Hi,

I have the following ASN.1 grammar: 

SubjectPublicKeyInfo    ::=     SEQUENCE {
       algorithm       AlgorithmIdentifier,
       subjectPublicKey        BIT STRING
}

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When I do a decode my pem file with this, the BIT STRING seems to be stored as an array (or ref to array) with 2 elements, but I cant figure out what those two elements are really containing...

Any idea ?

Thanks.

Update --- Ok I figured it out:

A BIT STRING is stored as an array with two elements.
- The first element contain the bit strings data
- The second element contain the bit string length

When encoding a bitstring, using Convert::ASN1::encode, you can specify it two ways (at least)

$asn->prepare(q<
    str BIT STRING
>)
# Method1: length is multiple of 8
$asn->encode(str => "UU");
# Method2: length is explicit
$asn->encode(str => ["UU", 12]);

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The first call will encode the bitstring "0101010101010101" (16 bits)
The second call will encode the bitstring "010101010101" (12 bits)

In reply to Convert::PEM and BIT STRING by droopycom

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