What causes "Neither PUB key nor PRIV key:: nested asn1 error" when building a public key in ruby?

I've got the same problem and it had a different cause. Now guess what :)

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The damn password was wrong :( Searched 3 days for that "solution". Could have been a "Sorry dude, that's the wrong password!" instead of "nested asn1 error" imho but anyways, maybe this will help somebody.

If you are using dotenv for instance, you have to surround the value with " and have \n for newlines.

PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----\nMIICW  ... UcuUtU0eIl\n-----END RSA PRIVATE KEY-----"

A pem file is not a public key, it is a base64-encoded X509 certificate that contains, among its many fields, a public key. I don't know Ruby, or the OpenSSL ruby module, but I would look for some function that reads in PEM files and outputs an X509 certificate, then another function to extract the public key from the certificate.