pico-hsm/doc/sign-verify.md

Sign and verify

Pico HSM supports in place signature of arbitrary data. It supports the following algorithms:

• RSA-PKCS
• SHA1-RSA-PKCS
• SHA256-RSA-PKCS
• SHA224-RSA-PKCS
• SHA384-RSA-PKCS
• SHA512-RSA-PKCS

First, we generate the data:

$ echo "This is a test string. Be safe, be secure." > data

Obtain the public key and convert it to PEM format:

$ pkcs11-tool --read-object --pin 648219 --id 1 --type pubkey > 1.der
$ openssl rsa -inform DER -outform PEM -in 1.der -pubin > 1.pub

At this moment, you are able to verify with the public key in 1.pub. The signature is computed inside the Pico HSM with the private key. It never leaves the device.

RSA-PKCS

This algorithm is used to sign raw data.

To sign the data:

$ cat data | pkcs11-tool --id 1 --sign --pin 648219 --mechanism RSA-PKCS > data.sig

To verify the signature:

$ openssl rsautl -verify -inkey 1.pub -in data.sig -pubin
This is a test string. Be safe, be secure.

SHA1-RSA-PKCS

This algorithm is used to sign digests. It supports SHA1, SHA224, SHA256, SHA384 and SHA512.

To sign the data:

$ cat data | pkcs11-tool --id 1 --sign --pin 648219 --mechanism SHA256-RSA-PKCS > data.sig

To verify the signature:

$ openssl rsautl -verify -inkey 1.pub -in data.sig -pubin|openssl asn1parse -inform DER 
    0:d=0  hl=2 l=  49 cons: SEQUENCE          
    2:d=1  hl=2 l=  13 cons: SEQUENCE          
    4:d=2  hl=2 l=   9 prim: OBJECT            :sha256
   15:d=2  hl=2 l=   0 prim: NULL              
   17:d=1  hl=2 l=  32 prim: OCTET STRING      [HEX DUMP]:6A0DFAFE96E1835B593812BFCDDED93AB52F67CF8B8ABB6C77A05C6DA5CAA960
$ sha256sum 6a0dfafe96e1835b593812bfcdded93ab52f67cf8b8abb6c77a05c6da5caa960  data

The signature is valid if both hashes are equal.

RSA-X-509

This algorithm is used for signing raw data. In this algorithm, the data must be padded with a length equal to the size of private key (128, 256, 512 bytes for RSA-1024, RSA-2048 and RSA-4096, respectively).

First, we pad the data. The original data file occupies 29 bytes. Thus, for a 2048 bits key, a padding of 227 bytes is needed:

$ cp data data_pad
$ dd if=/dev/zero bs=1 count=227 >> data_pad

To sign the data:

$ cat data_pad | pkcs11-tool --id 4 --sign --pin 648219 --mechanism RSA-X-509 > data.sig

To verify the data:

$ openssl rsautl -verify -inkey 4.pub -in data.sig -pubin -raw
This is a test string. Be safe, be secure.