Cryptographic Token Interface Standard

PKCS#11

PKCS #1 RSA PSS

The PKCS #1 RSA PSS mechanism, denoted CKM_RSA_PKCS_PSS, is a mechanism based on the RSA public-key cryptosystem and the PSS block format defined in PKCS #1. It supports single-part signature generation and verification without message recovery. This mechanism corresponds only to the part of PKCS #1 that involves block formatting and RSA, given a hash value; it does not compute a hash value on the message to be signed.

It has a parameter, a CK_RSA_PKCS_PSS_PARAMS structure. The sLen field must be less than or equal to k* -2-hLen and hLen is the length of the input to the C_Sign or C_Verify function. k* is the length in bytes of the RSA modulus, except if the length in bits of the RSA modulus is one more than a multiple of 8, in which case k* is one less than the length in bytes of the RSA modulus.

Constraints on key types and the length of the data are summarized in the following table. In the table, k is the length in bytes of the RSA. 




 Table 41, PKCS #1 RSA PSS: Key And Data Length   
Function Key type 

Input length

 

Output length

   


C_Sign1 RSA private key 

hLen 

 

k 

   


C_Verify1 RSA public key 

hLen, k 

 

N/A

  

 



1 Single-part operations only.


2 Data length, signature length.


For this mechanism, the ulMinKeySize and ulMaxKeySize  fields of the CK_MECHANISM_INFO structure specify the supported range of RSA modulus sizes, in bits.


 
 



RSA Security Inc. Public-Key Cryptography Standards - 
PKCS#11 - v220