PKCS#7 signature parsing failure caused by an invalid ASN.1 structure in the eContent field

[ebourg]

I'm trying to parse an Authenticode signature which has an invalid ASN.1 structure in the eContent field. The structure contains a BIT STRING encoded as 03 01 01, which is invalid since it's impossible to have 0 bits and a 1 bit padding:

ASN1BitString detects it and throws an IllegalArgumentException "invalid pad bits detected":

Exception in thread "main" org.bouncycastle.cms.CMSException: IOException reading content.
	at org.bouncycastle.cms.CMSUtils.readContentInfo(CMSUtils.java:186)
	at org.bouncycastle.cms.CMSSignedData.<init>(CMSSignedData.java:95)
	at net.jsign.BrokenSignedDataTest.main(BrokenSignedDataTest.java:15)
Caused by: org.bouncycastle.asn1.ASN1Exception: invalid pad bits detected
	at org.bouncycastle.asn1.ASN1InputStream.createPrimitiveDERObject(ASN1InputStream.java:588)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:171)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:345)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:356)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:345)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:345)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.readTaggedObjectDL(ASN1InputStream.java:339)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:178)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:356)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:356)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:345)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.readTaggedObjectDL(ASN1InputStream.java:339)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:178)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:356)
	at org.bouncycastle.asn1.ASN1InputStream.readVector(ASN1InputStream.java:368)
	at org.bouncycastle.asn1.ASN1InputStream.buildObject(ASN1InputStream.java:210)
	at org.bouncycastle.asn1.ASN1InputStream.readObject(ASN1InputStream.java:244)
	at org.bouncycastle.asn1.ASN1Primitive.fromByteArray(ASN1Primitive.java:47)
	at org.bouncycastle.cms.CMSUtils.readContentInfo(CMSUtils.java:176)
	... 2 more
Caused by: java.lang.IllegalArgumentException: invalid pad bits detected
	at org.bouncycastle.asn1.ASN1BitString.createPrimitive(ASN1BitString.java:513)
	at org.bouncycastle.asn1.ASN1InputStream.createPrimitiveDERObject(ASN1InputStream.java:531)
	... 40 more

Would it be possible to have an optional "lazy" parsing mode of the eContent field to keep it as an opaque OCTET STRING instead of parsing its structure?