15.2.2 Digital Signature Algorithm (DSA)

Bigloo has rudimentary (but usually sufficient) support for DSA. While it is not possible to generate new DSA keys inside Bigloo one can sign or verify with Bigloo.

DSA keys can be read and written using read-pem (PEM).

For consistency with RSA we have named DSA keys in a similar way as the RSA keys. The public part of a DSA key can be found in the class DSA-Key while the private part is added in the Complete-DSA-Key subclass.

Bigloo Cryptography class: DSA-Key

Bigloo Cryptography class: Complete-DSA-Key

(class Dsa-Key
   p::bignum q::bignum g::bignum y::bignum)
(final-class Complete-Dsa-Key::Dsa-Key
   x::bignum)) ;; the private key

Bigloo Cryptography procedure: extract-public-dsa-key complete-key

Returns a DSA-Key without the private x.

Bigloo Cryptography procedure: dsa-sign m key

Signs the bignum m using the private dsa key key. The result are two values: r and s.

A typical call to dsa-sign is hence of the following form

(receive (r s)
  (dsa-sign secret-key hashed-msg-bignum)
  (process-signature r s))

Bigloo Cryptography procedure: dsa-verify m key r s

Verifies a signature (consisting of r and s).

DSA works very similar to RSA. Have a look at RSA’s example section.

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