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pk-crypto: Use RFC6979 when signing with an ECC or DSA key.

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* guix/pk-crypto.scm (bytevector->hash-data): Add #:key-type parameter.
  Use the 'pkcs1' flag when KEY-TYPE is 'rsa', and 'rfc6979' when
  KEY-TYPE is 'ecc' or 'dsa'.
  (key-type): New procedure.
* guix/scripts/authenticate.scm (read-hash-data): Add 'key-type'
  parameter.  Pass it to 'bytevector->hash-data'.  Adjust caller
  accordingly.
* tests/pk-crypto.scm (%ecc-key-pair): New variable.
  ("key-type"): New test.
  ("sign + verify"): Pass #:key-type to 'bytevector->hash-data'.
  ("sign + verify, Ed25519"): New test.
This commit is contained in:
Ludovic Courtès 2014-03-19 21:40:10 +01:00
parent 0f4139e97e
commit 32a1eb8025
3 changed files with 65 additions and 11 deletions
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27
guix/pk-crypto.scm
View file

@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@ -39,6 +39,7 @@
canonical-sexp-list?
bytevector->hash-data
hash-data->bytevector
key-type
sign
verify
generate-key
@ -232,15 +233,31 @@ Return #f if that element does not exist, or if it's a list."
"Return an s-expression representing NUMBER."
(string->canonical-sexp (string-append "#" (number->string number 16) "#")))
(define* (bytevector->hash-data bv #:optional (hash-algo "sha256"))
(define* (bytevector->hash-data bv
#:optional
(hash-algo "sha256")
#:key (key-type 'ecc))
"Given BV, a bytevector containing a hash, return an s-expression suitable
for use as the data for 'sign'."
for use as the data for 'sign'. KEY-TYPE must be a symbol: 'dsa, 'ecc, or
'rsa."
(string->canonical-sexp
(format #f "(data (flags pkcs1) (hash \"~a\" #~a#))"
(format #f "(data (flags ~a) (hash \"~a\" #~a#))"
(case key-type
((ecc dsa) "rfc6979")
((rsa) "pkcs1")
(else (error "unknown key type" key-type)))
hash-algo
(bytevector->base16-string bv))))
(define (hash-data->bytevector data)
(define (key-type sexp)
"Return a symbol denoting the type of key representing by SEXP--e.g., 'rsa',
'ecc'--or #f if SEXP does not denote a valid key."
(case (canonical-sexp-nth-data sexp 0)
((public-key private-key)
(canonical-sexp-nth-data (canonical-sexp-nth sexp 1) 0))
(else #f)))
(define* (hash-data->bytevector data)
"Return two values: the hash value (a bytevector), and the hash algorithm (a
string) extracted from DATA, an sexp as returned by 'bytevector->hash-data'.
Return #f if DATA does not conform."

9
guix/scripts/authenticate.scm
View file

@ -39,11 +39,12 @@
(call-with-input-file file
(compose string->canonical-sexp get-string-all)))
(define (read-hash-data file)
"Read sha256 hash data from FILE and return it as a gcrypt sexp."
(define (read-hash-data file key-type)
"Read sha256 hash data from FILE and return it as a gcrypt sexp. KEY-TYPE
is a symbol representing the type of public key algo being used."
(let* ((hex (call-with-input-file file get-string-all))
(bv (base16-string->bytevector (string-trim-both hex))))
(bytevector->hash-data bv)))
(bytevector->hash-data bv #:key-type key-type)))
;;;
@ -64,7 +65,7 @@
(leave
(_ "cannot find public key for secret key '~a'~%")
key)))
(data (read-hash-data hash-file))
(data (read-hash-data hash-file (key-type public-key)))
(signature (signature-sexp data secret-key public-key)))
(display (canonical-sexp->string signature))
#t))

40
tests/pk-crypto.scm
View file

@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@ -31,7 +31,7 @@
;; Test the (guix pk-crypto) module.
(define %key-pair
;; Key pair that was generated with:
;; RSA key pair that was generated with:
;; (generate-key (string->canonical-sexp "(genkey (rsa (nbits 4:1024)))"))
;; which takes a bit of time.
"(key-data
@ -48,6 +48,20 @@
(q #00E9AD22F158060BC9AE3601DA623AFC60FFF3058795802CA92371C00097335CF9A23D7782DE353C9DBA93D7BB99E6A24A411107605E722481C5C191F80D7EB77F#)
(u #59B45B95AE01A7A7370FAFDB08FE73A4793CE37F228961B09B1B1E7DDAD9F8D3E28F5C5E8B4B067E6B8E0BBF3F690B42991A79E46108DDCDA2514323A66964DE#))))")
(define %ecc-key-pair
;; Ed25519 key pair generated with:
;; (generate-key (string->canonical-sexp "(genkey (ecdsa (curve Ed25519) (flags rfc6979 transient)))"))
"(key-data
(public-key
(ecc
(curve Ed25519)
(q #94869C1B9E69DB8DD910B7F7F4D6E56A63A964A59AE8F90F6703ACDDF6F50C81#)))
(private-key
(ecc
(curve Ed25519)
(q #94869C1B9E69DB8DD910B7F7F4D6E56A63A964A59AE8F90F6703ACDDF6F50C81#)
(d #6EFB32D0B4EC6B3237B523539F1979379B82726AAA605EB2FBA6775B2B777B78#))))")
(test-begin "pk-crypto")
(let ((sexps '("(foo bar)"
@ -148,8 +162,30 @@
(and (string=? algo "sha256")
(bytevector=? value bv))))))
(test-equal "key-type"
'(rsa ecc)
(map (compose key-type
(cut find-sexp-token <> 'public-key)
string->canonical-sexp)
(list %key-pair %ecc-key-pair)))
(test-assert "sign + verify"
(let* ((pair (string->canonical-sexp %key-pair))
(secret (find-sexp-token pair 'private-key))
(public (find-sexp-token pair 'public-key))
(data (bytevector->hash-data
(sha256 (string->utf8 "Hello, world."))
#:key-type (key-type public)))
(sig (sign data secret)))
(and (verify sig data public)
(not (verify sig
(bytevector->hash-data
(sha256 (string->utf8 "Hi!"))
#:key-type (key-type public))
public)))))
(test-assert "sign + verify, Ed25519"
(let* ((pair (string->canonical-sexp %ecc-key-pair))
(secret (find-sexp-token pair 'private-key))
(public (find-sexp-token pair 'public-key))
(data (bytevector->hash-data