RFC4055, pg.5 and RFC8017, pg. 64, for SHA-1, and the SHA-2 family, the algorithm parameter has to be NULL and both explicit NULL parameter and implicit NULL parameter (ie, absent NULL parameter) are considered to be legal and equivalent. However, this implementation does not accept a valid PKCS input with implicit NULL parameter.
N = 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
|N| = 256 bytes
d = 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
e = 3
H = SHA-256 (OID = 0x608648016503040201)
m = "hello world!"
I = 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
S = 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
I was testing PKCS#1 v1.5 signature verification as implemented in cryptonite and noticed it rejects valid signature whose encoded message uses an implicit NULL parameter for hash algorithm (where digestAlgorithm ANS.1 der encoded does not have NULL parameter TLV; that is,
0x0500is absent). According to RFC4055, pg.5 and RFC8017, pg. 64, for SHA-1, and the SHA-2 family, the algorithm parameter has to be NULL and both explicit NULL parameter and implicit NULL parameter (ie, absent NULL parameter) are considered to be legal and equivalent. However, this implementation does not accept a valid PKCS input with implicit NULL parameter.Reference notation and concrete values
N: public modulus|N|: length of public modulusd: private exponente: public exponentH: hash functionm: messageI: to-be-singed RSA PKCS#1 v1.5 signature scheme input structureS: signature value obtained byI^d mod N