On Thu, Nov 26, 2015 at 07:59:22PM +0000, Matt Caswell wrote:
> On 26/11/15 19:18, Matt Loah wrote:
> > While the public key in the context of OpenSSL Elliptic Curves algorithm
> > is stored as a EC_POINT pointer... and the private key as a BIGNUM
> > pointer... which functions (or which kind of them) should be called to
> > encrypt & to decrypt a message in C/C++ ?
>
> OpenSSL only supports ECDH and ECDSA, neither of which can be used to
> perform encryption.
This is not entirely true, in sufficiently recent versions of
OpenSSL, ECDSA keys can be used with CMS to encrypt keys.
Just create an ECDSA private key and email cerficate (example
attached), and then encrypt and decrypt some data:
$ printf "%s\n" sesame |
openssl cms -binary -outform DER -aes-128-cbc -encrypt -recip cert.pem |
openssl cms -binary -inform DER -decrypt -recip cert.pem -inkey key.pem
sesame
Examining the structure we see ECDSA enveloped keys
( https://tools.ietf.org/html/rfc3278.html#section-3.1 ):
$ printf "%s\n" sesame |
openssl cms -binary -outform DER -aes-128-cbc -encrypt -recip cert.pem |
openssl asn1parse -inform DER
0:d=0 hl=4 l= 263 cons: SEQUENCE
4:d=1 hl=2 l= 9 prim: OBJECT :pkcs7-envelopedData
15:d=1 hl=3 l= 249 cons: cont [ 0 ]
18:d=2 hl=3 l= 246 cons: SEQUENCE
21:d=3 hl=2 l= 1 prim: INTEGER :02
24:d=3 hl=3 l= 178 cons: SET
27:d=4 hl=3 l= 175 cons: cont [ 1 ]
30:d=5 hl=2 l= 1 prim: INTEGER :03
33:d=5 hl=2 l= 81 cons: cont [ 0 ]
35:d=6 hl=2 l= 79 cons: cont [ 1 ]
37:d=7 hl=2 l= 9 cons: SEQUENCE
39:d=8 hl=2 l= 7 prim: OBJECT :id-ecPublicKey
48:d=7 hl=2 l= 66 prim: BIT STRING
116:d=5 hl=2 l= 24 cons: SEQUENCE
118:d=6 hl=2 l= 9 prim: OBJECT :dhSinglePass-stdDH-sha1kdf-scheme
129:d=6 hl=2 l= 11 cons: SEQUENCE
131:d=7 hl=2 l= 9 prim: OBJECT :id-aes128-wrap
142:d=5 hl=2 l= 61 cons: SEQUENCE
144:d=6 hl=2 l= 59 cons: SEQUENCE
146:d=7 hl=2 l= 31 cons: SEQUENCE
148:d=8 hl=2 l= 26 cons: SEQUENCE
150:d=9 hl=2 l= 24 cons: SET
152:d=10 hl=2 l= 22 cons: SEQUENCE
154:d=11 hl=2 l= 3 prim: OBJECT :commonName
159:d=11 hl=2 l= 15 prim: UTF8STRING :Viktor Dukhovni
176:d=8 hl=2 l= 1 prim: INTEGER :01
179:d=7 hl=2 l= 24 prim: OCTET STRING [HEX DUMP]:54480EC3C3C51599E1A058B4B8C467643E49067C9ED810C3
205:d=3 hl=2 l= 60 cons: SEQUENCE
207:d=4 hl=2 l= 9 prim: OBJECT :pkcs7-data
218:d=4 hl=2 l= 29 cons: SEQUENCE
220:d=5 hl=2 l= 9 prim: OBJECT :aes-128-cbc
231:d=5 hl=2 l= 16 prim: OCTET STRING [HEX DUMP]:D7A3A11E3A6ADE4A36050CCF7E123377
249:d=4 hl=2 l= 16 prim: cont [ 0 ]
--
Viktor.
-------------- next part --------------
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-------------- next part --------------
-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQglgUxDgdcr1IRtjix
Sy39lOQOwpriCjByKX+Lh8k+SnmhRANCAATE5mgTFdY8CrqgDR8JBGTPhHNYhcd3
8+BagQdm7Zo1Z2zVJMdgjfp+bMxHmnVq06URyIAEGgonSvVY0tIjaOgO
-----END PRIVATE KEY-----
