General block cipher CBC with PKCS padding

Cipher <NAME> has a cipher-block chaining mode with PKCS padding, "<NAME>-CBC with PKCS padding", denoted CKM_<NAME>_CBC_PAD. It is a mechanism for single- and multiple-part encryption and decryption; key wrapping; and key unwrapping with <NAME>. All ciphertext is padded with PKCS padding.

It has a parameter, an initialization vector for cipher block chaining mode. The initialization vector has the same length as <NAME>'s blocksize.

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 99, General Block Cipher CBC with PKCS Padding: Key And Data Length
Function Key type Input length Output length

C_Encrypt <NAME> any input length rounded up to multiple of blocksize

C_Decrypt <NAME> multiple of blocksize between 1 and blocksize bytes shorter than input length

C_WrapKey <NAME> any input length rounded up to multiple of blocksize

C_UnwrapKey <NAME> multiple of blocksize between 1 and blocksize bytes shorter than input length

For this mechanism, the ulMinKeySize and ulMaxKeySize fields of the CK_MECHANISM_INFO structure may or may not be used. The CAST, CAST3, and CAST128 (CAST5) ciphers have variable key sizes, and so for these ciphers, the ulMinKeySize and ulMaxKeySize fields of the CK_MECHANISM_INFO structure specify the supported range of key sizes, in bytes. For the DES, DES3 (triple-DES), IDEA, and CDMF ciphers, these fields are not used.

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

Function	Key type	Input length	Output length
C_Encrypt	<NAME>	any	input length rounded up to multiple of blocksize
C_Decrypt	<NAME>	multiple of blocksize	between 1 and blocksize bytes shorter than input length
C_WrapKey	<NAME>	any	input length rounded up to multiple of blocksize
C_UnwrapKey	<NAME>	multiple of blocksize	between 1 and blocksize bytes shorter than input length