according to Tor's specifications, the fingerprint is

A fingerprint (a HASH_LEN-byte of asn1 encoded public key, encoded in hex, with a single space after every 4 characters) for this router's identity key. A descriptor is considered invalid (and MUST be rejected) if the fingerprint line does not match the public key.

But I can't manage to recalculate it.

If I correctly understand, the fingerprint is 20 bytes of HEX value of the 'authority_signing_key', right ?


1 Answer 1


Fingerprint is the SHA1 digest of Base64 decoded public key. For example, if RSA_PUB is the RSA public key of the authority_certificate than to calculate the Fingerprint:

> echo RSA_PUB | base64 -d | openssl sha1

Thanks Richard Horrocks, reminded me on Base64.

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