Cryptographic Token Interface Standard

PKCS#11

Triple-length DES Order of Operations

Triple-length DES encryptions are carried out as specified in FIPS PUB 46-3: encrypt, decrypt, encrypt. Decryptions are carried out with the opposite three steps: decrypt, encrypt, decrypt. The mathematical representations of the encrypt and decrypt operations are as follows:

DES3-E( {K1,K2,K3}, P) = E( K3, D( K2, E( K1, P)))

DES3-D( {K1,K2,K3}, C) = D( K1, E( K2, D( K3, P)))