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I can't find anywhere details on how to fingerprint a public RSA key in PKCS1 format.

There are a lot of examples on the internet on how to fingerprint an RSA public key in openssh format using ssh-keygen -lf id_rsa.pub but in my application I am receiving a public key in PCKS1 format and even if I can remove the -----BEGIN RSA PUBLIC KEY----- and -----END RSA PUBLIC KEY----- parts, base64 decode the contents and hash the resulting data, I can't find an example on how to verify this hash/fingerprint using openssl or ssh-keygen.

What am I doing wrong?

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closed as off-topic by e-sushi Jul 5 '17 at 2:05

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Programming questions are off-topic even if you are writing or debugging cryptographic code. Unless your question is specifically about how the cryptographic algorithm or protocol works, you should look into asking on Stack Overflow instead." – e-sushi
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ For what (fingerprint) standard would that be? I've seen SHA-1 over the modulus (as unsigned, big endian value) being used in PKCS#11. PKCS#1 itself does not contain a standard for fingerprinting keys AFAIK. $\endgroup$ – Maarten Bodewes Oct 19 '15 at 10:06
  • $\begingroup$ So how does one fingerprint a PKCS#1 key then? I've found this github.com/arekinath/node-sshpk and tried to feed it a PKCS#1 key and reqeust a fingerprint - I was offered the fingerprint of the openssh version. $\endgroup$ – s3v3n Oct 19 '15 at 11:07
  • $\begingroup$ Yes, that one encodes the key internally into SSH format and then fingerprints the key. $\endgroup$ – Maarten Bodewes Oct 19 '15 at 11:18