27591 2014-12-12 02:56:46 +0000 Must the reflected "publicExponent" for generated RSA keys exactly match input? 2016-05-24 00:04:34 +0000 1 1 1 Unclassified Web Cryptography Web Cryptography API Document unspecified PC Linux RESOLVED MOVED P2 normal --- 1 ericroman sleevi ietf public-webcrypto watsonm oldest_to_newest 116193 0 ericroman 2014-12-12 02:56:46 +0000 The Generate key operation for RSASSA-PKCS1-v1_5 says: 7. Set the publicExponent attribute of algorithm to equal the publicExponent attribute of normalizedAlgorithm. I am unsure if this implies that publicExponent is a normalized BigInteger or not. The section on BigIntegers says that "Values read from the API SHALL have minimal typed array length" Does this assignment count as such a "read"? Example: If generateKey() is called with publicExponent = 00000000000000010001, an implementation should be able to reflect key.algorithm.publicExponent as 010001 and not preserve the zeros. 116195 1 ericroman 2014-12-12 03:01:16 +0000 By comparison, the importKey operation is a bit clearer on this as it says: "Set the publicExponent attribute of algorithm to the BigInteger representation of the RSA public exponent." (Keys imported from format="jwk" can't have leading zeros in the public exponent, however those from format="pkcs8" or "spki" could I believe) 125355 2 ietf 2016-03-04 03:29:31 +0000 I have do not know what is meant by the phrase "read from the API". If I was going to guess, I would say that it applies to any value returned to the user from the API. Thus in step 7 there would be an implied normalization of the BigInteger value to remove any leading zero bytes. Yes you are correct that the exponent could in theory have a leading zero value if this is needed to make sure that it does not look like a negative number as ASN.1 only encodes signed numbers. I would assume that this leading byte would be stripped in this case as well. 126521 3 watsonm 2016-05-24 00:04:34 +0000 Moved to https://github.com/w3c/webcrypto/issues/61