Cryptographic Token Interface Standard

PKCS#11

RC2-CBC with PKCS padding

RC2-CBC with PKCS padding, denoted CKM_RC2_CBC_PAD, is a mechanism for single- and multiple-part encryption and decryption; key wrapping; and key unwrapping, based on RSA Security's block cipher RC2; cipher-block chaining mode as defined in FIPS PUB 81; and the block cipher padding method detailed in PKCS #7.

It has a parameter, a CK_RC2_CBC_PARAMS structure, where the first field indicates the effective number of bits in the RC2 search space, and the next field is the initialization vector.

The PKCS padding in this mechanism allows the length of the plaintext value to be recovered from the ciphertext value. Therefore, when unwrapping keys with this mechanism, no value should be specified for the CKA_VALUE_LEN attribute.

In addition to being able to wrap and unwrap secret keys, this mechanism can wrap and unwrap RSA, Diffie-Hellman, X9.42 Diffie-Hellman, EC (also related to ECDSA) and DSA private keys (see Section 12.6 for details). The entries in the table below for data length constraints when wrapping and unwrapping keys do not apply to wrapping and unwrapping private keys.

Constraints on key types and the length of data are summarized in the following table: 




 Table 74, RC2-CBC with PKCS Padding: Key And Data Length   
Function Key type 

Input length

 

Output length

   


C_Encrypt RC2 

any

 

input length rounded up to multiple of 8

   


C_Decrypt RC2 

multiple of 8

 

between 1 and 8 bytes shorter than input length

   


C_WrapKey RC2 

any

 

input length rounded up to multiple of 8

   


C_UnwrapKey RC2 

multiple of 8

 

between 1 and 8 bytes shorter than input length

  

 



For this mechanism, the ulMinKeySize and ulMaxKeySize  fields of the CK_MECHANISM_INFO structure specify the supported range of RC2 effective number of bits.


 
 



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